Midnight bat snacks reveal clues to managing endangered species

Environmental DNA (2022). DOI: 10.1002 / edn3.354.54″ width=”800″ height=”530″/>

Sample collection sites are in south-central Indiana, 50 km away. The Indianapolis Airport Project (IAP) consists of riverside patches of forest surrounded by agricultural, residential and commercial development (approximately 5,400 hectares of sampling area). The Hardwood Ecosystem Experiment (HEE) is a contiguous forest with active timber management (approximately 19,000 hectares of sampling area). The center of each study area is marked by a pink star. Credit: Timothy J. Divoll et al, Environmental DNA (2022). DOI: 10.1002 / edn3.354.07

How do we bring the threatened and endangered animals back from the brink? The task is never easy or simple, but one thing is undeniable: if we do not understand these animals and what they need to survive, we have little chance of success.

So bat rescue is arguably a more complicated endeavor than other species. After all, occult creatures appear only at night and are highly mobile, which makes it difficult to track their movements and behavior.

In a study that is the first of its kind, scientists from the University of Illinois and Brown University have revealed the diets of endangered Indiana bats and threatened northern long-eared bats, providing evidence for effective management of both the species and its habitats. The study was published in Environmental DNA.

“This was an in-depth study of these two endangered species in the landscapes where they co-exist. Nobody has done this before. This investigation gives us a much better sense of how not only bats coexist, but also how they benefit our forests and how, in turn, we can manage the forest to provide bats with a habitat Better,” says Joy O’Keeffe, assistant professor and wildlife extension specialist in the Illinois Department of Natural Resources and Environmental Sciences.

Previous research into the diet of these bats relied on old, outdated techniques that could miss important prey species. No study has yet investigated how the two species divide their prey resources for coexistence.

“When you have two closely related species that share the same habitat, it means that they are built similarly and need similar places to live and things to eat. And that raises a lot of questions about how they do it. Do they compete?? Or is there some system where they can Divide resources? Our job was to find out,” says Tim Devol, a data scientist at the Center for Computing and Visualization at Brown who completed his doctoral research with O’ Keefe.

Divoll and O’Keefe humanely caught bats and collected fecal samples at two Indiana sites — a large managed forest and an area with small forest patches near a major airport — over the course of four summers. The researchers identified insect prey from DNA in bat faeces and added size classification as a more practical way of looking at insect prey.

“If a bat sees two moths that are the same size and have the same flight pattern, the bat will not distinguish which one is. It will eat any moth it can catch,” Devol says. “I wanted to use an analysis that is better in line with how bats perceive their prey. We tend to assume that genetic classifications of prey are most important, but bats do not study classification.

“But taxonomic definition can be very interesting. For example, maybe there are some insects in the dataset that require specific host plants. We want to help managers realize this so that they can manage a variety of plant species that host a variety of insects, making It leads to healthier forests and more food options for bats.”

In general, both bat species ate many of the same insects, including moths, beetles, crickets, wasps, mosquitoes, and more. They also ate a large number of agricultural and forest pest species, demonstrating their role as providers of beneficial ecosystem services.

Somewhat surprisingly, the northern long-eared bat, the smaller of the two, captured slightly larger prey. According to the researchers, this is likely because the northern part is a collage, which means it grabs prey from surfaces, at least for some time. O’Keefe says bats that use the chopping strategy likely have an easier time locating larger insects on bark or leaves. This is in contrast to aerial hawkers, bats that prey on mid-flight; They will detect and follow anything that moves in the air, whether it is big or small.

This slight difference in prey size preference and feeding style may be enough for bats to avoid direct competition, but researchers cannot be certain of this study alone.

“It is difficult to determine if they are in direct competition without measuring the availability of different insect species, and we did not measure this in our study. But our previous research at the same forest site has shown that northern long-eared bats use much less space when hunting for Indiana bats. And they choose Habitat a little differently. At the end of the night, they might end up eating all the same things, but find them differently,” Devol says.

The diets of the bats were so similar that there were greater differences between locations – the forest or the airports – than between the bat species.

“This tells us that at some level, they are generalizing to whatever is available in a particular location. They may be flexible and specialized at certain times, but these two bats will mostly follow whatever is available,” Devol says. “They may use different hunting techniques and search at different heights of the forest, but both are likely to capture easy targets while searching for preferred prey.”

Study authors include Tim Devol, Veronica Brown, Gary McCracken, and Joey O’Keefe.


Sending bats signal about forest use by endangered species


more information:
Timothy J. Divoll et al, Prey size is more representative than prey taxa when measuring dietary interference in balanced forest bats, Environmental DNA (2022). DOI: 10.1002 / edn3.354.07

Presented by the University of Illinois at Urbana-Champaign

the quote: Midnight bat snacks reveal clues to managing endangered species (2022, September 13) Retrieved September 13, 2022 from https://phys.org/news/2022-09-midnight-snacks-reveal-clues-endangered .html

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