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: [EMAIL PROTECTED]
Jean Iron
9 Lichen Place
Toronto ON M3A 1X3
416-445-9297
e-mail: [EMAIL PROTECTED]
Jean Iron <[EMAIL PROTECTED]>
