Survival and causes of death of the Bonelli's Eagle released in Navarra, North of Spain.

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Gloria Giralda, Alfonso Llamas, Itziar Almarcegui, Julia Palacios, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1971769/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The Bonelli's eagle is one of the rarest and most threatened birds of prey in Europe, which means that great efforts are being made to guarantee its conservation. One of the lines of work is the reintroduction of specimens in areas where the species has recently become extinct and those in which the factors that caused its disappearance have been corrected. The present study presents the results of one of these reintroduction projects carried out in Navarra, Northern Spain, between 2011 and 2021. Forty-seven individuals (36 born in captivity and 11 from wild nests) were released in five places close to historical territories. After those 11 years of work, the occupation of two of the historical and the creation of a new one has been achieved. 44.68 % of the birds died in the first year after their release and 19.14%, during the first month in the field. No significant differences were found associated with the sex or the origin of the specimens in survival during the first month or during the first year after release. 48 % of deaths were related to anthropogenic causes (electrocution, wind farm collision, indeterminate trauma, shooting and poisoning), while 44% were due to predation by mammals or big raptors. This last result had not been described until now and suggests that, when the causes of death of human origin are corrected, those of natural origin appear. The application of this type of actions as a conservation tool for the species is discussed. Captive GPS electrocution predation reintroduction Figures Figure 1 Figure 2 Figure 3 Introduction The Bonelli's eagle ( Aquila fasciata ) is one of the rarest birds of prey in Europe. This species shows an irregular and highly fragmented distribution throughout the southern palearctic, from the Iberian Peninsula to China, and several Indonesian islands (BirdLife International. 2022) generally occupying cliffs and mountain areas from sea level to almost 4000 m.o.s. in the Himalayas (Carrete et al. 2006 ; Carrascal and Seoane, 2009 ; Bosch et al. 2010 ; Orta et al. 2016 ; Irizi et al. 2019 ). The European population has around 1100–1200 pairs (BirdLife International, 2022), of which more than 700 are found in the Iberian Peninsula (Viada, 2021 ), so the management of the species in this region is essential to guarantee its conservation in Europe. This population suffered a great decrease in the last decades of the 20th century, even becoming extinct in certain regions, which has led to the fact that today it is classified as vulnerable in Spain (Viada, 2021 ). Among the factors that may have caused this decline are electrocution (Real et al. 2001 ; Rollan et al. 2020), direct persecution (Real et al. 2001 ; Rollan et al. 2016 ; Martínez-Abraín et al. 2009 ), the loss of quality of nesting areas (Real, 2004; Real et al. 2016 ) or the increased impact of diseases such as trichomoniasis associated with increased consumption of feral dove due to the decline of other wild prey (Santos et al. 2019 ). To try to reduce the impact of these factors, various European projects have been carried out in the mediterranean countries, mainly aimed at correcting power lines and improving the habitat for the species ( http://www.lifebonelli.org/index.php/at/life-bonelli/description-and-objectives ; https://www.aquila-a-life.org/index.php/en/aquila-a-life/the-project/description-and-goals ), but in which the release of specimens in regions where the species had recently become extinct has also been included. The reintroduction of a species is a very common practice in wildlife management (Evans et al. 2009 ; Brichieri-Colombi and Moehrenschlager, 2016 ; Badia-Boher et al. 2021), but the viability of these actions is highly variable (Brichieri-Colombi and Moehrenschlager, 2016 ), with cases of great success (Evans et al. 2009 ; Bogliani et al. 2011 ; Rueda et al. 2021 ) and others in which its effect has been null or even negative due to the introduction of pathogens (Villanúa et al. 2008 ; García et al. 2021 ), the genetic contamination (Seddon et al. 2005 ; Blanco-Agular et al. 2008; Laikre et al. 2010 ) or the negative impact on other species present in the area of release (Villanúa et al. 2006 ). The success of these releases depends on multiple factors, including the quality of the habitat (Wolf et al. 1987 ; Moehrenschlager and Lloyd 2016 ) or the origin and age of the released specimens (Badia-Boher et al. 2022 ) which, according to the IUCN/SSC (2013) criteria, must be assessed before carrying out a release. This same organization suggests that, once a reintroduction project has been completed, an analysis must be carried out to assess its real impact, as well as to detect the possible factors that may have influenced its development. In this paper we present the results of a Bonelli's Eagle reintroduction project in a region where it had disappeared as a breeder, describing the survival achieved, the causes of death detected and analyzing the factors that could influence its survival in the field. Methods Study area This study was carried out in the province of Navarre, northeastern of the Iberian Peninsula (Fig. 1 ). Despite being a relatively small region, its peculiar location between the Pyrenees, with peaks of more than 2,000 m and average rainfall close to 2,000 mm per year, and the Ebro valley, located at 300 m and average rainfall below 300 mm per year, makes Navarre have three different biogeographical regions, the Alpine, the Atlantic and the Mediterranean (Lorda et al. 2011; Martija et al. 2021 ) with a wide variety of habitats. Until the last decades of the 20th century, Navarra had up to 7 territories of Bonelli's eagle in the Mediterranean area (Fig. 1 )(Fernández, 1994 ; Torrea et al. 2021 ), constituting the northern limit of the distribution area of ​​the species in the Iberian Peninsula. Progressively, these pairs disappeared until they became extinct as breeders in 2005 (Torrea et al. 2021 ). Faced with this situation, the Government of Navarra decided to start a project to recover the species, relying on Life funds from the European Union, which included the release of specimens using the hacking technique. Five release points were selected (Fig. 1 ) that were close to the historical territories of the species, were part of the Natura 2000 Network, were free of uncorrected power lines and whose hunting management was directed by hunters favorable to the presence of this bird of prey and were willing to carry out habitat improvements and repopulation with wild rabbits to increase the availability of prey for the eagles. This filter was intended to minimize the risks of electrocution, direct persecution and lack of availability of prey, main factors causing the disappearance of the species (Real et al. 2001 ; Martínez-Abraín et al. 2009 ; Rollan et al. 2016 , 2020). Released birds Between 2011 and 2021, a total of 47 bonelli's eagle chicks were released from both captive breeding centers and wild nests (Table 1 ) using the hacking technique. Table 1 Date, place, origin and sex of the released specimens. Year Place Wild ♂ Wild ♀ Captive ♂ Captive ♀ 2011 A 0 0 1 1 2012 A 0 0 2 0 2014 A 1 2 0 0 2015 B 0 0 5 0 2016 B 2 0 3 1 2017 C 0 0 6 2 2018 D 3 0 1 1 2019 D 0 1 0 5 2020 D 1 1 2 1 2021 E 0 0 2 3 All the eagles were equipped with GPS transmitters (PTT-100, Microwave, e-obs and Ornitela 30-45g) equipped with tri-axial accelerometry, programmed to send a location every 5 minutes and placed with chest harness according to García et al. ( 2021 ). The total weight of the tag and harness never exceeded 50 g. which represents 2.2% of the weight of Bonelli's eagles in our region (see García et al. 2021 for details), thus remaining below the recommended 3% to avoid a negative effect associated with marking (Vukovich et al. 2009). This intensive monitoring allows the rapid detection of any traumatic event suffered by the specimens, which facilitates a correct identification of the causes of death (Arrondo et al. 2021 ). Statistical analysis Eagle survival was estimated with the help of Kaplan-Meier product limit estimation (Kleinbaum and Klein, 2005 ) and log-rank tests were used to test the null hypothesis of no differences based on sex or the origin (wild or captive bred)(Gortázar et al 2000 ). This analysis was run in the software PAST (Hammer et al. 2001 ) and was repeated for survival during the first month and the first year. Results With the release of specimens during the last 11 years, the occupation of 2 of the territories that disappeared at the end of the 90s and the creation of a new territory where there was no record of the reproduction of this species before has been achieved (Fig. 1 ) . Of the 47 eagles released, 21 (44.68%) died in the first year after their release and of these, 9 (19.14%), during the first month in the field. No significant differences were found associated with the origin or the sex of the specimens in survival during the first month or during the first year after release, although a certain tendency for males to survive longer than females is detected (Fig. 2 ) Regarding the causes of death, 48% had an anthropic origin (electrocution, wind farm collision, indeterminate trauma, shooting and poisoning) (Fig. 3 ), with electrocution standing out as the main cause of death. 