Figure S1. Effect of assuming a constant removal probability when it is actually decreasing or increasing in time. Proportion of remaining carcasses (solid black lines) and the corresponding daily removal probabilities (dotted black lines) for four simulation scenarios. To obtain the proportions of remaining carcasses and the removal probabilities , Weibull distributions for the persistence times were assumed. For simulating decreasing removal probabilities with time, a was set to 0.7, and for increasing removal probabilities a was set to 1.3. k was then obtained using the mean assumed persistence time T: k ¼ ðCð1 þ ð1=aÞÞ=T. The proportion of remaining carcasses per day is S(t) ¼ e [-(kt) a ] and the daily removal probability (1-s(t))¼1-e [-(k(tþ1)) a ] /e [-(kt) a ] , where s is the probability that a carcass remains ('survives') one day. Grey solid lines are the proportion of remaining carcasses under the (false) assumption of a constant removal rate (grey dotted lines). 350 Ó WILDLIFE BIOLOGY 17:4 (2011)
his article is a tutorial for the R-package carcass. It starts with a short overview of common methods used to estimate mortality based on carcass searches. hen, it guides step by step through a simple example. First, the proportion of animals that fall into the search area is estimated. Second, carcass persistence time is estimated based on experimental data. hird, searcher efficiency is estimated. Fourth, these three estimated parameters are combined to obtain the probability that an animal killed is found by an observer. Finally, this probability is used together with the observed number of carcasses found to obtain an estimate for the total number of killed animals together with a credible interval.
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