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

Abstract

Reptiles are the most species-rich terrestrial vertebrate group with a broad diversity of life history traits. Biotelemetry is an essential methodology for studying reptiles as it compensates for several limitations when studying their natural history. We evaluated trends in terrestrial 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 Studies continue to rely on outdated methods to quantify space-use (including Minimum Convex Polygons and Kernel Density Estimators), often failing to report subtleties regarding decisions that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.

Malayan kraits (Bungarus candidus) show affinity to anthropogenic structures in a human dominated landscape

“…Although the study sample of B. candidus (n = 14 [adult males = 9, juvenile males = 4, adult female = 1]) somewhat lower than the average sample for snake spatial studies over the last 20 years; our tracking intensity was comparable to the average (Crane et al, 2021), and we were likely more consistent than average snake telemetry studies.…”

“…We compared space use estimates to two previously published B. candidus tracking datasets (Mohammadi et al, 2014; Knierim et al, 2018), and one unpublished dataset shared on the Zenodo data repository (Smith and Knierim, 2021), originating from the Sakaerat Biosphere Reserve (approximately 41 kilometers to the south of our study site): two adult males from within the forested area of the reserve [one tracked every 27.8 ± 0.99 hours over a period of 103 days, the other tracked every 38.63 ± 11.2 hours over a period of 30.58 days] (Mohammadi et al, 2014; Smith and Knierim, 2021), and a juvenile male from agriculture on a forest boundary [tracked every 50.19 ± hours for 66.91 days] (Knierim et al, 2018). The previous studies on B. candidus only tracked the movements of a single individual each, had coarser tracking regimes, and used traditional–fundamentally flawed methods (Silva et al, 2020; Crane et al, 2021)–to estimate space use (Mohammadi et al, 2014; Knierim et al, 2018). Therefore, we ran dBBMMs with these previous datasets using the same window and margin size (ws = 19, ms = 5).…”

Artificial shelters provide suitable thermal habitat for a cold-blooded animal

“…Space use was defined as an area used by an animal throughout the study duration 61 . We calculated variograms, fit movement models, and estimated spatial probability density functions via the ctmm package 62 for each individual via an area-corrected, autocorrelated kernel density estimation (AKDE C ) that was optimally weighted to determine the distribution of occupancy using the continuous-time movement model.…”

Malayan kraits (Bungarus candidus) show affinity to anthropogenic structures in a human dominated landscape

“…We compared space use estimates to two previously published B. candidus tracking datasets 34 , 36 , and one unpublished dataset shared on the Zenodo data repository 54 , all originating from the Sakaerat Biosphere Reserve (approximately 41 km to the south of our study site): two adult males from within the forested area of the reserve [one tracked every 27.8 ± 0.99 h over a period of 103 days, the other tracked every 38.63 ± 11.2 h over a period of 30.58 days] 34 , 54 , and a juvenile male from agriculture on a forest boundary [tracked every 50.19 ± h for 66.91 days] 36 . The previous studies on B. candidus only tracked the movements of a single individual each, had coarser tracking regimes, and used traditional—fundamentally flawed methods 55 , 56 —to estimate space use 34 , 36 . Therefore, we ran dBBMMs with these previous datasets using the same window (19) and margin size (5).…”