April 20, 2023 report
Assessing how time lags influence the response of mammal and bird populations to change
Bob Yirka
news contributor
A team of zoologists and life scientists from the Zoological Society of London, the Natural History Museum in London and Our World in Data at the Global Change Data Lab has conducted an assessment of how time lags influence the response of mammal and bird populations to both climate and land-use change. In their study, reported in Proceedings of the Royal Society B, the group analyzed data from the Living Planet Database and used it to manipulate models to assess the true impact of change on mammal and bird populations.
A large number of animals are at risk of extinction due to human activities. The researchers in this new effort suggest that there are currently two main drivers that put mammals and birds at risk: loss of habitat and global warming. They also note that models that are currently used to assess animal population risks do not include time lag influences, which, they contend, lead to serious miscalculations. In their work, time lags are defined as periods of time that it takes for a given population of creatures to start declining due to external factors, such as loss of land or reductions in available food.
Prior to diving into the data, the team set themselves the goal of answering five general questions: Do lag times better explain changes in population than other factors? Are lags better described in years or generations? Are there differences in lags between species? Do environmental changes vary across lags? And what are the ecological repercussions of lags on future population trends?
In analyzing entries in the database, which stores information on more than 600 species of mammals and birds, the team narrowed their focus to 751 populations, including 712 species in 664 locations. They found that lag times varied widely from less than 10 years to more than 40, depending on the species. They note that the longer lag times for some species suggests that many of them may already be at risk.
The team then used the results of their analysis to reconfigure current models and found that inclusion of lag times shows that many more species of mammals and birds are at risk than has been shown in other studies. They suggest that unless changes are made soon, targets adopted by governments to protect certain species might already be out of reach.
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More information: Richard Cornford et al, Ongoing over-exploitation and delayed responses to environmental change highlight the urgency for action to promote vertebrate recoveries by 2030, Proceedings of the Royal Society B: Biological Sciences (2023).
Journal information: Proceedings of the Royal Society B
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