Spotted bat (Euderma maculatum) COSEWIC assessment and status report: chapter 12

Technical Summary

Euderma maculatum

Spotted Bat – Oreillard maculé

Range of Occurrence in Canada:
British Columbia

Extent and Area information

extent of occurrence (EO)(km²) :
10,600 km²
specify trend (decline, stable, increasing, unknown) :
Stable
are there extreme fluctuations in EO (> 1 order of magnitude)?
No
area of occupancy (AO) (km²) :
Unknown
specify trend (decline, stable, increasing, unknown)
-
are there extreme fluctuations in AO (> 1 order magnitude)?
-
number of extant locations :
80*
specify trend in # locations (decline, stable, increasing, unknown) :
Unknown
are there extreme fluctuations in # locations (>1 order of magnitude)?
No
habitat trend:  specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :
Stable?

Population information

generation time (average age of parents in the population) (indicate years, months, days, etc.) :
Unknown
number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)
<1000
total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :
Stable
if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)
-
are there extreme fluctuations in number of mature individuals
(> 1 order of magnitude)?
No
is the total population severely fragmented (most individuals
found within small and relatively isolated (geographically or
otherwise) populations between which there is little exchange,
i.e., < 1 successful migrant / year)?
No
list each population and the number of mature individuals in each :
-
specify trend in number of populations (decline, stable,
increasing, unknown)
-
are there extreme fluctuations in number of populations
(>1 order of magnitude)?
-

Threats (actual or imminent threats to populations or habitats)

  • disturbance to cliff roosting sites
  • loss of riparian foraging habitat
  • impact of pesticides on the moth prey base
Rescue Effect (immigration from an outside source)
Moderate
does species exist elsewhere (in Canada or outside)?
Yes

status of the outside population(s)?

  • Rare
  • Idaho S2
  • Montana S1
  • Washington S3
is immigration known or possible?
Yes
would immigrants be adapted to survive here?
Yes
is there sufficient habitat for immigrants here?
Yes

Quantitative Analysis

  • *80 occurrences;
  • 40 element occurrences

An element occurrence for small bats is defined by the Heritage Ranking System as sites occupied historically or at present that are separated by 10 km or more

Other Status

  • COSEWIC: Special Concern 1988
  • British Columbia: S3S4

Status and Reasons for Designation

Status:  Special Concern

Alpha-numeric code: [The estimated Canadian population (<1000 adults) met criterion for Threatened D1, but it was designated Special Concern because there is a possibility of rescue effect from neighbouring populations in the United States. Foraging and roosting habitats appear to be secure in Canada.]

Reasons for Designation: In Canada, this species occurs in the intermontane grasslands of southern British Columbia. It is a distinctively coloured bat that is unmistakable to identify. Unlike any other Canadian species of bat, it has echolocation calls that are within the range of human hearing. It roosts in crevices in large cliff faces. It is considered the most easily and best censused species of bat in Canada. Population estimates, based on relatively good census effort, suggest that there are fewer than 1000 adults. At this time, numbers appear to be stable, and there are relatively few threats to populations or habitats. Perhaps the biggest threat to this species is its small population size. Use of pesticides on its prey, loss of foraging habitat, and disturbance at roosting sites by rock climbers are potential threats. Rescue may be possible from neighbouring populations in the United States; however, movements of individuals between Canadian and US populations are not documented.

Applicability of Criteria

Criterion A (Declining Total Population): < 1000 adults in Canada.

Criterion B (Small Distribution, and Decline or Fluctuation): 10600 km² in Canada.

Criterion C (Small Total Population Size and Decline): No evidence of population decline.

Criterion D (Very Small Population or Restricted Distribution): Meets the criterion for Threatened under D1. < 1000 adults in Canada.

Criterion E (Quantitative Analysis): Probability of extinction in Canada, unknown.

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