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MARCH
2007 BIRD OF THE MONTH |
SOUND THE TRUMPET FOR THE RETURN OF TRUMPETER SWANS
By March Mahr
CLICK HERE FOR .PDF VERSION
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JUDY SUBLETT PHOTO |
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The Trumpeter Swan (Cygnus buccinator)
is the largest waterfowl in North America and the
largest swan in the world. Yet there’s more than their
size to blow a horn about—Trumpeter Swans are making a
comeback. Once abundant and widespread within a wide
band extending from Alaska along the Pacific Coast to
the Midwest in the U.S., and throughout western Canada,
Trumpeter Swans were nearly extinct by 1900. Both their
numbers and their distribution were severely reduced by
extensive market hunting, the commercial plumage trade,
and widespread loss of wetland habitat. The only
Trumpeters that survived were those that lived
year-round in remote areas or whose traditional
migration patterns avoided areas of human settlement.
Decades of conservation efforts have rescued the Rocky
Mountain Trumpeters from near extinction, creating a
conservation success story. Trumpeters breeding in the
Greater Yellowstone Ecosystem have responded well to
international restoration programs, growing from only 69
birds remaining worldwide in 1932, to nearly 500 in
recent years.
These birds are joined each winter by
an additional several thousand Trumpeters
from western Canada to form
the Rocky Mountain population of Trumpeter Swans.
In 1993, I was first introduced to the grace
and bravado of Trumpeter Swans when I spent a
summer conducting field research at Red Rocks
Lakes National Wildlife Refuge in the Centennial
Valley of southwestern Montana. I was frequently
distracted from surveying plants by a sharp bugle
announcing the arrival of Cygnus Flight #756. With
wings spanning up to eight feet, and both neck and
legs fully extended, Trumpeters are powerful flyers
capable of speeds up to 50 miles per hour. I also
enjoyed watching flotillas of swans and their cygnets
(young of the year) bobbing on the shallow lakes of
the refuge, swimming with their necks erect in regal
beauty.
Red Rocks Lakes National Wildlife Refuge
was established in 1935 specifically to protect
Trumpeter Swans because nearly half (i.e., less
than 40 birds) of the Trumpeter Swans known to
exist were found in this area. Today, the refuge
continues to be one of the most important habitats
in North America for these majestic birds. Over the
years, the Red Rock Lakes refuge flock has served
as an important source of breeding birds for reintroduction
efforts in other parts of the country. You may
be thinking, “Brrr! Isn’t the Yellowstone area freezing
in the winter?!” Yes, it can be a frigid place; yet the
area’s system of warm springs provides year-round
open waters where Trumpeters find food and cover
even in the coldest weather.
Trumpeter Swans must remain near open
water to obtain their preferred diet of aquatic plants.
Their staple diet includes waterweed, pondweed,
water milfoil, and duck potato. A mature adult will
consume up to 20 pounds of wet herbage each day!
They also feed occasionally on grain,
seeds, freshwater invertebrates, snails,
and worms. Trumpeters have broad flat
bills with fine tooth-like serrations along
the edges that strain water when they eat
aquatic vegetation. They use their strong
webbed feet to dig into the pond or lake
bottom for roots, shoots, and tubers, then
plunge their heads and necks underwater
to eat what they have dug up. Their long
necks and powerful bills allow them to
reach down three to four feet and pull up
roots and stems other birds can’t reach.
Aside from Trumpeters, there are
two other species of swans in North
America: the native Tundra Swan (Cygnus columbianus,
formerly known as the Whistling Swan); and
the non-native Mute Swan (Cygnus olor), a Eurasian
species that has been introduced or escaped from
captivity, and now breeds in several parts of North
America.
This spring on Smith Lake, I saw several
big, white swans. Trumpeter? Tundra? Since Trumpeters
often mix with flocks of the more common
Tundra Swan during migration, I consulted my field
guide. Following are a few tips to help with species
identification:
Size:
Trumpeters are much larger than Tundra
Swans but both are huge birds and size differences
may be difficult to distinguish unless the two
species are side by side or seen at close range.
Voice: Their call is a sure method of species
identification if you’re lucky to hear it. Trumpeters
have a loud, low-pitched, hoarse, bugling call of hurp
or hur di di, which D.A. Sibley likens to the honk of a
European taxi. Tundra Swans have a high-pitched,
quavering, melancholy klooo or kwooo with an accentuated
oo-oo-oo sound, and a hooting or barking
quality that may sound like ‘whoops’ from a distance.
Head and Bill:
Trumpeters have a black bill
with red border on their lower mandible; bill is heavy
in proportion to head with a straight profile; angular
head shape somewhat resembles a Canvasback
Duck; V-shaped forehead with a pointed front border
of white into the black; eye not distinct from bill. Tundra
Swans also have a black bill, usually have some
yellow on the lore in front of the eye however this
spot may be absent on some Tundras; bill more
dish-shaped in profile, smaller in proportion to head
compared to Trumpeter; head smoothly rounded;
U-shaped forehead; eye usually distinct from bill.
This spring when a big white bird’s in view,
be sure to look carefully at the edge of the bird’s
lower mandible for a red border or stripe of lipstick;
check the eye area for any yellow on the lore; and
see whether the eye is distinct from the bill or is contained
in the black mask of the face. At a quick
glance you should be able to see the size and position
of a Tundra Swan’s eye easily, while that of a
Trumpeter is more hidden. Happy birding! |
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