Over the past 100,000 years, hooved mammals that migrate have experienced a higher rate of extinction compared to non-migratory species, according to a study publishing November 5th in the open access journal PLOS Biology by Joel Abraham at Princeton University, US, and colleagues.
Animal migrations are amongst the most dramatic spectacles in nature. However, human activities have disrupted many migrations, by physically blocking them with roads and fences, or through changes in the availability of resources, driven by climate change. As a result, many migratory species have experienced population declines, or even extinction, in recent decades. Yet the vulnerability of migratory species to extinction may not be a new phenomenon. The success of migration as a strategy depends on animals' ability to accurately predict the timing and location of resources like food and water, making them vulnerable to past and present environmental change.
Hooved mammals, known as ungulates, are well-known for their large populations and long-distance migrations. To investigate the vulnerability of migratory ungulates to extinction, researchers used fossil evidence and data from modern-day species to infer the migratory behavior of 51 ungulates that went extinct in the last 100,000 years. They found that 80% of ungulates that went extinct during this period were migratory. In contrast, only 46% of modern ungulates migrate. This suggests that migratory ungulates have been at greater risk of extinction during recent geological epochs. However, statistical modelling indicated that new migratory species have also evolved more frequently. The researchers estimated that in lineages of migratory ungulates, a new species has evolved 2.8 times per million years, compared to 1.7 new species per million years for non-migratory lineages. Finally, the researchers evaluated whether migratory ungulates that went extinct during this period had unique combinations of traits that were lost from the ecosystem as a result of their extinction. In Africa, extinctions of migratory ungulates caused a 2.7% decline in functional diversity, but at a global level, the effect was minimal.
The results indicate that migratory ungulates have experienced greater extinction rates over the last 100,000 years compared to non-migratory species, supporting the idea that migration is a risky evolutionary strategy. With mounting pressures on migratory species, due to urbanization, hunting and climate change, conservationists should prioritize migratory species, the authors say.
The authors add, "While it's well-established that migratory animals are at risk today from human activity, it's not clear whether greater risk has always been a feature of migration – after all, migrating can be very costly. In our study, we find two lines of evidence that migration enhances extinction rates and thus exposes ungulates to greater risk: firstly, we inferred the behavior of many extinct ungulates and found that they were much more likely to be migratory than present-day ungulates; secondly, we estimated ungulate macroevolutionary parameters and found that migration was associated with elevated extinction rates. Both these patterns suggest that migration may bias species towards extinction, emphasizing the riskiness of relying on migration, particularly in a world rapidly being altered by humans.
"We were also very intrigued to discover that migratory behavior is associated with elevated speciation rates in ungulates. That's a pattern that has been shown in birds, but it's very cool to see that it holds true in ungulates as well – perhaps migration always enhances speciation, no matter the taxa!"
In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: https://plos.io/3UlsZ6I
Citation: Abraham JO, O'Brien K, Upham NS, Jesmer BR, Bibi F, Faith JT (2026) Phylogenetic evidence that migratory behavior increases ungulate extinction rates. PLoS Biol 24(11): e3004072. https://doi.org/10.1371/journal.pbio.3004072
Author countries: United States, Germany
Funding: JOA and KO were supported by the NSF Graduate Research Fellowship Program (respective Fellow IDs: 2019256075 and 2020294514; https://www.nsf.gov/funding/initiatives/grfp ). JTF is supported by a grant from the United States National Science Foundation (2224318; https://www.nsf.gov/ ). NSU is supported by the United States National Institutes of Health (1R35GM156919-01; https://www.nih.gov/ ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
