The secretive Least Bittern is near the northern
edge of its breeding range on the Carden Alvar. It is listed as
Threatened in Canada by the Committee on the Status of
Endangered Wildlife in Canada (COSEWIC). The greatest threat to this
species is the loss of marshes.
IDENTIFICATION: The Least Bittern is tiny,
barely larger than a meadowlark, but with a longer neck and longer
legs. It is most often seen when it flushes with dangling legs and
flies low for a short distance before dropping back into cover. On
flying and perched birds, note the buffy inner wing patches as shown
in the photo.
SONG and CALL: Peak activity periods are
dawn and dusk. The male's song (also heard at night) is a series of
five or six low cuckoo-like notes coo-coo-coo-coo-coo
repeated at regular intervals. Its cackling kek-kek-kek-kek
call could be mistaken for a railís call.
WHEN: The best time to see a Least Bittern
is after the eggs have hatched starting about mid-June. The adults
become more visible when bringing food to their young, often flying
in broad daylight. The parents feed young for up to 30 days.
WHERE: Watch and listen for Least Bitterns
by the channel at the Prospect Road Marsh and in cattails along
Centennial Park Road 33. In the 1990s, Brian Henshaw and I canoed
Cranberry Lake where we saw Least Bitterns in ideal habitat. The
Sedge Wren Marsh is unsuitable habitat for Least Bitterns because it
is a shallow water marsh dominated by sedges and grasses.
HABITAT: Least Bitterns prefer large deep
cattail marshes with scattered areas of open water. They are most
numerous in young marshes known as the hemi-marsh stage,
which have an interspersion of 50% emergent vegetation and 50% open
water. Productive marshes begin to stagnate in about 10 years.
MARSH MANAGEMENT: Many marshes, including
the Prospect Road Marsh, are filling in with dense vegetation. They
are in an old or lockup stage with most of their nutrients stored in
organic plant matter, and they have a low biodiversity and fewer
marsh birds. Unproductive marshes need rejuvenation to restore
hemi-marsh conditions for Least Bitterns, Pied-billed Grebes,
Common Gallinules and other marsh birds. Hillman Marsh Conservation
Area and Tiny Marsh Provincial Wildlife Area are examples of managed
ACKNOWLEDGMENTS: I thank Michel Gosselin
for proofing and Jean Iron for the photo.