New breeding colony and notes on the reproductive phenology of Scarlet Ibis (Eudocimus ruber) in Brazil’s World Heritage Site

New breeding colony and notes on the reproductive phenology of Scarlet Ibis (Eudocimus ruber) in Brazil’s World Heritage Site | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Short Report New breeding colony and notes on the reproductive phenology of Scarlet Ibis (Eudocimus ruber) in Brazil’s World Heritage Site Edgar FERNANDEZ, Gabriel DE LA TORRE, Evelyn Aparecida BUKALONSKI, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7104859/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Mar, 2026 Read the published version in Ornithology Research → Version 1 posted 9 You are reading this latest preprint version Abstract The Scarlet Ibis ( Eudocimus ruber ) is recognised for its vivid scarlet colour and inhabits various wetland environments in South America. Historically, Scarlet Ibis populations were common along the coast of southern and southeastern Brazil until the 19th century. However, dramatic population declines during the 20th century led to the species' regional disappearance. In February 2025, we opportunistically recorded a new breeding colony of Scarlet Ibis at the São Paulo and Paraná states limits. The colony covers an area of ​​approximately 2 ha, with mostly nests built in mangrove trees ( Rizophora mangle ) above the water body. We estimated approximately 40 active nests, but the colony reaches four times the number of nests observed (approximately 200) during the breeding seasons, according to the local community. We observed different reproductive stages, with five nests containing eggs, two nests had nestlings at varying developmental stages, and one nest appeared to be inactivated. Identifying this new Scarlet Ibis breeding colony enhances our understanding of the species' current distribution and reproductive behavior, guiding new conservation efforts in that region. Barra do Ararapira Estuary Protected Areas Ramsar Sites Wetland Figures Figure 1 Figure 2 Full Text The Scarlet Ibis ( Eudocimus ruber ) is recognised for its vivid scarlet colour and inhabits various wetland environments in South America. Its vibrant plumage has fascinated observers for centuries, dating back to early descriptions by Hans Staden in 1550 during his stay on the coast of Santos (Staden 1557). In Brazil, this species is distributed in two disjunct populations located in the northern and southeastern regions, primarily inhabiting mangrove ecosystems (Gonçalves et al. 2010, Olmos and Silva e Silva) 2003). Historically, Scarlet Ibis populations were common along the coast of southern and southeastern Brazil until the 19th century (Straube 2012). However, dramatic population declines during the 20th century led to the species' regional disappearance (Olmos and Silva e Silva 2003, Chupil and Monteiro-Filho 2018, Fernandez et al. 2019). In the 1970s, this population might have been close to collapse (Olmos and Silva e Silva 2003, Grose 2016, Chupil and Monteiro-Filho 2018), with no documented records in Santa Catarina (SC) for approximately 150 years (Grose 2016) and about 80 years in Paraná (PR) (Mafra 1952), and only a few records in São Paulo (SP) (Lago-Paiva 1994). The 1990s marked the reappearance of individuals along the São Paulo coast, including observations of nesting (Olmos and Silva e Silva 2003, Grose 2016). This gradual recolonization culminated in sightings of animals foraging in Paraná by 2008 (Wasilewski et al. 2008, Fernandez et al. 2019) and continuous presence in the Paranaguá Estuarine Complex from 2009 (Vigário et al. 2020, Miotto et al. 2024) and Guaratuba Bay from 2008 (Fernandez et al. 2019). Further south, in 2011, individuals were recorded in Babitonga Bay, Santa Catarina (Fink 2013, Fink and Cremer 2015, Grose 2016). When discussing the breeding biology of the species, historical records, including those by Auguste de Saint-Hilaire (Mafra, 1952), identified breeding locations for Scarlet Ibis in Guaratuba Bay, Paraná, particularly referencing the "Ilha dos Guarás" during August and November. There are recent records of active breeding colonies in Northern Ilha Comprida/SP (24°42´01”S 47°28’01”W; Paludo et al. 2018) and Babitonga Bay/SC (26°29”66”S 48°79’58”W; Fink and