Dr Mike Fowler of Swansea University’s College of Science co-authored the research, published by the Proceedings of the Royal Society B, which examined competition between blue tits and great tits at four sites in Europe.  The study focussed on two sites in Belgium, one in the Netherlands and one in the UK which are home to breeding pairs of the two species and where counts have been collected for more than 15 years.

Climate Change and Competition

‌Dr Fowler said: “Blue tits and great tits compete for both food and roosting sites, but they generally coexist with each other.  As we know that climate fluctuations can affect the distribution, behaviour and life cycle of plants and animals we set out to find whether climate change could change the competitive relationships between these two bird species.”

The aim of the research team was to examine whether the strength of competition between great tits and blue tits had changed over time, and if this could be linked to climate fluctuations to enable them to better forecast the consequences of the change in the strength of competition for species coexistence.

The study found that long-term climate change can, but does not always affect competition between blue tits and great tits, the data from one of the Belgian sites indicated that competitive interactions between the species had shifted, which had the potential to disrupt their long-term ability to coexist.

‌Dr Fowler said:  “Our study has shown for the first time that climate change can affect competition between coexisting vertebrate species in the field. We can conclude that climate change may have important effects on ecological communities resulting from changing competition between interacting species. This research highlights the need for future studies that considers how both short and long term environmental variation impacts on the species competition.”

Picture One: Blue tit nestling peering out of its nestbox (courtesy of Dr Frank Adriaensen, University of Antwerp, Belgium).

Picture Two: Blue tits competing over a single nest box (courtesy of Professor Niclas Jonzén, Lund University, Sweden).