COSSARO Candidate Species at Risk Evaluation Form for Barn Owl (Tyto alba)

Committee on the Status of Species at Risk in Ontario (COSSARO)

Assessed June 2010 by COSSARO as Endangered

June 2010

Final

Part 1: COSSARO Candidate species at risk evaluation form – June 2010

Barn Owl (Tyto alba)

Current designations:

GRANK – G5
NRANK Canada – N3
COSEWIC – Eastern population: Endangered (May 2000)
SARA – Endangered (Schedule 1) General Status Canada – Sensitive ESA 2007 – Endangered
SRANK – S1
General status Ontario – At Risk

Distribution and status outside Ontario:

Distribution almost worldwide. Two designatable units in Canada, eastern and western.

Eligibility criteria

Native status

  • Yes. Native in Canada, occurrences in Quebec, Ontario and British Columbia

Taxonomic distinctness

  • Yes. Considered a valid species in all recent taxonomic treatments. No clear genetic answer to question about whether east and west populations are distinct.

Designatable units

One designatable unit in Ontario, two in Canada

Priority-setting criteria

Recent arrival

  • No. Long known as a native bird

Non-resident

  • No.

Primary criteria (rarity and declines)

1. Global rank

  • Not in any category. G5

2. Global decline

  • Not in any category.

3. Northeastern North America ranks

THR. (Ranked S1, S2, SH, or SX in 13 of 19 (68%) of Northeastern North American jurisdictions in which it occurs and is ranked. The species is ranked S3 in an additional 6 jurisdictions.)

4. Northeastern north america decline

END. (The Barn Owl is a species of Special Concern in 5 (Vermont, Pennsylvania, New York, Maryland, and Massachusetts), Threatened in 4 (Rhode Island, Ohio, Connecticut, and Ontario), and Endangered in 2 (Michigan and Iowa) northeastern jurisdictions (Appendix 1; Blodget 1989). Based on the number of northeastern jurisdictions where the species is ranked S1 or S2, or is listed as Threatened or Endangered, it appears that Barn Owls are still in decline. Therefore, "Endangered" status is presumed for this criterion in the absence of information regarding population decline from Natural Heritage Programs.

5. Ontario occurrences

END. (Ontario population ≤ 20 mature birds (Badzinski 2007)).

6. Ontario decline

END (Virtually all sites checked in 2008 for which previous (1986 or 2001) population counts are estimates are available, have declined (Table 1 in COSEWIC 2010). Twelve of 25 (48%) Element Occurrence records in the NHIC database are considered extirpated and at least a couple of others have not been recently checked and may be extirpated.)

7. Ontario’s conservation responsibility

  • Not in any category (Ontario makes up <5% of the species global range (COSEWIC 2010).)

Secondary criteria (threats and vulnerability)

1. Population sustainability

  • Not in any category

2. Lack of regulatory protection for exploited wild populations

  • Not in any category (Barn Owls are not migratory, and are protected in Ontario by FWCA and SARA.)

3. Human threats

END. (Loss of nesting habitats (old barns and silos), loss of foraging habitat and mortality along roads are important threats to the survival of Barn Owls in Ontario.)

4. Specialized life history or habitat-use characteristics

END. (The short adult life span, puts Barn Owls at risk, particularly in light of the loss of habitat for nesting and foraging. Although Barn Owls can be prolific breeders, they are not achieving high levels of reproduction in Ontario.)

COSSARO criteria met (primary/secondary)

Endangered – 3/2
Threatened – 1/0
Special concern – 1/0

Summary

Barn Owl (Tyto alba)

One of the two Canadian populations occurs in Ontario (consisting of ~20 adult birds), the other is in British Columbia. Although this species has high reproductive potential because they lay large clutches and may reproduce at any time of the year, adults live less than 3 years. Even though in British Columbia and elsewhere in their range these birds regularly use nest boxes, this has not happened in Ontario. In Ontario, birds have suffered from loss of nesting sites (old barns and silos) and foraging habitat (due to the spread of agriculture and succession). There has been no change in the population in Ontario since the last assessment. Changes in land use and farming practices are the main threats to the population in Ontario. This species is Endangered in Ontario.

Information sources

Badzinski, D.S. 2007. Barn Owl. Pp. 288-289 in Cadman, M.D., D.A. Sutherland, G.G. Beck, D. Lepage, and A.R. Couturier, eds. Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources, and Ontario Nature, Toronto, xxii + 706 pp.

Blodget, B.G. 1989. Common Barn-owl. Pp. 81-87 in Proc. Northeast Raptor Management Symposium and Workshop (B. Giron Pendleton, ed.). National Wildlife Federation Scientific and Technical Series No. 13.

COSEWIC 2010. Update Status Report on Barn Owl (Tyto alba) – Eastern Population and Western Population. Committee on the Status of Endangered Wildlife in Canada. Ottawa.

Appendix 1

Northeastern North America rank, status and decline

CT S2
DE S3
IL S1S2
IN S2
IA S1B
KY S3
LB  
MA S2B, S2N
MB  
MD S3
ME  
MI S1
MN  
NB  
NF  
NH  
NJ S3B
NS  
NY S1S2
OH S2
ON S1
PA S3B, S3N
PE  
QC  
RI S1B, S1N
VA S3B, S3N
VT S1B, S1N
WI S1B, S1N
WV S2B, S2N

Occurs as a native species in 19 of 29 northeastern jurisdictions S-rank or equivalent information available for 19 of 19 jurisdictions = 100 % S1, S2, SH or SX in 13 of 19 = 68 %

Part 2: Ontario evaluation using COSEWIC criteria

Regional (Ontario) COSEWIC criteria assessment

Criterion A – Decline in total number of mature individuals

Not in any category: no evidence of decline over at least 10 years

Criterion B – Small distribution and decline or fluctuation

Not in any category

Criterion C – Small and declining number of mature individuals

Not in any category

Criterion D – Very small or restricted total population

Endangered (D1) [≤ 20 adults in the population]

Criterion E – Quantitative analysis

No data available

Rescue effect

There remains the possibility that vagrant individuals from populations south of Lake Erie may end up in Ontario, but there is no evidence of this having happened in at least 10 years.