One of Madagascar's largest bat species is showing a striking physical change, with researchers finding that its skulls have become approximately 6 per cent smaller over the past four decades. The findings, published in the Journal of Mammalogy on October 29, 2026, point towards a possible connection between shrinking body size and increased hunting pressure. The research, also reported by Science News and conservation-focused publications, raises fresh questions about how human activity is changing wildlife populations and threatening species already facing population decline.
The Malagasy flying fox (Pteropus rufus), known for its impressive wingspan and fox-like facial features, is among the world's largest bats. Found across Madagascar, these fruit-eating mammals play an important ecological role by dispersing seeds and helping maintain forest ecosystems. The research was led by Emily Cornelius Ruhs and Steven Goodman of Chicago's Field Museum. To investigate the apparent change, the scientists examined 121 preserved specimens held in nine natural history museums across the United States and Europe. The specimens represented more than 150 years of the species' history. The team recorded measurements of 12 different features of the bats' skulls and teeth. Their analysis revealed that specimens collected before the 1980s had skulls that were, on average, 3.6 millimetres longer than those collected in subsequent decades. This represents a difference of approximately 6 per cent.
Why hunting could be changing their size
Researchers believe the timing of the physical change may be significant. Until the 1980s, flying foxes were largely hunted on a small scale to provide food for individual families and local communities. However, hunting gradually became more commercialised, with bats increasingly being sold in markets and served in restaurants. The researchers suspect that larger bats may have become easier targets because of their size and the greater amount of meat they provide. This could have resulted in disproportionate hunting of larger individuals, gradually changing the physical characteristics seen in subsequent generations. A report by Mongabay also highlighted the importance of the species as a food source in Madagascar, where flying foxes are hunted for both household consumption and commercial sale. Some hunters use nets, while others shoot the animals before selling them. However, hunting is not necessarily the only explanation. The researchers have also identified deforestation, changing climatic conditions and shifts in fruit availability as possible contributors. The study establishes a strong association between the increase in commercial hunting and the decline in skull size, but does not conclusively establish that hunting alone caused the change.
A shrinking species faces wider conservation concerns
The findings are particularly concerning because Malagasy flying foxes are already facing pressure from multiple directions. Beyond their role as a food source, the bats are important seed dispersers and pollinators. By feeding on fruits and nectar and moving between trees, they help support forest regeneration and maintain Madagascar's biodiversity. Their slow reproductive rate makes the situation more complicated. The loss of larger, sexually mature individuals could potentially affect the population's ability to reproduce and recover from continued hunting pressure. A study of this kind also highlights why museum collections are valuable to conservation science. Preserved specimens offer researchers a rare opportunity to compare wildlife across generations and identify physical changes that might otherwise go unnoticed.
The researchers believe further monitoring and stronger protection, particularly around breeding sites, will be important to safeguard the species. They also want to understand whether similar physical changes are occurring in other fruit bats hunted across Madagascar. The findings offer a reminder that human activity can leave lasting effects on wildlife, sometimes in ways that become visible only after decades of change.
