Conservation Information

• There are three species of bluebirds in North America: Eastern, Western and Mountain Bluebirds.

• Eastern Bluebird numbers declined throughout the late 1800s and much of the twentieth century, suffering an almost 90% decline in population. Among many other reasons, competition for nesting space from invasive species such as House Sparrows and European Starlings contributed to this century-long decline.

• While bluebirds can live up to four or five years old, it is likely that up to 70% of all Bluebirds die before reaching their first birthday. The oldest recorded Eastern Bluebird was ten years old, with the oldest Western and Mountain Bluebird being recorded at approximately six years old.

• According to the statistics from the Breeding Bird Survey, survey-wide estimates of the Eastern Bluebird population show an increase of 2.4% per year for each year since 1966. The Audubon Society’s Christmas Bird Counts from 1980 to 2004 also show a three-fold increase in population. Habitat and nest cavities had been disappearing for many years, but bluebirds have made an incredible come back due to thousands of bluebird nest boxes being installed across the country.

General Information

• Eastern bluebirds prefer grassland habitats with few trees and little to no undergrowth. They are commonly found in open pastures or suburban areas.

• Their song consists of a low-pitched warbling sound of 1-3 notes with several phrases.

        o Unpaired male Bluebirds may sing up to 1,000 songs per hour, but average around four to five hundred songs per hour.

• Bluebirds have no blue pigments in their feathers. Instead, each feather barb has a thin layer of cells that absorb all wavelengths of color except blue. Only the blue wavelength is reflected and scattered, resulting in their blue appearance to our eyes.

         o Females have duller plumage than males; this may reduce their visibility to predators.

         o Eastern Bluebirds appear duller then usual after molting in the late summer due to their new body feathers have dull brownish tips. As the feather’s tips get worn down through the winter season, the remaining color is bright and beautiful for the next breeding season.

Nesting Behaviors

• Nesting occurs from March through August. Only the female incubates the 4-6 eggs which she maintains at a temperature of 98 to 100ºF.

• All bluebirds are cavity nesters and can use an artificial nest box.

• Bluebirds raise their young in old or pre-existing nesting cavities and have a nesting success rate of about 60%. In contrast, birds that construct a new nesting cavity each year (such as woodpeckers) have a success rate of up to 85%. Predators are less likely to find a new nesting cavity than one that has been in existence for a few years. Hence the reason bluebirds occasionally move nesting sites between broods.

         o It is common to see a pair of bluebirds occupying a nesting cavity previously used by Northern Flickers, and Hairy, Downy, and Red-bellied Woodpeckers.

         o Eastern Bluebirds will select these abandoned cavities 75% of the time.

• Males may carry nest material to the nest, but they do not participate in the actual building. They spend much time guarding their mates during this time to prevent them from mating with other males.

         o Pairs may build their second nests on top of the first nest, or they may nest in an entirely new site.

• Both sexes defend territories; however, the males tend to defend territory edges while the females primarily defend the nest site. The male continues to take care of the recently fledged young while the female begins to re-nest. Young of the first brood will occasionally help raise their siblings in the second brood.

• Bluebirds are generally monogamous, staying together throughout the breeding season. They may breed together for more than one season. However, some birds may switch mates during a breeding season to raise a second brood. Occasionally they can have a third brood.

• Families stay together until fall when they merge with other family flocks. Some bluebirds residing in the northern portions of the range migrate to southern latitudes, but those residing in southern latitudes tend to be residential.

o Adult Bluebirds tend to return to the same breeding territory year after year, but only 3-5% of young birds return to where they hatched.

Feeding Behaviors

• Bluebirds are insectivores, or insect eaters. Their bills are made for softer food items such as insects and fruit.

         o Bluebirds love mealworms! A small dish filled with live or dried mealworms can help attract them to a yard if they are in the area.

• A bluebird can spot caterpillars and insects in tall grass at the remarkable distance of over 50 yards!

         o They catch their food using a sit-and-wait technique called “drop-hunting”. This behavior can be spotted when bluebirds are seen on an elevated perch where they are searching for insects. Once an insect is spotted, they drop to the ground to capture it in their bill.

• Bluebirds consume about 4 grams of food per day, or about 12% of their body weight. This is equivalent to a two-hundred pound human eating 24 pounds of food each day.