How animals navigate over large-scale environments remains a riddle. Specifically, it is debated whether animals have cognitive maps. The hallmark of map-based navigation is the ability to perform shortcuts, i.e., to move in direct but novel routes. When tracking an animal in the wild, it is extremely difficult to determine whether a movement is truly novel because the animal’s past movement is unknown. We overcame this difficulty by continuously tracking wild fruit bat pups from their very first flight outdoors and over the first months of their lives. Bats performed truly original shortcuts, supporting the hypothesis that they can perform large-scale map-based navigation. We documented how young pups developed their visual-based map, exemplifying the importance of exploration and demonstrating interindividual differences.

Summary Every evening, from late spring to mid-summer, tens of thousands of hungry lactating female lesser long-nosed bats ( Leptonycteris yerbabuenae ) emerge from their roost and navigate over the Sonoran Desert, seeking for nectar and pollen [ 1 , 2 ]. The bats roost in a huge maternal colony that is far from the foraging grounds but allows their pups to thermoregulate [ 3 ] while the mothers are foraging. Thus, the mothers have to fly tens of kilometers to the foraging sites—fields with thousands of Saguaro cacti [ 4 , 5 ]. Once at the field, they must compete with many other bats over the same flowering cacti. Several solutions have been suggested for this classical foraging task of exploiting a resource composed of many renewable food sources whose locations are fixed. Some animals randomly visit the food sources [ 6 ], and some actively defend a restricted foraging territory [ 7 , 8 , 9 , 10 , 11 ] or use simple forms of learning, such as “win-stay lose-switch” strategy [ 12 ]. Many species have been suggested to follow a trapline, that is, to revisit the food sources in a repeating ordered manner [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. We thus hypothesized that lesser long-nosed bats would visit cacti in a sequenced manner. Using miniature GPS devices, aerial imaging, and video recordings, we tracked the full movement of the bats and all of their visits to their natural food sources. Based on real data and evolutionary simulations, we argue that the bats use a reinforcement learning strategy that requires minimal memory to create small, non-overlapping cacti-cores and exploit nectar efficiently, without social communication.

Background Urbanization is one of the most influential processes on our globe, putting a great number of species under threat. Some species learn to cope with urbanization, and a few even benefit from it, but we are only starting to understand how they do so. In this study, we GPS tracked Egyptian fruit bats from urban and rural populations to compare their movement and foraging in urban and rural environments. Because fruit trees are distributed differently in these two environments, with a higher diversity in urban environments, we hypothesized that foraging strategies will differ too. Results When foraging in urban environments, bats were much more exploratory than when foraging in rural environments, visiting more sites per hour and switching foraging sites more often on consecutive nights. By doing so, bats foraging in settlements diversified their diet in comparison to rural bats, as was also evident from their choice to often switch fruit species. Interestingly, the location of the roost did not dictate the foraging grounds, and we found that many bats choose to roost in the countryside but nightly commute to and forage in urban environments. Conclusions Bats are unique among small mammals in their ability to move far rapidly. Our study is an excellent example of how animals adjust to environmental changes, and it shows how such mobile mammals might exploit the new urban fragmented environment that is taking over our landscape.

Background Urbanization is rapidly changing our planet and animals that live in urban environments must quickly adjust their behavior. One of the most prevalent behavioral characteristics of urban dwelling animals is an increased level of risk-taking. Here, we aimed to reveal how urban fruitbats become risk-takers, and how they differ behaviorally from rural bats, studying both genetic and non-genetic factors that might play a role in the process. We assessed the personality of newborn pups from both rural and urban colonies before they acquired experience outdoors, examining risk-taking, exploration, and learning rates. Results Urban pups exhibited significantly higher risk-taking levels, they were faster learners, but less exploratory than their rural counterparts. A cross-fostering experiment revealed that pups were more similar to their adoptive mothers, thus suggesting a non-genetic mechanism and pointing towards a maternal effect. We moreover found that lactating urban mothers have higher cortisol levels in their milk, which could potentially explain the transmission of some personality traits from mother to pup. Conclusions Young bats seem to acquire environment suitable traits via post-birth non-genetic maternal effects. We offer a potential mechanism for how urban pups can acquire urban-suitable behavioral traits through hormonal transfer from their mothers.

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.