Loggerhead Shrike
The eastern population of the Loggerhead Shrike in Canada is on the
brink of extirpation and there are several key questions that must
be answered as soon as possible to conserve this
species. Initiated in 1999, the Loggerhead Shrike colour banding
program in Ontario is intended to furnish much needed information
on post-fledgling survivorship, immigration and emigration
rates among and between the four sub-populations in Ontario (Napanee,
Smiths Falls, Carden and Grey-Bruce/Manitoulin), longevity, age structure,
overall population size, and site faithfulness. It will also help assess
the efficacy of a planned release program, and could
contribute some information on wintering areas.
A report has been created that's designed to inform interested parties about the
species, their habitat requirements and details on the shrike banding program.
Background
The Loggerhead Shrike has suffered a serious decline throughout
its North American breeding range over the last 50 years. The decline of the eastern
population has been particularly widespread, persistent and severe, and is believed to
have occurred primarily as a result of habitat loss, as well as effects of pesticides on
young shrikes, predation, and collisions with vehicles. Loggerhead Shrikes have been
designated as Endangered in Canada since 1991, and Endangered in Ontario since 1992.
The OBAR project involves the implementation of recovery actions for the eastern
migrant population of Loggerhead Shrikes (Lanius ludovicianus migrans) through
population and habitat monitoring, landowner contact and education, and the development of
a captive breeding and release program. Bird Studies Canada is an active partner in the
Canadian Loggerhead Shrike Recovery Team which is coordinating recovery actions for this
species across the country.
Where Are They Found?
The Loggerhead Shrike occurs exclusively in North America in habitat characterized by
short grasses, interspersed with spiny shrubs and low trees. Pastures and hay meadows with
hedges or shrubs are particularly suitable. Shrubs and trees are required for nesting and
perching as well as for sites on which to impale their prey, which ranges from ants and
spiders to small birds and mammals.
In Ontario, the Loggerhead Shrike breeds almost entirely in three core areas, all of
which are located on limestone plains immediately adjacent to the Canadian shield. These
core areas are the Carden Plain, northeast of Lake Simcoe; the Napanee Plain, just north
of Lake Ontario in the Kingston area; and the Smith's Falls Plain, in eastern
Ontario. The map below shows the approximate locations of these three core areas within
the shrike's historic breeding range in Ontario.
Current Status
Once considered a fairly common breeding bird from eastern Manitoba through Ontario,
Quebec and the northeastern United States, populations of the eastern subspecies of the
Loggerhead Shrike have declined sharply over the last 50 years. The Loggerhead Shrike is
now very nearly gone from all of its former Canadian range.
Extensive annual surveys began in the Ontario core areas in 1992 to monitor the
Loggerhead Shrike population. During these surveys information on the number of pairs and
single birds and their habitats is collected with the help of volunteers. As shown above,
the number of shrikes in the province decreased substantially between 1992 (55 pairs) and
1997 (17 pairs). In 1998 the population rebounded slightly to 30 pairs, which is similar
to numbers counted in 1995 and 1996. The Ontario population is currently at extreme risk
of extirpation.
Threats to Shrikes
Perhaps the greatest threat to the Loggerhead Shrike is the loss and fragmentation of
suitable habitat due to natural succession and recent changes in agricultural land use,
particularly the conversion of pastures and hayfields to rowcrops. This has resulted in
the removal of hedgerows, shrubs and trees which are essential to the shrike's
lifestyle. The Loggerhead Shrike Recovery Team has gathered information on habitat quality
and availability in Ontario and Quebec, and is currently developing a "Habitat
Conservation Plan" which will address causes of decline and possible methods of
reversal through habitat restoration.
Another potentially serious problem facing this species stems from collision with motor
vehicles. Loggerhead Shrikes are often found along roadways, where they perch on fences
and utility lines and hunt along the open roadsides. In 1998 in Ontario, three young
shrikes were killed by vehicle collisions, and several near-collisions between adult
shrikes and cars were reported. The Recovery Team erected road signs asking cars to slow
down in areas where shrikes were present, and distributed fliers to local residents.
Unfortunately, there appeared to be no significant decrease in traffic speed before and
after the signs were erected. Some individual motorists, however, noticeably reduced their
speed after seeing the signs. In 1999 the Recovery Team will place larger signs at all
sites where shrikes are at risk, which, in conjunction with public service announcements,
should reduce the number of shrike traffic fatalities.
Another potential problem faced by Loggerhead Shrikes in Ontario is the application of
the dust-supressant Dombind on roads near or in shrike territories. The use of Dombind
appears to increase the density of insects on these roads, which subsequently attracts
shrikes to these areas and places them at greater risk of traffic collisions. There is
also some concern that low levels of dioxins, furans and other contaminants in Dombind may
have a negative effect on shrikes feeding from these surfaces. The Loggerhead Shrike
Recovery Team has been working with the Ontario Ministry of the Environment to phase out
the use of Dombind on roads in shrike habitat, and in 1998 the use of Dombind in some
shrike territories was stopped after the initial application. The future of Dombind use is
currently unclear. However, the Ministry of the Environment announced their plans in
December 1998 to phase out the use of this substance on all roadways in Ontario within two
years.
Captive Breeding and Release
A captive breeding program for the eastern migrant race of the Loggerhead Shrike began
in Ontario in 1997. Bird Studies Canada, in conjunction with the Loggerhead Shrike
Recovery Team, developed the protocol for captive breeding, with the purpose of
maintaining genetic diversity of this subspecies and providing a stock of birds for
possible reintroduction to the wild. In 1997, 15 young birds were taken into captivity,
and in 1998 an additional 28 young were taken. These birds are currently housed at the
Metro Toronto Zoo and McGill University. Happily, two pairs of shrikes bred in captivity
in 1998, producing a total of 5 nestlings. The total captive population currently consists
of 49 individual shrikes. The Recovery Team is currently determining which release methods
will be used, and where the shrikes will be released. Sites in both Ontario and Quebec are
being considered.
How you can help
1. If you have Loggerhead Shrikes on your property, contact the Ontario Birds at Risk
(OBAR) Coordinator at Bird Studies Canada or the Ontario Ministry of Natural Resources
(see below) for a copy of the landowner's resource guide that outlines various
methods of managing and/or restoring habitat sites for shrikes. You will also qualify for
an exemption from municipal property taxes.
2. Participate in the OBAR program by becoming involved in volunteer surveys of
Ontario's core breeding areas. Keep track of sightings of Loggerhead Shrikes and
other rare birds in Ontario and report these to OBAR.
