The influence of risk factors associated with captive rearing on post-release survival in translocated cirl buntings Emberiza cirlus in the UK

Abstract

Population decline resulting from agricultural intensification led to contraction of the range of the cirl bunting Emberiza cirlus in the UK to a small area of south Devon. As part of the UK Biodiversity Action Plan for the species, a project to re-establish a population in suitable habitat in Cornwall was undertaken during 2006–2011, in which chicks were removed from the nest in Devon, hand-reared and then delayed-released. The survival of the birds to four time points in the year after release was analysed in relation to the effect of rearing factors, using a multivariable logistic regression model. Individuals with higher body weight at capture were more likely to survive to 1 January and 1 May in the year following release, and individuals released in June and July were more likely to survive than those released in August. Individuals released in 2006 and 2011 had a higher survival rate than those released during 2007–2010. Timing of capture, time spent at each stage in captivity, medication and the detection of parasites in the brood had no significant effect. Immunosuppressive disease, weather factors and predator activity may have led to some of the observed differences in survival. This analysis provides evidence with which to plan future translocation projects for cirl buntings and other passerine birds.

Disease surveillance and risk factors affecting mortality of captive cirl buntings (Emberiza cirlus) in a translocation for conservation purposes

“…21 Respiratory lesions occur in aspergillosis in captive passerine birds, but this was not detected in any captive birds in this project; however a bird which died shortly after release was found to have chronic aspergillosis. 18 Hepatic changes were the most frequent pathological finding in birds which died at all three housing stages; however a greater percentage of birds were affected by hepatic changes in those years with the highest mortality, 2007 (54%), 2009 (54%) and 2011 (71%) (Table 6). The changes seen were non-specific and included enlargement, abnormal colouration and necrosis which have all been reported in passerines following infection with Haemoproteus spp, avian polyomavirus, Buggy Creek virus, avian paramyxovirus, Plasmodium relictum, Salmonella spp, Yersinia pseudotuberculosis and as a result of aflatoxicosis.…”

“…To increase the evidence base for future translocations of cirl buntings and other passerine birds, this study sought to examine the effect of specific capture and rearing risk factors on the health and survival of the cirl buntings during their rearing in captivity between 2006 and 2011, and to assess the impact of the preventive medicine protocols developed during the DRA. A second paper analyses the effect of rearing factors on post‐release survival 18 …”

Biosecurity for Translocations: Cirl Bunting (Emberiza cirlus), Fisher’s Estuarine Moth (Gortyna borelii lunata), Short-Haired Bumblebee (Bombus subterraneus) and Pool Frog (Pelophylax lessonae) Translocations as Case Studies

“…The biosecurity protocols were communicated through a DRM protocol document, with hard copies distributed and discussions held annually at a pre-season meeting in conjunction with a site visit and updated recommendations from previous years explained. Analysis of reintroduction success reported no detected mortality associated with non-native infectious agents (Fountain et al, 2016) which the biosecurity was designed to prevent. Cirl bunting mortality was associated with a wide variety of infectious agents, causing disease secondary to apparent immunosuppression, e.g.…”

“…Isospora spp (McGill et al, 2010), and Campylobacter spp already harboured by the birds (native parasites and carrier hazards). The pre-release mortality rate was highest in 2007 (42.5%; n = 26/73; Fountain et al, 2016) and as a consequence quarantine and hygiene guidelines and their execution were reassessed and made more stringent where it was judged appropriate by veterinarians with expertise in wild animal management (Molenaar and Sainsbury 2008) and in the four subsequent years of rearing the mortality rate was markedly reduced (19.5%; n = 50/257) (Fountain et al, 2016).…”

A novel method for using ecoacoustics to monitor post‐translocation behaviour in an endangered passerine

“…Monitoring post‐release dispersal is frequently challenging and expensive and in small passerine species often requires expensive radiotransmitters, antenna arrays, or dedicated staff tracking individually marked birds (Bain, French, Baker, & Clarke, ; Dougill et al., ; Fountain et al., ). These high‐cost methods often only provide a brief window of monitoring data, only apply to a few individuals, and can be intrusive for the animals, even leading to injuries and increased mortality (Barron, Brawn, & Weatherhead, ; Pierce, Stevens, Mulder, & Salewski, ).…”