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TELUS Tower, Red Deer
(Platform is 302 feet (92 m)
above ground level.
Instrument package
Final adjustment of the
camera
in the nest box.
Nest box hoisted to the top.
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Peregrine falcons regularly return to
their favourite nesting sites. The TELUS tower in Red
Deer has been used for years. Normally, peregrines nest on steep
cliffs, sometimes returning to the same nest for years.
Recently they have adopted tall buildings as nesting
sites. Some good building nest sites in Canada include: Edmonton, Red Deer, Calgary, Saskatoon, Regina,
Brandon, Winnipeg, London, Toronto, Ottawa, Montreal,
Quebec City, and Saint John. They are about
crow-sized; the females being larger than the males.
Visually, look for the black "teardrop" (malar) and
the dark bluish-grey crown, back, and upper wing
surface. The throat is white, the underparts are white
to buff, and there are blackish-brown bars on the sides,
thighs, abdomen, underwings, and the lower breast area.
Peregrines in flight are distinguished from hawks by
their more streamlined appearance. They have relatively
small heads and long pointed wings, an adaptation that
allows them to fly rapidly. They have powerful talons
and a hooked beak. The beak is equipped with a notch or
"tooth" that aids in severing the spinal cord of the
birds they prey on. Peregrines have extremely acute
eyesight making them effective hunters at dawn and dusk.
Some captive peregrines have been known to live up to 20
years, but life spans in the wild are much shorter.
During migration, they have been known
to fly up to 500 kilometres in a day. A female Peregrine that nested in Edmonton flew
to Mazatlan, Mexico, in less than eight days and
returned in six days. Peregrines banded in the Northwest Territories have
been recovered in Argentina; most arctic nesters
apparently “leapfrog” more southern North American
falcons to winter farther south in South America. In
fact, the Peregrine Falcon was named for the lengthy
migrations of some populations: “peregrine,” from the
Latin adjective peregrinus, means “coming from
foreign parts” or “wanderer.”
Peregrines’ prey species vary greatly from region to
region and even from one nesting site to the next. For
example, in parts of the Queen Charlotte Islands,
British Columbia, Peregrines feed almost entirely on the
Ancient Murrelet, a small seabird plentiful there. On
the east coast of Labrador, Peregrines eat Black
Guillemots, another common seabird, and small mammals
such as mice and voles. At Rankin Inlet, on the west
shore of Hudson Bay, Peregrines eat mostly lemmings and
shorebirds. In southern Canada, they eat a variety of
birds that live in wetlands, including Franklin’s Gulls,
Black Terns, Lesser Yellowlegs, Eared Grebes, Northern
Flickers, Green-winged Teals, and Soras. In cities,
Peregrines eat some pigeons, but these rarely account
for more than 20 percent of their diet.
Renowned as the "fastest
bird in the world", they can dive at speeds over 300
km/hour when attacking prey. A stooping (diving) Peregrine is a hurtling wedge of
streamlined feathers. Its feet lie back against its tail
and its wings are half closed. Its usual method of
disabling or killing medium-sized and large prey is to
deliver a fierce blow with a half-closed foot during a
dive. If the quarry is too heavy to carry, the Peregrine
allows it to fall to the ground, then lands to kill and
feed on it. It snatches small prey such as swallows or
sandpipers in mid-flight with its talons or strikes the
prey down and then retrieves it. The Peregrine’s flights
at intended prey are often unsuccessful. The ability of
the individual bird, the agility of the prey, and the
availability of escape cover affect the success of each
stoop. As is usual in predator–prey relationships, the
Peregrine singles out aberrant or weaker individuals as
prey.
With few enemies and a long lifespan, Peregrines,
like other predators, are at the top of a food chain.
Peregrines were exposed to much higher levels of
pesticide residues than the levels found in air or water
because they because they eat birds that may have eaten grain or
insects treated with pesticides, the Peregrines were
exposed to much higher levels of pesticide residues than
were found in the air or water. Pesticide residue levels
in their bodies would have been many times higher than
the levels in their prey species. At high levels, these
chemicals caused reproductive failure by interfering
with breeding behaviour, eggshell formation, and
hatching success. Thus Peregrine populations gradually
dwindled because of the lack of breeding success.
In 1969 in Canada and in 1972 in the United States,
restrictions were placed on the use of DDT, a persistent
pesticide that contributed to the Peregrine’s decline.
Nevertheless, Canadian Peregrines and their prey species
probably continued acquiring contaminants on their
wintering grounds in Central and South America.
Peregrine Falcons, like virtually all birds of prey,
now receive legal protection in most parts of North
America. In other parts of the world, however,
protection is much less complete, and populations are
endangered by adults being shot and young being taken
from nests.
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