Four species of owls were studied in a 'farmland area surrounding the lower Ythan Valleyr Aberdeenshire from 1972 to 1975. Twenty-six pairs of Tawny Owls were located in isolated woods and large areas of woodland where territories were small. Radiotransmitters were fitted to owls in isolated woodlots to determine their nocturnal hunting ranges. Birds hunted extensively over open farmland and plantations away from their core-areas of woodland or farm steading. A strong selection was displayed for mixed deciduous woodland which formed less than 5% of the study area. Exclusive territories were maintained up to 3 km in length. Fewer Long-eared and Short-eared Owls were found in the study area and less information was obtained on their hunting ranges. Barn Owls were located infrequently. Diets were determined by the analysis of pellets and the identification of food items at nest sites. The vole, Microtus, was the most important species taken by all owl species except the Barn 0171 for which shrews formed the greatest biomass. Changes in the diet of Tawny and Long-eared Owls were found in the breeding season when more rabbits and Starlings were taken. Trapping in eight habitat types revealed that small mammals are most abundant in autumn and least abundant in spring and early summer. Size of hunting ranges, use of habitats and diets of owls were related to changes in the availability of their prey. Interspecific competition between owls in the study area is considered to be avoided by temporal activity and habitat selection.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:458191 |
| Date | January 1977 |
| Creators | Hardy, Anthony Richard |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU428201 |
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