Post‐reintroduction distribution and habitat preferences of a spatially limited island bird species

Abstract

Investigating habitat use and preferences of a threatened species can be challenging, especially if wild populations have decreased to such low numbers that they occupy only fractions of their former natural range. Hence, assessing habitat suitability of a potential release site for a threatened species before a reintroduction attempt can be difficult because frequently no comparable baseline data are available. In these instances, post-release monitoring data can inform about habitat use and preferences of a reintroduced species. Here, we use monitoring data of an endangered endemic island bird, the Chatham Island black robin Petroica traversi, to investigate habitat preferences and the temporal change in distribution patterns across 26 years following a reintroduction. We show that densities and distribution of black robin pairs at the reintroduction site have changed significantly over the years. Spatial distribution of pairs is clustered, and this clustering has intensified as the population increased. We used the maximum entropy method MaxEnt to model habitat suitability on the island, showing that black robins clearly prefer forested areas inland that are within 70 m to the forest edge at lower elevations (<40 m a.s.l.) and on slopes that have a N-NE aspect. The model also identified one area on the island that comprises suitable habitat, but is currently uninhabited. Applying maximum observed densities to the available area of each suitability class, carrying capacity is estimated as 170 nesting pairs across the island, highlighting the need to find further appropriate habitat urgently. Overall, these topographical and habitat preferences considerably restrict this species' potential distribution, a constraint that has serious conservation implications for future population growth of current populations and (re)introductions to new locations. This study demonstrates that post-release data can reveal relevant limitations to habitat use of highly threatened species.

Monitoring body condition score of reintroduced banteng (Bos javanicusD’Alton, 1923) into Salakphra Wildlife Sanctuary, Thailand

“…Reintroduction is a restoration program in which animals are translocated to areas within their historic range when the population and habitat of the animal there have decreased (Conant, 1988). The role of captive breeding and reintroduction programs that aim to augment or reestablish wildlife populations has increased dramatically (Ebenhard, 1995), including the endangered banteng (Bos javanicus d' Alton, 1823), into parts of its former natural range (Armstrong & Seddon, 2008;Moorhouse, Gelling & Macdonald, 2009;Massaro et al, 2018).…”

Postrelease movement and habitat selection of translocated pine martensMartes martes

“…A study on released otters similarly found that the movement (i.e., exploration) distance of individuals released into unoccupied areas was much lower than those released into areas containing conspecifics (Sjoasen, 1997). Density‐dependent dispersal (Massaro, Chick, Kennedy, & Whitsed, 2018) is therefore a likely driver of greater settlement distance in second‐year animals. However, these second‐year animals did settle faster than those released in the first year (Figure 3b), possibly spending less time searching for appropriate habitat near to release sites and dispersing immediately out of the large forest blocks into empty territories.…”

Novel Conditions in Conservation Translocations: A Conservative-Extrapolative Strategic Framework

“…• Post-release resource use, where expectations based only on relict populations are unlikely to anticipate the full range of potential responses of the reintroduced population under novel conditions (Mihoub et al, 2014;Massaro et al, 2018).…”