The Marsh Wren
By Gord Gadsden
April 1, 2008
The Marsh Wren is a typical wren in most senses. They are an active and often noisy bird who are sometimes quite bold offering plenty of opportunity to view them. They can also be very typical in being difficult to see as they sneak around in dense cover. In our area, Marsh Wrens are most common during the summer in most marshy habitats where they feed and nest. During the winter, most migrate from our area leaving their status as uncommon to rare. Marsh Wrens are our only common wren species found in marsh habitats and almost always among reed grasses and cattails. Like all other wrens they are brown but sport a black and white back patch and a strong stripe over the eye.
During breeding, the males sing almost incessantly all day long and often at night as well. They aggressively protect a territory from other Marsh Wren males. When not singing, they are building nests. A nest is a fully enclosed affair with an opening near the top. The nest is made of cattail and grass leaves woven in around cattail stems or other marsh plants. Cattail seed fluff is used to fill in the holes and to pad the interior. Marsh Wrens will build several nests in their territory ranging from just four or five but up to twenty-two. Only the male builds nests but the female, and sometimes females if the territory has ample food supplies and nests, will select and then line the nest with feathers and fluff. She will then use this nest to lay her eggs. The other nests act as decoys for predators, a roost for the male and shelter during the non-breeding season. The wrens have a somewhat sinister method to help increase the amount of available food for them and their young. They will destroy the eggs and young of other marsh bird species to ensure that there are less hungry mouths in the area. In turn, it is noted that Red-winged Blackbirds will also destroy Marsh Wren eggs and can sometimes be seen chasing Marsh Wrens away from the area around their nests.
Marsh Wrens feed on the multitude of insects that can be found in a marsh. They will pick insects right off the water while hanging off cattail stems. They are also known to eat the contents of the eggs they destroy. As Marsh Wrens require healthy ecosystems with plenty of insects, they are a great indicator of a healthy marsh. Always, they are entertaining birds as they busy themselves singing, chasing other wrens and building nests.
Links and sources:
Ehrlich, Dobkin and Wheye, (1988)
Sibley, D. (2000)