The eastern bluebird
What better season to share some information on the eastern bluebird. April and May in Pennsylvania are the months to see most birds nesting. I'll use this week to detail the bluebird as it begins its first nest of the year.
The eastern bluebird (Sialia sialis) was once a very common resident throughout Pennsylvania. The many farmsteads, with the wooden fence posts around their pastures and ever present apple trees, offered the ideal habitats for these beautiful birds.Bluebirds are members of the thrush family, but unlike the other thrushes, bluebirds nest in cavities. This is what nearly caused the bluebird's demise.Introduced to our eastern cities, the European starlings and house sparrows rapidly expanded their range to almost everywhere in the U.S. Unfortunately, they utilized the same nesting locations as the less aggressive bluebirds.Bluebirds used natural cavities (abandoned woodpecker holes) in wooden fence posts or in the mature apple trees found at these farms.The "bully boys" starlings and house sparrows claimed these holes. To make matters worse, metal posts soon replaced wood, and more "efficient" farming led to the removal of those old apple trees. The bluebird populations plummeted.In the late 1960s and 1970s an effort began to start bluebird trails. Budding naturalists built bluebird boxes and mounted them in the proper locations.I joined that effort and at one point in the early 1980s, I had constructed about 90 boxes and monitored those for quite a few years.The chief reason bluebird boxes increased bluebird populations was the proper diameter entrance hole. A 1½-inch hole excluded the starlings, they were too fat.The sparrows were still able to utilize them, but having plenty of boxes available usually left one or two for the bluebirds to use. If not, you evict the sparrows.The male bluebird has a bright blue head, back and tail. Its breast is fainter than the robins. The female is a very pale blue. Bluebird pairs begin searching for nest locations mid- to late-February.Nesting begins about mid-April.The female lays one egg a day until her clutch of four to six eggs is complete. She normally incubates them for 14 days.After hatching, the young remain in the nest about 18 days, being fed by both parents. The young fledge and for a short time will remain close to the nest box still being fed by mom and dad.The second nesting occurs about two weeks after the first and I generally find them containing one less egg.It is best to remove the first nest and the parasites that may remain in the nest box bottom. Don't worry about leaving your scent, birds generally have a poor sense of smell.Not all bluebird boxes are utilized by bluebirds. Tree swallows and house wrens will use them too. Swallows and wrens feed on many of the same backyard pests.I place a few posts throughout my garden giving bluebirds low perches to drop down and assist me in "pest control."If you monitor your box and aren't sure that you have bluebirds nesting, note that I have never seen a feather brought into a bluebird nest.Bluebird eggs are generally pale blue. In the last 35-40 years I have found only a few nests with white eggs.Remember, keep those nature eyes open, and if you have a nesting pair in your yard, I'm sure the male's beautiful plumage will attract you.Test your knowledge: How many bird species have been recorded in Carbon County? A. 55 B. 105 C. over 200 D. nearly 500Check in next week for the answer.Last week's answer: Female birds of prey are generally larger than the male.Contact Barry Reed at