a b s t r a c tFundamental questions in ecology and conservation require reliable data about population size and structure. For freshwater turtles, such data are often obtained via mark-recapture trapping, but commonly used trap types are biased in the sex and age classes they sample although these biases are seldom quantified. We present data from 11 populations of Western painted turtles (Chrysemys picta bellii; 1107 turtles total, n caught per pond 6-322) captured in hoop traps, dip-nets, and basking traps to examine bias in captures and the impact on estimates of population size and sex/age ratios. Hatchlings and juveniles were primarily captured in dip-nets, while hoop nets had the lowest capture rates for adults. Most turtles were caught only once; among recaptures, the majority were recaptured in the same trap type. Estimates of population size and sex/age ratios varied strongly when we calculated results from each trap type separately versus combining all captures. These results show clearly that turtle sampling that uses only one trap type will almost certainly mis-estimate population size and sex/age ratios. These results are troubling in the light of current practice: of population studies of North American turtles published during 2009-2014, 45% used only one trap type, and 49% of studies did not even mention possible sampling biases. The conservation implications are serious, as current trapping efforts probably result in erroneous population estimates and sex/age ratios, which may encourage management actions that are not needed or may obscure actions that are in fact necessary for viable populations.
Wide-ranging species typically differ morphologically across their ranges. Bergmann's rule suggests that taxa in colder environments are bigger than related taxa in warmer locations. We examined 767 painted turtles (Chrysemys picta) in ten populations near their northwestern range edge in south-central British Columbia, Canada, in conjunction with previous data, to test the hypotheses of (1) a Bergmann's latitudinal cline, and (2) that males and females show similar latitudinal variation in size. We also explicitly test the impact of high local variation on range-wide inference. Female and male turtles showed similar latitudinal clines in body size; the degree of sexual dimorphism did not change across the range. Importantly, local variation in sexual dimorphism across ponds was nearly as high as the previously observed continental variation. Indeed, we found both the lowest and the highest degrees of sexual size dimorphism that have ever been reported for this species. Further, differing criteria in the literature for identifying mature females compound the difficulty of interpreting latitudinal clines in size or dimorphism. Our results highlight the need for much more systematic local and regional sampling as inputs for latitudinal or other comparative analyses such as Rensch's rule because insufficient sampling of high local variation may mask important ecological and evolutionary patterns.
The codling moth is a serious pest of apples in most regions of the world where this fruit is produced. The sterile insect technique is one strategy used to control this pest and is employed as part of an area-wide integrated pest management program for the codling moth in British Columbia, Canada. Modified fixed wing aircraft are the most common method for the release of sterile insects in large area-wide pest management programs. However, aerial release with a full-size aircraft can be prohibitively expensive. We evaluated the use of small, uncrewed aircraft systems (UASs) for the release of sterile codling moths. Sterile codling moths released from greater altitudes were more broadly distributed and drifted more in strong winds, compared to those released from lower altitudes. Most of the released insects were recaptured in a 50 m wide swath under the release route. Recapture rates for aerially released insects were 40–70% higher compared to those released from the ground. UASs provide a promising alternative to ground release and conventional aircraft for the release of sterile codling moths.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.