A long-distance migrant between South and North America, American Redstarts are easy to recognize warblers due to their black and orange or gray and yellow coloring. In this article we will look at 11 facts about American Redstarts, such as their use of plumage color to flush insects out of hiding.
11 Facts About American Redstarts
1. American Redstarts migrate between North and South America.
American Redstarts divide their time between North and South America. They spend spring and summer in the eastern half of the United States, as well as most of Canada. Populations breed on both the pacific and Atlantic coasts.
In the winter, American Redstarts live in Central America, South America, and the Caribbean islands. On their return trips, they don’t arrive back in North America until the middle or end of May. Small populations spend the winter on the California coast and the southern tip of Florida.
2. Males’ and females’ feathers are different colors.
The males and females of many songbird species have slight or dramatic variations in the colors of their feathers. American Redstarts are no exception, with males and females having very similar patterned feathers, but different colors.
It’s easy to tell the difference between the two sexes because males are black and orange, while females are gray, white, and yellow. Both share the same profile and are a similar size. You may notice in the photo they have color in the same places. Males have red and yellow carotenoids (pigments) that mix together to produce their orange color. Females only have yellow carotenoids.
3. Males don’t grow adult plumage until they are two years old.
Immature males look like females up until they are two years old. So the first year they are biologically able to mate, they still have a gray and yellow appearance. Only about 50% of first year males are successful in finding a mate, which might be due to not yet having their adult coloring. Until they molt into their mature male plumage, they work overtime to try and woo females, usually by way of singing.
4. Their habitat includes second-growth forest and shrubs
Human development has not disturbed the American Redstart very much. They naturally prefer early-successional forests or “second-growth” forests with quickly-growing trees, so they quickly return to recently-logged forests. In their forest home, they prefer large, uninterrupted tracts of land 1,000 acres or more. When possible they prefer to be near a water source. Water sources are more likely to support insect populations, which is their main diet.
In their winter home in Central and South America they enjoy shade coffee plantations, wet forest, citrus orchards and mangroves.
5. Redstarts use multiple tactics for insect catching
Redstarts feed mainly on insects. This includes flies, moths, beetles, larvae and leafhoppers. They forage through shrubs and trees, searching branches and leaves for insects. They can pick them right off the plant, or flush them from their hiding place. By fanning out their tail and stretching out their wings, they can flash their orange or yellow coloring to try and startle their prey.
American redstarts are members of the warbler family, and warblers tend to get most of their insects by grabbing them off vegetation. However redstarts also hunt insects in flight, and do this more than most warbler species, competing with the masters of in-flight insect hunting, the flycatchers.
6. They won’t visit feeders, but they can be attracted to backyards.
Because American Redstarts’ main food source is insects, they don’t visit seed feeders. You can attract them to your backyard by planting native vegetation that supports insects or having a water feature. They are most likely to visit suburban yards during their migration. In the fall, they add berries into their diet. So having small berry producing plants like serviceberry and magnolia will make good places for them to stop and fuel-up for their journey south.
7. Both males and females defend their territory.
While males make more territorial claims than females do, both sexes actively defend their nesting and foraging territory. Females sometimes get into physical altercations too.
These fights, which take the form of clawing and strikes, rarely result in injury. The typical male boundary defense includes acrobatic flying, aggressive songs, and flying in circles near the intruder.
8. Males and females share nest duties
American Redstarts have a unique co-parenting relationship. The male woos his mate by showing her suitable nest sites, and she gets to inspect and test out each one until she chooses the one she likes. Birch, hawthorn, ash, alder and cedar are common choices. She will build the nest herself in 3-7 days.
Females handle the incubation, but once the eggs hatch, males help find food for the babies. They are mature enough to fledge in as little as 9 days. At that point, the parents divide the brood in two and take responsibility for feeding the fledglings for a little while longer.
9. Males may have a second mate.
Sometimes the male redstart will have two mates at once. While his first mate incubates their eggs, he will goes out looking for a second mate. Although if successful in finding a second mate, he won’t just abandon the first. In fact, studies show he will work to help feed both families, but contributes more food and care to his first family.
In some species of songbirds, both males and females engage in extra-pair mating, but in American Redstarts, scientists believe only males seek to mate outside of their existing pair bonds.
10. They hit prey to subdue it.
When an American Redstart captures a large insect like a worm or grub, it whacks it against a branch or rock to subdue it before eating. Many songbirds that capture large prey have a similar practice. Its purpose is to make sure that the prey is immobile before consumption.
11. Cowbirds often parasitize American Restart nests.
American Redstarts are victims of nest site parasitism from Brown-headed Cowbirds. The process is as follows: A cowbird comes across an unattended American Redstart nest. She lays 1-2 eggs in the nest and leaves.
When the nest’s owner returns, she can’t tell which eggs are hers, so she incubates them all. Upon hatching, the cowbird chick grows rapidly and may push other eggs or young out of the nest.