88% of the deaths due to anthropic causes occurred more than 100 km from the release point and outside Navarra. Deaths due to predation accounted for 44%, highlighting those attributed to big raptors (Fig. 3 ) and they were located mostly (94%) within the Navarra region. Furthermore, deaths attributed to mammal’s predation (red fox or feral dog) were concentrated within two weeks of release and less than 1 km from the release point. Discussion The establishment of 3 territories in the study area after 11 years of releases can be considered a success according to the criteria of the IUCN/SSC (2013), especially considering that the maximum number recorded in the 90s for the Bonelli's eagle in the region was 5–7 pairs (Torrea et al. 2021 ). However, this positive result is also due to the rest of the actions carried out within the life projects, such as the correction of power lines, improvements in the habitat or the awareness of the hunters in Navarra, which have allowed the released birds to survive and reach to settle in the area. The first year survival of the released individuals (54.38%) is within the values ​​described for the species in different wild populations of the Iberian Peninsula (Real & Mañosa 1997 ; Arroyo et al. 1998 ; Balbontín et al. 2003 ; Soutullo et al. 2008 ) and southern France (Hernández-Matias et al. 2011), with a minimum survival of 36% (Arroyo et al. 1998 ) and a maximum of 69% (Balbontin et al. 2003), and is very similar to that recorded in previous works with the species on the island of Mallorca with specimens from captive breeding (53.33% Badia-Boher et al. 2021). Regarding the causes of death detected, our work coincides with previous studies carried out in the Iberian Peninsula in that the majority of deaths are due to causes of anthropic origin, mainly electrocution (Real et al., 2001 ; Rollan et al. 2016 , Grefa, 2020). However, our results show percentages of birds electrocuted, poisoned or shot to death that are much lower than those described in these studies. This difference is due to the great importance that predation acquires in our area, reaching 44% of casualties, while, for example, in the work of Real et al ( 2001 ) it did not reach 0.5%. The increased role of predation is due, in our opinion, not only to an increase experienced by the Golden Eagle ( Aquila chrysaetos ) (Del Moral, 2009) and the Eagle Owl ( Bubo bubo ) (Escandell and Escudero, 2020 ) main predators identified, but above all to a decrease in deaths from human causes. Throughout these 11 years, agreements have been signed with the main electricity companies present in Navarra to guarantee that electric pole designs with low risk of electrocution are used in the new lines and that the existing ones are progressively corrected in accordance with guidelines and courses implemented (Grefa, 2020) and a subsidy line has been created for the correction of power lines of small owners (Gobierno de Navarra, 2022). Because of these actions, several thousand kilometers of power lines have been corrected, making the electrocution rate in Navarra 50 times lower than that found in the south of the Peninsula (GREFA, 2020). However, the large movements that this species makes throughout the Iberian Peninsula (Real and Mañosa, 1997 ; Cadahia et al. 2009) and even the south of France (Hernandez-Matías et al. 2010) means that these correction measures lines are insufficient if they are not applied throughout the country or even at European level. When correcting the causes that led to its disappearance at the end of the 90s, those of natural origin that were hidden by the high number of electrocutions, poisonings or deaths by gunshots that occurred in those years appear. After this unexpected result, it is necessary to reassess the capacity of current habitats to house the Bonelli's eagle, taking into account the current abundance of both its prey (Carrascal and Seoane, 2009 ; Caro et al. 2011 ; Real et al. al., 2016; Martínez-Miranzo et al. 2019 ), as well as their competitors and even predators (Carrete et al. 2006 ; López-López, 2011 ; Gil Sánchez, 2018 ). Our work shows that it is possible to recover historical territories of Bonelli's eagle through the release of birds with hacking techniques, but also that many highly interrelated factors intervene in the management of the species and that require a continuous review of the criteria. The development of long-term monitoring with radio-tagged specimens will allow obtaining the necessary information to direct the management of the species. Declarations ACKNOWLEDGEMENTS We want to especially thank Sonia Moreno, Arantxa San Julián, Eduardo Primo, Alberto Lizarraga, Susana Cárcamo, Silvia Erlanz and the Environmental Guards of the Navarra’s Government who collaborated in the monitoring of the released specimens. Joseba Oroz and Silvestre Belzunegi collaborated with the design and installation of the release cages. The Government of Navarra provided the necessary permits for the release of the birds. All members of the Aquila Life project helped us in the interpretation of the results. FUNDING INFORMATION This study was supported by the Life Bonelli and Aquila Life projects. CONFLICTS OF INTEREST/ COMPETING INTEREST The authors declare no competing interests. AVAILABILITY OF DATA AND MATERIAL The datasets analyzed during the current study are available from the corresponding author on reasonable request. AUTHORS CONTRIBUTIONS G. Giralda, A. Llamas, A. Zaldua and J. Palacios elaborated and managed the projects Life Bonelli and Aquila Life. I. Almarcegi and J. Torrea performed fieldwork. A. Mateo and D. Villanúa performed necropsies and determination of causes of death. Statistical analyses were performed by A. Zufiarre. D. Villanúa wrote initial draft of the manuscript. All authors participated equally in the discussion and preparation on the final version of the manuscript. References Arrondo E, García-Alfonso M, Blas J, Cortés-Avizanda A, De la Riva M, Devault TL, Fiedler W, Flack A, Jimenez J, Lambertucci SA, Margalida A, Oliva-Vidal P, Phipps WL, Sanchez-Zapata JA, Wikelski M, Donázar JA (2021) Use of avian GPS tracking to mitigate human fatalities from bird strikes caused by large soaring birds. J Appl Ecol 58: 1411-1420 Arroyo B, Ferreiro E, Garza V (1998) Causas de la regresión del Águila Perdicera Hieraaetus fasciatus en España Central. In: Meyburg BU, Chancellor RD, Ferrero JJ (ed) Holarctic Birds of Prey. Badajoz: ADENEX-WWGBP. pp 291–304. Badia-Boher JA, Hernández-Matías A, Viada C, Real J (2022) Raptor reintroductions: Cost-effective alternatives to captive breeding. Anim Conserv 25: 170-181 Balbontín J, Penteriani V, Ferrer M (2003) Variations in the age of mates as an early signal of changes in population trends? The case of Bonelli’s Eagle in Andalusia. Biol Conserv 109: 417–423. BirdLife International (2022) Species factsheet: Aquila fasciata . Downloaded from http://www.birdlife.org on 01/06/2022. Bogliani G, Viterbi R, Nicolino M (2011). Habitat use by a reintroduced population of Bearded Vultures ( Gypaetus barbatus ) in the Italian Alps. J raptor res 45(1):56-62 DOI: 10.3356/JRR-09-69.1 Blanco-Aguiar JA, González-Jara P, Ferrero ME, Sánchez-Barbudo I, Virgós E, Villafuerte R, Dávila JA (2008) Assessment of game restocking contributions to anthropogenic hybridization: the case of the Iberian red-legged partridge. Anim