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Wildlife
in Ontario
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Peregrine
Falcons
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Closer Look Index
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The
peregrine falcon was historically distributed throughout the
Great Lakes- St. Lawrence Region. In the 1940's and 1950's
however, the population started to decline rapidly. The Canadian
Wildlife Service (CWS) started looking for toxic chemicals
in Canadian wildlife and found that the levels of DDT in the
environment was very high during that time. |
| DDT
is dichlorodiphenyltrichloroethane. During World War II, it
was used as an insecticide to control diseases such as malaria
that is spread by mosquitoes and typhus, which is vectored
by lice. Unfortunately, DDT is a persistent chemical (it does
not break down quickly) so it remains in the environment for
a long time. DDT also bioaccumulates, which means that it
becomes more concentrated as it is passed from organism to
organism through the food chain. This is especially harmful
for peregrines and humans as they are both at the top of the
food chain. Additionally, DDT dissolves in fat so it is stored
in the animals' fatty tissues. |
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DDT
has been banned in North America since 1970 but it is still
being used in South American countries. Peregrines that
migrate south for the winter are still exposed to DDT. DDT
affects the falcon's ability to reproduce successfully in
several ways:
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the female may become infertile and unable to lay eggs,
- the
eggshell may be thin or soft and easily broken,
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the embryo in the egg may die
- the
mothers would just abandon their nests.
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Peregrines
were listed as an endangered species and a nationwide recovery
programs was launched in North America. Captive breeding facilities
were established and the young falcons were released through
hacking programs. |
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Hacking
is a technique to release birds of prey at the site (usually
the ledge of a building or cliff) without the care of an adult
bird. Food is provided for the bird in a hack box until it
is able to hunt by itself. The hack box also provides protection
for the young birds from predators and adverse weather conditions. |
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Most
of the Ontario peregrines have been banded by the Ministry
of Natural Resources before their flight feathers fully develop,
which is when the chicks are about 3 or 4 weeks old. Bird-banding
makes it easier to identify the birds without having to recapture
them and provides information on how the birds live, thier
migratory routes and even the genetic structure of the population. |
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Recently,
radio transponders are used to locate, record and map the
flight and behavioral patterns of the falcons that have been
released from the Richmond Hill site. |
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The
transponder is attached to the back of the birds and then
they are released. To prevent the falcons from undue stress
during this process, a small cloth bag is placed over its
head. The transponder is very lightweight and does not affect
the flight of the falcons. |
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The camera records the data,
which can be used to monitor the development and survival
of the peregrines. |
| In northern Ontario, the peregrine falcons
are continuing to recover and more young are being naturally
produced each year. In northern Ontario, the populations are
slowly expanding to recolonized former habitat ranges. |
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In southern Ontario, the falcons
have spread into several large cities, which are essentially
new habitats for the peregrines. Reports have shown that there
has been little recolonization in the cliffs of southern Ontario,
where peregrines frequently nested. |
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