Spotted bat (Euderma maculatum) COSEWIC assessment and status report: chapter 2

COSEWIC Executive Summary

Spotted Bat
Euderma maculatum

Species information

The Spotted Bat,Euderma maculatum, belongs to the Order Chiroptera, Family Vespertilionidae, tribe Plecotini. The genus is monotypic; no subspecies are recognized for the species. A combination of jet black fur contrasting with prominent white spots on the rump and shoulders and enormous ears make this is the most spectacular bat in Canada.

Distribution

Globally, the Spotted Bat ranges from Mexico, across the western United States to southern British Columbia in Canada. Because the Spotted Bat can be detected and identified by its echolocation calls that are readily audible to most human observers, it distribution can be determined from acoustic surveys. Surveys done over the past two decades have revealed that this bat inhabits valleys of the Okanagan, Similkameen, Thompson, Fraser and Chilcotin River in British Columbia. The 80 distributional records (roosting and foraging records) for Spotted Bats in Canada represent about 40 element occurrences. The area of occupancy is unknown; the extent of occurrence in Canada is about 10,590 km² representing less than 5% of the species' global range.

Habitat

Known summer day roosts including maternity colonies of the Spotted Bat are in the crevices or cracks (2.0 to 5.5 cm wide) of high, vertical cliff faces. This species is not known to use night roosts in Canada. It may hibernate in cliffs within its Canadian range or migrate to the United States to overwinter. The Spotted Bat forages over marshes, riparian habitats, open fields, golf courses, and clearings in forest. Habitat suitability maps developed for the southern Okanagan Valley reveal that foraging habitat is widespread but roosting habitat is fragmented and patchily distributed. The impacts of agricultural development and urbanization on Spotted Bat roosting habitat are minimal.

Biology

Females produce a single young in the breeding season. The limited data suggest that the young are born in Canada in late June or early July. The age at sexual maturity is unknown.

Spotted Bats move 6 to 10 km from their day roost to foraging sites. From May to July, this bat shows a strong fidelity to its day roost, returning to the same roost site night after night. By early August, the daily movements become less predictable. Nothing is known about seasonal or long distance migratory movements.

This species may feed mostly on moths (5-12 mm in length). Flying Spotted Bats capture flying prey after detecting and tracking it by echolocation. The low frequency echolocation calls are dominated by the 9-12 kHz range (within the range of human hearing), rendering them inaudible or only detectable at close range by most moths with bat detecting ears.

The social structure is unknown--it is unclear if this bat roosts alone or in groups.

Population sizes and trends

Spotted Bats can be inventoried by acoustic surveys at potential roost sites or foraging areas. Although there has been no systematic inventory done throughout the entire Canadian range applying a standard methodology, the available census data suggest the Canadian population may be less than 1,000 total Spotted Bats. Seven population counts done in the southern Okanagan Valley over the past 20 years suggest the population trend is stable.

Limiting factors and threats

Specialized roosting requirements and a patchy distribution make the Spotted Bat a species of conservation concern throughout its range. The availability of suitable roosting sites may be a limiting factor for the Spotted Bat in Canada. There are no known threats to habitat used for foraging or roosting. There is no evidence that foraging habitat or moth prey are limiting. Known threats are generic threats such as disturbance to cliff roosts sites and pesticides.

Special significance of the species

The Spotted Bat is one of three western North American bat species that are confined to the intermontane grasslands of British Columbia in Canada. Its audible, low frequency echolocation calls that can be detected without the aid of electronic bat detectors make this bat an ideal species for research, detailed inventories, and educational programs that promote bat conservation.

Existing protection or other status designations

The Spotted Bat was designated Special Concern by COSEWIC in 1988; the global heritage status rank is G4 (apparently secure); national ranks are N3N4 (vulnerable to apparently secure) for the United States and N3 (vulnerable) for Canada. Three states (Montana, Oregon, and Wyoming) rank the Spotted Bat as S1 (critically imperilled); four states rank this species as S1S2 or S2 (critically imperilled or imperilled).  British Columbia has designated the Spotted Bat as S3S4 (vulnerable to apparently secure). This species is protected from killing under the provincial Wildlife Act, and it is listed as an Identified Wildlife Species under the revised British Columbia Provincial Forest and Range Practices Code. Nonetheless, the Forest and Range Practices Code only applies to provincial crown land; in the southern portion of the Canadian range more than 50% of this species’ habitat is exempt from the code.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed  under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Species
Any indigenous species, subspecies, variety, or geographically or genetically distinct population of wild fauna and flora.

Extinct (X)
A species that no longer exists.

Extirpated (XT)
A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A species facing imminent extirpation or extinction.

Threatened (T)
A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC) *
A species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**
A species that has been evaluated and found to be not at risk.

Data Deficient (DD) ***
A species for which there is insufficient scientific information to support status designation.

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Page details

Date modified: