Six bat species have been confirmed on Mayne Island through DNA testing. 

  • Yuma Myotis
  • Long-legged Myotis
  • Silver-haired Bat
  • Hoary Bat
  • Big Brown Bat
  • California Myotis

 Our overarching concern 

Currently in North America certain bat species are being impacted by a disease called White Nose Syndrome which is caused by the fungus Pseudogymnoascus destructans (Pd). So far, the disease is most prevalent in eastern Canada and the United States, but a few incidences have been confirmed in Washington State and other places in western North America. A program has been implemented to monitor bat populations and health, and to help detect this deadly pathogen before it spreads to colonies on the island. 

White Nose Syndrome can have a 90-100% mortality rate on infected colonies, and early detection of the fungus could prevent the spread and future outbreaks. Species which have contracted White Nose Syndrome elsewhere in North America, and which are also found on Mayne Island, are the Big Brown BatYuma Myotis, Long-legged Myotis, and the Silver-Haired Bat.

White Nose Syndrome has a greater impact on bat species that hibernate over winter in colonies than on migratory bats. Also, some bats can carry just the spores but not the disease. The spores remain viable for some time, and it is thought that the fungus is spread by bat-to-bat contact and by humans who come in contact with the spores. The spores can attach to outdoor gear and can be transmitted to new areas through activities such as climbing and caving. The spores are not harmful to humans but are detrimental to bat colonies, so proper sanitation is important before and after visiting caves and other places where bats might hibernate. 

The Bats of Mayne Island, Part 1

Yuma Myotis
Yuma Myotis. Photo: Michael Durham

Yuma Myotis 

One of the six bat species confirmed on Mayne Island through DNA testing is the Yuma Myotis. This species is found in western North America between British Columbia and central Mexico, and their range spans east into the central United States. They are a medium-sized bat weighing around 6 grams with an average wingspan of 235 millimetres. They measure 84 to 99 millimeters in length. Yuma bats are identifiable by short pale brown to black fur on their backs, and undersides which are lighter in colour. 

This bat species commonly uses habitats near bodies of water, and of all the bat species in North America, the Yuma Myotis is the one most likely to be found around water. The Yuma Myotis roosts in buildings, snags, rock crevices, caves, and other structures. This species is the most likely to use bat houses as an alternative to buildings in which they commonly roost. 

The largest maternity colonies in British Columbia are formed by the Yuma Myotis. Males roost individually or in small groups separate from the female maternity colonies. Few to no observations have been documented of the Yuma Myotis hibernating in British Columbia, and their winter habitats are not well understood. 

They are nocturnal insectivores and become active at dusk. Feeding takes place during the first two hours after darkness. Their diet consists of small insects such as moths, midges, caddisflies, craneflies, beetles, mayflies and other insects. To hunt in dim lit conditions, they use echolocation to find their prey. 

This species, as well as many others of this group, are seen as being beneficial and effective for insect management and pest control in agriculture. The Yuma Myotis is not at risk as healthy populations range across its habitat, although declines have been noted due to the destruction of some of their roost sites, particularly riparian habitats. In other regions across North America, the Yuma myotis has been impacted by White Nose Syndrome and is a species to monitor for the spread of the fungus. 

a. https://animaldiversity.org/accounts/Myotis_yumanensis/

b.https://bcbats.ca/bat-basics/bat-species-in-bc/

Long-Legged Myotis

Long legged myotis
Long legged myotis. Photo: Nathan Scott, Creative Commons

The Long-legged Myotis is another bat species that has been confirmed on Mayne Island using DNA testing. This species’ range spans from central Mexico to the southern extents of Alaska and exists throughout much of Western Canada. The Long-Legged Myotis are one of the largest myotis species in British Columbia, with a wingspan of 215 to 217 millimeters, and are 83 to 100 millimeters in length. Their fur is reddish brown to black, and the fur on their undersides extends under their wings to their knees and elbows. The fur on their ventral side (underside) is a unique feature that helps with identification. They also have rounded short ears and a steep forehead. 

The Long-Legged Myotis roost in rock crevices, cliffs, fissures in the ground, stumps, in the bark of trees, but uncommonly roost in buildings. In fact, the large roost found on Mayne Island (over 100 bats) is only the second record in BC of this bat species in a building and, because of this, is considered a special monitoring site.  Few summer female maternity colonies have been found in British Columbia, but one that was observed was in an old barn with up to 300 individuals. There are ongoing studies regarding male summer roost sites and winter hibernation in the province. 

This bat species is also nocturnal and becomes active around dusk, remaining out in its habitat throughout most of the night. The Long-Legged Myotis hunts above water, forest clearings, and within the forest canopy. They predominantly eat moths, but are opportunistic hunters and will also eat termites, spiders, flies, beetles, leafhoppers, and lacewings. While hunting, the Long-Legged Myotis flies a “repetitive circuit” throughout the evening and during their foraging flights. 

The Long-Legged Myotis also play an important ecological role in the ecosystem as they contribute to insect management. The Long-Legged Myotis is not at risk as healthy populations range across its habitat. The Long-Legged Myotis is susceptible to White Nose Syndrome and has been impacted by the fungus elsewhere in North America and is being monitored to detect pathogen spread. 

a. https://linnet.geog.ubc.ca/efauna/Atlas/Atlas.aspx?sciname=Myotis%20volans&Subspecies=&ilifeform=31

b.https://animaldiversity.org/accounts/Myotis_volans/

c. https://www.eopugetsound.org/articles/long-legged-myotis-myotis-volans


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