Cognitive map-based navigation in wild bats revealed by a new high-throughput tracking system
Data files
Jul 09, 2020 version files 48.95 MB
Abstract
Seven decades of research on the “cognitive map”, the allocentric representation of space, have yielded key neurobiological insights, yet we still lack field evidence from free-ranging wild animals. Using a system capable of tracking dozens of animals simultaneously at high accuracy and resolution, we assembled a large dataset of 172 foraging Egyptian fruit bats comprising >18M localizations collected over 3,449 bat-nights across 4 years. Detailed track analysis, combined with translocation experiments, revealed that wild bats seldom exhibit random search but instead repeatedly forage in goal-directed, long and straight flights that include frequent shortcuts. Alternative non-map-based strategies were ruled out by simulations, time-lag embedding and other trajectory analyses. Our results are consistent with expectations from cognitive map-like navigation and support previous neurobiological evidence from captive bats.
All bat procedures were approved by the Hebrew University of Jerusalem Animal Care and Use Committee (permit NS-15-14660-2). Bats were mist-netted on fruit trees or cave entrances and tagged with ATLAS in 38 capture sessions spanning all seasons between 2015-2019. Bats were tagged with ATLAS – a reverse-GPS system that localizes extremely light-weight, low-cost tags. Each ATLAS tag transmits a unique radio signal detected by a base-station network distributed in the study area. Tag localization is computed using nanosecond-scale differences in signal time-of-arrival to each station, enabling nearly real-time tracking and alleviating the need to retrieve the tag or to have some power-consuming remote-download capability. Bats were tagged by gluing the tag to their back (138 individuals) or by a custom-made collar (34 individuals). We applied a simple 10-second median filter to eliminate localization errors and smoothen the data.
The data are in a comma-delimited text file. Each row is a single localization of a single tag. There are 10 columns, as follows:
1) Tag (bat) number
2) X-coordinate (metric, ITM coordinate system)
3) Y-coordinate (metric, ITM coordinate system)
4) Timestamp (Unix epoch time) in UTC
5-10) Time in human-readable format: Year, Month, Day, Hour, Minute, Second