Human impacts on coastal bird populations in the Solent
This thesis applies techniques of assessment, monitoring and prediction to cases of potential losses of ornithological diversity within the Solent, UK, through overexploitation of resources, disturbance and habitat loss. An annual commercial harvest of the eggs of Black-headed Gulls was studied to a...
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| Format: | Thesis |
| Language: | English |
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University of Southampton
2007
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| Online Access: | https://eprints.soton.ac.uk/466364/ https://eprints.soton.ac.uk/466364/1/1124982.pdf |
| Summary: | This thesis applies techniques of assessment, monitoring and prediction to cases of potential losses of ornithological diversity within the Solent, UK, through overexploitation of resources, disturbance and habitat loss. An annual commercial harvest of the eggs of Black-headed Gulls was studied to assess impacts on their breeding success and distribution within the Solent. Data from long-term monitoring of seabirds breeding along the south coast of England indicated that egg harvesting and the associated disturbance may be directly and negatively influencing the breeding distribution of Black-headed Gulls and also the protected Mediterranean Gull that breeds in its colonies. Data suggests that egg harvesting has prevented the colonisation of Mediterranean Gulls on these sites, whereas un-harvested sites have seen rapid colonisation in the last 10 years. On this basis, both EU and UK legislation may be being violated. As well as its gull colonies, the Solent sustains important populations of wintering shorebirds that rely on the food resource supplied by estuaries and tidal flats. The quantity and composition of macrobenthic invertebrate prey in the Southampton Water SPA was sampled with a stratified-random design for ANOVA. Bootstrap resampling indicated that the individual-based predictive model of site quality for shorebirds over-wintering on Southampton Water. This model accurately predicted the observed shorebird distribution, on the assumption that non-starving birds moved within restricted sections of the site, consuming any prey that yielded a threshold energy assimilation rate. Dunlin and curlew were the species predicted to be most sensitive to loss of prey biomass or overall habitat area, with losses of 5-10% provoking significant impacts on survival. When the area for the proposed development of a port terminal at Dibden Bay was modelled as habitat loss, the impacts on shorebird survival were eliminated by the proposed mitigation. |
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