A new study from the School of Zoology at Tel Aviv University reveals that fruit bats employ a variety of strategies in their competition with other animals for food. The research team examined bat behavior in the presence of black rats, which vie for the same food sources. They found that the bats' behavior changes with the seasons and food availability: in winter, bats tend to avoid and act cautiously toward rats, while in summer, when competition is more intense, the bats are sometimes not afraid to engage in conflict - even at the risk of injury. The researchers note that the study, conducted over seven months and documented in a semi-natural bat colony, provides a rare glimpse into the way animals balance the dangers of predation with the need to compete for resources.
A Rare Glimpse into Animal Competition
The research was conducted by the laboratory team of Prof. Yossi Yovel at Tel Aviv University's School of Zoology, Wise Faculty of Life Sciences, author of The Genius Bat. It was led by PhD students Xing Chen and Adi Rachum, with the assistance of Liraz Attia and Dr. Lee Harten. The findings were published in the journal BMC Biology.
Prof. Yovel explains that over the course of hundreds of hours of video documentation, more than 150,000 bat landings near a food source were analyzed. The researchers found that when rats were present, the number of bats' landings dropped dramatically due to fear of confrontation and rat attacks. In addition to competing for food, rats are known to prey on bats, especially on young bats. The bats that did land near food sources displayed heightened vigilance - pausing to scan their surroundings for long periods before approaching the food. This reduced their success in obtaining food by about 20%. Moreover, in some cases rats were observed attacking landing bats, underscoring the real threat they pose.
Prof. Yossi Yovel
From Fear to Boldness
"We learned that the interactions between bats and rats are diverse and vary with the seasons, depending on food availability," says Prof. Yovel. "In winter, when rats were relatively scarce, the bats behaved more cautiously - they avoided landings and showed constant vigilance. In contrast, in spring, with the sharp increase in food abundance (which also meant more encounters with rats), the situation changed, and the bats sometimes even attacked the rats. This behavior apparently improved their foraging success rate, which rose to 60% in summer compared to only 35% in winter."
Prof. Yovel concludes: "We tend to describe relationships between different species in simplistic terms - either as competition or predation. This study shows how complex such relationships can be and how animals are able to adapt their response strategies to changing circumstances. Because observations in nature are scarce, this complexity is usually difficult to quantify. What we achieved in this study therefore provides another example of the adaptability and intricate lives of wild animals in urban environments."
