Species Spotlight: Silver-Haired Bat
To celebrate the run up to Halloween, we want to shine the moonlight on each of the eight bat species of Ontario. In this series of blog posts, we will be highlighting the key info for each species and will provide some exclusive recordings we have collected this year in our Batacea Guelph Bat Watch project.
In this post, we will be spotlighting the silver-haired bat (scientific name: Lasionycteris noctivagans).
Silver-haired bats are dark in color (dark brown to black fur), with silver frosted-like tips along their back. They have round, hairless ears, partially furred tail membrane and their slow flight distinguishes them from other Canadian bat species.
Range and Ecology
Silver-haired bats are common across North America, and in Canada can be found throughout British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick and Nova Scotia.
This species typically roosts in mines, caves and dead trees. Females form small maternity colonies, and roost in trees near other suitable roost trees, which presumably reduces the cost of roost switching behavior and minimizes the risk of exiting the roost nightly.
Silver-haired bats forage in forested areas associated with freshwater (wetlands/rivers/streams/ponds), mainly feeding on soft-bodied insects such as moths, Chironomids and mayflies, but also are known to feed on beetles.
Below is a slowed video of a silver-haired bat filmed at one of our 2020 sampling sites using an infra-red camera.
This species is currently classified as 'Least Concern' according to the IUCN Red List, with stable long-term population trends.
Similar to hoary bats, silver-haired bats (particularly females) are one of the three tree bat species most commonly killed by wind turbines (over 75% of the mortalities).
Throughout our 2020 summer surveys, silver-haired bats were regularly recorded across all four of our survey sites, making up 9% of the total number of recordings for 2020.
Spectrograms from silver-haired bats overlap considerably with big brown bat spectrograms, making it sometimes difficult to distinguish the two species. Silver-haired bat calls form a smooth curve ending around 30 kHz (peak energy). Their call shape is similar to that of the hoary bat, however silver-haired bats call at a higher frequency (26-30 kHz).
To listen to the silver-haired bat call snippet above, download the MP4 file below.
To explore more silver-haired bat spectrograms, check out the iNaturalist Bat Spectrogram project.