Management Background and Release Conditions Structure Post-release Movements in Reintroduced Ungulates

Abstract

One of the greatest challenges in restoring species to the wild is insufficient knowledge about their habitat requirements and movement ecology. This is especially true for wide-ranging species such as the scimitar-horned oryx (Oryx dammah). Once widespread across Sahelo-Saharan grasslands, oryx were declared Extinct in the Wild in 1999. Here, we integrate GPS/satellite tracking, remote sensing, and movement analyses to assess how reintroduced oryx respond to wild conditions. We monitored two groups of oryx, reared under different captive management regimes and released in different seasons, for 12 months after release. Our study provides the first movement trajectories and home range estimates for this species. We expected oryx movements after release to represent trade-offs between risky, energetically expensive exploration and resource exploitation. Oryx raised under semi-free ranging conditions and released during the wet season ("ranging") exhibited this pattern of exploration followed by home range establishment. In contrast, oryx raised in small pens and released during the dry season ("penned") explored far less novel terrain. Ranging oryx exhibited seasonal shifts in activity and movement timing, while penned oryx simply reduced overall movement and continuously accessed supplemental food and water. Sahelian ecosystems exhibit strong seasonal cycles and extensive spatial variation. In this highly variable environment, reintroduced oryx will need to disperse from the release site to acquire adequate forage throughout the year. Thus, we experimentally varied acclimation period, and expected dispersal to decrease with acclimation period length. Post-release dispersal ranged from 2 to 90 km: ranging oryx acclimated for ca. 6 months moved 40-60 km from the release site, while penned oryx acclimated for ca. 1 month remained within 5-25 km. Our results demonstrate that captive management and environmental conditions at release strongly influence the extent to which reintroduced oryx disperse and adapt to wild conditions. We also show that-in contrast to previous studies-longer acclimation periods do not necessarily lead to site fidelity. Finally, our findings demonstrate the importance of tracking a large proportion of reintroduced individuals to (1) accurately record post-release behaviors and vital rates, and (2) adaptively evaluate pre-and post-release management actions to improve conservation outcomes.

Assessing genetic diversity and connectivity in a tule elk (Cervus canadensis nannodes) metapopulation in Northern California

“…Because augmentations are typically opportunistic rather than components of a systematic genetic management plan that includes genetic monitoring, few data exist with which to evaluate whether translocated individuals successfully breed and integrate genetically into recipient populations (CDFW 2018). Based on other systems, successful integration of translocated individuals into restored populations can vary substantially and be influenced by demographic, behavioral, and environmental conditions, numbers and sex of individuals released, and even the pre-release circumstances of source populations, such as whether captive or free-ranging and the genetic diversity of source stocks (Flesch et al 2020;Mertes et al 2019;Ralls et al 2018;Renan et al 2018;Youngmann et al 2020;Zecherle et al 2020). Future augmentations should therefore incorporate post-release demographic and genetic monitoring programs, including telemetry of reintroduced individuals and pedigree reconstruction to evaluate social integration and reproductive success of released individuals.…”

Post-release Movement Behaviour and Survival of Kulan Reintroduced to the Steppes and Deserts of Central Kazakhstan

“…Little data is available on individual post-release movements of reintroduced kulan, but experiences with other large mammals suggest that "soft release" helps create social bonds and reduces the likelihood of homing and large-scale exploratory movements (Mertes et al, 2019;Resende et al, 2021) in line with natal habitat preference induction (NHPI, Stamps and Swaisgood, 2007). Captive-bred kulan reintroduced in Israel following a soft release approach, initially settled in a ca.…”

Short-term effects of GPS collars on the activity, behavior, and adrenal response of scimitar-horned oryx (Oryx dammah)

“…Importantly, none of our analyses indicated long-term adverse effects that would have more serious animal welfare concerns. This is especially true when considering the significant benefit of using GPS collars to improve our understanding of scimitarhorned oryx ecology and inform conservation and management of the species upon reintroduction [57].…”