Cremer 2015), but no evidence of breeding activities between these two breeding sites (Figure 1). On 05 February 2025, during a field trip dedicated to monitoring marine mammals, and other megafauna species we opportunistically recorded a new breeding colony of Scarlet Ibis close to the Praia do Pontal do Leste, situated on the extreme south of Ilha do Cardoso State Park, near of Superagui National Park, at the São Paulo and Paraná states limits (25°17’58”S 48°05’31”W, Figure 1). The region is part of the Biosphere reserve (UNESCO,1991) and is a World Heritage Site (UNESCO, 1999). The colony is settled in a growth of mangrove trees, mainly composed of Rhizophora mangle , around a natural lake connected with the estuary by a narrow water body in the northern part and surrounded by “ restinga ” and dune formations (Figure 1). On 14 February 2025, we conducted a second field expedition and applied specific methods to characterize the breeding site. For this, we used a DJI Mini 2 drone (SZ DJI Technology Co., Ltd.) and binoculars (10 X 42) to quantify the number of nests, a 4 m ruler stick to measure the nest height, and a 4 m rod with a mirror attached at the end to identify nest activity. Based on field observations and drone images, the colony covers an area of approximately 2 hectares, with most nests built in trees above the water body. During the expedition, we estimated approximately 40 active nests. However, according to residents, notably Mr. Feliciano, the colony has shifted location over the past decade, reaching four times the number of nests observed (approximately 200) during the breeding seasons. All the nests analyzed were in Rhizophora mangle trees, consistent with patterns reported in previous studies (Olmos and Silva e Silva, 2003; Grose, 2016), located at least 1.8 m above the water surface (Table 1). Observations revealed different reproductive stages, with five nests containing eggs, two nests having nestlings at varying developmental stages, and one nest appearing to be inactive (Table 1, Figure 2). These findings align with the species’ breeding phenology, possibly originating from the second and third nesting pulses (Olmos and Silva e Silva 2001). Furthermore, the adult Scarlet Ibis exhibited nuptial coloration (Figure 2), which typically alters in plumage and beak during the breeding season, from November through February (Fink, 2013; Grose, 2016). This new colony can be a “steppingstone” between the previously known breeding colonies, shortening the distance between both sites and increasing the gene flow. We presume the establishment of this new colony may be driven by factors such as habitat availability, anthropogenic pressures on traditional nesting areas, or natural population expansion. This discovery underscores the importance of wetlands and mangrove conservation in supporting biodiversity resilience and adaptability. In conclusion, identifying this new Scarlet Ibis breeding site enhances our understanding of the species' current distribution and reproductive behavior, guiding new conservation efforts in that region. The recovery of this emblematic species can attract attention to the area and serve as both a "Charismatic" and "Umbrella" species to support the efforts of the current protected areas and the entire wetland region, including the Ramsar sites. Declarations Financial Funds This study was conducted as part of the Marine Megafauna Ecology project; however, no funding was allocated explicitly for the Scarlet Ibis records, as they were gathered opportunistically . Author Contribution EF and GT were responsible for the fieldwork, analysed the data, prepared the figures, and wrote the main manuscript. EB contributed to the fieldwork. CD designed the project survey, reviewed the analysis and figures, and contributed to writing the main manuscript. All authors reviewed the manuscript. Acknowledgement We are grateful to the UFPR team of the Beach Monitoring Project of the Campos Basin (PMP-BS) for their assistance with logistics and to the team of Laboratório de Ecologia e Conservação (UFPR) for their help in the field. CD received a research productivity fellowship from the Brazilian National Council for Scientific and Technological Development (CNPq—Brasil n° 316593/20235–0).The authors