Unveiling the Limitations of Scat Surveys to Monitor Social Species: A Case Study on River Otters

Abstract

We examined the relationship between the production of sites with feces (i.e., latrines) and river otter (Lontra canadensis) abundance to determine whether scat surveys were adequate for monitoring relative population size for species leaving activity signs in a clumped distribution on the landscape. We conducted winter riparian transects to simultaneously monitor otter abundance via snow tracks and latrine sites along the rivers of Kouchibouguac National Park and surrounding area in New Brunswick, Canada. Our data showed that latrine abundance poorly reflected otter abundance for given stretches of rivers because the relationship was nonlinear and reached a plateau. The number of latrine sites was not related to the time period since last snowfall, which indicated that otters repetitively defecated at the same sites. Individual otters and groups did not produce activity signs over larger distances as a function of time, which indicated that they tend to stay in their home ranges in winter. We discuss why scat survey protocols based on determining presence—absence of a species at predetermined search sites may poorly reflect population size, as well as population fluctuations in time. Caution is advised when interpreting data from such surveys for species for which feces or other activity signs surveyed play a role in intraspecific communication and tend to be in a clumped distribution on the landscape.

The dispersion and detection patterns of mtDNA‐assigned red fox Vulpes vulpes scats in Tasmania are anomalous

“…). Foxes frequently return to the same locations in their home range (Carter, Luck & McDonald ), and the distribution of fox scats and those of other territorial mammals is clumped (Belt, Delibes & Raw ; Gallant, Vasseur & Berube ). This would increase the probability of encountering additional scats once single ones have been located and suggests that our model that assumes even scat distribution is likely to provide a conservative estimate of fox scat detection probability in this regard.…”

“…A weekly pool of scats (n s ) was assumed to be apportioned evenly over a home range despite a greater likelihood of a clustering of scats due to recurrent marking (Belt, Delibes & Raw ; Gallant, Vasseur & Berube ) that had yielded replicated genotypes in molecular surveys (Marks et al . ).…”

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“…This method is more conservative for estimating wildlife relative abundance with respect to marking intensity (the number of faeces found per length), which is a method recently criticised in the literature (e.g. Gallant et al 2007;Harrington et al 2007). Bertolino and Ingegno (2009) recently highlighted the importance of modelling the distribution of coypu to determine habitat requirements of the species.…”

Detecting genomic damages in the frog Dendropsophus minutus: preserved versus perturbed areas

“…Amphibian population declines are associated with "habitat loss" connected mainly to agricultural expansion. It is likely to represent the single most important human activity affecting lowland populations (Gallant et al 2007;Mann et al 2009). …”