Northern Myotis

(Myotis septentrionalis)

Status: Endangered (COSEWIC & ESA 2013)

Table of Contents:

Species Identification
Diet
Habitat and Range
Biology and Behaviour
Similar Species
Threats/Reasons for Being Endangered
Conservation and Recovery Strategies
How You Can Help

Photo by Dave Thomas: https://flic.kr/p/grW9fV

Species Identification:

The Northern Myotis is a small bat, 8 cm in length and weighing 5-8 grams- which is about the weight of a toonie. They have a 25 cm wingspan, with dull yellow-brown fur, a grey underside, and black ears, wings and tail. They are also known as Northern Long-eared Bats, since they have long, rounded ears. They can be identified by a small piece of skin that covers part of the inside of their ear. However, like most bat species they are very difficult to identify unless inspected closely.

Diet:

Like all bat species, the Northern Myotis feeds at night using echolocation. They will feed on spiders and insects, including mosquitoes, moths, beetles, wasps, and flies. They will either catch prey in the air, or collect it off of the ground or leaves. Their preferred feeding habitat occurs along the edge and within forests.

Photo by Brian Wulker: https://flic.kr/p/fVqmSP

Map taken from Government of Ontario: https://www.ontario.ca/page/little-brown-myotis-northern-myotis-and-tri-colored-bat-recovery-strategy#section-7

Habitat and Range:

About 40% of the global range of the Northern Myotis occurs in Canada. They are found in all provinces and territories except Nunavut, and down through the eastern half of the Northern United States. The Northern Myotis can be found throughout Ontario in forested areas. They can be found throughout The Land Between, but sightings are generally rare since they are hard to identify and populations are low.

Northern Myotis bats prefer to overwinter in caves, mines, or deep rock crevices. These sites need to have very specific requirements in order for bats to survive cold winters, so ideal hibernation sites are often hard to find. Summer sites are often in old buildings like barns, houses, old trees, or small caves if they are available. Northern Myotis bats prefer to forage over water, forest edges, or any open areas that occur within forests. They generally avoid large open spaces for protection, but need gaps in the forest canopy in order to maneuver and hunt. Their overwintering sites can be hundreds of kilometers from their summer breeding and foraging sites.

Biology and Behaviour:

Northern Myotis bats emerge from winter hibernation in the early spring and make their way to their summer habitat. They feed at night and rest (roost) during the day. They are most often found roosting individually or in small groups under bark, and in cavities of trees in early to mid stages of decay. They are also known to roost in human-made structures in fragmented habitat areas Females give birth in the spring and early summer, generally to one baby (pup) at a time. Pups are able to fly and forage for themselves after one month. Northern Myotis bats tend to congregate in large numbers, in the late summer or early fall at the entrance to their overwintering site. Bats may swarm to mate, socialize, or to assess the suitability of a potential overwintering location. They generally hibernate from late fall to early spring in caves or abandoned mines and wells where conditions are humid (greater than 80%) and where the temperature remains above freezing (2-10 Celsius). Where their habitat ranges overlap, the Little Brown Myotis, Northern Myotis, and Tri-coloured Bat can be found hibernating in the same structures. Predators of the Northern Myotis include owls, hawks, some snakes, raccoons, and cats.

Photo by Dave Thomas: https://flic.kr/p/RnoH3a

Similar Species:

The Northern Myotis is similar in appearance and colouration to Little Brown Myotis, but the Northern Myotis bat’s outer ear structure is long, thin, and pointed at the tip, whereas the Little Brown Myotis has rounded tipped ear flaps.

Threats/ Reasons for being at Risk:

1. White Nose Syndrome (WNS): White Nose Syndrome (WNS) is a deadly disease caused by infection by the fungus Pseudogymnoascus destructans. Currently this is the greatest threat to the recovery of the Northern Myotis, as well as many other bat species. The fungus infects and grows on their skin while they hibernate, causing severe damage to tissues. This results in the development of white-grey patches of fungus on their noses, wings and ears. Infection further results in an elevated metabolic rate, which causes the bats to be awakened from their state of hibernation. This results in the depletion of their energy stores required to survive the winter. Energy loss combined with the physical effects of infection eventually result in mortality. The fungus is spread through bat-to-bat contact, through bat contact with contaminated hibernation sites, and through human and predator movement from contaminated caves to non-contaminated caves. Approximately 30% of the Canadian range of the Northern Myotis has been impacted by WNS, and populations at known overwintering sites have declined by about 94%. WNS is predicted to be spreading at a rate of 200 - 250 km per year. If this rate continues, it is predicted that all hibernation sites in Canada will be affected by 2025 - 2028.

