Population Estimation Methods for Free-Ranging Dogs: A Systematic Review.

Vinícius Silva Belo,Guilherme Loureiro Werneck,Juliane Kaminski,Eduardo Sérgio Da Silva,Claudio José Struchiner,David Soeiro Barbosa

doi:10.1371/journal.pone.0144830

Abstract

The understanding of the structure of free-roaming dog populations is of extreme importance for the planning and monitoring of populational control strategies and animal welfare. The methods used to estimate the abundance of this group of dogs are more complex than the ones used with domiciled owned dogs. In this systematic review, we analyze the techniques and the results obtained in studies that seek to estimate the size of free-ranging dog populations. Twenty-six studies were reviewed regarding the quality of execution and their capacity to generate valid estimates. Seven of the eight publications that take a simple count of the animal population did not consider the different probabilities of animal detection; only one study used methods based on distances; twelve relied on capture-recapture models for closed populations without considering heterogeneities in capture probabilities; six studies applied their own methods with different potential and limitations. Potential sources of bias in the studies were related to the inadequate description or implementation of animal capturing or viewing procedures and to inadequacies in the identification and registration of dogs. Thus, there was a predominance of estimates with low validity. Abundance and density estimates carried high variability, and all studies identified a greater number of male dogs. We point to enhancements necessary for the implementation of future studies and to potential updates and revisions to the recommendations of the World Health Organization with respect to the estimation of free-ranging dog populations.

Highlights

In Ecology, the term “population” defines a group of organisms of one species that interbreed and live in the same place at the same time [1]
A great percentage of them are domiciliary and restricted animals, there is still a great percentage of animals continuously circulating on the street [8] forming specific population groups which are named free-roaming, PLOS ONE | DOI:10.1371/journal.pone
Even though publications with free roaming dogs were less frequent than with domiciliary dogs [9], non-restricted dogs had their population size estimated in different studies [10]

Summary

Introduction

In Ecology, the term “population” defines a group of organisms of one species that interbreed and live in the same place at the same time [1]. A great percentage of them are domiciliary and restricted animals, there is still a great percentage of animals continuously circulating on the street [8] forming specific population groups which are named free-roaming, PLOS ONE | DOI:10.1371/journal.pone.0144830. Even though publications with free roaming dogs were less frequent than with domiciliary dogs [9], non-restricted dogs had their population size estimated in different studies [10]. Stray dogs can be considered the primary victims of irresponsible owners who reject their pets into the streets [10, 11]. The existence of free-roaming dogs is considered an important problem, for the animal welfare and for Public Health [12, 13]

Methods

Results

Conclusion