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Title: Demographic analysis of the impact of conservation action on stone curlew populations
Author: Johnston, A.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2009
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The aim of this PhD was to make statistical models of demographic rates and the factors affecting them and to use these to quantify the effects of conservation management on population size and growth. I used GLMs to assess components of individual breeding attempts and models of re-nesting to estimate annual productivity. Per attempt breeding success declined through the season and annual productivity was positively affected by fieldworker interventions to prevent breeding failures. Breeding success on artificial nesting plots differed in some respects from that not on plots on arable farmland and semi-natural habitat, but the effects varied with time of year and there was no substantial reduction in breeding success associated with having large proportion of the population breeding on plots. There was no evidence that breeding success had declined over time. An analysis of survival of birds from colour-ring resightings showed that juvenile survival was negatively correlated with hatching date. Annual survival of full-grown birds increased over first year or two of life, but there was evidence of an age-related decline in annual survival later in life. There was no indication that survival rates had declined as population size had increased. A simulation model indicated that if fieldworker nest interventions were halted, then both the breeding populations in England would decline, unless all arable nesting attempts took place on specially created plots of suitable breeding habitat. The models also predicted that the loss of set-aside would not have a strong negative effect on population trends. Analyses showed that a substantial proportion of breeding attempts were on specially created artificial nesting plots, especially in the Wessex population. Plots in arable habitats had a higher probability of occupancy with increasing distance from woodland.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available