ESTIMATING REPRODUCTIVE TIMING AND FREQUENCYWe assessed the reproductive status of females of both speciesusing visual observations of colour-marked individuals. Slothsprovide maternal care for a single young several months followingparturition, and juveniles are readily observed clinging totheir mothers (Taube et al. 2001). We estimated the timing ofbirth as the midpoint between the last date a female was observedwithout a juvenile and the first date she was observed with ajuvenile. We estimated the timing of juvenile independence as themidpoint between the last date a female was observed with ajuvenile and the first date she was observed without a juvenile.We limited these calculations to instances where ≤2 weeks elapsedbetween consecutive observations such that the average error intiming was likely ≤1 week. We considered an adult female tohave successfully reproduced if she was observed with a juvenileon a single occasion. We used somewhat different criteria to identifyadult females that did not breed for the two species because(i) C. hoffmanni reared young throughout the annual cycle,whereas B. variegatus reared young over a considerably shorterperiod (see below) and (ii) B. variegatus females were easier tolocate than C. hoffmanni females. As a result, we considered anadult female B. variegatus to not have reproduced if it wasobserved without young on at least five occasions from Januaryto June (in May 2012), with at least 1 week elapsing between
consecutive observations. For C. hoffmanni, we considered an
adult female to not have bred in a given year if she was not
observed caring for a juvenile at least once in each of the four
annual quarters (i.e. 3-month periods). Choloepus hoffmanni not
meeting this criterion, or that were observed for <6 months in a
given year, were considered to be of unknown reproductive status.
We limited estimates of the proportion of breeders to 2010
and 2011 (i.e. not 2012) for C. hoffmanni because this species
breeds throughout the year and sampling ended in May 2012.
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