Tri-coloured Bat

(Perimyotis subflavus)

Status: Endangered (ESA 2016, COSEWIC 2012)

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

Species Identification:

The Tri-coloured Bat is a small bat species, with a wingspan of 23 cm and 5 to 9 grams in weight. They are reddish-brown to yellowish-brown in colour, with brown ears and face, orange-red arms, and dark brown wings. This bat is named for the hairs on its back which are black at the base, yellow in the middle, and brown at the tip, giving it a tri-coloured look. The Tri-coloured Bat used to be called the Eastern Pipistrelle.

Diet:

Tri-coloured Bats- like most bats, feed using echolocation primarily at dusk, and then again a few hours before dawn. They eat flying insects including moths, beetles, mosquitoes, wasps, and flies. They are also known to even eat spiders directly off of their webs. The Tri-coloured Bat most often feeds over ponds and rivers that are near forested areas. Under optimal feeding conditions, males can eat half their body weight or more in insects each night, and pregnant/nursing females can eat their entire body weight or more!

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

Habitat and Range:

While these bats are found throughout Eastern North America, they are considered rare across much of their range since populations are both scattered and low in numbers. They are found throughout eastern and central United States, as well as down into Mexico along the eastern coast. About 10% of the Tri-coloured Bats global range occurs in Canada. They are found across Eastern Canada in Ontario, Quebec, New Brunswick, and Nova Scotia. In Ontario, they are only found in scattered areas from Southern Ontario to north of Sudbury. They can be found in The Land Between, but sightings are generally rare as they are hard to identify unless captured.

During the summer months, Tri-coloured Bats can be found in many different forested habitats. They will roost in older forests with larger trees and potential tree cavities, and forage along rivers or streams either within or near forests. They are also known to use human structures like barns, churches, bridges, and old houses as summer roosting sites. They will travel to their hibernation sites where they congregate in larger numbers to overwinter in caves or underground caverns.

Biology and Behaviour:

Tri-coloured Bats are the first to enter hibernation and the last to leave, which generally occurs in early to mid-spring. They feed at night on spiders and insects; rest (roost) during the day. Tri-coloured Bats prefer to either roost alone or in small colonies in foliage or tree cavities. In more fragmented habitat areas, they may roost in abandoned human-made structures or barns.

Female Tri-coloured Bats will gather together in small groups during pup rearing, where they will give birth to 1-2 pups per year. Mating season occurs in mid-fall before hibernation. They will then migrate distances ranging from 53 to 780 km between their summer and hibernating locations. At their hibernation sites, Tri-coloured Bats tend to swarm in large numbers at the entrances before heading in for hibernation. Bats may swarm to mate, socialize, or to assess the suitability of a potential overwintering location. They hibernate from late fall to early spring in caves where conditions are humid (greater than 80%) and where the temperature remains above freezing (2 to 10 Celsius). The Tri-coloured Bat has very strict hibernation requirements and typically hibernates individually in the deepest, most temporally-stable parts of a cave, on the warmest walls available Where their habitat ranges overlap, the Little Brown Bat, Northern Myotis, and Tri-coloured Bat can be found hibernating in the same structures.

Similar Species:

Since most Ontario bat species are the same size and are generally spotted from far away, they can be difficult to distinguish. However, the Tri-coloured Bat has lighter fur and arms compared to the Northern Myotis and the Little Brown Bat.

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 and is the greatest threat to the recovery of the Tri-coloured Bat, along with many other bat species. The fungus infects and grows on bat skin while they hibernate, causing severe damage to tissues and 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 awaken from their state of hibernation. This results in the depletion of their energy stores that are required to survive the winter. Energy loss combined with the physical effects of infection eventually result in mortality The fungus thrives in the same humidity and temperature conditions required by hibernating bats. The spores of the fungus can remain viable in hibernation sites, as well as in the guano (feces) and soil, for many years without the presence of bats, potentially severely impeding the ability of the bats to recover. 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, spreading the fungal spores as they go. Nearly 100% of the Canadian range of the Tri-coloured Bat has been impacted by WNS, and populations at known overwintering sites have declined by about 75%.

2. Predation: Predation by domestic and/or barn cats may pose a significant threat to bats, particularly as their populations are already severely impacted by White Nose Syndrome. Predation by cats around roosting areas, particularly on bat pups, can have a significant impact on populations by removing the new individuals from groups and therefore decreasing the number of bats that are added to the next generation.

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. As there are currently approximately 2577 wind turbines operating in Ontario, 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 Tri-coloured Bat 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 The Tri-coloured Bat 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 of the bat, and therefore its 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 that causes WNS.
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. If you elect to put up a bat box on your property, 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.