have no conflicts of interest. The area was accessed for the beach monitoring program under permit (ABIO/IBAMA 640-2015), and the Marine Mammals Project (SISBIO/ICMBIO 18688). No biological samples from birds or nests were collected during these observations. Data Availability The manuscript is based on a limited number of samples; however, data collected in the field will be available upon request to the authors References Chupil H, Monteiro-Filho EL (2018) History of the Scarlet Ibis Eudocimus ruber in south and south-east Brazil. Bulletin of the British Ornithologists’ Club , 138 (4), 281-285. https://doi.org/10.25226/bboc.v138i4.2018.a1 Fernandez E, Silva F, Wasilewski M (2019) The Scarlet Ibis (Eudocimus ruber): it is necessary to know it to preserve it . Instituto Guaju. São Paulo: ArteSam Editora, 16p. Fink D (2013) Characterization of waterbird colonies in Babitonga Bay and preliminary assessment of their contamination. Master's thesis. Department of Health and Environment, University of the Region of Joinville. 92 p. Retrieved from: http://univille.edu.br/community/mestrado_saude_meio_ambiente/VirtualDisk.html/downloadDirect/526371. Fink D, Cremer MJ (2015) The return of the Scarlet Ibis: first breeding event in southern Brazil after local extinction. Revista Brasileira de Ornitologia , 23 , 385-391. Gonçalves EC, Ferrari SF, Burlamaqui TCT, Miranda L, Santos MS, Silva A, Schneider, MPC (2010) Genetic diversity and differentiation of three Brazilian populations of Scarlet ibis ( Eudocimus ruber ). Journal of Ornithology , 151 , 797-803. https://doi.org/10.1007/s10336-010-0515-y Grose AV (2016) The Scarlet Ibis Eudocimus ruber (Aves: Threskiornithidae) in the Babitonga Bay estuary, northern coast of Santa Catarina: repopulation, distribution, and biology. Doctoral thesis. Department of Zoology, Federal University of Paraná. 84 p. Retrieved from: http://hdl.handle.net/1884/45492. Lago-Paiva C (1994) Notas sobre a ocorrência e distribuição de Eudocimus ruber (L., 1758) (Aves, Threskiornithidae) no Estado de São Paulo. Acta Biol. Leopoldensia 16: 119–124. Mafra J (1952) History of the municipality of Guaratuba. Guaratuba: s.e., 17p. Miotto ML, Domit C, Melo GDD, Domenico MD (2024) Aquatic avifauna in a subtropical estuarine system, a World Heritage site (Paraná, southern Brazil). Ocean and Coastal Research , 72 , e24041. https://doi.org/10.1590/2675-2824072.23104 Olmos F, Silva e Silva R (2001) Breeding biology and nest site characteristics of the Scarlet ibis in southeastern Brazil. Waterbirds 24: 58–67. Olmos F, Silva e Silva R (2003) Scarlet Ibis: environment, flora, and fauna of the Santos– Cubatão mangroves, Brazil. São Paulo: Empresa das Artes, 216p. Staden H (1557) Viagem ao Brasil. Academia Brasileira, Rio de Janeiro, 186p. Straube FC (2012) Ruinas e urubus: história da ornitologia no Paraná. Período de Naterer 1 (1820-1834). Hori Cadernos Técnicos, Curitiba, 264p. Paludo D, Campos FPD, Collaço FL, Fracasso HAA, Martuscelli P, Klonowski VS (2018) Reproduction of Eudocimus ruber in the Iguape-Cananéia-Ilha Comprida estuary complex, São Paulo, Brazil. Atualidades Ornitológicas 202: 8–15. Vigário DC, Krul R, Spach HL (2020) Ecologia de Eudocimus ruber (Pelecaniformes, Threskiornithidae) no litoral do estado do Paraná, Brasil. Oecologia Australis , 24 , 970-970. Wasilewski M, Silva FC, Nascimento M, Scherer-Neto P (2008) Occurrence and documented record of the Scarlet Ibis Eudocimus ruber (Threskiornithidae, Aves) in Guaratuba Bay, Paraná. Atualidades Ornitológicas Journal 145: 10–11. Table Table 1 – Breeding nest information of Scarlet Ibis ( Eudocimus ruber ), recorded in the Praia de Pontal do Leste, located in the geographical border of São Paulo and Paraná states, in February 2025. Nest Date Height (m) from water surface Nest tree Active Nest Eggs Nestling 1 14 Feb 2025 2,5 Rizophora mangle yes 2 - 2 14 Feb 2025 2,2 Rizophora mangle yes 2 - 3 14 Feb 2025 2,5 Rizophora mangle yes 1 - 4 14 Feb 2025 2,4 Rizophora mangle yes - 2 5 14 Feb 2025 2,4 Rizophora mangle yes - - 6 14 Feb 2025 1,8 Rizophora mangle no - - 7 14 Feb 2025 2 Rizophora mangle yes 2 - 8 14 Feb 2025 2,5 Rizophora mangle yes - 1 9 14 Feb 2025 2,8 Rizophora mangle yes 2 - Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 04 Mar, 2026 Read the published version in Ornithology Research → Version 1 posted Editorial decision: Revision requested 05 Nov, 2025 Reviews received at journal 05 Nov, 2025 Reviewers agreed at journal 24 Oct, 2025 Reviews received at journal 24 Oct, 2025 Reviewers agreed at journal 15 Oct, 2025 Reviewers invited by journal 13 Oct, 2025 Editor assigned by journal 25 Jul, 2025 Submission checks completed at journal 25 Jul, 2025 First submitted to journal 11 Jul, 2025 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. 