| dc.description.abstract | Upland breeding birds are under threat from a wide range of environmental and climatic changes, and many upland species are showing substantial population declines. A detailed understanding of the breeding ecology of these species is essential in order to monitor changes in breeding performance and to identify suitable conservation solutions. The primary aim to this thesis work was to build an increased understanding of the breeding ecology of ground-nesting passerines on upland moorlands. My work used and further contributed to data collected over a 10 year period on ground-nesting birds on a 4.3km2 study site on the upland moorlands of Dartmoor National Park. An in-depth nest recording study was conducted for Meadow Pipit (Anthus pratensis), Stonechat (Saxicola rubicola) and Whinchat (Saxicola rubetra), and a broad nest recording effort captured the diversity of breeding species across the study site. An assessment of the avian diversity of the study site identified a total of 34 breeding species, highlighting the need for community-focused conservation approaches which consider the breeding requirements across the avian community. For Meadow Pipit, Stonechat and Whinchat the breeding parameters of clutch size, brood size and nest success were established, and interannual variation was assessed. Clutch size showed no interannual variability, brood size showed minor variability in Stonechat and Meadow Pipit, and nest success was variable interannually across all three species. The timing of breeding of the three species was assessed in the context of current upland vegetation management practices (vegetation burning and Bracken control). Considerable overlap was shown in the timing of breeding of all three species, and the current permitted timings of both vegetation management techniques. These results highlights a potential conflict between bird conservation and current upland management practices, and I identify recommended adjustments in those management timings to minimise these conflicts. Nest site selection was investigated for two topographical components of microclimate; altitude and solar coefficient. Although Meadow Pipit, Stonechat and Whinchat showed interspecific differences in their nest microclimates, evidence for potential nest site selection was found only in Whinchat, and no links between nest success and nest site characteristics were found. Further work is needed to better understand the factors driving nest site selection in these three species. The importance of foraging habitat for breeding performance was investigated in a study using Meadow Pipit as a focal species. No associations between breeding performance (nest success and nestling growth rate) were found for four main study site habitat characteristics and overall vegetation diversity. A wider range of spatial scales and habitat characteristics need to be investigated to improve understanding on how vegetation affects Meadow Pipit breeding. Finally, the study looked into the wider usefulness of citizen science data, comparing two volunteer-driven survey approaches for Cuckoo (Cuculus canorus) occurrences in Devon. A citizen science initiative, collecting opportunistic Cuckoo sightings, was launched and compared with existing systematic breeding season surveys. The two survey methods are compared at two spatial scales. We find that whilst overall similarity between results from the two survey methods increases when results are aggregated to a scale more reflective of Cuckoo range sizes, findings remain significantly different. Further work is needed to establish the error associated with the different survey approaches. Overall, this thesis contributed to an improved understanding of the breeding ecology of Meadow Pipit, Stonechat, Whinchat and Cuckoo. The breeding parameters established here provide a valuable baseline for monitoring change, and the details on bird diversity and timing of breeding can provide useful evidence to help minimise conflict between upland conservation management and bird conservation. | en_GB |
