In the spring, bats are more "bold" and are not afraid to engage in conflicts with rats in the fight for food.
A new study of School of Zoology at Tel Aviv University reveals that fruit bats use a variety of strategies in their struggle for food with competing animals. In the current study, the research team examined the behavior of the bats in the presence of common rats that compete with them for the same food source, and found that the behavior changes according to the seasons and food supply – winter is characterized by avoidance and caution of rats, while in summer, when competition is greater, the bats are sometimes unafraid of fights that may even end in injury. The research team notes that the study, which lasted seven months and was recorded in a semi-natural colony of bats, provides a rare glimpse into how animals navigate the risk of predation and competition for resources.
The study was conducted by the laboratory team of Prof. Yossi Yuval from the School of Zoology at Tel Aviv University, led by doctoral students Chen-Xing and Adi Rahum, and with the assistance of Liraz Attia and Dr. Li Harthan. The study was published in the scientific journal BMC Biology.
Prof. Yuval explains that as part of the study, and over hundreds of hours of video recording, more than 150 bat landings near a food source were examined. The researchers found that when rats were present, the rate of landings dropped dramatically due to fear of confrontation and attacks from the rats. In addition to competing for food, rats are known to prey on bats, especially young ones. The bats that did land near food sources showed high alertness – they stopped and scanned the environment for long periods before approaching the food, which reduced their success in obtaining food by about 20%. In addition, cases were recorded in which rats attacked bats that had landed, which reinforced their perception as a real threat.
"We learned that interactions between bats and rats are diverse and vary seasonally according to food availability," adds Prof. Yuval. "In winter, when the presence of rats was relatively rare, the bats behaved more cautiously - they avoided depressions and demonstrated constant vigilance. In spring, however, with the sharp increase in food abundance (which also included an increase in encounters with rats), the situation changed and the bats sometimes actually attacked the rats. This behavior probably resulted in the success rate in finding food in depressions increasing to 60% in summer compared to only 35% in winter."
Prof. Yuval concludes: "We tend to describe the relationships between different species in a simplistic way as relationships of competition or predation. This study shows how complex such relationships can be and how animals know how to change their response strategies depending on the circumstances. This complexity is usually difficult to quantify in nature due to the paucity of observations, which we were able to do in this study. This is also another example of the adaptability and complex life of wild animals in an urban environment."
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