By Paige Erickson-McGee (HAT Stewardship Coordinator) and Ben van Drimmelen (HAT Bat Volunteer since 2014)
Bats may roost in unusual places this time of year as they leave summer roosts. (C) L Parker
Bats are known for their remarkably high diversity and broad geographic range. Bats make up one-fifth of all mammals on the planet, are known from all continents except Antarctica, and over 1100 species have been identified. Bats pop up in the fossil record around 52 million years ago in the Green River Formation of Wyoming USA, with a giant walking bat roaming New Zealand around 16 million years ago. It is thought that the first bats could not echolocate and instead relied on sight, smell and touch to find food.
Today BC is particularly rich in bats species; 16 of Canada’s 19 occur in BC and 7 of those are found nowhere else in Canada. There are 9 species that occur on Vancouver Island and all are insectivorous.
Learn more about BC Bats here.
How can I identify which bat I saw?
Identification of bat species isn’t easy. The Little Brown Myotis and the Yuma Myotis, for example, look the same, even in the hand. They are only identifiable by a DNA sample, usually collected in the form of guano. Other less certain methods include acoustic detection of their ultrasonic calls that can narrow down the species likely to be flying overhead. However, echolocation calls are not unique to each species so genetic sampling is needed to be certain. HAT works with the BC Community Bat Program to submit samples of guano for genetic testing from roosts across Southern Vancouver Island. If you have a roost and would like to identify the species, check out this instructional document first.
Why is there a bat flying around in my house and where do bats live?
Most small mammals have large litters and don’t live long, but bats are different. Typically having only 1 pup per year with a 50% survival rate means bat families are slow to grow. If they make it to adulthood, they can (Little Brown bats) live to be 30 years old. The pups can fly when they are a month old, but are still pretty clumsy and are reluctant to leave the roost for long. That is when people find bats in their homes – often a young bat is lost and looking for a safe place to roost.
To report bats to the BC Community Bat Program, fill out this online form.
Do all bats live in bat boxes?
No! Depending on the species of bat they might prefer rock crevices or dead trees and many of our local bats prefer to sleep alone. This diversity makes it pretty difficult to do much to conserve bats. Bat boxes aren’t a suitable place for most species; they are only used by 3 of the 9 species - Little Brown Myotis, Big Brown Bat, and Yuma Myotis. Townsend’s Big-eared Bats will roost in human structures like attics, but they will not use typical bat boxes and require more open roost structures like mines or “bat condos” to roost happily. That means bat conservation has to depend on us protecting the range of forest and wetland bat habitats. Learn more about BC Bats here. To report bats to the BC Community Bat Program, fill out this online form.
Why do I have bats living in our attic?
Humans have shared buildings with bats for thousands of years, probably as early as first humans built living structures. These attic-dwelling bat species are defined as synanthropic, which means they have a strong ecological association with humans. Bats have been observed using buildings as roosting and foraging sites, temporary shelters, for reproduction and hibernation. Buildings have become an important resource for bats where natural roosting habitat is limited. For example, natural structures like wildlife trees (large trees with cavities or loose bark) are often felled because of forest harvesting or safety concerns.
This human association is for the bats’ own benefit and have adapted to these human structures over thousands of years. By taking up residence in these warmer human-made roosts, the bats have more energy stores for pregnancy and faster/safer development of their pups. They are also (in theory) being less exposed to natural predators in urban environments. Although buildings can provide optimal conditions for roosting, bats in these structures are vulnerable to human disturbance or injury, either by intentional or accidental means. For more information about bats and buildings, visit this page.
Can I put my bat box anywhere?
Unfortunately, a single bat house offers little variety in temperature, certainly much less than in a building. What they need is a variety of temperatures in their roosts called micro-climates. The preferred roost temperature varies with the seasons, with the gender of the roosting bats and with the age of the bats, particularly the pups. Why is temperature important?
Even when bat boxes are used by those box-tolerant species, there is a problem. Bats get lots of protein by eating insects, but very little carbohydrates or fats, so bats have a very tight energy budget. To save energy, bats use a hibernation-like state called torpor to lower their metabolic rate and let the temperature in the roost help them maintain a required body temperature. Therefore, they can’t generate much heat on their own; they have to find roosts that offer the temperatures they need. For this reason it is best to have your bat box in the full sun, especially in the morning when the bats return home and the air is much colder.
How do I encourage the bats to use a bat box?
Unfortunately bats are creatures of habit and if they have a current home that works perfectly for them they are unlikely to move. A bat box is a great way to make habitat available so that if a bat roost is destroyed nearby they have somewhere to do.
In the mean time make sure that your box(es) are as appealing as possible to the bats. One way to do this is to install more than one box to offer a variety of temperature, you can even link the boxes with crawl-way tunnels. Placement is critical, so bat boxes should be installed with advice from a local chapter of the BC Community Bat Program. To learn more about bat boxes or houses, click here.
What do I do if I have bats living in my house?
There is no need to panic if you find bats in a building. Bats are simply small animals that are trying to find a suitable home. Some bat colonies can remain safely in buildings without creating a risk for humans. If you can become comfortable with bats in your building, we encourage you to learn to live with them. Bats do not damage buildings (remember they are not rodents), and an important colony may be relying on the site. The Community Bat Programs of BC provides some advice on how to live with bats.
The first step is to assess your situation. Are the bats causing a problem? If so, is it the bats themselves, or the side effects of the bats (such as noise, smell or guano) that are the issue? Leaving bats where they are is usually the best option for bat conservation but may not be an appropriate option for the homeowner. Check out the Living with Bats Guidebook that outlines how to successfully maintain a bat colony and be safe in your home. In order to do a full assessment of your home or building with bats, follow the steps in the Got bats: a BC Guide for Managing Bats in Buildings Guidebook.
Don’t bats carry diseases like COVID and Rabies?
They do not transmit SARS-Cov-2, the virus that causes COVID-19. Transmission is from people to people. That virus has not been found in any bat species in North America. Bats have “super immunity” - can carry lots of viruses without getting sick themselves (so might be a source of information to help us find a vaccine). Bats are not immune to rabies, but less than 1% carry the virus in BC. They sometimes catch it, but sicken and die. Therefore, don’t touch a sick-looking bat like one on the ground; but there’s little risk from live, healthy bats. However, it is a very serious disease, so never touch bats. If you would like to learn more about Bats and Human Health visit the BC Bats website.
To learn more about COVID-19 and bats, read this information bulletin.
How can I help bats?
· Report bats to the BC Community Bat Program
· Register your bat house or box with the Program and check for bat activity in the summer months
· Support organizations that are working locally to protect forest and wetland habitats like Habitat Acquisition Trust
· Advocate to preserve our remaining old growth forests (bats depend on them)
· Encourage friends/neighbours to keep the bats in their attics rather than forcing them out
· Volunteer for bats by participating in the Annual BC Bat Count
· Support a bat conservation group or program like the Adopt-a-Bat Campaign