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Mazar, O.

Publications and source records attributed to Mazar, O..

3 recordsLinked to original sources

How bats exit a crowded colony when relying on echolocation only - a modeling approach

Bats face a complex navigation challenge when emerging from densely populated roosts, where vast numbers take off at once in dark, confined spaces. Each bat must avoid collisions with walls and conspecifics while locating the exit, all amidst overlapping acoustic signals. This crowded environment creates the risk of acoustic jamming, in which the calls of neighboring bats interfere with echo detection, potentially obscuring vital information. Despite these challenges, bats navigate these conditions with remarkable success. Although bats have access to multiple sensory cues, here we focused on whether echolocation alone could provide sufficient information for orientation under such high-interference conditions. To explore whether and how they manage this challenge, we developed a sensorimotor model that mimics the bats echolocation behavior under high-density conditions. Our model suggests that the problem of acoustic jamming may be less severe than previously assumed. Frequent calls with short inter-pulse intervals (IPI) increase the sensory input flow, allowing integration of echoic information across multiple calls. When combined with simple movement-guidance strategies--such as following walls and avoiding nearby obstacles--this accumulated information enables effective navigation in dense acoustic environments. Together, these findings demonstrate a plausible mechanism by which bats may overcome acoustic interference and underscore the role of signal redundancy in supporting robust echolocation-based navigation. Beyond advancing our understanding of bat behavior, they also offer valuable insights for swarm robotics and collective movement in complex environments.

animal behavior and cognition↗

Seasonal challenges of tropical bats (Rousettus aegyptiacus) in temperate zones

Egyptian fruit bats (Rousettus aegyptiacus) manage to survive and flourish in a large geographic range despite the variability of natural and anthropogenic conditions in this range. To examine the challenges faced by free-ranging R.aegyptiacus living at the northern edge of their distribution, we performed a retrospective analysis of [~]1500 clinical cases reported by a bat rescue NGO over 25 months, from all over Israel. All cases of injured or stranded bats were evaluated and categorized according to date, place, sex, age, and etiology of the morbidity. The analysis of the data showed an increase in all types of morbidity during the wintertime, with more than twice the number of cases in comparison with the summertime, over two consecutive years. Moreover, we found that the number of abandoned pups peaks during spring till autumn when adult morbidity is minimal. We characterize two prominent types of previously undescribed morbidity in R.aegyptiacus, one in the form of bacterial illness, and the other associated with feet deformation which affects bats in addition to major anthropogenic-related threats related to synanthropic predators. We analyze the reasons driving winter morbidity and conclude that winter weather and specifically low temperature best explains this morbidity. We hypothesize that R.aegyptiacus, a fruit-bat of tropical origin is facing major seasonal difficulties near the northern edge of its distribution, probably limiting its further spread northward.

ecology↗

A spectral jamming avoidance response does not help bats deal with jamming

For decades, researchers have speculated how echolocating bats deal with acoustic interference created by conspecifics when flying in aggregations. It is thus surprising that there has been no attempt to quantify what are the chances of being jammed, or how such jamming would affect a bats hunting. To test this, we developed a computer model, simulating numerous bats foraging in proximity. We used a comprehensive sensorimotor model of a hunting bat, taking into consideration the physics of sound propagation and bats hearing physiology. We analyzed the instantaneous acoustic signals received by each bat, and were able to tease apart the effects of acoustic interference and of direct resource competition. Specifically, we examined the effectiveness of the spectral Jamming Avoidance Response - a shift in signal frequencies - which has been suggested as a solution for the jamming problem. As expected, we found that hunting performance deteriorates when bats forage near conspecific. However, applying a Jamming Avoidance Response did not improve hunting, and our simulations clearly demonstrate the reason: bats have adequate natural signal variability due to their constant adjustment of echolocation signals to the task. The probability to be jammed is thus small and further shifting the frequencies does not mitigate spectral jamming. Our simulations reveal both negative and positive insight: they show how bats can hunt successfully in a group despite potential sensory interference and they suggest that a Jamming Avoidance Response is not useful.

animal behavior and cognition↗