SREL Reprint #3343
Trap characteristics and species morphology explain size-biased sampling of two salamander species
Thomas M. Luhring1,2, Grant M. Connette3, Christopher M. Schalk1,4
1Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802, USA
2Current Address: Biological Sciences, University of Nebraska, 410 Manter Hall, Lincoln, NE 68588, USA
3Conservation Ecology Center, Smithsonian Conservation Biology Institute, National Zoological Park,
1500 Remount Road, Front Royal, Virginia 22630, USA
4Biodiversity Research and Teaching Collections, Department of Wildlife and Fisheries Sciences,
210 Nagle Hall, Texas A&M University, College Station, Texas 77843, USA
Abstract: Demographic studies often depend on sampling techniques providing representative samples from populations. However, the sequence of events leading up to a successful capture or detection is susceptible to biases introduced through individual-level behaviour or physiology. Passive sampling techniques may be especially prone to sampling bias caused by size-related phenomena (e.g., physical limitations on trap entrance). We tested for size-biased sampling among five types of passive traps using a 9-year data set for two species of aquatic salamanders that have a 20 and 61 fold change in length over their ontogeny (Amphiuma means, Siren lacertina). Size-biased trapping was evident for both species, with body size distributions (body length mean and SD) of captured individuals differing among sampling techniques. Because our two species differed in girth at similar lengths, we were able to show that size biases (in length) were most likely caused by girth limitations on trap entry rates, and potentially by differences in retention rates. Accounting for the biases of sampling techniques may be critical when assessing current population status and demographic change.
Keywords: Amphiuma means, body size, detection probability, inventory, passive trapping, population monitoring, sampling bias, Siren lacertina
SREL Reprint #3343
Luhring, T. M., G. M. Connette, and C. M. Schalk. 2016. Trap characteristics and species morphology explain size-biased sampling of two salamander species. Amphibia-Reptilia 37(1): 79-89.
This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).