REM: performance on a high-density fallow deer ( Dama dama ) population
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ORIGINAL PAPER
REM: performance on a high-density fallow deer (Dama dama) population Andrea Marcon 1,2
&
Paolo Bongi 3 & Daniele Battocchio 1 & Marco Apollonio 1
Received: 29 October 2019 / Accepted: 8 July 2020 # Mammal Research Institute, Polish Academy of Sciences, Bialowieza, Poland 2020
Abstract We present an application of the random encounter model (REM) to estimate population density of a closed population of fallow deer (Dama dama). REM promises to be a powerful tool for providing density estimates for species which are not individually recognisable, but it still requires thorough testing to assess its limits and performance. In our study area, effective fencing prevents animals from migrating in or out of the area thus assuring a closed population; still the application of REM presented several challenges, including a very high density (more than 600 ind/km2) and a constant fission/fusion of groups of the study species. We applied both stratified and unstratified analysis approach, and we estimated density over a range of daily range values. The REM approach underestimates the true density value of about 31% and 28% the CV of the estimates was 0.39 and 0.52, for stratified and unstratified approach, respectively. Still it provides evidence in support of REM as a method for providing density estimates of free-ranging unmarked individuals with a fission–fusion social structure. Keywords Field test . Fenced area . Total count . Known density . Camera trapping
Introduction Estimation of population size is one of the most debated issues in wildlife management, and has challenged wildlife ecologists and managers for decades. In recent years, researchers in Europe have raised the question about the need for density estimation, calling for a more ecosystem-oriented view which focuses on the environmental impact of ungulate populations in forests and agricultural land rather than on their actual numbers (Morellet et al. 2007). Nevertheless, some management practices, e.g. the setting of hunting quotas, still require an estimation of population abundance as it often is a legal requirement. Moreover, even if the number of animals alone is not enough to infer the actual impact of the animal population
Communicated by: Marietjie Landman * Andrea Marcon [email protected] 1
Department of Veterinary Medicine, University of Sassari, 07100 Sassari, Italy
2
Via Cavin di Sala 39/A, 30036 Santa Maria di Sala, VE, Italy
3
P.zza Don S. Venturini 3 Olivola, Aulla, 54010 Massa, Italy
on the environment, this data is among the prerequisites to evaluate population–environment interactions. Camera traps are a widespread method for surveying wildlife populations as evidenced by the rapid increase in such studies (O’Connell et al. 2010) but their use for estimating density of species that are not individually recognisable remains a challenge. In most studies, camera trapping is used to investigate terrestrial mammals (Karanth et al. 2004; Karanth et al. 2006; Oliveira-Santos et al. 2008; Berzi et al. 2010; Manzo et a
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