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15:46:34","extension":"html","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":56313,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7104859/v1/417564c2773162d6dc3f5fe9.html"},{"id":94473830,"identity":"2279ee97-bd0d-4450-8ee0-8df93b7bdbe7","added_by":"auto","created_at":"2025-10-27 15:45:52","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1855870,"visible":true,"origin":"","legend":"\u003cp\u003eThe new Scarlet Ibis breeding colony, the breeding area, and the nest locations recorded in the Praia de Pontal do Leste, located on the geographical border of São Paulo and Paraná. We also report the previously found breeding colonies in Ilha Comprida, São Paulo (Paludo et al., 2018) and Baia da Babitonga, Santa Catarina (Fink and Cremer, 2015)\u003c/p\u003e","description":"","filename":"Figura1REV2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7104859/v1/e2e9116c5db84db63c112d4e.jpg"},{"id":94473843,"identity":"b44a3578-bb79-4cba-9afb-80fbf2e76cfc","added_by":"auto","created_at":"2025-10-27 15:45:55","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":8381209,"visible":true,"origin":"","legend":"\u003cp\u003ePhotographic records of nest activities from the new Scarlet Ibis breeding colony, in the Praia de Pontal do Leste, located in the geographical border of São Paulo and Paraná states.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7104859/v1/dc5096e7379903fdf89a2b88.jpg"},{"id":104250750,"identity":"565fab2f-8fe0-455c-8b51-3e30c8ea3b12","added_by":"auto","created_at":"2026-03-09 16:07:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10560523,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7104859/v1/33496106-38f1-4b66-925e-31abb3bc764c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"New breeding colony and notes on the reproductive phenology of Scarlet Ibis (Eudocimus ruber) in Brazil’s World Heritage Site","fulltext":[{"header":"Full Text","content":"\u003cp\u003eThe Scarlet Ibis (\u003cem\u003eEudocimus ruber\u003c/em\u003e) is recognised for its vivid scarlet colour and inhabits various wetland environments in South America. Its vibrant plumage has fascinated observers for centuries, dating back to early descriptions by Hans Staden in 1550 during his stay on the coast of Santos (Staden 1557). In Brazil, this species is distributed in two disjunct populations located in the northern and southeastern regions, primarily inhabiting mangrove ecosystems (Gon\u0026ccedil;alves et al. 2010, Olmos and Silva e Silva) 2003).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHistorically, Scarlet Ibis populations were common along the coast of southern and southeastern Brazil until the 19th century (Straube 2012). However, dramatic population declines during the 20th century led to the species\u0026apos; regional disappearance (Olmos and Silva e Silva 2003, Chupil and Monteiro-Filho 2018, Fernandez et al. 2019). In the 1970s, this population might have been close to collapse (Olmos and Silva e Silva 2003, Grose 2016, Chupil and Monteiro-Filho 2018), with no documented records in Santa Catarina (SC) for approximately 150 years (Grose 2016) and about 80 years in Paran\u0026aacute; (PR) (Mafra 1952), and only a few records in S\u0026atilde;o Paulo (SP) (Lago-Paiva 1994). The 1990s marked the reappearance of individuals along the S\u0026atilde;o Paulo coast, including observations of nesting (Olmos and Silva e Silva 2003, Grose 2016). This gradual recolonization culminated in sightings of animals foraging in Paran\u0026aacute; by 2008 (Wasilewski et al. 2008, Fernandez et al. 2019) and continuous presence in the Paranagu\u0026aacute; Estuarine Complex from 2009 (Vig\u0026aacute;rio et al. 2020, Miotto et al. 2024) and Guaratuba Bay from 2008 (Fernandez et al. 2019). Further south, in 2011, individuals were recorded in Babitonga Bay, Santa Catarina (Fink 2013, Fink and Cremer 2015, Grose 2016).