SLU news

Molecular methods showed that a Japanese bat had eaten a bird

Published: 12 July 2019

The vast majority of the bats are insectivorous, but many bats are known to occasionally forage on other, rarer prey, including fish or birds. One example is the Asian species birdlike noctule (Nyctalus aviator). A few years ago a researcher found bird feathers in fecal pellets. Thanks to molecular methods a research group could show that one bat really had eaten a bird and also which bird it was. One of the researchers comes from SLU.

The researchers studied six species of Japanes bats. They were mainly interested in their insect prey. However, when confirming the species identity of the samples from the bats’ faecal DNA one of the retrieved sequences was identified as a bird. The researchers were able to identify the bird to the species level (Locustella ochotensis).

“An earlier study by my colleague Dr. Fukui had revealed that the bats in Japan feed on migrating birds. But we were able to go further and identify the actual bird species. Moreover, our bat had foraged on the bird  while pregnant and during bird’s breeding season. This is all new information, and raises more questions on the behavior of both bats and birds”, says Eero Vesterinen, a Finnish researcher now working at the Swedish University of Agricultural Sciences (SLU).

The behaviour remain unstudied

While the frequency and significance of this behaviour remain unstudied, it may serve as an important nutritional strategy during key life stages, such as reproduction.The next step would be to gather a larger sample set throughout the season, to more accurately analyse the importance of birds in the bat’s diet.

“This doesn´t change our view of what Nyctalus aviator eat. Insects and other arthropods still constitute the main diet.”

A lot of new findings

In many cases, it is practically impossible to go deeper into dietary analysis without the help of DNA applications. Eero Vesterinen and other researchers have already successfully applied the most advanced molecular methods to study bats’, birds’, and dragonflies’ diet, as well as laerge-scale plant-herbivore interactions and tick-host-pathogen webs.

In Japan, most of the earlier research was based on observations of morphological analysis. The research group is the first to apply more modern methods there. Finnish bats’ diet are more well-studied. They researchers have not found any spectacular prey like birds (even though there are such observation also from Europe) but they have learnt a lot of other interesting things.

“By sequencing the DNA present in the droppings we have realized that such different animals as bats, birds and dragonflies actually share the same prey", says Eero Vesterinen.

Scientific article

Molecular evidence of bird-eating behavior in Nyctalus aviator, Olga Heim, Anna I. E. Puisto, Dai Fukui, Eero J. Vesterinen Acta Ethologia

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