Land use change is one of the greatest threats to global biodiversity, and agricultural intensification has severely affected farmland birds in Europe. As a rapidly declining long-distance migrant and obligatory brood parasite, the common cuckoo Cuculus canorus is an interesting species on which to investigate the impacts of land use on birds. My thesis focuses on understanding the causes and mechanisms behind cuckoo declines in Britain by exploring relationships between land use, cuckoos, their hosts and adult cuckoo prey. Cuckoo population trends vary between habitat types, resulting in changes to cuckoo-habitat associations. There was little evidence of preference for semi-natural or agricultural habitats where cuckoos were widespread before their declines began, but they were strongly selective of semi-natural grass, heath and woodland by the 2000s while avoiding farmland. This suggests that female cuckoos specialised in parasitizing dunnocks (Prunella modularis) are now scarce while meadow pipit (Anthus pratensis) cuckoos have been retained in semi-natural habitats. However, as habitat cover had a consistently stronger statistical effect than host abundance on the presence or retention of cuckoos, the availability of other resources may limit current cuckoo distribution. The probability of cuckoo presence increased with the abundance of known cuckoo prey, predominantly large, hairy moth caterpillars. These species have undergone greater declines than other moths and their population trends also vary by habitat: abundance has increased in semi-natural habitats but declined in improved grassland and woodland. Therefore changing prey abundance may be a key driver of cuckoo declines in farmland. Although fundamental questions on the causes of cuckoo declines remain unanswered, maintaining semi-natural habitats as a stronghold for cuckoos in Britain might be an effective conservation strategy in the immediate future. However, measures adopted under agri-environment schemes which increase moth abundance may offer long-term mitigation of cuckoo declines while benefiting other insectivorous species.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:600109 |
| Date | January 2014 |
| Creators | Denerley, Chloe |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=205390 |
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