Conserv 11:535–545 Brichieri-Colombi TA, Moehrenschlager A (2016) Alignment of threat, effort, and perceived success in North American conservation translocations. Conserv Biol 30: 1159–1172. https://doi.org/10.1111/cobi.12743. Bosch R, Real J, Tinto A, Zozaya EL, Castell C (2010) Home range and patterns of spatial use in territorial Bonelli’s Eagles Aquila fasciata . Ibis 152: 105–117. Bustamante J (1998) Use of simulation models to plan species reintroductions: the case of the Bearded Vulture in southern Spain. Anim Conserv 1:229–238. Cadahía L, López-López P, Urios V, Soutullo A, Negro JJ (2009) Natal dispersal and recruitment of two Bonelli’s Eagles Aquila fasciata : a four-year satellite tracking study. Acta Ornithol 44:193-198. Caro J, Ontiveros D, Pleguezuelos JM (2011) The feeding ecology of Bonelli’s eagle ( Aquila fasciata ) floaters in southern Spain: implications for conservation. Eur J Wildl Res 57:729–736 Carrascal LM, Seoane J (2009) Factors affecting large-scale distribution of the Bonelli’s Eagle Aquila fasciata in Spain. Ecol Res 24: 565–573. Carrete M, Sánchez-Zapata JA, Tella JL, Gil-Sancez JM, Moleón M (2006) Components of breeding performance in two competing species: habitat heterogeneity, individual quality and density-dependence. Oikos 112: 680-690. Clark WS, Schmitt NJ (1999) A field guide to the raptors of Europe, the Middle East, and North Africa. Oxford University Press, USA. Del Moral JC (Ed.). 2009. El águila real en España. Población reproductora en 2008 y método de censo. SEO/BirdLife. Madrid. Egea-Casas O, López-López P, Álvarez E, Cortone G, Galán M., Iglesias-Lebrija JJ, Lo Valvo M, Martínez J, Merlino S, Viada C, Di Vittorio M (2022) Assessing reintroduction outcome: comparison of the juvenile post-fledging dependence period between wild and reintroduced Bonelli’s eagles in two Mediterranean islands. Preprint. https://doi.org/10.21203/rs.3.rs-1540050/v1 Escandell V, Escudero E (2020) Tendencias de aves nocturnas. Available at: https://seo.org/wp-content/uploads/2021/04/Separata_Sacre_2020.pdf Evans RJ, Wildson JD, Amar A, Douse A, Maclennan A, Ratcliffe N, Whitefield DP (2009) Growth and demography of a re-introduced population of White-tailed Eagles Haliaeetus albicilla. Ibis: 151, 244–254 Fernández, C. (1994). Plan de Recuperación del águila perdicera ( Hieraaetus fasciatus ) en Navarra. Informe inédito para la Dirección de Medio Ambiente del Gobierno de Navarra. García JR, Viñuela J, Calero-Riestra M, Sánchez-Barbudo I, Villanúa D, Casas F (2021) Risk of Infection, Local Prevalence and Seasonal Changes in an Avian Malaria Community Associated with Game Bird Releases. Diversity 13: 657 DOI: 10.3390/d13120657 García V, Lebrija JJ, Moreno-Opo R (2021) Null effects of the Garcelon harnessing method and transmitter type on soaring raptors. Ibis, 163: 899-912 Gil Sánchez JM (2018) Capítulo 6: Conservación. In: Peral, T. Águila de Bonelli. Madrid. Gobierno de Navarra (2022) https://www.navarra.es/es/tramites/on/-/line/Ayudas-para-la-correccion-de-lineas-electricas-de-alta-tension-en-zonas-de-proteccion Gortázar C, Villafuerte R, Martín M (2000) Success of traditional restocking of red-legged partridge for hunting purposes in areas of low density of northeast Spain Aragon. Z Jagdwiss 46: 23-30 GREFA (2020) Libro Blanco de la electrocución en España. Análisis y propuestas. AQUILA a-LIFE (LIFE16 NAT/ES/000235). 100pp. Madrid. Hammer Ø, Harper DAT, Ryan PD (2001) PAST: Palaeontological Statistics software package for education and data analysis. Hernández-Matías A, Real J, Pradel R, Ravayrol A, Vincent-Martín N, Bosca F, Cheylan G. (2010) Determinants of territorial recruitment in Bonelli´s Eagle ( Aquila fasciata ) populations. Auk 127: 173-184. Hernández-Matías A, Real J, Pradel R, Ravayrol A, Vincent-Martín N (2011) Effects of age, territoriality and breeding on survival of Bonelli’s Eagle Aquila fasciata. Ibis 153: 846–857 Hernández-Matías A, Real J, Moleón M, Palma L, Sánchez-Zapata JA, Pradel R, Carrete M, Gil-Sánchez JM, Beja P, Balbonti J, Vincent-Martín N, Ravayrol A, Benítez JR, Arroyo B, Fernandez C, Ferreiro E, García J (2013) From local monitoring to a broad-scale viability assessment: a case study for the Bonelli’s Eagle in western Europe. Ecol Monogr 83: 239–261 Irizi A, Aourir M, Znari M, Aziz El Agbani M, Qninba A (2019) Spatial distribution and breeding territories of Bonelli’s Eagle Aquila fasciata in the western Anti-Atlas Mountains, Morocco. Ostrich 90: 241-246 IUCN/SSC (2013) Guidelines for Reintroductions and Other Conservation Translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission, viiii + 57 pp. Kleinbaum DG, Klein M (2005) Survival analysis: a self-learning text. Springer. Laikre L, Schwartz MK, Waples RS, Ryman N, Working Group GeM (2010) Compromising genetic diversity in the wild: unmonitored large-scale release of plants and animals. Trends Ecol Evol 25:520–529. López-López P (2011) Demographie et compétition entre l’Aigle de Bonelli Aquila fasciata et l’Aigle royal Aquila chrysaetos : implications pour la gestión et la conservation d’espèces menacées. In: Scher, O. y M. Lecacheur (Eds.). La conservation de l’Aigle de Bonelli: 53-57. Actes du colloque international, 28 et 29 janvier, 2010, Montpellier. CEN LR, CEEP, CORA FS and DREAL LR: 53-57. Martija M, Carreño S, Hernández R (2021) Estudio de variabilidad climática. Áreas de intervención para la gestión adaptativa del paisaje y medio construido en Navarra- Acción C6 del Proyecto LIFE-IP NAdapta-CC (LIFE 16 IPC/ES/000001) de la Unión Europea. Pamplona. Tecnalica Research and Innovation para Navarra de Suelo y Vivienda S.A. (NASUVINSA) y Servicio de Economía Circular y Cambio Climático del Gobierno de Navarra. Martínez-Abraín A, Crespo J, Jiménez J, Gómez JA, Oro D (2009) Is the historical war against wild life over in southern Europe? Anim Conserv 12: 204-208. Martínez-Miranzo B, Banda E, Aguirre JI (2019) Home range requirements in Bonelli’s eagle ( Aquila fasciata ): prey abundance or trophic stability? Eur J Wildl Res 65:85 Moehrenschlager A, Lloyd, N (2016) Release considerations and techniques to improve conservation translocation success, In press in Jackowski DS, Angermeier P, Slotow R, Millspaugh J, editors. Reintroduction of fish and wildlife populations. University of California Press, Oakland. Orta J, Kirwan GM, Christie DA, Boesman P, Marks JS (2016) Bonelli's Eagle ( Aquila fasciata ). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona. Real J, Mañosa S (1997) Demography and conservation of western European Bonelli’s Eagle Hieraaetus fasciatus populations. Biol Conserv 79: 59–66. Real J, Mañosa, S (2001) Dispersal of juvenile and immature Bonelli’s Eagles in northeastern Spain. J Raptor Res 35:9–14. Real J, Grande JM, Mañosa S, Sánchez-Zapata JA (2001) Causes of death in different areas for Bonelli’s Eagle Hieraetus fasciatus in Spain. Bird Study 48: 221–228. Real J, Bosch R, Tintó A, Hernández-Matías A (2016) Identifying key habitats for the conservation of Bonelli’s Eagle Aquila fasciata using radiotracking. Ibis 158: 556–568. Resano-Mayor J, Real J, Moleón M, Sáchez-Zapata JA, Palma L, Hernández-Matías A (2016) Diet–demography relationships in a long‐lived predator: from territories to populations. Oikos 125: 262–270. Rollan A, Real J, Bosh R, Tinto A, Hernández-Matías A (2010) Modelling the risk of collision with power lines in Bonelli’s Eagle Hieraaetus fasciatus and its conservation implications. Bird Conserv Int 20:279–294. Rollan A, Hernández-Matías A, Real J (2016) Guidelines for the conservation of Bonelli’s eagle populations. Barcelona, Spain: Universitat de Barcelona. Rueda C, Jimenez J, Palacios MJ, Margalida A. (2021) Exploratory and territorial behavior in a reintroduced population of Iberian lynx. Nature Scientifc Reports 11:14148 doi.org/10.1038/s41598-021-93673-z Santos N, Jambas J, Monteiro A, Amaral J, Martins N, Garcia J, Martinez-Fernández A, Morris Tyler K, Almeida T, Abrantes J, Esteves PJ (2019) Trichomonas Infection in a Community of Free-Ranging Domestic and Wild columbiformes and Bonelli’s Eagle ( Aquila fasciata ). Front Vet Sci 6:148. doi: 10.3389/fvets.2019.00148 Seddon PJ, Soorae PS, Launay F. (2005) Taxonomic bias in reintroduction projects. Anim Conserv 8:51–58. Soutullo A, López-López P, Urios V (2008) Incorporating spatial structure and stochasticity in endangered Bonelli’s Eagle’s population models: implications for conservation and management. Biol Conserv 141: 1013–1020. Torrea J, San Julión A, Primo E, Lizarraga A (2021) Seguimiento de la población del águila de Bonelli ( Aquila fasciata ) en Navarra. unpublished report for the Government of Navarra Viada C (2021) Aguila perdicera, Aquila fasciata . En: López-Jiménez, N. (Ed.): Libro Rojo de las Aves de España, pp. 534-542. SEO/BirdLife. Madrid. Villanúa D, Casas F, Viñuela J, García de la Morena E, Morales MB (2006) First occurrence of Eucoleus contortus in a Little Bustard Tetrax tetrax : Negative effect of Red-legged Partridge Alectoris rufa releases on steppe bird conservation? Ibis 149:405-406 DOI: 10.1111/j.1474-919X.2006.00620.x Villanúa D, Pérez-Rodríguez L, Casas F, Alzaga V, Acevedo P, Viñuela J, Gortázar C (2008) Sanitary risks of Red-legged Partridge releases: introduction of parasites. Eur J Wildl Res 54: 199-204 DOI: 10.1007/s10344-007-0130-2 Vukovich M, Kilgo JC (2009) Effects of radio transmitters on the behavior of Red-headed Woodpeckers. J Field Ornithol 80(3): 308-313. Wolf C, Griffith B, Reed C, Temple S ( 1987) Avian and mammalian translocations: Update and reanalysis of 1987 survey data. Conserv Biol 10: 1142–1154. