Bats communicate and work together for more efficient foraging

Social hunting strategies are already well documented in many animal species when prey is distributed from unpredictably in the landscape. In a new research doc, Manuel Roeleke and his team from the University of Potsdam and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) have now demonstrated for the first time that animals – in this case, the common noctule bat – band together and form a sensory cell network to increase their chances of finding their prey. Analyzes published today in the scientific journal Proceedings of the National Academy of Sciences show that predators can adapt to varying environmental conditions through flexible, networked foraging strategies with conspecifics.

Many predators need to find food daily. If the prey is unevenly distributed across the landscape and only available for a short time, this task is like finding the needle in a haystack. Animals that depend on such unpredictable prey have therefore often developed social strategies for feeding: when searching for prey, individuals are in contact with each other and exchange information about their environment. An international research team led by the University of Potsdam and Leibniz-IZW has now observed for the first time that common noctule bats (Nyctalus noctula) temporarily join together to form mobile sensory networks while foraging. “The common noctule is particularly well adapted to such surveys because its prey – swarms of insects – disperse in totally unpredictable ways in the open airspace,” explains the paper’s lead author, Manuel Roeleke. “Furthermore, the distance over which bats can locate insects by ultrasound is relatively small, approximately to 15 meters. This makes it difficult for them to track their prey. On the other hand, bats can perceive their own congeners over a great distance. from greater distances, in ideal circumstances up to 15 meters. Searching in groups should therefore be more fruitful.”

Overall, the scientists analyzed the flight patterns of 81 common noctule bats. This was made possible by small radio transmitters which send signals to an array of antennae. Florian Jeltsch from the University of Potsdam explains: “With the state-of-the-art ‘ATLAS’ system, we can simultaneously record the movement of dozens of individual animals. Thanks to the great support of local farmers and private landowners, we have been able to operate tracking technology in the Uckermark district of East Germany since 2018 – a special opportunity to study animal movements and biodiversity in the European agricultural landscape.” His colleague Christian Voigt from Leibniz-IZW adds: “With the ‘ATLAS’ system, it is now possible to record the interactions of bats in flight. Our data support the mobile sensory network theory: when searching for insects, bats fan out but remain in acoustic get hold of and, if necessary, adjust their flight paths to each other in order to search an area as massive as possible.” If an individual bat in the array finds a swarm of prey insects, its neighbors are notified by way of changes in flight movements and through ultrasonic calls specifically used for insect hunting. This gradually makes all the animals in the sensory network aware of the rewarding hunting area.

The scientific team compared the foraging efficiency of bats “networked” mice and individual hunters depending on group size and food distribution. To achieve this, they used a computer model developed by co-author Cara Gallagher using the empirically determined movement patterns. “Networking and the exchange of information has proven particularly useful for bats when food sources are widely distributed in space,” says Roeleke. “Thus, our model showed that ‘networked’ animals needed 15% of less time to stalk their prey than bats that ignored their conspecifics while feeding.” By feeding in groups, bats can find prey even in large-scale cultivated landscapes and thus contribute effectively to the control of agricultural “pests”. If this is to continue in the future, bats need constant protection, especially their roost system. When local populations become too few, bats can no longer form effective networks. As solitary animals, it is then difficult for them to find food quickly and reliably.

HuntingChiropteraGottfried Wilhelm LeibnizMusic BandInsectZoo ParkPotsdamUniversity

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