Disappearance rate of chimpanzee scats: Implications for census work on Pan troglodytes

Abstract

Scat (faeces) decay rate estimates are used to calculate animal species abundance and density. For African great apes, this has been measured only for Gorilla; chimpanzee scats are assumed to decay at a faster rate due to lower fibre content. We provide the first systematic measure of scat decay rate duration for Pan troglodytes schweinfurthii, in Kanyawara, Kibale National Park, Uganda. We used two methods:(1) multiple visits to obtain prospective decay rates (PDR) (N = 96 scats) and (2) a novel approach of time-lapse photography (TLP) (N = 17 scats). Most of the visited scats (67%) decayed in ≤24 hr, and median decay rate duration from photographic documentation was 18 hr. Using regression analyses, we tested 11 covariables to determine predictors for decay rate duration. Greater volume of scat and reduced levels of diurnal dung beetle activity were positively associated with longer decay rate duration. Given a high prevalence of dung beetle activity (88% of scats), particularly within 3 hr post-defaecation, we suggest the use of the alternative term, disappearance rate of scats. With a rapid disappearance rate, scat count surveys of unhabituated chimpanzees are challenging; further work is then needed for Pan spp.to determine spatial and temporal differences at intra-and inter-species level. employant des analyses de r egression, nous avons test e 11 covariables pour d eterminer des indicateurs pour la dur ee de la d ecomposition. Un plus grand volume de crottes et une activit e diurne plus faible des bousiers etaient positivement li es a une dur ee de d ecomposition plus longue. Etant donn e une forte pr evalence de l'activit e des bousiers (88% des crottes), sp ecialement dans les trois heures qui suivent la d ef ecation, nous sugg erons un terme alternatif, le taux de disparition des crottes.

Structure of Chimpanzee Gut Microbiomes across Tropical Africa

“…The effects of time between defecation and sampling have been shown to be minor ( 7 ). Due to the presence of dung beetles, rain, and maggots, ape feces generally do not persist for more than a few days ( 107 ). Furthermore, samples older than 3 days are highly degraded and generally do not yield viable DNA for reliable chimpanzee genotyping ( 108 ).…”

Bison (Bison bison) dung Decays Slowly but Can Still be Used to Track Short- and Long-Term Habitat Usage

“…We found that transition rates to later classes during dung decay vary substantially across the year, and full decay of bison dung takes longer than many other well-studied combinations of ecosystems and herbivore (Table 4, Chapman 2004;Kuehl et al 2007;Phillips et al 2018;Erena, Debella, and Bekele 2019).…”

“…For example, captive European Bison defecated 28% less in the winter than in the summer, even with supplemental feed (Eycott et al 2013). For studies that want to convert dung densities to actual population numbers, we recommend that researchers either exercise Erena, Debella, and Bekele 2019;Castle and MacDaid 1972;Rodriguez et al 1998;Phillips et al 2018;Kuehl et al 2007;Tsparid et al 2009;Chapman 2004;Olivier, Ferreira, and caution in using the rate found in this study or determine defecation rates from a larger time span.…”

“…Estimated dung decay ( D ), defined as the time for dung breakdown, determines how long dung counts can be used to estimate habitat usage. For instance, if an animal has a fast dung decay rate (e.g., some apes with a D < 7 days; Kuehl et al 2007; Phillips et al 2018), then dung counts only track recent population density and habitat usage. On the other hand, when dung decay rates are long (several months), it is possible to determine long-term usage instead of short-term usage.…”