Lots of movement, little progress: A review of reptile home range literature

Abstract

Reptiles are the most species-rich vertebrate group with a broad diversity of life history traits. Biotelemetry is an essential methodology for reptiles as it compensates for several limitations when studying their natural history. We evaluated trends in reptile spatial ecology studies focusing upon quantifying home ranges for the past twenty years. We assessed 290 English-language reptile home range studies published from 2000-2019 via a structured literature review investigating publications’ study location, taxonomic group, methodology, reporting, and analytical techniques. Substantial biases remain in both location and taxonomic groups in the literature, with nearly half of all studies (45%) originating from the USA. Snakes were most often studied, and crocodiles were least often studied, while testudines tended to have the greatest within study sample sizes. More than half of all studies lacked critical methodological details, limiting the number of studies for inclusion in future meta-analyses (55% of studies lacked information on individual tracking durations, and 51% lacked sufficient information on the number of times researchers recorded positions). Studies continue to rely on outdated methods to quantify space-use (including Minimum Convex Polygons and Kernel Density Estimators), often failing to report subtleties on decisions that have substantial impact on home range area estimates. Moving forward researchers can select a suite of appropriate analytical techniques tailored to their research question (dynamic Brownian Bridge Movement Models for within sample interpolation, and autocorrelated Kernel Density Estimators for beyond sample extrapolation). Only 1.4% of all evaluated studies linked to available and usable telemetry data, further hindering scientific consensus. We ultimately implore herpetologists to adopt transparent reporting practices and make liberal use of open data platforms to maximize progress in the field of reptile spatial ecology.

A Habitat Selection Multiverse Reveals Largely Consistent Results Despite a Multitude of Analysis Options

“…Critical to KDEs, operation is a bandwidth or smoothing factor (h) that alters the resulting area treated as used by the animal (Silva et al, 2020). For this analysis, we use the reference bandwidth (href) as it is commonly used (Crane et al, 2020), while also quickly and consistently calculable on a individual-by-individual basis. An alternative common method to determine smoothing factor is Least Squares Cross Validation (LSCV).…”