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1971769","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":136211581,"identity":"0bb5dd0d-ce91-4241-b388-ac6bd60e9bc8","order_by":0,"name":"Gloria Giralda","email":"","orcid":"","institution":"Gobierno de Navarra","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gloria","middleName":"","lastName":"Giralda","suffix":""},{"id":136211582,"identity":"6c2aca70-de8b-430b-a388-f173bbdf4fae","order_by":1,"name":"Alfonso Llamas","email":"","orcid":"","institution":"Navarra Environmental 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Management","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Diego","middleName":"","lastName":"Villanúa","suffix":""}],"badges":[],"createdAt":"2022-08-17 15:46:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1971769/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1971769/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":26527992,"identity":"dab8aa46-e9ad-44db-8109-859cbe06acbc","added_by":"auto","created_at":"2022-09-15 21:18:21","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":86009,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of the historical territories of the Bonelli's eagle (circles), release points (triangles) and territories established because of the reintroduction project (squares).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-1971769/v1/4e1dd07eec6e52109f25fb97.jpeg"},{"id":26527994,"identity":"af5d7d19-3d1e-4151-8887-b516f0d5160e","added_by":"auto","created_at":"2022-09-15 21:18:21","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":15450,"visible":true,"origin":"","legend":"\u003cp\u003eSurvival of males and females during the first month and the first year after release.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-1971769/v1/e645bd343be5faa089f0cd0f.jpeg"},{"id":26527993,"identity":"901d4835-3bd5-43be-ab7c-c9a20294ccd9","added_by":"auto","created_at":"2022-09-15 21:18:21","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":317871,"visible":true,"origin":"","legend":"\u003cp\u003eCauses of death of the released birds in the eleven years of monitoring.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-1971769/v1/2a4ab894f1e93229987aba49.jpeg"},{"id":29684622,"identity":"dd7eb84b-a1ca-4a89-a91e-9edeef7ebd16","added_by":"auto","created_at":"2022-11-29 20:31:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":967760,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1971769/v1/168899e4-d0af-4c50-bf4f-3075471594f6.pdf"}],"financialInterests":"","formattedTitle":"Survival and causes of death of the Bonelli's Eagle released in Navarra, North of Spain.","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe Bonelli's eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e) is one of the rarest birds of prey in Europe. This species shows an irregular and highly fragmented distribution throughout the southern palearctic, from the Iberian Peninsula to China, and several Indonesian islands (BirdLife International. 2022) generally occupying cliffs and mountain areas from sea level to almost 4000 m.o.s. in the Himalayas (Carrete et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Carrascal and Seoane, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Bosch et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Orta et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Irizi et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The European population has around 1100\u0026ndash;1200 pairs (BirdLife International, 2022), of which more than 700 are found in the Iberian Peninsula (Viada, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), so the management of the species in this region is essential to guarantee its conservation in Europe. This population suffered a great decrease in the last decades of the 20th century, even becoming extinct in certain regions, which has led to the fact that today it is classified as vulnerable in Spain (Viada, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Among the factors that may have caused this decline are electrocution (Real et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Rollan et al. 2020), direct persecution (Real et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Rollan et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Mart\u0026iacute;nez-Abra\u0026iacute;n et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), the loss of quality of nesting areas (Real, 2004; Real et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) or the increased impact of diseases such as trichomoniasis associated with increased consumption of feral dove due to the decline of other wild prey (Santos et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). To try to reduce the impact of these factors, various European projects have been carried out in the mediterranean countries, mainly aimed at correcting power lines and improving the habitat for the species (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://www.lifebonelli.org/index.php/at/life-bonelli/description-and-objectives\u003c/span\u003e\u003cspan address=\"http://www.lifebonelli.org/index.php/at/life-bonelli/description-and-objectives\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e; \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.aquila-a-life.org/index.php/en/aquila-a-life/the-project/description-and-goals\u003c/span\u003e\u003cspan address=\"https://www.aquila-a-life.org/index.php/en/aquila-a-life/the-project/description-and-goals\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e), but in which the release of specimens in regions where the species had recently become extinct has also been included. The reintroduction of a species is a very common practice in wildlife management (Evans et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Brichieri-Colombi and Moehrenschlager, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Badia-Boher et al. 2021), but the viability of these actions is highly variable (Brichieri-Colombi and Moehrenschlager, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), with cases of great success (Evans et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Bogliani et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Rueda et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) and others in which its effect has been null or even negative due to the introduction of pathogens (Villan\u0026uacute;a et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Garc\u0026iacute;a et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), the genetic contamination (Seddon et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Blanco-Agular et al. 2008; Laikre et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) or the negative impact on other species present in the area of release (Villan\u0026uacute;a et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). The success of these releases depends on multiple factors, including the quality of the habitat (Wolf et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e1987\u003c/span\u003e; Moehrenschlager and Lloyd \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) or the origin and age of the released specimens (Badia-Boher et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) which, according to the IUCN/SSC (2013) criteria, must be assessed before carrying out a release. This same organization suggests that, once a reintroduction project has been completed, an analysis must be carried out to assess its real impact, as well as to detect the possible factors that may have influenced its development. In this paper we present the results of a Bonelli's Eagle reintroduction project in a region where it had disappeared as a breeder, describing the survival achieved, the causes of death detected and analyzing the factors that could influence its survival in the field.