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Eastern Loggerhead
Shrikes haven’t bred in the Maritimes since 1972, while
the last recorded nest in Quebec dates back to 1995. In Ontario
and Manitoba, there are currently only a few dozen breeding pairs
left in the wild, with the majority of confirmed pairs in the
Carden Plain and Napanee Plain areas of Ontario.
In 1991, the
Eastern Loggerhead Shrike was declared endangered under the federal
Committee on the Status of Wildlife in Canada. It is also protected
under the federal Migratory Birds Convention Act, 1994, the Federal
Species at Risk Act, 2003 and by various provincial endangered
species legislation.
The
exact reasons for the decline of shrikes across North America remain
unclear. However, ongoing research by shrike biologists and wildlife
groups suggests that there are several possible causes:


The
exact reasons for the decline of shrikes across North America
remain unclear. However, ongoing research by shrike biologists
and wildlife groups suggests that there are several possible
causes:
Loss
of habitat and Fragmentation
Due to changing
land use patterns, new farming methods, increasing urbanization
and other factors, shrike habitat is disappearing.
The amount
of unimproved pasture in the Prairie provinces shrunk 39 per
cent between 1946 and 1986. In southern Ontario, 65 per cent
of prime Eastern Loggerhead Shrike habitat has vanished over
the past 50 years.

Chemicals
Pesticides,
herbicides and other chemicals have contributed to the decline
of many bird species in Canada and elsewhere. Scientists are
now working to find out whether chemicals are affecting the health
of shrikes, and if so, to what extent.
Predators
As land use patterns change the landscape, the number of many shrike
predators has increased. These include house cats, as well as nest
predators such as blue Jays and American crows.
Accidents
Many
of the trees and shrubs that shrikes use for nesting and perching
are located close to roads. Unfortunately, that means that shrikes
are sometimes killed by passing vehicles. One way to reduce collisions
is to encourage drivers to slow down by posting "Endangered
Species Ahead" road signs in appropriate areas.

West
Nile Virus
Eastern Loggerhead
Shrikes are extremely susceptible to West Nile Virus, which is
carried by infected mosquitoes. However, we have not seen a marked
decline in the number of wild shrikes since WNV hit Ontario in
2002.
Climate
Change
Climate change
is a potential threat. Although warmer global temperatures are
encouraging insects to hatch out earlier, shrikes are still arriving
at their breeding grounds at their usual time. This may mean
their nesting period no longer matches the spike in insect numbers,
so there’s less food available to sustain them.
Migration
and Over-wintering
We’re
still not sure where Canadian shrikes spend the winter or what
routes they take when they fly south. However, more and more
evidence suggests that factors during migration or over-wintering
are contributing to the drop in shrike numbers.

Hundreds of
species are considered "at risk" in Canada. Why focus
on the Eastern Loggerhead Shrike? One compelling reason is that
grassland birds, and the loggerhead shrike in particular, have
shown a more persistent and drastic decline than any other group
of birds.
In fact, the
Eastern Loggerhead Shrike has shown the greatest rate of population
decline of any perching bird in Canada between 1970 and 1991.
Shrike numbers have been in decline throughout North America
since the International Breeding Bird Survey began in 1966.
This is significant
because wildlife scientists consider shrikes an "indicator" species
among grassland birds. What affects the shrike also affects the
boblink, eastern meadowlark, the short-eared owl, the upland
sandpiper and other grassland birds that are becoming increasingly
rare.
But the decline
is also important on a broader scale because healthy shrikes
mean a healthy environment. As predators, shrikes are near the
top of the food chain. Their bodies accumulate insecticides and
other chemicals that their prey have already absorbed.
Thus, like
the proverbial canary in the coal mine, the shrike's declining
numbers suggest an environment out of balance.
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