Separation of property in bats

Males and females use different habitats

Although males and females of the bicolor bat use similar sleeping places, they otherwise live in different habitats. © MPI of Ornithology
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When males and females use different resources of one species, this makes it difficult to estimate the size of the population. But it is precisely this that plays an important role in protecting rare and endangered species. For the two-color bat researchers have now found that both sexes even use very different habitats, they practice so to speak, a separation of property in terms of habitat.

In species conservation, it is essential to know the population size of threatened species from counts or estimates. However, when groups within a species, such as males and females, behave differently, this greatly complicates an estimate. Because, for example, in a sexual Segratation, both groups can use other rest areas, chase other food or even live completely separated for much of the time.

Ecological niches of both sexes compared

Scientists at the Max Planck Institute for Ornithology in Radolfzell and their colleagues at the Swiss Center for Bat Protection have now found a way to get better estimates of population sizes even for species with sexual segregation. They examined bicolor bats (Vespertilio murinus) in Switzerland. This species of bats is distributed from the Netherlands to China, but is rare in Europe. Although males and females are outwardly similar and both sexes prefer similar sleeping quarters during the summer, on closer inspection, they are very different, as the new study shows.

The scientists calculated the ecological niches of both sexes using radio-telemetry data. In doing so, they used data obtained by observing the behavior of individual male and female bicoloured bats in conjunction with ecological-geographical data from the Swiss Federal Statistical Office. They were given information about the type and number of suitable habitats and were able to create maps of suitable habitats. These maps show where, according to analysis, a habitat suitable for males or females is available in Switzerland.

No overlap of habitats of both sexes

They found that the ecological niches of both sexes are fundamentally different and that no overlapping of suitable habitats can be found throughout Switzerland. In addition, they were able to define the degree of specialization of both sexes more precisely. "The females of the bicoloured bat are highly specialized because they only use lakeshore as a hunting ground, " explains Marielle van Toor from the Max Planck Institute for Ornithology. display

"The males, on the other hand, are also very specialized, but still more flexible in their habitat choice, " the researcher continues. You'll also be comfortable in open landscapes, on forest edges and on rivers. Therefore, they have almost three times more suitable habitat in the study area than the females. From an ecological point of view, males and females behave like two different species of animals.

Species protection must take into account habitat requirements

The studies showed that the females are much more vulnerable than the males and that the necessary conservation measures should concentrate on this smaller group within the total population. So far, the monitoring of bat populations has been based on acoustic signals, the so-called bioacoustic monitoring, which allows only conclusions about the number of animals, but not on their gender. In the future, the protection of species should also take into account the different habitat requirements, according to the researchers' recommendation.

"Species with sexual segregation are not necessarily concerned with preserving their habitat, " adds Marielle van Toor, "but it is much more important to protect the habitat of the more demanding sex. For the bicolor bat in Switzerland, this means devoting itself to the preservation of wetlands and lakes, so that the females and their cubs will continue to have access to good sources of food in the future. (Animal Conservation, 2011; Doi: 10.1111 / j. 1469-1795 2011.00454.x)

(Max Planck Society, 25.03.2011 - NPO)