The effect of pre-release captivity on post-release performance in reintroduced eastern bettongs Bettongia gaimardi

Abstract

Reintroductions are used to re-establish populations of species within their indigenous range, but their outcomes are variable. A key decision when developing a reintroduction strategy is whether to include a temporary period of confinement prior to release. Pre-release confinement is primarily used for the purpose of quarantine or as a delayed-release tactic to influence the performance or behaviour of founders post-release. A common difference between these approaches is that quarantine tends to be conducted in ex situ captivity, whereas delayed releases tend to involve in situ confinement at the release site. Although these practices are commonly viewed independently, it may be possible for a single confinement period to be used for both purposes. We tested whether temporarily holding wild eastern bettongs Bettongia gaimardi in ex situ captivity for - days prior to release (delayed release) influenced their body mass, pouch occupancy or survival during the first . years post-release, compared to founders released without confinement (immediate release). Our results suggest that exposing founders to captivity did not alter their body mass or performance post-release, despite being heavier and having fewer pouch young when released. We conclude that, for this species, ex situ captivity does not represent a tactical opportunity to improve post-release performance but can be used for quarantine without affecting the probability of establishment.

Adapting reintroduction tactics in successive trials increases the likelihood of establishment for an endangered carnivore in a fenced sanctuary

“…Effective survival and post-release dispersal did not differ between captive and wild founders in the Trials 1 and 2, which is consistent with results found in the reintroduction of the eastern bettong (Bettongia gaimardi, [11]) and releases of the Tasmanian devil (Sarcophilus harrisii, [78]). It is worth noting that there may be inherent differences between captive and wild founders which could impact genetic diversity, as well as performance beyond-the-fence where additional threats are present (e.g., introduced and native predators, roads, human interaction).…”

“…The success of reintroduction programs can be improved by employing 'tactics', defined as techniques which can influence post-release performance and persistence [10]. Tactics may include the selection of founders, release environment and methods [11,12], and the provision of supplementary food and shelter [8]. These tactics should be guided by well-defined objectives termed 'strategies', which might include, for example, maximising survival or minimising post-release dispersal [10].…”

Effects of digging by a native and introduced ecosystem engineer on soil physical and chemical properties in temperate grassy woodland

“…The two reserves contain important remnants of Yellow Box-Blakely’s Red Gum Grassy Woodland, which is listed as a critically endangered ecological community (Australian Government, 2006). In 2009, a 485 ha predator-proof sanctuary was established in Mulligan’s Flat reserve to provide protection for the native wildlife and allow the reintroduction of several locally extinct species, including the eastern bettong ( Bettongia gaimardi ) which was introduced in 2012 (Batson et al, 2016). Within the sanctuary, feral predators (cats, foxes and dogs) and hares were removed, and rabbits were managed at low numbers.…”

Bioturbation by a reintroduced digging mammal reduces fuel loads in an urban reserve

“…) restricts the broad‐scale reintroduction of mammals outside of fenced reserves or islands; however, the reintroduction of mammals may still be feasible in some urban areas (e.g., Craigie Bushland [this project] and Mulligan's Flat [Batson et al. ]). Encouragingly, quenda (and some other bandicoot species) occur outside of fenced areas.…”

“…Few reintroduction programs have occurred in urban areas, but there is a growing awareness of the benefits of engaging people with nature ( van Heezik and Seddon 2018). In Australia, the threat of predation from introduced cats and foxes (Woinarski et al 2015) restricts the broad-scale reintroduction of mammals outside of fenced reserves or islands; however, the reintroduction of mammals may still be feasible in some urban areas (e.g., Craigie Bushland [this project] and Mulligan's Flat [Batson et al 2016]). Encouragingly, quenda (and some other bandicoot species) occur outside of fenced areas.…”