\u003c/p\u003e\n\u003cp\u003eWhen discussing the breeding biology of the species, historical records, including those by Auguste de Saint-Hilaire (Mafra, 1952), identified breeding locations for Scarlet Ibis in Guaratuba Bay, Paran\u0026aacute;, particularly referencing the \u0026quot;Ilha dos Guar\u0026aacute;s\u0026quot; during August and November. There are recent records of active breeding colonies in Northern Ilha Comprida/SP (24\u0026deg;42\u0026acute;01\u0026rdquo;S 47\u0026deg;28\u0026rsquo;01\u0026rdquo;W; Paludo et al. 2018) and Babitonga Bay/SC (26\u0026deg;29\u0026rdquo;66\u0026rdquo;S 48\u0026deg;79\u0026rsquo;58\u0026rdquo;W; Fink and Cremer 2015), but no evidence of breeding activities between these two breeding sites (Figure 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOn 05 February 2025, during a field trip dedicated to monitoring marine mammals, and other megafauna species we opportunistically recorded a new breeding colony of Scarlet Ibis close to the Praia do Pontal do Leste, situated on the extreme south of Ilha do Cardoso State Park, near of Superagui National Park, at the S\u0026atilde;o Paulo and Paran\u0026aacute; states limits (25\u0026deg;17\u0026rsquo;58\u0026rdquo;S 48\u0026deg;05\u0026rsquo;31\u0026rdquo;W, Figure 1). The region is part of the Biosphere reserve (UNESCO,1991) and is a World Heritage Site (UNESCO, 1999). The colony is settled in a growth of mangrove trees, mainly composed of \u003cem\u003eRhizophora mangle\u003c/em\u003e, around a natural lake connected with the estuary by a narrow water body in the northern part and surrounded by \u0026ldquo;\u003cem\u003erestinga\u003c/em\u003e\u0026rdquo; and dune formations (Figure 1). On 14 February 2025, we conducted a second field expedition and applied specific methods to characterize the breeding site. For this, we used a DJI Mini 2 drone (SZ DJI Technology Co., Ltd.) and binoculars (10 X 42) to quantify the number of nests, a 4 m ruler stick to measure the nest height, and a 4 m rod with a mirror attached at the end to identify nest activity. Based on field observations and drone images, the colony covers an area of approximately 2 hectares, with most nests built in trees above the water body. During the expedition, we estimated approximately 40 active nests. However, according to residents, notably Mr. Feliciano, the colony has shifted location over the past decade, reaching four times the number of nests observed (approximately 200) during the breeding seasons.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll the nests analyzed were in \u003cem\u003eRhizophora mangle\u003c/em\u003e trees, consistent with patterns reported in previous studies (Olmos and Silva e Silva, 2003; Grose, 2016), located at least 1.8 m above the water surface (Table 1). Observations revealed different reproductive stages, with five nests containing eggs, two nests having nestlings at varying developmental stages, and one nest appearing to be inactive (Table 1, Figure 2). These findings align with the species\u0026rsquo; breeding phenology, possibly originating from the second and third nesting pulses (Olmos and Silva e Silva 2001). Furthermore, the adult Scarlet Ibis exhibited nuptial coloration (Figure 2), which typically alters in plumage and beak during the breeding season, from November through February (Fink, 2013; Grose, 2016).\u003c/p\u003e\n\u003cp\u003eThis new colony can be a \u0026ldquo;steppingstone\u0026rdquo; between the previously known breeding colonies, shortening the distance between both sites and increasing the gene flow. We presume the establishment of this new colony may be driven by factors such as habitat availability, anthropogenic pressures on traditional nesting areas, or natural population expansion. This discovery underscores the importance of wetlands and mangrove conservation in supporting biodiversity resilience and adaptability. In conclusion, identifying this new Scarlet Ibis breeding site enhances our understanding of the species\u0026apos; current distribution and reproductive behavior, guiding new conservation efforts in that region. The recovery of this emblematic species can attract attention to the area and serve as both a \u0026quot;Charismatic\u0026quot; and \u0026quot;Umbrella\u0026quot; species to support the efforts of the current protected areas and the entire wetland region, including the Ramsar sites.