An analysis of birds colonising the United Kingdom: how well does climatic suitability predict current distributions?

Mr James Cranston1, Dr Regan Early1, Dr Nick Isaac2

1University Of Exeter, Penryn, United Kingdom, 2Centre for Ecology and Hydrology, Wallingford, United Kingdom

Natural colonists – species which are establishing in novel areas outside their current range, which haven’t been introduced there by human action, transport or activities, are increasingly being described across the globe.

Accurate attribution of specific natural colonists’ arrivals to the correct driver, such as global warming, is important. Assisted migration has been presented as a responsibility to ecological refugees created by anthropogenic climate change. A similar logic invokes a responsibility to species range shifting with anthropogenic climate change. However, this logic could be reversed for species which are spreading due to human disturbance of natural landscapes, particularly if these species had harmful ecological effects.

Since nineteen-hundred over 100 natural colonists have established in the United Kingdom and the rate appears to be increasing (Gurney 2015). We focus here on 14 European birds newly arrived in Britain.

In this system, we ask two questions: 1) what areas in the UK are predicted to be climatically suitable for colonising bird species based on their European distributions; 2) whether modelled climatic suitability outperforms habitat suitability and  proximity to current breeding populations as a predictor of the colonists’ current distributions.

We find that climatic suitability has a limited performance as a predictor, with most species currently distributed in cells nearest their source populations. This could suggest that changes in the suitability of source sites have led to these expansions, or that species have been released from previous constraints in the UK, such as human persecution.


Currently in the third year of his Phd. He is focusing at species colonising the UK, with chapters focused on the spread, trends and impacts of colonists as well as attitudes amongst workers in the biodiversity domain towards these new arrivals.  Before his PhD, he completed a MSc in Biodiversity, Conservation and Management at Oxford University  with a thesis on species translocations and his undergraduate in Zoology at Cambridge.

Similar Posts