Hazardous Roommates: Birds and Bat Predators Living Together

Jim Crocker
14th March, 2024

Hazardous Roommates: Birds and Bat Predators Living Together

Key Findings

  • In Italy, blue tits successfully raised chicks near predatory greater noctule bats
  • The study suggests greater noctules may only hunt birds in flight, not in nests
  • This challenges the belief that these bats threaten nesting birds' survival
In the intricate web of predator-prey interactions, the ripple effects of fear can alter the behavior and survival of species. A recent study from the Università degli Studi di Napoli Federico II[1] sheds light on these dynamics by examining the relationship between the greater noctule bats (Nyctalus lasiopterus) and their potential avian prey, specifically the Eurasian blue tits (Cyanistes caeruleus). The greater noctule is known for its unusual diet, which includes birds, particularly during migration periods. This has led to assumptions about the risk these bats pose to nesting birds. The study, however, presents a unique case that challenges these assumptions, documenting Eurasian blue tits successfully nesting and raising chicks in close proximity to a colony of greater noctules. This finding is intriguing because it suggests that the bats may not be hunting birds within nesting sites, as previously thought. The researchers observed over a month that parent blue tits were able to feed their chicks without interference from the bats. By the end of the study period, at least two chicks were alive and well, being fed outside their tree cavity. This behavior indicates that the presence of greater noctules might not be as threatening to nesting birds as once believed. The study posits that greater noctules specialize in capturing birds in flight rather than within confined spaces like tree cavities. This behavior could explain why the Eurasian blue tits were able to reproduce successfully despite sharing roosting space with a predator known to eat birds. Previous research has highlighted the complexity of predator-prey interactions. For example, studies have shown that owls hunt bats[2], and that invasive species like rose-ringed parakeets can displace and even kill competing species such as the greater noctule[3]. These interactions can have profound impacts on prey species, including changes in their behavior and distribution. The concept of non-consumptive effects (NCEs) further complicates the picture[4]. These are changes in prey behavior and physiology that occur due to the presence of predators, even without direct predation. For instance, birds may change their nesting habits or reduce their reproductive output due to the stress of living near predators[5]. The observation from the Università degli Studi di Napoli Federico II contributes to this body of research by suggesting that the fear of predators, and the subsequent impact on prey species, may be more nuanced than previously thought. If greater noctules are indeed not a threat to nesting birds, the fear-driven changes in bird behavior and reproductive success might not occur in this context. This could have implications for our understanding of how fear shapes ecosystem dynamics. The study also underscores the importance of direct observation in understanding predator-prey interactions. While previous research has provided valuable insights into these relationships[2][3][5], the current study shows that there is still much to learn about the specific behaviors of predators and their prey. In conclusion, the research from the Università degli Studi di Napoli Federico II offers a fresh perspective on the interactions between greater noctule bats and nesting birds. It challenges the notion that greater noctules pose a significant threat to birds within nesting sites and encourages further investigation into the complex ways in which predators and prey coexist. This study not only contributes to our understanding of these species but also highlights the need for continued research to unravel the intricate and context-dependent nature of predator-prey relationships.

WildlifeEcology

References

Main Study

1) Dangerous neighbours: Birds and bird-eating bats sharing tree cavities.

Published 12th March, 2024

https://doi.org/10.1002/ece3.11098

Related Studies

2) Continuous low-intensity predation by owls (Strix aluco) on bats (Nyctalus lasiopterus) in Spain and the potential effect on bat colony stability.

https://doi.org/10.1098/rsos.230309

3) Nest-site competition and killing by invasive parakeets cause the decline of a threatened bat population.

https://doi.org/10.1098/rsos.172477

4) The context dependence of non-consumptive predator effects.

https://doi.org/10.1111/ele.13614

5) Costs of fear: behavioural and life-history responses to risk and their demographic consequences vary across species.

https://doi.org/10.1111/ele.12573


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