Wild seabirds are more likely to split up in windy weather, according to a new study.
The paper, published in the journal Animal Behaviour, was led by Edinburgh Napier University and also involved the UK Centre for Ecology & Hydrology (UKCEH) and Biomathematics and Statistics Scotland (BioSS).
It reveals that environmental conditions before the breeding season appear to have an impact on mate faithfulness – whether birds reunite with the same partner to breed each year, or ‘divorce’ to form a different pair. The findings are significant given that climate change is bringing about warmer and windier weather conditions.
The researchers studied two decades of data on the breeding habits of more than 1,500 European shags on the Isle of May National Nature Reserve, in the Firth of Forth, and compared them with late winter weather records. The species was chosen due to their long lifespan and tendency to change partners between breeding seasons.
While the birds analysed for this study had a fidelity rate of 45%, this varied markedly from year to year.
Wind delivers biggest blow
Although age and previous breeding success have been established as strong predictors of mate faithfulness, this paper demonstrates how weather conditions in the lead-up to the breeding season are also a significant factor affecting seabird mating habits. Out of the weather conditions analysed, wind speeds had the strongest effect on whether couples stayed together.
Importantly, birds that remained with the same partner tended to lay eggs earlier, which is strongly tied to how many chicks they rear.
Co-author Professor Francis Daunt of UKCEH said: “This study is one of the few to test how changing environments influence social behaviours in wildlife. It is excellent to see our long-term data used to tackle these important questions, given the current concerns about the impacts of future climate change.”
The researchers say further investigation is needed into how shifting environmental conditions could disrupt social relationships among wildlife.
Challenges to breeding
Meanwhile, separate research has shown how trends in seabird breeding success in a warming world differ by marine ecosystems of the northern hemisphere.
The study, carried out by an international team including scientists at UKCEH, is accompanied by an interactive online tool to explore seabird and climate dynamics globally.
Breeding success (the percentage of eggs laid that result in fledglings) is in noticeable and chronic decline in the Arctic, Northern European Seas and Northwest Atlantic. It is more constant in the Northeast and Northwest Pacific, and Hawaiian region.
The study included data from UKCEH-led research on the Isle of May collected over 30 years for six species - common guillemot, razorbill, Atlantic puffin, European shag, black-legged kittiwake and northern fulmar.
The paper, led by the Farallon Institute in California, is published in the journal Communications Earth and the Environment.