Bats aren’t just for Halloween: Insectivorous Bats in North America

Post provided by CHLOE ROBINSON (@CVROBINSON92)

The Hoary bat (Lasiurus cinereus) is the most widespread bat in the US. ©Veronica Zamora-Gutierrez

Hello! This is my first post as Blog Editor for Methods in Ecology and Evolution and I’m thrilled to be starting with an exciting, thought-provoking topic in the wake of Halloween. But first, let me introduce myself. I currently work as a Postdoctoral Fellow and Project Manager in the Hajibabaei Lab at the Centre for Biodiversity Genomics (University of Guelph, ON, Canada) and my undergraduate and postgraduate degrees are both from Swansea University (UK). My research background is largely focused around the application of environmental DNA (i.e. free DNA found in natural environments) to detect and monitor aquatic species and answer ecological questions through both single-species detection and DNA metabarcoding.

At the moment, I’m working on the STREAM project, which combines community-based monitoring with DNA metabarcoding to gain a better understanding of freshwater health across Canada. One of my favourite parts about being in this position is the opportunity to get involved with other research being conducted in the Hajibabaei Lab. This is how I branched out into the wonderful world of bat ecology.

Bat Ecosystem Services: Insect Control

The Californian leaf-nose bat (Macrotus californicus) catches insects from foliage as opposed to during flight. © Veronica Zamora-Gutierrez

Every year around Halloween we watch the shelves being filled with spooky paraphernalia, with one of the key features being bats. Now bats as a whole are often portrayed as creepy, blood-sucking vermin that get stuck in your hair, but the reality is that bats hold very unique niches (i.e. play an important role within an ecosystem).

A majority (around 70%) of the world’s bats are insectivorous (eat exclusively insects). Because of this, bats are important for controlling insect populations, which is particularly important for agriculture. In the US, the pest services provided by bats is estimated to be worth more than $3.7 billion a year in reduced crop damage and pesticide use.

Bat Declines and White-Nose Syndrome

Little brown bat (Myotis lucifugus) infected with white-nose syndrome. ©Ryan von Linden/New York Department of Environmental Conservation

Unfortunately, as with many other species, bats worldwide are experiencing population declines due to a combination of natural and anthropogenic stressors. The greatest natural threat to insectivorous bats in the Northern hemisphere is a disease referred to as white-nose syndrome (WNS). This is a disease caused by a fungus called Pseudogymnoascus destructans. It’s a skin infection that often causes 100% mortality for a species. This fungus was first detected in a cave in Upstate New York in February 2006 and has since expanded across the eastern half of the United States and Canada.

Tracking the Effects of White-Nose Syndrome

Following the spread of WNS, some species of bat suffered drastic declines, one of which being the little brown bat (Myotis lucifugus). This species has been wiped out across most of its former range. It’s predicted that little brown bats will be reduced to just 1% of their pre-WNS population numbers by 2030.

These declines are primarily determined through collecting acoustic data (i.e. feeding and social calls) from bats. As technology develops, this data is often collected using autonomous recording units (ARUs). ARUs collect basic acoustic data on a range of bat species, but there can be errors during the process of classifying bat calls to species.

In ‘Modelling misclassification in multi‐species acoustic data when estimating occupancy and relative activity’, Wright et al. focus on developing a model to classify and analyse bat calls. Their method can give you improved confidence in your data by reducing the rate of false positives and negatives. Considering bats provide vital ecosystem services for the North American economy, in terms of insect control, the ability to accurately estimate the presence, absence and relative activity of specific bat species is vitally important.     

Looking to the Future

Northern yellow bat (Lasiurus intermedius) relies on forests for roosting and forages over a variety of natural habitats. ©Veronica Zamora-Gutierrez

Despite the previous declines of bats in North America, there is some evidence that some populations, particularly of the little brown bat, are recovering post-WNS. A combination of improved methods to detect and monitor bats, prevention of further spread of WNS and protection of key habitats is aiding the conservation efforts. Overall, bats are important and valuable group of species and contribute to the economy all year around – not just on Halloween!

Just like bats in North America, the future of the Methods.blog is looking bright. I’m excited to be contributing ecology-based blog posts. I’m planning to have a particular focus on non-invasive methods for biodiversity monitoring and addressing big ecological questions. In addition to ecological blogs, I’m passionate about producing blogs on mental health awareness and LGBTQ+ experiences in academia. I’ll also be highlighting the fantastic papers published in Methods in Ecology and Evolution on topical ‘international’ holidays. I look forward to being part of the Methods in Ecology and Evolution team for the upcoming year.

To find out more on developing models for ARU data analyses, read the full Methods in Ecology and Evolution article ‘Modelling misclassification in multi‐species acoustic data when estimating occupancy and relative activity


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