Scientists in Ireland spent three years studying what two common bat species eat by analyzing their droppings. They found that Brown long-eared bats are flexible eaters that prefer moths but will eat whatever insects are available, while Soprano pipistrelle bats are pickier and mostly stick to flies. The study looked at nearly 4,600 droppings collected from bat roosts across Irish farmland and identified hundreds of different insect species in their diets. Understanding what bats eat helps us appreciate how important they are for controlling insect populations and keeping ecosystems healthy.

The Quick Take

  • What they studied: What insects two types of Irish bats eat and how their diets change across different farmland areas and seasons
  • Who participated: Nearly 4,600 droppings collected from 12 bat roosts (homes where bats gather) over three years, from two bat species living in Irish pastureland
  • Key finding: Brown long-eared bats eat a wide variety of insects (mostly moths) and adapt their diet based on what’s available, while Soprano pipistrelle bats prefer flies and are more selective about their food choices
  • What it means for you: This research helps us understand that different bat species play different roles in controlling insect populations. Protecting farmland habitats is important because the types of insects available directly affect which bats can survive in an area. However, this study focused on Irish bats, so results may not apply to other regions.

The Research Details

Researchers collected bat droppings from 12 maternity roosts (where female bats give birth and raise babies) across Irish farmland during three different seasons over three years. They used advanced DNA technology called metabarcoding to identify which insect species were in each dropping. This method is like reading a tiny genetic barcode on each insect fragment to figure out exactly what the bat ate. By collecting samples at three different times of year (when bats are pregnant, nursing babies, and after babies are independent), the scientists could see how bat diets changed throughout the year.

This approach is important because it gives scientists a detailed picture of what bats actually eat in the real world, rather than just guessing based on observations. The DNA method can identify insects that are too small or broken down to recognize by eye. By studying two different bat species side-by-side in the same landscape, researchers could compare their hunting strategies and understand how different species use the same environment.

This is a solid research study because it collected a large number of samples (4,627 droppings) over multiple years and seasons, which makes the findings more reliable. The use of DNA technology is accurate and can identify insects that other methods might miss. The study focused on real bats in their natural habitat rather than laboratory conditions. However, the study only looked at Irish farmland, so the results may not apply to bats in forests, cities, or other countries.

What the Results Show

The Brown long-eared bat showed a diverse diet, eating from 392 different insect species, with 62% being moths and 31% being flies. This bat species was flexible and changed what it ate depending on what insects were available in different areas. The Soprano pipistrelle bat was more selective, eating from 350 insect species but with 83% of its diet consisting of flies. This bat stuck to its preferred food type more consistently across different locations.

Both bat species’ diets changed depending on the season and the type of farmland around their roosts. Areas with different types of plants and land use supported different insect populations, which directly affected what the bats could eat. One roost showed an unusual pattern where the Brown long-eared bat ate many more flies than normal, suggesting these bats can quickly adapt when their preferred food becomes scarce.

The study found that the surrounding landscape—specifically what crops were grown and how the land was managed—significantly influenced which insects were available for bats to eat. Seasonal changes also mattered, with different insects being available during pregnancy, nursing, and post-nursing periods. The research showed that both bat species could survive in Irish pastureland, but they do so by eating different types of insects, which means they don’t compete directly with each other for food.

Previous research suggested these two bat species had different hunting styles, but this study provides the first detailed evidence of exactly how different their diets are. The finding that Brown long-eared bats are generalists (eating many types of food) and Soprano pipistrelles are specialists (preferring specific foods) matches what scientists expected based on their different hunting behaviors. This study adds important new information about how these differences play out in Irish farmland specifically.

This study only looked at two bat species in Ireland, so the results may not apply to other bat species or other countries. The research focused on farmland habitats, so we don’t know if these same patterns occur in forests or cities. The study used DNA from droppings, which can only tell us what bats ate, not how much energy they got from different foods or how important each insect type is for their survival. Additionally, the study couldn’t identify every single insect fragment, so some prey items may have been missed.

The Bottom Line

Based on this research, farmers and conservation groups should maintain diverse farmland habitats with varied plants and insects to support healthy bat populations. Protecting areas with natural vegetation alongside pastures appears beneficial. However, these recommendations are specific to Irish farmland and may need adjustment for other regions. More research is needed before making major land management changes based solely on this study.

Farmers, conservation organizations, and environmental planners in Ireland and similar farmland regions should care about these findings. Anyone interested in protecting bats or understanding how ecosystems work will find this valuable. However, if you live in a forest region or different climate, these specific findings may not directly apply to your local bats.

Changes to bat populations based on habitat improvements would likely take several years to become noticeable, as bats live relatively long lives and populations change slowly. You might see increased bat activity within one season if you improve local habitat, but significant population growth would take 3-5 years or longer.

Want to Apply This Research?

  • Track local bat sightings and the types of insects visible in your area during different seasons. Note which insects appear when and correlate this with bat activity observations. Use a simple log: date, time, bat species (if identifiable), weather conditions, and insect types observed.
  • If you have farmland or a large garden, consider planting native wildflowers and reducing pesticide use to increase insect diversity. This creates better food sources for local bats. You can track the changes in insect populations you observe over time using the app.
  • Set up a long-term monitoring system by recording bat activity monthly using acoustic recordings or visual observations, and track seasonal changes in insect abundance. Compare your observations across seasons and years to see if habitat improvements correlate with increased bat activity. Share your data with local conservation groups to contribute to citizen science efforts.

This research describes what bats eat in Irish farmland and should not be used to make medical or health claims about humans. While the study provides valuable information about bat ecology and conservation, individual results may vary based on location, climate, and specific habitat conditions. Consult with local wildlife experts or conservation organizations before making significant changes to land management based on this research. This study was conducted on wild bat populations in specific conditions and may not apply to captive bats or other geographic regions.