Projecting the effects of climate change on prey selection and dietary competition in communities of European reedbed warblers

Davies, Sarah Rhiannon 2020. Projecting the effects of climate change on prey selection and dietary competition in communities of European reedbed warblers. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Climate change remains one of the greatest threats to natural systems worldwide. Songbirds are sensitive to changes in invertebrate prey resources and may respond to climate-mediated shifts by either broadening or narrowing the range of prey types consumed. This PhD used a latitudinal gradient as an analogue for future climate change, to explore how warming might alter diet, prey selectivity and dietary overlap in reedbed warblers breeding in Europe. The diets of six reedbed warbler species along the gradient were elucidated via metabarcoding of prey remains in faecal samples. Local weather, prey availability and warbler diets in the reedbeds of Catalonia (southern Europe) were monitored and compared with northern and southern reedbed sites in England and Wales (UK), to infer future patterns of prey availability and changes to potential competitive responses by warblers to future warming across the gradient. Each warbler species showed subtle differentiation in diet; as did different age classes of the reed warbler (Acrocephalus scirpaceus); including the size of prey captured, taxonomic composition, and the proportion of aquatic and terrestrial arthropods consumed (Chapter 2, 3 and 4). Partitioning was often masked by high dietary overlap when local prey abundance was high, but lower overlap was observed during scenarios of lowered prey abundance. Changes in dietary overlap were also associated with maximum temperature and rainfall, with contrasting responses in the two countries, likely mediated through impacts upon local warbler prey (Chapter 5). The extent of overlap along the gradient could be predicted using a continuum of prey abundance and richness. Our findings have implications for sympatric birds in both the UK and Spain, potentially affecting future competitive interactions and coexistence. These consequences may be alleviated by carefully controlled habitat restoration and management, with the aim of promoting aquatic

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	12 March 2021
Last Modified:	19 Apr 2023 08:26
URI:	https://orca.cardiff.ac.uk/id/eprint/139655

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