Protecting and enhancing the natural values of Salt Spring Island and its surrounding waters



What are Bats?

Bats are small mammals that fly using wings formed from webbing between their very long fingers. There are at least eight species of bats on Salt Spring Island, several of which are of special conservation concern. Island bats are important consumers of insect pests including carpenter ants, termites, mosquitoes, wasps, and bark beetles. Bats can minimize crop and forest pest damage. Bats also serve to transfer nutrients across the environment through their flight paths.

Learn about bats in buildings: GOT Bats7 Steps Evict Bats

Learn about bat houses: Bat_houses_in_BC_2015

Salt Spring Island Bats

Shown below are bat species that might be encountered on Salt Spring.

Yuma Myotis

Myotis yumanensis  This common Salt Spring bat can appear similar to the Little Brown Myotis and the two species may occupy the same roosts. The Yuma bat is distinguished from the Little Brown Myotis by

Little Brown Bat

Myotis lucifugus This is a small bat about the length of a human finger and the weight of a large coin. It takes flight at dusk to feed upon a variety of insects that are captured

Western Long-eared Myotis

Myotis evotis  This tiny bat has dark long ears and may have darkish shoulder patches. A fine fringe of hairs is present on the edge of the tail membrane. These bats roost under loose bark,

California Myotis

Myotis californicus This tiny bat has moderately-sized ears that would extend beyond the nose if pushed forward. It has a keel on the calcar, the ankle spur that supports the airfoil membrane (see below). A single

Long-legged Myotis

Myotis volans  This large Myotis bat has belly fur extending as far as the knees and elbows. The ears are rounded and fairly short. The Long-legged Myotis is associated with coniferous forests, especially old growth.

Big Brown Bat

Eptesicus fuscus  This very large bat can weigh 2- 4 times that of our smaller bat species. Ears are black and the distinctively long fur is brownish and oily. The large strong jaws are suited

Silver-haired Bat

Lasionycteris noctivagans  This bat is recognizable by its white-tipped hairs and short round ears with blunt ear tragus. It is often solitary in behavior, roosting in snags and live trees and hibernating under tree bark

Hoary Bat

Lasiurus cinereu  The hoary bat is has a grizzled camouflage appearance including some yellowish fur. Unlike most bats, the tail membrane is furred, which provides insulation for this tree-roosting bat. The hoary bat is solitary;

Townsend’s Big-eared Bat

Corynorhinus townsendii Townsend’s bat is recognizable by its enormous ears and glandular bulbs between the eyes and nostrils. Like most bats, the big-eared bat has a low reproductive rate, the female giving birth to a

Lives of Salt Spring Bats

Bats are active during the night, when they hunt insects on the wing, and bats may also be observed flying at dawn and at dusk. During the day they rest upside down in snags, live trees, tree cavities, under loose bark, in rock crevices, caves, or in attics, roofs, sheds, barns, and out-buildings. Some bat species congregate in groups and others are solitary.

Bats navigate in darkness using the echoes of their high-pitched calls (“echolocation”) that bounce off objects in the environment, like a radar system. Each Salt Spring species can be identified by the pitch, duration, and shape of its call.

In winter most bats likely hibernate locally although some migrate south. Some Salt Spring bats are active year-round but hole up and become torpid during poor weather. Torpor and hibernation allow the body temperature to drop, eliminating the need to feed in poor weather in order to heat the body.

Bat reproductive rates are low, unlike other small mammals such as mice, so population recovery from environmental impacts is problematic. Bats typically mate in the late summer or fall, and the female bat stores sperm until after hibernation. Young are born in June and July. Most Salt Spring bats have but a single pup and nurse the young for several weeks.

Bat Habitat Requirements and Environmental Threats

Bats require an abundant food supply — a nursing female may consume her body weight in food in a single evening – and bats require habitats that are productive of insects. Patches of native trees, shrubs, and herbs, natural meadows, and wetlands provide a reliable food source for bats. Wetlands are especially valuable – lakes, streams, ponds, marshes, swamps, bogs, and fens – and are focal points for bat feeding. These scarce but vital highly productive habitats are threatened by land development for housing, industry, and agriculture, which can alter hydrology, pollute waterways, and decimate wetlands.


Another risk of the insectivorous diet is exposure to insecticides. The enormous throughput of insects combined with the long lifespan of a bat (which can be decades) can result in unhealthy accumulation of insecticides in the bat’s body.


