Reintroduction of the red-billed chough (Pyrrhocorax pyrrhocorax) to Jersey, Channel Islands.
Résumé
Red-billed choughs (Pyrrhocorax pyrrhocorax) are a rarity in the British Isles having a fragmented population of less than 500 breeding pairs. Choughs died out in Jersey, a British Channel Island, at the turn of the 20th century after changes in agricultural practices led to a drastic loss of food sources (i.e. soil and dung invertebrates). Egg collecting and farmers’ general discrimination against corvids also impacted numbers.
Durrell Wildlife Conservation Trust managed several soft releases of captive-bred choughs (2013 to 2018). Continued post-release veterinary care, close daily monitoring, supplemental feeding, and stakeholder engagement have all contributed to the success. After an absence spanning a century, Jersey once again has a resident chough breeding population and conservation grazing in action along the north coast.
Choughs are the flagship species for a multi-partner project, Birds On The Edge, which aims to restore Jersey’s depleted coastland bird populations through habitat management.
Classifications
Région
Ampleur de la mise en œuvre
Ecosystème
Thème
Conservation des espèces et interventions axées sur l’approche « Une seule santé »
Défis
Objectifs d’Aichi
Défis
- Lack of suitable foraging habitat to maintain a viable chough population. Only 18% of Jersey’s land cover is natural vegetation the majority of which is dominated by bracken.
- Limited captive-breeding success at Jersey Zoo resulted in (1) a reliance on importing birds from a UK zoo, (2) a reduced capacity to select suitable candidates for release, (3) releasing sub-adults and adults in the first cohort, not juveniles (<6months old) which are more manageable and adaptable to change.
- Choughs are an intelligent, social species quick to learn when not under stress. Recapture techniques for the initial releases and continued post-release management constantly change as the birds learn how staff operate, e.g. which side of the aviary the release hatches are operated from, and try to evade capture.
Bénéficiaires
Red-billed choughs
Associated coastal grassland bird species in Jersey
Jersey’s island biodiversity
Islanders
Tourists
Students
Blocs Constitutifs
Comment les blocs constitutifs interagissent-ils entre eux dans la solution?
The success of the reintroduction to date has required five key components. The first step was a feasibility assessment to ensure a reintroduction was the most appropriate tool. Once established, a clearly defined plan was developed and implemented involving captive breeding for release, soft releases over several years and intensive post-release management.
Durrell’s commitment to restoring the species continued after the birds began breeding in the wild. Support for the population now consists of nest management and protection as well as supplemental feeding and veterinary assistance if needed.
Throughout the reintroduction, there has been a continuous need to evaluate and feedback into the management of the releases and the breeding population. The future of the population and the effectiveness of the wider Birds On The Edge objectives will rely on analysis, evaluation, and continued commitment by the project partners, stakeholders, and Jersey islanders.
Galerie interactive
Impacts
The red-billed chough is no longer locally extinct in Jersey. There is now a resident breeding population of ten pairs consisting of both captive-reared and wild-hatched birds. Conservation grazing was initiated in Jersey to ensure suitable foraging habitat is maintained for the choughs. Together these actions contribute to safeguarding the island’s biodiversity.
In 2020, a wild-hatched Jersey chough was discovered living in Normandy, France. Natural re-colonisation in Normandy and across the Channel Islands is now a feasible option potentially reconnecting the depleted French and British populations.
The success of the project has inspired other organisations to plan chough reintroductions in the UK (Kent and Isle of Wight) and potentially the Julian Alps, Slovenia. Both locations using the species to drive habitat restoration.
Local stakeholder engagement has enabled greater public awareness of Jersey’s conservation issues and knowledge of corvids, a group unfairly persecuted by islanders.
Capacity building through participation and teaching is a valuable resource. Jersey Zoo student placements regularly assist the reintroduction and post-release monitoring acquiring new skills such as radio-tracking and husbandry techniques.The Durrell Conservation Academy integrate the project into their curriculem including field trips for course participants and visting University groups.
Histoire
Hand-rearing has played an important role in the reintroduction’s success. Eight of the forty-three choughs released were hand-reared. All eight survived for at least three years or more post-release and six went on to breed in the wild.
Jersey Zoo developed artificial incubation and hand-rearing techniques through a need to encourage double-clutching in captivity and to intervene when an egg or chick was compromised. Some critics questioned the suitability of hand-reared corvids for release due to their notoriety for imprinting.
Precautions were taken to avoid imprinting (feeding with a hand puppet, audio playback of chough calls in-between feeds and creche rearing). Chicks moved to an enclosure within the release aviary pre-fledge so that when they did fledge, they strongly associated the aviary as home. This makes it easier to manage the initial release phase. Whilst confined to the aviary they could safely observe and interact with the previously released cohort who returned for supplemental food and, in some cases, to roost. They then strongly associate the release aviary as home making it easier to manage their release.
In 2016, an imprinted female called Gianna was used to help foster rear four chicks for release. She effectively formed a pair bond with her keepers allowing them to co-parent the chicks as a sire and dam would in the wild. The chicks, hatched in an incubator, were hand-reared for the first five days then moved to a nest box in Gianna’s aviary. At four weeks of age, they moved to the release aviary where keepers continued to hand-feed.
Compared to fully hand-reared or parent-reared chicks, the fostered chicks took longer to integrate into the flock already living at liberty. They would stay near staff (<5 meters) when foraging outside of the aviary rather than with the main flock. Day by day keepers would move closer to the main flock to encourage the chicks to join. Eventually, one by one, they joined the flock and began roosting with them away from the aviary.
One chick has since reared three broods. Another became the first to establish a breeding territory away from the release site. Using hand-reared and/or foster-reared birds has clearly paid off. In addition, via monthly blogs and social media, their story has engaged stakeholders and the general public strengthening support for Birds On The Edge.
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