Too many dogs in the park I: Comparing four methods for estimating the abundance of open populations of free-ranging dogs in the Tehuacan-Cuicatlan Biosphere Reserve, Mexico.

Abstract The Tehuacan Cuicatlan Biosphere Reserve (TCBR), encompasses several human settlements, in addition to a garbage dump that serves as the main subsidy to maintain populations of free-ranging dogs (FRD) and feral dogs (FD), Canis lupus familiaris. Little is known about the best monitoring methods to estimate population indicators of FRD. Four monitoring methods were applied: one method applied exclusively for the garbage dump, and three different methods in two sampling sites, over the same spatial scale, to estimate the population indicators that guide decision-making on mitigation measures in the presence of FRD in protected natural areas (PNA). FRD monitoring is an essential activity for the management and control of their free-living populations, mainly in PNA, where they can become harmful to the environment. Through the application of four different monitoring methods to estimate FRD population indicators, we determined which of these are best adapted to varied sampling efforts. Traditional monitoring methods and, specifically, the capture-mark-recapture method applied to FRD are mainly designed for closed populations. Due to the complexity of free-living monitoring, and since FRD are reclusive in the presence of humans, we adapted a method for an open population at a landfill, mainly based on a study conducted in India. The four methods used in FRD monitoring in open populations show advantages and disadvantages, but we consider that in some situations (e.g., costs, execution time, materials, etc.) the capture-mark-recapture (C-M-R) model based on photographs and individual identification best fits most sampling models in relation to sampling effort, analysis, and expected outcomes.