Bats require a variety of roosting sites — for resting during the day, for resting while on feeding expeditions at night (to digest and avoid predators), and for winter hibernation. Roosting bats are sensitive to temperature and humidity. Bats have a large surface area in relation to their volume, and are at great risk of body heat depletion when weather is poor, and thus require large volumes of food to compensate for heat loss when active. Reproductive female bats may seek sunny warm roosts in summer and huddle together, which helps raise temperature as needed for care of young. Non-reproductive females and males often seek cooler summer day roosts to conserve energy. If a bat colony is disturbed in poor weather, the arousal of bats from torpor may result in mass starvation.


Other threats to bats include forest clearing, domestic cats, wind turbines, and cave exploration. Nutrient pollution of ponds and lakes may result in toxin-producing algae harmful to bats. A fungal infection, white nose syndrome, has caused massive bat die-offs in eastern North America, and has been detected nearby. White nose syndrome causes respiratory acidosis, altered energy metabolism, and starvation. Human entry into caves may facilitate spread of the disease. A decontamination protocol for spelunkers can be found here:

Decontamination Protocol

Creating and Protecting Bat Habitat on your Property

  • Protect known bat roosts. Bat roosts can be detected by the presence of small droppings (guano) nearby and sometimes the bats can be heard chattering with high-pitched squeaks. Bat droppings are segmented, unlike mouse droppings of similar size (see image).
  • Avoid disturbing or harassing roosting bats.
  • Protect potential bat roosts such as caves, rock crevices, and wildlife trees, which include large trees, hollow trees, and dead trees (snags). Tall, large-diameter sun-exposed trees with a clear flight path can provide excellent bat roost sites. If wind-throw of dead trees is a concern, such trees can be topped and/or anchored to adjacent healthy trees. The latter system has been used even in residential neighbourhoods in Victoria BC.
  • Protect caves and deep crevices with signs and bars that allow bat passage but that deter humans and predators.
  • Conserve old outbuildings that serve as bat roosts.
  • Install a maternity bat house on a building, pole, or tree, at least 3 metres high, at a location that receives at least 10 hours of sunlight per day and that has a clear commuting flight path. A bat house for this latitude should be at least 60cm x 60 cm with a landing strip at least 10 cm deep at the bottom. Details of bat box construction and siting can be found here: Bat_houses_in_BC
  • Protect streams, ponds, and foreshore, including waterside vegetation, all of which are productive of bat food.
  • Create ponds and small wetlands on your property; examples can be seen at local nature reserves such as at Blackburn Lake.
  • Conserve native plants on which insect larvae feed.
  • Prevent domestic cats from roaming outside, as they prey upon bats.
  • Conserve natural ecosystems, including ponds, meadows, and forest.
  • Avoid use of insecticides and avoid chemical contamination of lands and waterways.
  • Provide a bird bath with clean drinking water for bats.
  • Do not handle or otherwise capture bats. This can stress them and disrupt their activities, and it can put you at risk of illness. Even dead bats can transmit disease. It is illegal to handle or possess wildlife other than invasive species without a license or permit. Report dead bats to the Conservancy.
  • If closing a bat roost in a building, this should be done between September and April, or preferably when the bats have left for the winter. A bat house should be provided for their return. It is illegal to exterminate bats. See the following publications on bats in buildings and bat evictions: GOT bats7 steps Evict


 Identification Tips for Salt Spring Bats:

The first four bats listed have a distinct keel on the calcar (ankle spur) – see image at right:

Hoary Bat: A large bat with frosted fur including yellow patches.

Big Brown bat: A huge bat with long oily fur.

Long-legged Myotis: Moderate size, small ears, underwing furred elbow to knee

California Myotis: Tiny bat with moderately long ears.

The next four bats do NOT have a distinct keel on the calcar ( ankle spur) – see image at right:

Townsend’s Big-eared Bat: Huge ears about half body length.

Silver-haired Bat: White-tipped hairs.

Western long-eared Myotis: Tiny bats with long ears that could extend well beyond snout.

Little Brown Myotis and Yuma Myotis: Tiny bats, ears would not extend beyond snout.

Ankle spur keel (protrusion below foot):

Other British Columbia Bats

In addition to the bats shown above, there are six species unlikely to be found on Salt Spring:

Western Small-footed Myotis (Myotis ciliolabrum)

North Long-eared Myotis (Myotis septentrionalis)

Fringed Myotis (Myotis thysanodes)

Western Red Bat (Lasiurus borealis)

Spotted Bat (Euderma maculatum)

Pallid Bat (Antrozous pallidus)


Further Information on Pacific Coast Bats: Washington State Bats  and BC bats

Frequently Asked Questions about Bats: Download Bat FAQ sheet