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy area\u003c/h2\u003e \u003cp\u003eThis study was carried out in the province of Navarre, northeastern of the Iberian Peninsula (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Despite being a relatively small region, its peculiar location between the Pyrenees, with peaks of more than 2,000 m and average rainfall close to 2,000 mm per year, and the Ebro valley, located at 300 m and average rainfall below 300 mm per year, makes Navarre have three different biogeographical regions, the Alpine, the Atlantic and the Mediterranean (Lorda et al. 2011; Martija et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) with a wide variety of habitats. Until the last decades of the 20th century, Navarra had up to 7 territories of Bonelli's eagle in the Mediterranean area (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)(Fern\u0026aacute;ndez, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Torrea et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), constituting the northern limit of the distribution area of ​​the species in the Iberian Peninsula. Progressively, these pairs disappeared until they became extinct as breeders in 2005 (Torrea et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Faced with this situation, the Government of Navarra decided to start a project to recover the species, relying on Life funds from the European Union, which included the release of specimens using the hacking technique. Five release points were selected (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) that were close to the historical territories of the species, were part of the Natura 2000 Network, were free of uncorrected power lines and whose hunting management was directed by hunters favorable to the presence of this bird of prey and were willing to carry out habitat improvements and repopulation with wild rabbits to increase the availability of prey for the eagles. This filter was intended to minimize the risks of electrocution, direct persecution and lack of availability of prey, main factors causing the disappearance of the species (Real et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Mart\u0026iacute;nez-Abra\u0026iacute;n et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Rollan et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, 2020).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eReleased birds\u003c/h2\u003e \u003cp\u003eBetween 2011 and 2021, a total of 47 bonelli's eagle chicks were released from both captive breeding centers and wild nests (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) using the hacking technique.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDate, place, origin and sex of the released specimens.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYear\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePlace\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWild ♂\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWild ♀\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCaptive ♂\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCaptive ♀\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2011\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2021\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eE\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAll the eagles were equipped with GPS transmitters (PTT-100, Microwave, e-obs and Ornitela 30-45g) equipped with tri-axial accelerometry, programmed to send a location every 5 minutes and placed with chest harness according to Garc\u0026iacute;a et al. (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The total weight of the tag and harness never exceeded 50 g. which represents 2.2% of the weight of Bonelli's eagles in our region (see Garc\u0026iacute;a et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e for details), thus remaining below the recommended 3% to avoid a negative effect associated with marking (Vukovich et al. 2009). This intensive monitoring allows the rapid detection of any traumatic event suffered by the specimens, which facilitates a correct identification of the causes of death (Arrondo et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eEagle survival was estimated with the help of Kaplan-Meier product limit estimation (Kleinbaum and Klein, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) and log-rank tests were used to test the null hypothesis of no differences based on sex or the origin (wild or captive bred)(Gort\u0026aacute;zar et al \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). This analysis was run in the software PAST (Hammer et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) and was repeated for survival during the first month and the first year.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eWith the release of specimens during the last 11 years, the occupation of 2 of the territories that disappeared at the end of the 90s and the creation of a new territory where there was no record of the reproduction of this species before has been achieved (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eOf the 47 eagles released, 21 (44.68%) died in the first year after their release and of these, 9 (19.14%), during the first month in the field.\u003c/p\u003e \u003cp\u003eNo significant differences were found associated with the origin or the sex of the specimens in survival during the first month or during the first year after release, although a certain tendency for males to survive longer than females is detected (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eRegarding the causes of death, 48% had an anthropic origin (electrocution, wind farm collision, indeterminate trauma, shooting and poisoning) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), with electrocution standing out as the main cause of death. 88% of the deaths due to anthropic causes occurred more than 100 km from the release point and outside Navarra.\u003c/p\u003e \u003cp\u003eDeaths due to predation accounted for 44%, highlighting those attributed to big raptors (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) and they were located mostly (94%) within the Navarra region. Furthermore, deaths attributed to mammal\u0026rsquo;s predation (red fox or feral dog) were concentrated within two weeks of release and less than 1 km from the release point.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe establishment of 3 territories in the study area after 11 years of releases can be considered a success according to the criteria of the IUCN/SSC (2013), especially considering that the maximum number recorded in the 90s for the Bonelli's eagle in the region was 5\u0026ndash;7 pairs (Torrea et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). However, this positive result is also due to the rest of the actions carried out within the life projects, such as the correction of power lines, improvements in the habitat or the awareness of the hunters in Navarra, which have allowed the released birds to survive and reach to settle in the area.\u003c/p\u003e \u003cp\u003eThe first year survival of the released individuals (54.38%) is within the values ​​described for the species in different wild populations of the Iberian Peninsula (Real \u0026amp; Ma\u0026ntilde;osa \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Arroyo et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Balbont\u0026iacute;n et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Soutullo et al. \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) and southern France (Hern\u0026aacute;ndez-Matias et al. 2011), with a minimum survival of 36% (Arroyo et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1998\u003c/span\u003e) and a maximum of 69% (Balbontin et al. 2003), and is very similar to that recorded in previous works with the species on the island of Mallorca with specimens from captive breeding (53.33% Badia-Boher et al. 2021).