Night Bird Hunter

2007/05/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Zoologia

European bats are generally insectivorous. Therefore, it has been discussed about the great nocturnal bat (Nyctalus lasiopterus), since in 2001 researchers from the Doñana Natural Park declared that it also hunted birds. The beliefs asked for more evidence and now evidence has been published that seems to agree.

In 2001, Doñana researchers, led by Carlos Ibáñez, published that they found feathers in the excrements of the great bat at night, even a specimen with feathers in the mouth. It is a sign that hunts the passing birds of the great nocturnal bats: in migratory times, autumn-spring, it was believed that hunted not only insects but also birds.

This practice is unusual and requires a lot of flying skills. Therefore, other experts, such as the Swiss Arlettaz, were believers. Therefore, in Doñana they continued to seek further evidence and Arlettaz himself met them.

Blood tests were used to determine the diet of the bat. According to the diet, the proportion of carbon isotopes in blood is different from that of nitrogen isotopes. Thanks to this, they learned that in spring the bat eats birds, only insects in summer, and in autumn, more than in spring, birds. These results coincide with the passing season of the birds that pass in spring and autumn. In spring winter survivors pass through Doñana, and in autumn in larger quantities, with young.

Therefore, doubts have now been resolved and all experts agree that the great bat at night is bird hunter.