Effects of telemetry collars on two free-roaming feral equid species

There are two species of free-roaming feral equids in North America: horses (Equus caballus) and donkeys or "burros" (E. asinus). Both species were introduced as domestic animals to North America in the early 1500s and currently inhabit rangelands across the western United States, Canada, and all continents except Antarctica. Despite their global distribution, little is known about their fine scale spatial ecology. Contemporary research tools to assess space use include global positioning system (GPS) tracking collars, but older models were problematic due to stiff collar belting causing poor fit. We tested modern designs of GPS collars on n = 105 horses and n = 60 burros for 4 years in five populations (3 horse, 2 burro) across the western United States, to assess whether collars posed welfare risks to horses or burros. We found no difference in survival of collared versus uncollared mares and jennies, and no difference in survival of their foals. In 4036 of 4307 observations for horses (93.7%) and 2115 of 2258 observations for burros (93.6%), collars were observed symmetrical, maintaining proper fit on the neck. Fur effects from collars (sweaty neck, indented fur, broken fur) were seen in 3% of horse observations and 25% of burro observations. Superficial effects (chafes and marks on skin surface) were seen in 2% of horse observations and 11% of burro observations; no severe effects from collars were seen. Body condition was not affected by collars; mean body condition of collared horses was 4.70 ± 0.54 (mean ± s.d) and 4.71 ± 0.65 for collared burros. Behavior results indicated minimal effects; collared horses stood slightly more than uncollared, and collared burros stood and foraged more in one population, but not in the other. For 6.3% of observations of horses and 6.4% of observations of burros, we found an effect of time wearing a collar on the cumulative sum of fur effects which increased over time (burros: rs = 0.87, P = <0.0001; horses: rs = 0.31, P = 0.002). Burros also showed an increase over time in the number of superficial effects, but horses did not. Collars occasionally moved into the wrong position, shifting forward over the ears; we observed this on 19 horses and 1 burro. Of those, most collars went over the ears in summer (n = 12). All collars were equipped with a remote release mechanism as well as a timed-release mechanism for redundancy, thus removed when observed in wrong position to avoid rubbing or discomfort. Our finding of no consequential physical effects in 98% of horse observations, and 89% of burro observations suggests the consequences of collars on free-roaming equid welfare and survival is biologically insignificant, although collars should be monitored regularly and continue to be equipped with a remote release mechanism to remove a collar if needed. With frequent welfare-driven, visual monitoring, collaring of free-roaming equids can be a safe and useful tool to increase our understanding of their spatial ecology, demography, habitat use, behavior, and interactions with other wildlife.

Minimising mortalities in capturing wildlife: refinement of helicopter darting of chital deer (Axis axis) in Australia

Abstract ContextHelicopter darting has been used to capture wild deer, but this method has never been used for chital deer (Axis axis). AimThe aims of this study were to develop, assess and refine a helicopter darting technique for wild chital deer in northern Australia by quantifying: (1) reliable pharmacological doses for immobilisation; (2) the efficacy of the technique (including the duration of procedures); and (3) the frequency of adverse animal welfare events. MethodsThe study was conducted in three stages: an initial protocol (n=25 deer captured) in July−August 2018; a refined second protocol implemented in June 2019 (n=12 deer captured); and a further refined third protocol implemented in June 2019 (n=12 deer captured). Parameters to estimate the duration of procedures were measured and the frequency of several adverse animal welfare events during capture were quantified: mortality (at the time of capture and within 14 days of capture), hyperthermia, hypoxaemia, dart inaccuracy and manual restraint. Finally, GPS location collars with a mortality-sensing function were used to monitor post-release mortality. ResultsMortality within 14 days of capture was 40% for the first stage, 25% for the second stage and 17% for the third stage. Considerable refinement of procedures occurred between stages in consultation with an Animal Ethics Committee. One-third of all 15 mortalities occurred at the time of capture and were attributed to ballistic trauma from dart impact and acute capture myopathy. The majority (n=10) of mortalities, however, occurred post-release and were only detected by mortality-sensing GPS location collars. These post-release mortalities were attributed to capture myopathy. ConclusionsHelicopter darting of wild chital deer poses animal welfare risks, but these can be minimised through the selection of the most appropriate pharmacological agents and attempts at preventing factors such as hyperthermia and hypoxaemia that contribute to the development of capture myopathy. Further research into capture protocols is needed for helicopter-based immobilisation of chital deer. Fitting animals with GPS location collars enabled post-release mortality, which was significant, to be evaluated.