\u003c/p\u003e \u003cp\u003eRegarding the causes of death detected, our work coincides with previous studies carried out in the Iberian Peninsula in that the majority of deaths are due to causes of anthropic origin, mainly electrocution (Real et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Rollan et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2016\u003c/span\u003e, Grefa, 2020). However, our results show percentages of birds electrocuted, poisoned or shot to death that are much lower than those described in these studies. This difference is due to the great importance that predation acquires in our area, reaching 44% of casualties, while, for example, in the work of Real et al (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2001\u003c/span\u003e) it did not reach 0.5%. The increased role of predation is due, in our opinion, not only to an increase experienced by the Golden Eagle (\u003cem\u003eAquila chrysaetos\u003c/em\u003e) (Del Moral, 2009) and the Eagle Owl (\u003cem\u003eBubo bubo\u003c/em\u003e) (Escandell and Escudero, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) main predators identified, but above all to a decrease in deaths from human causes. Throughout these 11 years, agreements have been signed with the main electricity companies present in Navarra to guarantee that electric pole designs with low risk of electrocution are used in the new lines and that the existing ones are progressively corrected in accordance with guidelines and courses implemented (Grefa, 2020) and a subsidy line has been created for the correction of power lines of small owners (Gobierno de Navarra, 2022). Because of these actions, several thousand kilometers of power lines have been corrected, making the electrocution rate in Navarra 50 times lower than that found in the south of the Peninsula (GREFA, 2020). However, the large movements that this species makes throughout the Iberian Peninsula (Real and Ma\u0026ntilde;osa, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Cadahia et al. 2009) and even the south of France (Hernandez-Mat\u0026iacute;as et al. 2010) means that these correction measures lines are insufficient if they are not applied throughout the country or even at European level.\u003c/p\u003e \u003cp\u003eWhen correcting the causes that led to its disappearance at the end of the 90s, those of natural origin that were hidden by the high number of electrocutions, poisonings or deaths by gunshots that occurred in those years appear. After this unexpected result, it is necessary to reassess the capacity of current habitats to house the Bonelli's eagle, taking into account the current abundance of both its prey (Carrascal and Seoane, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Caro et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Real et al. al., 2016; Mart\u0026iacute;nez-Miranzo et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), as well as their competitors and even predators (Carrete et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; L\u0026oacute;pez-L\u0026oacute;pez, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Gil S\u0026aacute;nchez, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Our work shows that it is possible to recover historical territories of Bonelli's eagle through the release of birds with hacking techniques, but also that many highly interrelated factors intervene in the management of the species and that require a continuous review of the criteria. The development of long-term monitoring with radio-tagged specimens will allow obtaining the necessary information to direct the management of the species.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eACKNOWLEDGEMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe want to especially thank Sonia Moreno, Arantxa San Juli\u0026aacute;n, Eduardo Primo, Alberto Lizarraga, Susana C\u0026aacute;rcamo, Silvia Erlanz and the Environmental Guards of the Navarra\u0026rsquo;s Government who collaborated in the monitoring of the released specimens. Joseba Oroz and Silvestre Belzunegi collaborated with the design and installation of the release cages. The Government of Navarra provided the necessary permits for the release of the birds. All members of the Aquila Life project helped us in the interpretation of the results.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFUNDING INFORMATION\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Life Bonelli and Aquila Life projects.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONFLICTS OF INTEREST/\u003c/strong\u003e\u003cstrong\u003eCOMPETING\u0026nbsp;INTEREST\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAVAILABILITY\u0026nbsp;OF DATA AND MATERIAL\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAUTHORS CONTRIBUTIONS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eG. Giralda, A. Llamas, A. Zaldua and J. Palacios elaborated and managed the projects Life Bonelli and Aquila Life. I. Almarcegi and J. Torrea performed fieldwork. A. Mateo and D. Villan\u0026uacute;a performed necropsies and determination of causes of death. Statistical analyses were performed by A. Zufiarre. D. Villan\u0026uacute;a wrote initial draft of the manuscript. All authors participated equally in the discussion and preparation on the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003e\u003cstrong\u003eArrondo E, Garc\u0026iacute;a-Alfonso M, Blas J, Cort\u0026eacute;s-Avizanda A, De la Riva M, Devault TL, Fiedler W, Flack A, Jimenez J, Lambertucci SA,\u0026nbsp; Margalida A, Oliva-Vidal P, Phipps WL, Sanchez-Zapata JA, Wikelski M, Don\u0026aacute;zar JA (2021) \u003c/strong\u003eUse of avian GPS tracking to mitigate human fatalities from bird strikes caused by large soaring birds. J Appl Ecol 58: 1411-1420\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eArroyo B, Ferreiro E, Garza V (1998)\u003c/strong\u003e Causas de la regresi\u0026oacute;n del \u0026Aacute;guila Perdicera \u003cem\u003eHieraaetus fasciatus\u003c/em\u003e en Espa\u0026ntilde;a Central. In: Meyburg BU, Chancellor RD, Ferrero JJ (ed) Holarctic Birds of Prey. Badajoz: ADENEX-WWGBP. pp 291\u0026ndash;304.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBadia-Boher JA, Hern\u0026aacute;ndez-Mat\u0026iacute;as A, Viada C, Real J (2022)\u003c/strong\u003e Raptor reintroductions: Cost-effective alternatives to captive breeding. Anim Conserv 25: 170-181\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBalbont\u0026iacute;n J, Penteriani V, Ferrer M (2003) \u003c/strong\u003eVariations in the age of mates as an early signal of changes in population trends? The case of Bonelli\u0026rsquo;s Eagle in Andalusia. Biol Conserv 109: 417\u0026ndash;423.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBirdLife International (2022) \u003c/strong\u003eSpecies factsheet: \u003cem\u003eAquila fasciata\u003c/em\u003e. Downloaded from http://www.birdlife.org on 01/06/2022.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBogliani G, Viterbi R, Nicolino M (2011).\u003c/strong\u003e Habitat use by a reintroduced population of Bearded Vultures (\u003cem\u003eGypaetus barbatus\u003c/em\u003e) in the Italian Alps. J raptor res 45(1):56-62 DOI: 10.3356/JRR-09-69.1\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBlanco-Aguiar JA, Gonz\u0026aacute;lez-Jara P, Ferrero ME, S\u0026aacute;nchez-Barbudo I, Virg\u0026oacute;s E, Villafuerte R, D\u0026aacute;vila JA (2008)\u003c/strong\u003e Assessment of game restocking contributions to anthropogenic hybridization: the case of the Iberian red-legged partridge. Anim Conserv 11:535\u0026ndash;545\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBrichieri-Colombi TA, Moehrenschlager A (2016)\u003c/strong\u003e Alignment of threat, effort, and perceived success in North American conservation translocations. Conserv Biol 30: 1159\u0026ndash;1172. https://doi.org/10.1111/cobi.12743.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBosch R, Real J, Tinto A, Zozaya EL, Castell C (2010)\u003c/strong\u003e Home range and patterns of spatial use in territorial Bonelli\u0026rsquo;s Eagles \u003cem\u003eAquila fasciata\u003c/em\u003e. Ibis 152: 105\u0026ndash;117.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eBustamante J (1998)\u003c/strong\u003e Use of simulation models to plan species reintroductions: the case of the Bearded Vulture in southern Spain. Anim Conserv 1:229\u0026ndash;238.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eCadah\u0026iacute;a L, L\u0026oacute;pez-L\u0026oacute;pez P, Urios V, Soutullo A, Negro JJ (2009) \u003c/strong\u003eNatal dispersal and recruitment of two Bonelli\u0026rsquo;s Eagles \u003cem\u003eAquila fasciata\u003c/em\u003e: a four-year satellite tracking study. Acta Ornithol 44:193-198.