Researchers Uncover Alarming Rat Predation on Bats in Germany

A recent study has revealed a disturbing trend in northern Germany, where brown rats, known scientifically as Rattus norvegicus, are preying on local bat populations. Researchers documented these predation events near key hibernation sites for bats, raising significant concerns about the impact on species such as Myotis daubentonii and Myotis nattereri. The findings, published in the journal Global Ecology and Conservation, detail a systematic approach by rats to hunt bats, which could threaten their survival.

Investigative Findings from Bat Habitats

The investigation began in 2020, focusing on the Segeberger Kalkberg, one of two caves that serve as urban bat habitats in northern Germany. Over five weeks, researchers employed infrared surveillance cameras to observe the interactions between rats and bats. The cameras recorded 30 predation attempts, with 13 confirmed kills during this initial observation period. Additionally, the team discovered the remains of at least 52 bats stored in a cache, indicating not only regular feeding habits but also possible hoarding behavior, as many carcasses were not fully consumed.

The footage captured revealed two primary hunting strategies employed by the rats. They would either intercept bats midair or ambush them upon landing. In both scenarios, the rats positioned themselves strategically, executing swift attacks to deliver fatal bites. If the first bite did not incapacitate the bat, the rats used their forelegs to hold the victim in place for a second, more lethal bite.

Follow-up studies conducted between 2021 and 2024 yielded additional evidence of rat predation. The researchers found another cache of bat carcasses at the Lüneburger Kalkberg, mirroring the collection methods observed at the Segeberger Kalkberg. These findings further solidified the conclusion that brown rats are actively hunting and storing bats as a food source.

The Ecological Impact and Human Concerns

While brown rats are not considered natural predators of bats, their opportunistic feeding behavior suggests that bats may constitute a significant part of their diet in these locations. The researchers noted that in other habitats, such as near Japanese fish markets, brown rats have a diet consisting of approximately 86% fish. This adaptability raises concerns about the potential vulnerability of bat populations, which play essential roles in ecosystems worldwide, including insect control, seed dispersal, and pollination.

The implications of these predatory behaviors extend beyond ecological concerns. Both bats and rats are known carriers of various pathogens, which could pose risks to human health. Although the paper did not specifically explore the transfer of diseases, it highlighted the potential for pathogen exchange between these two wildlife reservoirs, emphasizing the need for heightened awareness and monitoring.

The findings from this study underscore an unexpected and alarming interaction in the natural world. As scientists continue to investigate the impact of rat predation on bats, the urgency for conservation efforts to protect these vital species becomes increasingly clear.