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Landmark-guided navigation is a common behavioral strategy for way-finding, yet prior studies have not examined how animals collect sensory information to discriminate landmark features. We investigated this question in animals that rely on active sensing to guide navigation. Four echolocating bats (Eptesicus fuscus) were trained to use an acoustic landmark to find and navigate through a net opening for a food reward. In experimental trials, an object serving as a landmark was placed adjacent to a net opening and an object serving as a distractor was placed next to a barrier (covered opening). The location of the opening, barrier and objects were moved between trials, but the spatial relationships between the landmark and opening, and between the distractor and barrier were maintained. In probe trials, the landmark was placed next to a barrier, while the distractor was placed next to the opening, to test whether the bats relied on the landmark to guide navigation. Vocal and flight behaviors were recorded with an array of ultrasound microphones and high-speed infrared motion-capture cameras. All bats successfully learned to use the landmark to guide navigation through the net opening. Probe trials yielded an increase in both the time to complete the task and the number of net crashes, confirming that the bats relied largely on the landmark to find the net opening. Further, landmark acoustic distinctiveness influenced performance in probe trials and sonar inspection behaviors. Analyses of the animals’ vocal behaviors also revealed differences between call features of bats inspecting landmarks compared with distractors, suggesting increased sonar attention to objects used to guide navigation.
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The skynet, a new method to capture bats over water
When monitoring bats, the greatest yield in capture rate for survey effort can often be found in riparian and lentic habitats. However, capturing bats over large bodies of water is usually challenging due to the logistics of deploying equipment and extracting bats whilst ensuring the safety of surveyors. We present a novel technique – the “skynet” – as one solution to this problem, allowing fast and safe deployment of a suspended mist net between two anchor points over open water. Preliminary fieldwork in a Croatian scrub-dominated landscape yielded a capture of 22 bats of five species over a 1600 m2 pond. Our results demonstrate that the method is effective compared to a simultaneous net positioning on the bank of the same water body, which yielded no bats. System design and recommendations for bespoke alterations, alternative equipment options, and future investigations are presented here.
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- Award ID(s):
- 2127290
- PAR ID:
- 10323733
- Date Published:
- Journal Name:
- Barbastella
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 1576-9720
- Page Range / eLocation ID:
- 215 to 221
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.14709/BarbJ.14.1.2021.18