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eCaro J, Ontiveros D, Pleguezuelos JM (2011) \u003c/strong\u003eThe feeding ecology of Bonelli\u0026rsquo;s eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e) floaters in southern Spain: implications for conservation. Eur J Wildl Res 57:729\u0026ndash;736\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eCarrascal LM, Seoane J (2009)\u003c/strong\u003e Factors affecting large-scale distribution of the Bonelli\u0026rsquo;s Eagle \u003cem\u003eAquila fasciata\u003c/em\u003e in Spain. Ecol Res 24: 565\u0026ndash;573.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eCarrete M, S\u0026aacute;nchez-Zapata JA, Tella JL, Gil-Sancez JM,\u0026nbsp; Mole\u0026oacute;n M (2006)\u003c/strong\u003e Components of breeding performance in two competing species: habitat heterogeneity, individual quality and density-dependence. Oikos 112: 680-690.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eClark WS, Schmitt NJ (1999) \u003c/strong\u003eA field guide to the raptors of Europe, the Middle East, and North Africa. Oxford University Press, USA.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eDel Moral JC (Ed.). 2009. \u003c/strong\u003eEl \u0026aacute;guila real en Espa\u0026ntilde;a. Poblaci\u0026oacute;n reproductora en 2008 y m\u0026eacute;todo de censo. SEO/BirdLife. Madrid.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEgea-Casas O, L\u0026oacute;pez-L\u0026oacute;pez P, \u0026Aacute;lvarez E, Cortone G, Gal\u0026aacute;n M., Iglesias-Lebrija JJ, Lo Valvo M, Mart\u0026iacute;nez J, Merlino S, Viada C, Di Vittorio M (2022) \u003c/strong\u003eAssessing reintroduction outcome: comparison of the juvenile post-fledging dependence period between wild and reintroduced Bonelli\u0026rsquo;s eagles in two Mediterranean islands. Preprint. https://doi.org/10.21203/rs.3.rs-1540050/v1\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEscandell V, Escudero E (2020) \u003c/strong\u003eTendencias de aves nocturnas. Available at: https://seo.org/wp-content/uploads/2021/04/Separata_Sacre_2020.pdf\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eEvans RJ, Wildson JD, Amar A, Douse A, Maclennan A, Ratcliffe N, Whitefield DP (2009)\u003c/strong\u003e Growth and demography of a re-introduced population of White-tailed Eagles \u003cem\u003eHaliaeetus albicilla. \u003c/em\u003eIbis: 151, 244\u0026ndash;254\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eFern\u0026aacute;ndez, C. (1994). \u003c/strong\u003ePlan de Recuperaci\u0026oacute;n del \u0026aacute;guila perdicera (\u003cem\u003eHieraaetus fasciatus\u003c/em\u003e) en Navarra. Informe in\u0026eacute;dito para la Direcci\u0026oacute;n de Medio Ambiente del Gobierno de Navarra.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGarc\u0026iacute;a JR, Vi\u0026ntilde;uela J, Calero-Riestra M, S\u0026aacute;nchez-Barbudo I, Villan\u0026uacute;a D, Casas F (2021) \u003c/strong\u003eRisk of Infection, Local Prevalence and Seasonal Changes in an Avian Malaria Community Associated with Game Bird Releases. Diversity 13: 657 DOI: 10.3390/d13120657\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGarc\u0026iacute;a V, Lebrija JJ, Moreno-Opo R (2021)\u003c/strong\u003e Null effects of the Garcelon harnessing method and transmitter type on soaring raptors. Ibis, 163: 899-912\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGil S\u0026aacute;nchez JM (2018)\u003c/strong\u003e Cap\u0026iacute;tulo 6: Conservaci\u0026oacute;n. In: Peral, T. \u0026Aacute;guila de Bonelli. Madrid.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGobierno de Navarra (2022) \u003c/strong\u003ehttps://www.navarra.es/es/tramites/on/-/line/Ayudas-para-la-correccion-de-lineas-electricas-de-alta-tension-en-zonas-de-proteccion\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGort\u0026aacute;zar C, Villafuerte R, Mart\u0026iacute;n M (2000)\u003c/strong\u003e Success of traditional restocking of red-legged partridge for hunting purposes in areas of low density of northeast Spain Aragon. Z Jagdwiss 46: 23-30\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eGREFA (2020)\u003c/strong\u003e Libro Blanco de la electrocuci\u0026oacute;n en Espa\u0026ntilde;a. An\u0026aacute;lisis y propuestas. AQUILA a-LIFE (LIFE16 NAT/ES/000235). 100pp. Madrid.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eHammer \u0026Oslash;, Harper DAT, Ryan PD (2001)\u003c/strong\u003e PAST: Palaeontological Statistics software package for education and data analysis.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eHern\u0026aacute;ndez-Mat\u0026iacute;as A, Real J, Pradel R, Ravayrol A, Vincent-Mart\u0026iacute;n N, Bosca F, Cheylan G. (2010) \u003c/strong\u003eDeterminants of territorial recruitment in Bonelli\u0026acute;s Eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e) populations. Auk 127: 173-184.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eHern\u0026aacute;ndez-Mat\u0026iacute;as A, Real J, Pradel R, Ravayrol A, Vincent-Mart\u0026iacute;n N (2011)\u003c/strong\u003e Effects of age, territoriality and breeding on survival of Bonelli\u0026rsquo;s Eagle \u003cem\u003eAquila fasciata. \u003c/em\u003eIbis 153: 846\u0026ndash;857\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eHern\u0026aacute;ndez-Mat\u0026iacute;as A, Real J, Mole\u0026oacute;n M, Palma L, S\u0026aacute;nchez-Zapata JA, Pradel R, Carrete M, Gil-S\u0026aacute;nchez JM, Beja P, Balbonti J, Vincent-Mart\u0026iacute;n N, Ravayrol A, Ben\u0026iacute;tez JR, Arroyo B, Fernandez C, Ferreiro E, Garc\u0026iacute;a J (2013) \u003c/strong\u003eFrom local monitoring to a broad-scale viability assessment: a case study for the Bonelli\u0026rsquo;s Eagle in western Europe. Ecol Monogr 83: 239\u0026ndash;261\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eIrizi A, Aourir M, Znari M, Aziz El Agbani M, Qninba A (2019) \u003c/strong\u003eSpatial distribution and breeding territories of Bonelli\u0026rsquo;s Eagle \u003cem\u003eAquila fasciata \u003c/em\u003ein the western Anti-Atlas Mountains, Morocco. Ostrich 90: 241-246\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eIUCN/SSC (2013)\u003c/strong\u003e Guidelines for Reintroductions and Other Conservation Translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission, viiii + 57 pp.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eKleinbaum DG, Klein M (2005)\u003c/strong\u003e Survival analysis: a self-learning text. Springer.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eLaikre L, Schwartz MK, Waples RS, Ryman N, Working Group GeM (2010)\u003c/strong\u003e Compromising genetic diversity in the wild: unmonitored large-scale release of plants and animals. Trends Ecol Evol 25:520\u0026ndash;529.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eL\u0026oacute;pez-L\u0026oacute;pez P (2011)\u003c/strong\u003e Demographie et comp\u0026eacute;tition entre l\u0026rsquo;Aigle de Bonelli \u003cem\u003eAquila fasciata\u003c/em\u003e et l\u0026rsquo;Aigle royal \u003cem\u003eAquila chrysaetos\u003c/em\u003e: implications pour la gesti\u0026oacute;n et la conservation d\u0026rsquo;esp\u0026egrave;ces menac\u0026eacute;es. In: Scher, O. y M. Lecacheur (Eds.). La conservation de l\u0026rsquo;Aigle de Bonelli: 53-57. Actes du colloque international, 28 et 29 janvier, 2010, Montpellier. CEN LR, CEEP, CORA FS and DREAL LR: 53-57.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eMartija M, Carre\u0026ntilde;o S, Hern\u0026aacute;ndez R (2021)\u003c/strong\u003e Estudio de variabilidad clim\u0026aacute;tica. \u0026Aacute;reas de intervenci\u0026oacute;n para la gesti\u0026oacute;n adaptativa del paisaje y medio construido en Navarra- Acci\u0026oacute;n C6 del Proyecto LIFE-IP NAdapta-CC (LIFE 16 IPC/ES/000001) de la Uni\u0026oacute;n Europea. Pamplona. Tecnalica Research and Innovation para Navarra de Suelo y Vivienda S.A. (NASUVINSA) y Servicio de Econom\u0026iacute;a Circular y Cambio Clim\u0026aacute;tico del Gobierno de Navarra.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eMart\u0026iacute;nez-Abra\u0026iacute;n A, Crespo J, Jim\u0026eacute;nez J, G\u0026oacute;mez JA, Oro D (2009) \u003c/strong\u003eIs the historical war against wild life over in southern Europe? Anim Conserv 12: 204-208.