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An Experimental Release of Rehabilitated Wild-Caught Sumatran Laughingthrush Garrulax bicolor: Assessment of Post-Release Survival and Dispersal Via Radio-Telemetry, North Sumatra, Indonesia

Bušina, Tomáš, Pasaribu, Nursahara, Hlavsa, Tomáš, Czerneková, Vladimíra, Kouba, Marek
Ornithological science 2018 v.17 no.2 pp. 135-147
Garrulax, aviaries, biodiversity, birds, captive animals, death, females, habitat destruction, home range, males, philopatry, population dynamics, radio telemetry, rain forests, survival rate, threatened species, trade, wildlife, Indonesia
Decline of biodiversity, especially in tropical areas and rainforests, due to human activity is a serious global issue. Recovery programs, including reintroductions, are one means of active species protection and biodiversity preservation. The Sumatran Laughingthrush Garrulax bicolor (SL), a little known passerine endemic to Sumatra Island, is currently suffering from serious population decline due to the intensity of the illegal wildlife trade and habitat loss in the region. Most local subpopulations have been extirpated and those remaining have been reduced, thus, urgent need for conservation has arisen. In this study, we carried out the soft-release of rehabilitated SLs, originating from the wild and kept in captivity. We released four SL pairs (N=8 individuals) in total and, by using radio-telemetry (VHF; <2 g tail-mounted tags); we assessed their survival rate and movement patterns. During the post-release period only one bird was monitored for the full, predetermined criterion period of three weeks for survival rate and site fidelity assessment and one death was confirmed directly. Affinity to the release site, defined by a 2 km radius around the release aviary, was lower for females, which left the release site within the first week after release leaving their fates unknown, compared with males which remained at the release site for up to three times longer. Therefore, only the males' home range sizes were calculated. As a standardised measure, only the first six days following release were included and 6-day home ranges were estimated as follows: 35.18±8.5 ha (mean±SE) with range 17.25–50.95 ha (N=4 males). We did not find significant differences in the distances of males from the release aviary with increasing days following release. As far as we know, this is the first field study providing novel knowledge of the recovery ability of the Sumatran Laughingthrush and of its post-release behaviour, which are crucial for species protection management.