Short-eared owl (Asio flammeus) COSEWIC assessment and status report: chapter 11

Range of Occurrence in Canada:

All jurisdictions

extent of occurrence (EO) (km²) (from Partners in Flight Database) :

ca. 7,500,000 km²

specify trend (decline, stable, increasing, unknown) :

Stable

are there extreme fluctuations in EO (> 1 order of magnitude)?

No

area of occupancy (AO) (km²) guesstimate based on habitat availability :

ca. 1,500,000 km²

specify trend (decline, stable, increasing, unknown)--assumed based on population decline :

Decline

are there extreme fluctuations in AO (> 1 order magnitude)?

Probably not

number of extant locations :

Not applicable

specify trend in # locations (decline, stable, increasing, unknown) :

Not applicable

are there extreme fluctuations in # locations (>1 order of magnitude)?

Not applicable

habitat trend:  specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :

Habitat loss occurring in southern parts of Canadian range

generation time (average age of parents in the population) (indicate years, months, days, etc.) :

2 years

number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)

from Partners in Flight estimates, based on Breeding Bird Survey and other data sources. Other estimates have been much lower (10,000-40,000). Ca. 350,000

total population trend:  specify declining, stable, increasing or unknown trend in number of mature individuals

Declining

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period) :

27% over 10 years (Christmas Bird Count data)

are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?

Probably not

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)?

Rescue Effect (immigration from an outside source) :

Moderate

does species exist elsewhere (in Canada or outside)?

Yes

status of the outside population(s)?

Declining

is immigration known or possible?

Yes

would immigrants be adapted to survive here?

Yes

is there sufficient habitat for immigrants here?

Unknown