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eMart\u0026iacute;nez-Miranzo B, Banda E, Aguirre JI (2019)\u003c/strong\u003e Home range requirements in Bonelli\u0026rsquo;s eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e): prey abundance or trophic stability? Eur J Wildl Res 65:85\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eMoehrenschlager A, Lloyd, N (2016) \u003c/strong\u003eRelease considerations and techniques to improve conservation translocation success, In press in Jackowski DS, Angermeier P, Slotow R, Millspaugh J, editors. Reintroduction of fish and wildlife populations. University of California Press, Oakland.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eOrta J, Kirwan GM, Christie DA, Boesman P, Marks JS (2016)\u003c/strong\u003e Bonelli's Eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds), Handbook of the Birds of the World Alive, Lynx Edicions, Barcelona.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eReal J, Ma\u0026ntilde;osa S (1997)\u003c/strong\u003e Demography and conservation of western European Bonelli\u0026rsquo;s Eagle \u003cem\u003eHieraaetus fasciatus \u003c/em\u003epopulations. Biol Conserv 79: 59\u0026ndash;66.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eReal J, Ma\u0026ntilde;osa, S (2001)\u003c/strong\u003e Dispersal of juvenile and immature Bonelli\u0026rsquo;s Eagles in northeastern Spain. J Raptor Res 35:9\u0026ndash;14.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eReal J, Grande JM, Ma\u0026ntilde;osa S, S\u0026aacute;nchez-Zapata JA (2001) \u003c/strong\u003eCauses of death in different areas for Bonelli\u0026rsquo;s Eagle \u003cem\u003eHieraetus fasciatus\u003c/em\u003e in Spain. Bird Study 48: 221\u0026ndash;228.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eReal J, Bosch R, Tintó A, Hern\u0026aacute;ndez-Mat\u0026iacute;as A (2016)\u003c/strong\u003e Identifying key habitats for the conservation of Bonelli\u0026rsquo;s Eagle \u003cem\u003eAquila fasciata\u003c/em\u003e using radiotracking. Ibis 158: 556\u0026ndash;568.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eResano-Mayor J, Real J, Mole\u0026oacute;n M, S\u0026aacute;chez-Zapata JA, Palma L, Hern\u0026aacute;ndez-Mat\u0026iacute;as A (2016)\u003c/strong\u003e Diet\u0026ndash;demography relationships in a long‐lived predator: from territories to populations. Oikos 125: 262\u0026ndash;270.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eRollan A, Real J, Bosh R, Tinto A, Hern\u0026aacute;ndez-Mat\u0026iacute;as A (2010) \u003c/strong\u003eModelling the risk of collision with power lines in Bonelli\u0026rsquo;s Eagle\u003cem\u003e Hieraaetus fasciatus\u003c/em\u003e and its conservation implications. Bird Conserv Int 20:279\u0026ndash;294.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eRollan A, Hern\u0026aacute;ndez-Mat\u0026iacute;as A, Real J (2016) \u003c/strong\u003eGuidelines for the conservation of Bonelli\u0026rsquo;s eagle populations. Barcelona, Spain: Universitat de Barcelona.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eRueda C, Jimenez J, Palacios MJ, Margalida A. (2021) \u003c/strong\u003eExploratory and territorial behavior in a reintroduced population of Iberian lynx. Nature Scientifc Reports 11:14148 doi.org/10.1038/s41598-021-93673-z\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eSantos N, Jambas J, Monteiro A, Amaral J, Martins N, Garcia J,\u0026nbsp; Martinez-Fern\u0026aacute;ndez A, Morris Tyler K, Almeida T, Abrantes J, Esteves PJ (2019) \u003c/strong\u003eTrichomonas Infection in a Community of Free-Ranging Domestic and Wild columbiformes and Bonelli\u0026rsquo;s Eagle (\u003cem\u003eAquila fasciata\u003c/em\u003e). Front Vet Sci 6:148. doi: 10.3389/fvets.2019.00148\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eSeddon PJ, Soorae PS, Launay F. (2005) \u003c/strong\u003eTaxonomic bias in reintroduction projects. Anim Conserv 8:51\u0026ndash;58.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eSoutullo A, L\u0026oacute;pez-L\u0026oacute;pez P, Urios V (2008) \u003c/strong\u003eIncorporating spatial structure and stochasticity in endangered Bonelli\u0026rsquo;s Eagle\u0026rsquo;s population models: implications for conservation and management. Biol Conserv 141: 1013\u0026ndash;1020.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eTorrea J, San Juli\u0026oacute;n A, Primo E, Lizarraga A (2021) \u003c/strong\u003eSeguimiento de la poblaci\u0026oacute;n del \u0026aacute;guila de Bonelli (\u003cem\u003eAquila fasciata\u003c/em\u003e) en Navarra. unpublished report for the Government of Navarra\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eViada C (2021) \u003c/strong\u003eAguila perdicera, \u003cem\u003eAquila fasciata\u003c/em\u003e. En: L\u0026oacute;pez-Jim\u0026eacute;nez, N. (Ed.): Libro Rojo de las Aves de Espa\u0026ntilde;a, pp. 534-542. SEO/BirdLife. Madrid.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eVillan\u0026uacute;a D, Casas F, Vi\u0026ntilde;uela J, Garc\u0026iacute;a de la Morena E, Morales MB (2006) \u003c/strong\u003eFirst occurrence of \u003cem\u003eEucoleus contortus\u003c/em\u003e in a Little Bustard \u003cem\u003eTetrax tetrax\u003c/em\u003e: Negative effect of Red-legged Partridge \u003cem\u003eAlectoris rufa\u003c/em\u003e releases on steppe bird conservation? Ibis 149:405-406 DOI: 10.1111/j.1474-919X.2006.00620.x\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eVillan\u0026uacute;a D, P\u0026eacute;rez-Rodr\u0026iacute;guez L, Casas F, Alzaga V, Acevedo P, Vi\u0026ntilde;uela J, Gort\u0026aacute;zar C (2008) \u003c/strong\u003eSanitary risks of Red-legged Partridge releases: introduction of parasites. Eur J Wildl Res 54: 199-204 DOI: 10.1007/s10344-007-0130-2\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eVukovich M, Kilgo JC (2009) \u003c/strong\u003eEffects of radio transmitters on the behavior of Red-headed Woodpeckers. J Field Ornithol 80(3): 308-313.\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003eWolf C, Griffith B, Reed C, Temple S\u003c/strong\u003e (\u003cstrong\u003e1987)\u003c/strong\u003e Avian and mammalian translocations: Update and reanalysis of 1987 survey data. Conserv Biol 10: 1142\u0026ndash;1154.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Captive, GPS, electrocution, predation, reintroduction","lastPublishedDoi":"10.21203/rs.3.rs-1971769/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1971769/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The Bonelli's eagle is one of the rarest and most threatened birds of prey in Europe, which means that great efforts are being made to guarantee its conservation. One of the lines of work is the reintroduction of specimens in areas where the species has recently become extinct and those in which the factors that caused its disappearance have been corrected. The present study presents the results of one of these reintroduction projects carried out in Navarra, Northern Spain, between 2011 and 2021. Forty-seven individuals (36 born in captivity and 11 from wild nests) were released in five places close to historical territories. After those 11 years of work, the occupation of two of the historical and the creation of a new one has been achieved. 44.68 % of the birds died in the first year after their release and 19.14%, during the first month in the field. No significant differences were found associated with the sex or the origin of the specimens in survival during the first month or during the first year after release. 48 % of deaths were related to anthropogenic causes (electrocution, wind farm collision, indeterminate trauma, shooting and poisoning), while 44% were due to predation by mammals or big raptors. This last result had not been described until now and suggests that, when the causes of death of human origin are corrected, those of natural origin appear. The application of this type of actions as a conservation tool for the species is discussed.","manuscriptTitle":"Survival and causes of death of the Bonelli's Eagle released in Navarra, North of Spain.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-09-15 21:18:19","doi":"10.21203/rs.3.rs-1971769/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2f21dba7-a6ac-4847-8c90-7ae38a8679ec","owner":[],"postedDate":"September 15th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-11-29T20:30:57+00:00","versionOfRecord":[],"versionCreatedAt":"2022-09-15 21:18:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1971769","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1971769","identity":"rs-1971769","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}