birdalert@ontbirds.ca

Ontario Rare Bird Alert

View all threads

Ontario Raptor Trends

JI
Jean Iron
Sat, Apr 5, 2003 7:43 PM

Dear Ontbirders,

With spring hawk watching at its best in the next few weeks, you may be
interested in the latest issue of Bird Trends (Number 9, Winter 2003) on
Canadian raptors published by the Canadian Wildlife Service (CWS). This
issue has many short notes summarizing data from Bird Studies Canada (BSC),
the Breeding Bird Survey, provincial/territorial governments, CWS, and
researchers. Here are a few highlights of interest to Ontario birders.

  1. Introduction: David Kirk of Aquila Applied Ecologists says "Most raptor
    species in Ontario seem to be doing fairly well, but adequate monitoring
    has really taken place in the southern and central part of the province."

  2. Red-shouldered Hawk: Debbie Badzinski of BSC reports that Ontario
    populations are stable or increasing. The Red-shouldered Hawk in Ontario
    has probably "reached equilibrium with available forest cover and
    fragmentation" and it is unlikely to ever return to its historical higher
    numbers. The latest population estimate for Canada is 2000 - 5000 pairs
    (Kirk et al. 1995). Note that the secretive Red-shouldered Hawk is NOT
    listed as an endangered species, either nationally or provincially, in
    Ontario. See number 5 below.

  3. Bald Eagle: Debbie Badzinski states that Bald Eagles are increasing in
    southern Ontario. However, they "appear to have shortened life spans of 8 -
    10 years, compared with up to 30 years in other populations (Whittan
    2000)." A possible explanation could be heavy metal poisoning from mercury
    and lead.

  4. Owls: Debbie Badzinski discusses population trends of nocturnal owls in
    Ontario. She writes "Annual fluctuations in owl populations are poorly
    understood...but presumably occur in response to prey availability." "Owl
    calling frequency may be related to prey abundance and consequently
    breeding effort. In years with low prey availability, owls may forego
    breeding and therefore be less territorial and less likely to vocalize."

  5. Ontario's Raptors At Risk: The Committee on the Status of Endangered
    Wildlife in Canada (COSEWIC) lists the eastern Barn Owl as Endangered; the
    anatum subspecies of the Peregrine Falcon as Threatened; the Short-eared
    Owl, Red-shouldered Hawk and tundrius subspecies of the Peregrine Falcon as
    Special Concern.

There is a lot more on Canadian hawks, eagles and owls in this 68 page
issue of Bird Trends.
It is online at http://www.cws-scf.ec.gc.ca/birds/news/index_e.cfm

Happy hawk watching and owl listening.

Ron Pittaway
Minden and Toronto
E-mail: jeaniron@sympatico.ca
Jean Iron
9 Lichen Place
Toronto ON  M3A 1X3
416-445-9297
e-mail: jeaniron@sympatico.ca

Jean Iron jeaniron@sympatico.ca

Dear Ontbirders, With spring hawk watching at its best in the next few weeks, you may be interested in the latest issue of Bird Trends (Number 9, Winter 2003) on Canadian raptors published by the Canadian Wildlife Service (CWS). This issue has many short notes summarizing data from Bird Studies Canada (BSC), the Breeding Bird Survey, provincial/territorial governments, CWS, and researchers. Here are a few highlights of interest to Ontario birders. 1. Introduction: David Kirk of Aquila Applied Ecologists says "Most raptor species in Ontario seem to be doing fairly well, but adequate monitoring has really taken place in the southern and central part of the province." 2. Red-shouldered Hawk: Debbie Badzinski of BSC reports that Ontario populations are stable or increasing. The Red-shouldered Hawk in Ontario has probably "reached equilibrium with available forest cover and fragmentation" and it is unlikely to ever return to its historical higher numbers. The latest population estimate for Canada is 2000 - 5000 pairs (Kirk et al. 1995). Note that the secretive Red-shouldered Hawk is NOT listed as an endangered species, either nationally or provincially, in Ontario. See number 5 below. 3. Bald Eagle: Debbie Badzinski states that Bald Eagles are increasing in southern Ontario. However, they "appear to have shortened life spans of 8 - 10 years, compared with up to 30 years in other populations (Whittan 2000)." A possible explanation could be heavy metal poisoning from mercury and lead. 4. Owls: Debbie Badzinski discusses population trends of nocturnal owls in Ontario. She writes "Annual fluctuations in owl populations are poorly understood...but presumably occur in response to prey availability." "Owl calling frequency may be related to prey abundance and consequently breeding effort. In years with low prey availability, owls may forego breeding and therefore be less territorial and less likely to vocalize." 5. Ontario's Raptors At Risk: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) lists the eastern Barn Owl as Endangered; the anatum subspecies of the Peregrine Falcon as Threatened; the Short-eared Owl, Red-shouldered Hawk and tundrius subspecies of the Peregrine Falcon as Special Concern. There is a lot more on Canadian hawks, eagles and owls in this 68 page issue of Bird Trends. It is online at http://www.cws-scf.ec.gc.ca/birds/news/index_e.cfm Happy hawk watching and owl listening. Ron Pittaway Minden and Toronto E-mail: jeaniron@sympatico.ca Jean Iron 9 Lichen Place Toronto ON M3A 1X3 416-445-9297 e-mail: jeaniron@sympatico.ca Jean Iron <jeaniron@sympatico.ca>