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFinancial Funds\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted as part of the Marine Megafauna Ecology project; however, no funding was allocated explicitly for the Scarlet Ibis records, as they were gathered opportunistically\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eEF and GT were responsible for the fieldwork, analysed the data, prepared the figures, and wrote the main manuscript. EB contributed to the fieldwork. CD designed the project survey, reviewed the analysis and figures, and contributed to writing the main manuscript. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe are grateful to the UFPR team of the Beach Monitoring Project of the Campos Basin (PMP-BS) for their assistance with logistics and to the team of Laborat\u0026oacute;rio de Ecologia e Conserva\u0026ccedil;\u0026atilde;o (UFPR) for their help in the field. CD received a research productivity fellowship from the Brazilian National Council for Scientific and Technological Development (CNPq\u0026mdash;Brasil n\u0026deg; 316593/20235\u0026ndash;0).The authors have no conflicts of interest. The area was accessed for the beach monitoring program under permit (ABIO/IBAMA 640-2015), and the Marine Mammals Project (SISBIO/ICMBIO 18688). No biological samples from birds or nests were collected during these observations.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe manuscript is based on a limited number of samples; however, data collected in the field will be available upon request to the authors\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eChupil H, Monteiro-Filho EL (2018) History of the Scarlet Ibis \u003cem\u003eEudocimus ruber\u003c/em\u003e \u003c/li\u003e\n\u003cli\u003ein south and south-east Brazil. \u003cem\u003eBulletin of the British Ornithologists\u0026rsquo; Club\u003c/em\u003e, \u003cem\u003e138\u003c/em\u003e(4), 281-285. https://doi.org/10.25226/bboc.v138i4.2018.a1 \u003c/li\u003e\n\u003cli\u003eFernandez E, Silva F, Wasilewski M (2019) \u003cem\u003eThe Scarlet Ibis (Eudocimus ruber): it is necessary to know it to preserve it\u003c/em\u003e. Instituto Guaju. S\u0026atilde;o Paulo: ArteSam Editora, 16p.\u003c/li\u003e\n\u003cli\u003eFink D (2013) \u003cem\u003eCharacterization of waterbird colonies in Babitonga Bay and preliminary assessment of their contamination.\u003c/em\u003e Master\u0026apos;s thesis. Department of Health and Environment, University of the Region of Joinville. 92 p. Retrieved from: http://univille.edu.br/community/mestrado_saude_meio_ambiente/VirtualDisk.html/downloadDirect/526371.\u003c/li\u003e\n\u003cli\u003eFink D, Cremer MJ (2015) The return of the Scarlet Ibis: first breeding event in southern Brazil after local extinction. \u003cem\u003eRevista Brasileira de Ornitologia\u003c/em\u003e, \u003cem\u003e23\u003c/em\u003e, 385-391.\u003c/li\u003e\n\u003cli\u003eGon\u0026ccedil;alves EC, Ferrari SF, Burlamaqui TCT, Miranda L, Santos MS, Silva A, Schneider, MPC (2010) Genetic diversity and differentiation of three Brazilian populations of Scarlet ibis (\u003cem\u003eEudocimus ruber\u003c/em\u003e). \u003cem\u003eJournal of Ornithology\u003c/em\u003e, \u003cem\u003e151\u003c/em\u003e, 797-803. https://doi.org/10.1007/s10336-010-0515-y\u003c/li\u003e\n\u003cli\u003eGrose AV (2016) \u003cem\u003eThe Scarlet Ibis Eudocimus ruber (Aves: Threskiornithidae) in the Babitonga Bay estuary, northern coast of Santa Catarina: repopulation, distribution, and biology.\u003c/em\u003e Doctoral thesis. Department of Zoology, Federal University of Paran\u0026aacute;. 84 p. Retrieved from: http://hdl.handle.net/1884/45492.\u003c/li\u003e\n\u003cli\u003eLago-Paiva C (1994) Notas sobre a ocorr\u0026ecirc;ncia e distribui\u0026ccedil;\u0026atilde;o de \u003cem\u003eEudocimus ruber\u003c/em\u003e (L., 1758) (Aves, Threskiornithidae) no Estado de S\u0026atilde;o Paulo. \u003cem\u003eActa Biol. Leopoldensia\u003c/em\u003e 16: 119\u0026ndash;124.\u003c/li\u003e\n\u003cli\u003eMafra J (1952) \u003cem\u003eHistory of the municipality of Guaratuba.