Insectivorous bats form mobile sensory networks to optimize prey localization: The case of the common noctule bat

Abstract

Animals that depend on ephemeral, patchily distributed prey often use public information to locate resource patches. The use of public information can lead to the aggregation of foragers at prey patches, a mechanism known as local enhancement. However, when ephemeral resources are distributed over large areas, foragers may also need to increase search efficiency, and thus apply social strategies when sampling the landscape. While sensory networks of visually oriented animals have already been confirmed, we lack an understanding of how acoustic eavesdropping adds to the formation of sensory networks. Here we radio-tracked a total of 81 aerial-hawking bats at very high spatiotemporal resolution during five sessions over 3 y, recording up to 19 individuals simultaneously. Analyses of interactive flight behavior provide conclusive evidence that bats form temporary mobile sensory networks by adjusting their movements to neighboring conspecifics while probing the airspace for prey. Complementary agent-based simulations confirmed that the observed movement patterns can lead to the formation of mobile sensory networks, and that bats located prey faster when networking than when relying only on local enhancement or searching solitarily. However, the benefit of networking diminished with decreasing group size. The combination of empirical analyses and simulations elucidates how animal groups use acoustic information to efficiently locate unpredictable and ephemeral food patches. Our results highlight that declining local populations of social foragers may thus suffer from Allee effects that increase the risk of collapses under global change scenarios, like insect decline and habitat degradation.

Evolution of explorative and exploitative search strategies in collective foraging

“…It is possible that these search features maybe correlated [Kurvers et al, 2010], in which case, groups would benefit from a mix of asocial explorers that find resource patches and social exploiters who harvest a found patch. The movement or space-use patterns can also affect how foragers acquire information (e.g., due to speed-accuracy trade-offs) [Spiegel and Crofoot, 2016] or how well they can communicate with each other [Roeleke et al, 2022]. Further investigations can modify the model's assumptions to test these effects of exploratory strategies on group-level efficiencies and general adaptability.…”

Acoustic evidence for seasonal resource-tracking migration by a top predator of the deep sea

“…Given that mesopelagic and bathypelagic prey can display significant heterogeneity in density (50), this approach might allow sperm whales to minimize diving effort in areas of low prey density and allot greater time and energy to horizontal movements to track seasonal-latitudinal forage variability. Because sperm whales echolocate to find prey, long-distance acoustic information on the foraging behavior of conspecifics might further direct this search, similar to the "mobile sensory networks" formed by echolocating bats (51). Social learning of foraging and movement strategies could also play a role (52,53), as sperm whales are highly-social animals (30).…”

Interindividual communication by bats via echolocation

“…Wright et al (2011) demonstrated that juvenile Eptesicus fuscus learned novel foraging techniques by flying with and listening to experienced foragers. Using radio-telemetry, Roeleke et al (2022) have recently demonstrated that Nyctalus noctula (Schreber, 1774) forage in groups and benefit by what they call a "mobile sensory network" that collectively can locate more prey than single individuals can.…”