Wetland Regulars: Red-winged Blackbirds
As spring arrives, one of the first signs of spring is to hear the trill in the marshes of a Red-winged Blackbird.
Red-winged Blackbirds are a common sight from March to September in the wetlands across Ontario. The males are easy to distinguish from females. Only the males are black and sport the bright red and yellow shoulder patches (called epaulets), which give the Red-winged Blackbird its name. The females are brownish with streaks across the chest and back with a light line over each eye.
The epaulets on the male are used in courtship, territorial displays such as establishing and holding territories, and taking territories from other birds. Successes are greatly affected by the size and color of the male’s epaulets, with bigger and brighter being better. When a male has to leave his territory for food or to look for vacant territories, he covers his epaulets with black scapular feathers (the feathers just above the epaulets) so only the yellow of the epaulets show. This way it is less likely that the male owning the territory will attack the wandering male.
This species is polygamous; one male will breed with multiple females within his territory (usually 1-6 females). Males return first in March, to set up a territory (around 1/8 to ¼ of an acre in size) before the females arrive a couple of weeks later. When the females arrive in April, they each set up a territory within the territory of a male. Females pick their territory based on its location and not based on which male that is holding it.
Females breed at around a year of age, sometimes with more than one male, but the males will not breed until they are two years old. This is one reason why there are many more breeding females compared to males - the yearling males do not take territories. Males hold their territory for the majority of their life, which is usually around two and a half years. They use a variety of calls to either attract females or to defend territories.
Nesting occurs in May, with the females laying three to five eggs that are blue-green with purple spots. They help to defend each other’s nests but also compete for the resident male’s attention. To build a nest, females collect leaves and grass, which they immerse in water before weaving into the nest.
In August, Red-winged Blackbirds go through a molt, losing and growing back new feathers. During this time they stay hidden in the marshes to avoid predators and only reappear once the molt is complete.
In September they start to head south in large flocks, some of which have over 30,000 individuals. Their wintering grounds are generally located in the southeastern United States, where they gather in large groups awaiting for spring to return.
Red-winged Blackbirds are the first sign of spring for many, but some areas have noticed a decline in their numbers due to the loss of wetland habitat. Let’s protect our Wetlands and make sure this springtime herald continues to be a common sight for generations to come.
If you would like to know more check out the Cornell University website or feel free to post a comment below.