\u003c/em\u003e Guaratuba: s.e., 17p.\u003c/li\u003e\n\u003cli\u003eMiotto ML, Domit C, Melo GDD, Domenico MD (2024) Aquatic avifauna in a subtropical estuarine system, a World Heritage site (Paran\u0026aacute;, southern Brazil). \u003cem\u003eOcean and Coastal Research\u003c/em\u003e, \u003cem\u003e72\u003c/em\u003e, e24041. https://doi.org/10.1590/2675-2824072.23104\u003c/li\u003e\n\u003cli\u003eOlmos F, Silva e Silva R (2001) Breeding biology and nest site characteristics of the Scarlet ibis in southeastern Brazil. \u003cem\u003eWaterbirds \u003c/em\u003e24: 58\u0026ndash;67.\u003c/li\u003e\n\u003cli\u003eOlmos F, Silva e Silva R (2003) \u003cem\u003eScarlet Ibis: environment, flora, and fauna of the Santos\u0026ndash; Cubat\u0026atilde;o mangroves, Brazil.\u003c/em\u003e S\u0026atilde;o Paulo: Empresa das Artes, 216p.\u003c/li\u003e\n\u003cli\u003eStaden H (1557) Viagem ao Brasil. Academia Brasileira, Rio de Janeiro, 186p.\u003c/li\u003e\n\u003cli\u003eStraube FC (2012) Ruinas e urubus: hist\u0026oacute;ria da ornitologia no Paran\u0026aacute;. Per\u0026iacute;odo de Naterer 1 (1820-1834). Hori Cadernos T\u0026eacute;cnicos, Curitiba, 264p.\u003c/li\u003e\n\u003cli\u003ePaludo D, Campos FPD, Colla\u0026ccedil;o FL, Fracasso HAA, Martuscelli P, Klonowski VS (2018) Reproduction of \u003cem\u003eEudocimus ruber\u003c/em\u003e in the Iguape-Canan\u0026eacute;ia-Ilha Comprida estuary complex, S\u0026atilde;o Paulo, Brazil. \u003cem\u003eAtualidades Ornitol\u0026oacute;gicas \u003c/em\u003e202: 8\u0026ndash;15.\u003c/li\u003e\n\u003cli\u003eVig\u0026aacute;rio DC, Krul R, Spach HL (2020) Ecologia de \u003cem\u003eEudocimus ruber\u003c/em\u003e (Pelecaniformes, Threskiornithidae) no litoral do estado do Paran\u0026aacute;, Brasil. \u003cem\u003eOecologia Australis\u003c/em\u003e, \u003cem\u003e24\u003c/em\u003e, 970-970.\u003c/li\u003e\n\u003cli\u003eWasilewski M, Silva FC, Nascimento M, Scherer-Neto P (2008) \u003cem\u003eOccurrence and documented record of the Scarlet Ibis Eudocimus ruber (Threskiornithidae, Aves) in Guaratuba Bay, Paran\u0026aacute;.\u003c/em\u003e \u003cem\u003eAtualidades Ornitol\u0026oacute;gicas Journal\u003c/em\u003e 145: 10\u0026ndash;11.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table","content":"\u003cp\u003eTable 1 \u0026ndash; Breeding nest information of Scarlet Ibis (\u003cem\u003eEudocimus ruber\u003c/em\u003e), recorded in the Praia de Pontal do Leste, located in the geographical border of S\u0026atilde;o Paulo and Paran\u0026aacute; states, in February 2025.\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"507\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eNest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003eDate\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003eHeight (m) from water surface\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eNest tree\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eActive Nest\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003eEggs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003eNestling\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e14 Feb 2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e2,5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cem\u003eRizophora mangle\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eyes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e14 Feb 2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e2,2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cem\u003eRizophora mangle\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eyes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e14 Feb 2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e2,5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cem\u003eRizophora mangle\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eyes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e14 Feb 2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e2,4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cem\u003eRizophora mangle\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eyes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e14 Feb 2025\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e2,4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cem\u003eRizophora