Newswise — New research reveals that European breeding birds have undergone an average range shift of 2.4km per year over the past three decades. Surprisingly, these changes differ significantly from what would be expected based solely on the changing climate and landcover during that period.
According to climate predictions alone, the researchers anticipated that the average range shifts per species should have been approximately 50% faster than observed.
The study, led by experts from Durham University, UK, utilized data from two Europe-wide bird distribution atlases, which were published with a 30-year interval.
Intriguingly, the researchers discovered that the local colonization and extinction events across species' ranges showed only weak correlations with the change in climate between the two survey periods. Instead, these events were found to be more influenced by the climatic conditions prevailing during the initial surveys.
A crucial factor influencing whether a new area was colonized or if a population faced extinction was the presence of other populations of the same species nearby. The proximity of these populations facilitated colonization and reduced extinctions, likely due to the birds' dispersal from neighboring areas.
This discovery emphasizes the significance of maintaining networks of local populations to mitigate extinctions and enhance population resilience against the impacts of climate change.
The study's findings have been published in the journal Nature Communications.
Professor Stephen Willis, one of the joint leads of the study from Durham University's Department of Biosciences, remarked, "Our findings reveal two intriguing responses to recent climate change. In certain regions, 'colonization lags' may lead to species being unable to keep pace with improving climates, possibly due to the unavailability of suitable habitats or prey in new areas."
On the other hand, when fewer extinctions occur in areas where we initially expected them, it could indicate the presence of "extinction debts." These debts occur when species face inevitable extinction due to unfavorable climate conditions. However, they manage to persist, sometimes for extended periods, because critical limiting factors, such as their preferred habitat, take time to undergo changes.
Dr. Christine Howard, one of the joint first-authors, added, "The significant role of non-climatic factors in influencing range changes emphasizes that climate is just one of many factors affecting European breeding bird populations. Issues like persecution remain a major problem for many species. Nevertheless, the swift recovery of certain species from past persecution or poisoning offers hope that populations can rebound once these impacts are effectively controlled."
Dr. Sergi Herrando, a co-author who played a leading role in compiling data for the latest distribution atlas, emphasized the significance of coordinated survey data collected across multiple countries in enhancing our understanding of species losses and gains.
He stated, "The research presented here exemplifies how coordinated survey data, gathered from numerous countries, can provide valuable insights into the factors influencing changes in species populations."
The data collection process for this study involved an impressive number of contributors. The second breeding atlas alone gathered data from 120,000 dedicated field workers, enabling a comprehensive survey covering an extensive area of 11 million square kilometers across 48 countries.
The research was funded in part by the National Environment Research Council, part of UK Research and Innovation.
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