Do habitat and thermal conditions explain the past, present and future distributions of British Rose-ringed Parakeets?

Bufton, Richard David James ORCID: 0000-0002-2763-4463 (2023). Do habitat and thermal conditions explain the past, present and future distributions of British Rose-ringed Parakeets? University of Birmingham. Ph.D.

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Abstract

The distributions of birds around the world are rapidly changing due to anthropogenic habitat and climate change. In this changing world, birds are indicators of the health or ill health of natural systems. Knowing the distributions of birds allows us to monitor the impacts of the changes humans have made to the planet, identify future threats to biodiversity, ecosystem services and to monitor potential hosts of zoonotic diseases. Introduced, invasive species can be especially harmful as they are released from their natural predators, and once established can adapt to their introduced range. Invasive species are those species that can cause harm to natural ecosystems or reduce populations of native species, or affect the profitability of economic activities, or cause ill-health in humans.

One well known invasive species is the Rose-ringed Parakeet (RRP) (Psittacula krameri), introduced to Great Britain (GB) through the trade in cage birds, from their native range in sub-tropical and tropical Africa and Asia. Having established a population of 8,600 breeding pairs in GB by 2013, mostly in or close to London, RRPs are showing signs of colonising wider parts of GB.

This study uses data collected by volunteer bird surveyors on behalf of the British Trust for Ornithology (BTO) for the Bird Atlas 2007-2011, and supplements it with data gathered through a newly created website for gathering sighting details of RRPs in GB. The website data shows that colonisation of GB by RRPs is ongoing. The Atlas data combined with habitat data, data on the density of humans and other environmental data at a 1km resolution, was then used to create Species Distribution Models (SDMs), using statistical and spatial software and validated using the website data, for the winter and the breeding season, that show RRPs distributions are limited mainly by ambient temperatures, but have the potential to colonise wider parts of the milder south-western GB.

Those SDMs were then adapted to 5km resolution to enable use of predictions of future climates made by the Met Office Hadley Centre. The new SDMs enabled the creation of predicted future distributions of RRPs in GB for 2021, 2031, 2061 and 2071. These show that as ambient temperatures rise with climate change, RRPs will be able to expand their range in GB. Expanding their range will bring RRPs into contact with more native species. Although RRPs are often thought of as birds of suburbia in GB, occupying more towns and cities will lead to easier access to rural areas surrounding those towns, which is likely to lead to more serious depredations on crops.

RRP distributions have been mainly within the cities of GB, and the pattern of colonising cities before rural areas may be one means of natural colonisation of GB by birds able to utilise human-altered habitats, or by other newly introduced species.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):