mangle\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 69px;\"\u003e\n \u003cp\u003eyes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 54px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n 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\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"ornithology-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"orni","sideBox":"Learn more about [Ornithology Research](https://link.springer.com/journal/43388)","snPcode":"43388","submissionUrl":"https://submission.nature.com/new-submission/43388/3","title":"Ornithology Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Barra do Ararapira, Estuary, Protected Areas Ramsar Sites, Wetland","lastPublishedDoi":"10.21203/rs.3.rs-7104859/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7104859/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Scarlet Ibis (\u003cem\u003eEudocimus ruber\u003c/em\u003e) is recognised for its vivid scarlet colour and inhabits various wetland environments in South America. Historically, Scarlet Ibis populations were common along the coast of southern and southeastern Brazil until the 19th century. However, dramatic population declines during the 20th century led to the species' regional disappearance. In February 2025, we opportunistically recorded a new breeding colony of Scarlet Ibis at the S\u0026atilde;o Paulo and Paran\u0026aacute; states limits. The colony covers an area of ​​approximately 2 ha, with mostly nests built in mangrove trees (\u003cem\u003eRizophora mangle\u003c/em\u003e) above the water body. We estimated approximately 40 active nests, but the colony reaches four times the number of nests observed (approximately 200) during the breeding seasons, according to the local community. We observed different reproductive stages, with five nests containing eggs, two nests had nestlings at varying developmental stages, and one nest appeared to be inactivated. Identifying this new Scarlet Ibis breeding colony enhances our understanding of the species' current distribution and reproductive behavior, guiding new conservation efforts in that region.\u003c/p\u003e","manuscriptTitle":"New breeding colony and notes on the reproductive phenology of Scarlet Ibis (Eudocimus ruber) in Brazil’s World Heritage Site","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-27 14:28:23","doi":"10.21203/rs.3.rs-7104859/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-05T17:54:55+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-05T17:36:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"160784021776313748640374884500904619314","date":"2025-10-24T15:39:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-24T14:19:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"46987395828169942555378824957104117827","date":"2025-10-15T11:56:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-13T10:42:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-25T11:08:49+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-25T11:06:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ornithology Research","date":"2025-07-11T23:57:51+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"ornithology-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"orni","sideBox":"Learn more about [Ornithology Research](https://link.springer.com/journal/43388)","snPcode":"43388","submissionUrl":"https://submission.nature.com/new-submission/43388/3","title":"Ornithology Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"7ab6435d-bbd6-495b-b78b-324f3c81d62c","owner":[],"postedDate":"October 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-09T16:04:03+00:00","versionOfRecord":{"articleIdentity":"rs-7104859","link":"https://doi.org/10.1007/s43388-026-00276-1","journal":{"identity":"ornithology-research","isVorOnly":false,"title":"Ornithology Research"},"publishedOn":"2026-03-04 15:59:54","publishedOnDateReadable":"March 4th, 2026"},"versionCreatedAt":"2025-10-27 14:28:23","video":"","vorDoi":"10.1007/s43388-026-00276-1","vorDoiUrl":"https://doi.org/10.1007/s43388-026-00276-1","workflowStages":[]},"version":"v1","identity":"rs-7104859","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7104859","identity":"rs-7104859","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}