2. Habitat loss: Like most Species at Risk, habitat loss is a major threat, especially hibernation site loss. Natural hibernating and roosting sites have been in decline for centuries, and bats have resorted to using human-made buildings and structures, which leads to eradication and even mortality when people discover them on their property. Forested foraging areas are also in decline, as much of these habitats have been converted for agriculture, urban development, and road construction. Bats may find roads as ideal foraging areas, making them more at risk of being hit by a car.

3. Wind turbines: Death results from collisions with turbine blades, or from injuries (barotrauma) resulting from the sudden drop in air pressure behind the turbines as a result of their spinning. An estimated 16 bats are killed per turbine per year in Canada. Since there are currently approximately 2577 wind turbines operating in Ontario (as of 2018), an average of 41,232 bats are killed by turbines each year in Ontario alone.

4. Pollution: The spraying of pesticides- specifically neonicotinoid insecticides, in agricultural and forested areas has the potential to severely impact populations of the Northern Myotis by killing the insects on which the bats feed. Decreased availability of food can lead to reduced fat stores for the winter, impacting the ability of the bats to overwinter effectively, and decreasing their overall body condition, resulting in lower reproductive success and survival rates. Combined with WNS, this can be deadly for populations. The Northern Myotis is further impacted by pesticide pollution through poisoning, as the bats may consume insects contaminated by the toxins. These effects can further reduce the overall fitness, and therefore their reproductive and survival success.

Conservation and recovery strategies:

White Nose Syndrome (WNS): Research into the causes, as well as potential treatments and mitigation measures for WNS is underway in Ontario and across North America. A White-nose Syndrome Response Plan has been developed by the Ontario Ministry of Natural Resources and Forestry that outlines the government’s plan to detect, research and mitigate the disease.

Wind Turbines: Some wind farms have been making adjustments to their turbines that minimize their impact to bats at times when the risk to bats is particularly high, such as at night during peak migration. These changes include periodic shutdowns of the turbines, increasing the minimum wind speed required to make the turbine blades turn, and arranging the blades to be more parallel with airflow, minimizing the change in air pressure behind the turbines. These measures have been found to significantly reduce bat mortality (60 to 70%), with only marginal losses (1%) of power.

General: Several North America-wide bat monitoring programs and organizations have been created. These organizations are gathering data and information on remaining bat populations so that effective conservation decisions can be made.

How can you help?

Avoid entering caves and mines where bats may be present, or where White-nose Syndrome (WNS) is known to occur. Travelling from cave to cave without properly decontaminating footwear and other gear can aid in the spread of the fungus.
Keep your domestic cats indoors. Cats have been known to be a significant cause of bat mortality, particularly to young pups before they learn how to fly.
Consider attracting bats to your backyard by leaving dead trees that can be used as roosts standing on your property, and by putting up bat boxes. Mount them on the side of a structure or on a pole or tree at least 10 inches above the tallest vegetation, as close to open water as possible, and in a location that receives at least 6 hours of sunlight per day.

Additional Resources:

Government of Ontario’s Northern Myotis page
Recovery Strategy for Little Brown Myotis (Myotis lucifugus), Northern Myotis (Myotis septentrionalis), and Tri-colored Bat (Perimyotis subflavus) in Canada

Sources:

Government of Ontario. 2021. Little Brown Myotis, Northern Myotis and Tri-colored Bat recovery strategy. Retrieved from: https://www.ontario.ca/page/little-brown-myotis-northern-myotis-and-tri-colored-bat-recovery-strategy#section-7

Government of Ontario. 2021. Northern Myotis. Retrieved from: https://www.ontario.ca/page/northern-myotis

COSEWIC. 2013. COSEWIC assessment and status report on the Little Brown Myotis Myotis lucifugus, Northern Myotis Myotis septentrionalis and Tri-colored Bat Perimyotis subflavus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xxiv + 93 pp. (www.registrelep-sararegistry.gc.ca/default_e.cfm).