European birds with narrow climate tolerance reduce population decline

New research suggests that conservation efforts can more effectively identify and protect the most at-risk bird species from climate change by better understanding the range of specific conditions needed to thrive.

The study, led by the University of East Anglia (UEA), examined the relationship between the range of climatic conditions a species can withstand, the range of climatic conditions in which the population can survive as a range of climate niches, and the likelihood that it will decrease in response to climate change.

For species living in similar regions of geographical space, species that can withstand a wider range of climatic conditions are less likely to experience a decline in population and are more likely to increase compared to people with narrow climate preferences.

The authors’ findings published in the Journal of Biogeography provide valuable insight into how climatic niche widths work as key factors in predicting vulnerability in the range of climate change. The paper is titled “The decline of European breeding birds associated with narrow climate niches.”

They argue that to incorporate species’ climate change niches into climate change risk assessments, they better inform conservation strategies and that variation in climate conditions within species ranges can provide greater nuance in understanding resilience to factors affecting populations.

“Determining which species is at greater risk is not easy and it can be that the species is declining for a variety of reasons,” says Karolina Zalewska, a graduate researcher at the UEA School of Environmental Sciences.

“Rare and smaller distribution species are more likely to be vulnerable to climate change. This study shows that more widely popular birds, such as house sparrows and general sterling, also face threats to their populations.

“Whether rare or widespread, or narrow climate change, these are species that are more susceptible to rapid changes brought about by climate change, compared to those with a wider niche, which may be one of the fundamental reasons behind the observed decline in population.

“Our results highlight the importance of understanding and incorporating levels of climate change exposure when assessing vulnerability to climate change and long-term population decline.”

Human-induced climate change is increasingly identified as a major threat to global biodiversity. However, the extent of this threat can be heterogeneous across species, as climatic conditions such as temperature and rainfall variables are more prevalent than across geographical regions due to differences in life history and different exposure to environmental changes.

Species with a wider geographical distribution experience a wider range of climatic conditions and are expected to be resilient due to environmental changes, but the recent population decline of many broad species suggests that other factors may be involved.

“Faced with the global biodiversity crisis and the challenges of climate change, a rapid assessment of species vulnerability to environmental change has become paramount to addressing conservation priorities,” said Professor Ardina Franco, co-author of the Faculty of Environmental Sciences.

“As climate change accelerates, our research highlights the need to prioritize the most risky species due to more restricted environmental requirements.”

The researchers used data on population trends for 159 European breeding birds across 29 European countries from a pan-European general bird surveillance scheme. These 40-year population trends were related to the experience of climatic condition species and their distribution areas.

They used 30 years of climate data on species breeding ranges to construct representations of climate niches and generate new indexes of climate niche widths that describe species distribution areas.

This analysis was used to explore how these variables influence long-term population trends, along with additional factors such as species diet, primary habitat type, migration status, and average weight.

“These findings help us understand the threats associated with climate change, allow for a rapid assessment of the importance of climate factors in population trends, and provide valuable tools to target species conservation,” added Miss Zareuska.

“In particular, the climate-to-range area index helps predict which species are more vulnerable to population decline.”

Within the species included in this study, population trends decreased for 58 people, 68 populations were stable, and 33 species were stable.

Similar to previous studies, the team found that species associated with farmland habitats in both the UK and in the broader European regions, such as corn bunting and Skylark, are likely to decrease.