This Week’s Creature Feature: Want Good Company?
The eastern bluebird is a symbol of both happiness and a healthy environment. The birds live at the edge of meadows, hunting in the grasses for insects. But they are easily affected by pesticides. So seeing the brilliant flash of blue fly by is a happy sign of a healthy field.
Bluebirds nest in tree cavities like abandoned woodpecker holes. They also easily adapt to living in a bluebird nesting box, and they do not seem to mind living close to people.
In the early 1900s, bluebirds were displaced by the invasive starlings brought over from Europe. A campaign to build nesting boxes was started. When the boxes were placed at least 10 yards away from woods, starlings were less likely to use them. Bluebirds happily used them, and their numbers started to rebound.
Then DDT came into use, and again the numbers plummeted. Since the DDT ban, bluebirds are again common.
In the winter they largely feed on berries and will form small flocks, which seems to help them find food. In the warmer months they eat mostly insects but also enjoy a fruit or berry treat.
The eastern bluebird has a reddish chest and a blue back and head. The female is duller blue than the male. They mate for life and stay close to each other all year. When a pair finds a nesting spot, they work together to make a loose nest of pine needles or grass. When the temperature is warm enough, the female lays three to five eggs in a clutch.
Neither mother nor father spends much time sitting on the nest. Instead, they guard and clean the site. When the young hatch, both parents are very attentive. After about 21 days, the young have left the nest and spend most of their time with their father.
After another week, the female may start fixing up the nest for another brood. If another clutch is laid, then the female does much of the care of the second and perhaps later families. I have witnessed four sets of hatchlings in one year.
In the winter, a parent sometimes returns to the nesting box for a few days with their offspring, and the birds take turns going in and out. This may be nostalgia, but it also may be to teach the young what a proper nesting cavity is.
In early spring, the males chase other males, offspring included, away from the nesting area.
I have a bluebird box in my yard in a design recommended by the Audubon Society. It has small vents for aeration and a slopped overhanging roof. The overhang prevents predation from crows. On the pole is a clear baffle to prevent raccoons and snakes from getting to the box. I clean it after each nesting and evict the house sparrows that sometimes insist in trying to take over.
When the young are hatched, I sometimes put out live mealworms, especially when the male is off somewhere with another brood and the female looks stressed trying to keep up.
Now is the time to set out a nesting box for the bluebirds. Avoid using pesticides where they feed and live. You can find a box design on-line, but do not build with pressure-treated lumber.