By Kate Crowley
We were beginning to think that we might not have any resident bluebirds this summer. We heard a male singing earlier in June, but then he vanished. Their chirrupy call is one my ears catch quickly, especially when it hasn’t been heard for eight months. It is a call that immediately illicit the word, ‘bluebird’ from both Mike and I.
The eastern bluebird is a conservation success story. In the first half of the 20th century they were common birds across the eastern U.S., especially around farmlands, since they prefer open spaces to nest and hunt for food. At that time people used wood fence posts around their farmsteads and fields. These naturally rotted and provided excellent nest cavities for this small relative of the robin. Aging trees with cavities created by woodpeckers also were favored by bluebirds. But by mid-century, it is estimated that the bluebird population had reached a point of 90% decline. Times changed and so did the landscape as the small farms were sold or absorbed into bigger, single crop aggregations. Wooden fences came down to be replaced with metal poles and wire. People found old and dying trees to be unsightly or worrisome if near buildings and so they too came down. In addition, two non-native species of birds are fierce competitors with bluebirds for nest sites. The house sparrow and European starling will invade bluebird houses and destroy the eggs or chicks and then make it their own. All of these problems would be more than enough for any bird to survive, but since bluebirds are mainly insect eaters the growing use of agricultural and garden pesticides had an impact on their food supply.
Luckily, some people recognized what was happening and started to take action to reverse the decline so that the bluebird didn’t join the passenger pigeon as just a fading memory. Nest boxes were made and put out in habitat that looked suitable. In 1934 the concept of Bluebird Trails came into existence in Illinois when made-made boxes were placed along rural roads and caring people monitored them throughout the summer breeding season. Bluebirds transitioned very quickly and easily to these (mostly) wooden boxes. The style that has gained most in popularity is known as the Peterson nest box, named after the man who came up with the design.
We have had these kinds of nest boxes in place for all of the 28 years we have lived here and they have been put to use nearly every one of those years, usually by bluebirds, but sometimes by tree swallows, who are also cavity nesters. In fact, it is suggested that you always put up two of the boxes near one another so that the two species can each have their own place and not get into fights over ownership.
This year the tree swallows visited briefly and moved on and as I said at the beginning we had about given up on the bluebirds, but then one day last week I was out working in the front yard and I heard a pair of the birds calling, both the male and female were making their special “cheery, cheery” call as if in conversation. They were also flying from one side of the yard to the other and occasionally landing on or near one of the nest boxes mounted on the old corral fence.
Then I watched them fly down to another nest box that stands near a big red pine. There was much ‘discussion’ going on as the male flew up to the entry hole and peered inside. The female was sitting on a nearby branch, but soon she flew down and fluttered impatiently around him until he moved away and she took her turn looking inside. Have you ever watched the TV show “House hunters”? The (usually) young couples spend hours looking and critiquing every little detail of the houses they’re shown. This is what I was reminded of as I watched the two bluebirds inspecting this nest box. Finally they flew off and resumed their search of just the right place in the neighborhood.
A couple days later I decided to look in one of the nest boxes on the corral fence. I opened it up and found a neat, compact nest and with my fingers I could feel four small warm eggs. Now I was really confused because there is no way the birds could have built the nest and laid 4 eggs in the two days since they were out looking at the other houses. I will never know what that was all about, but we are thrilled that they have started a new family, even if it is weeks later than normal.
Bluebirds can raise two to three broods of young each summer if conditions are right, but considering the delay of this season’s first nest, they will have to be very lucky and determined to raise two. The eggs are incubated for two weeks and it will be two or three more weeks before the chicks fledge from the nest. Following this, the female may start a second brood while the male helps the first ones forage and learn the ways of survival. Statistically, only 50% of young birds make it through their first year, so having multiple broods is the only way to increase a population over time.
While insects are their main food supply early in the year and through the summer, bluebirds will switch to fruit as the summer wanes, allowing some to overwinter in cold climates as long as there are fruits on trees for them to eat.
Be on the lookout for these cheerful, bright blue birds as you travel the backcountry roads for they will often perch on the wires of fences, as well as the higher electric wires. And for those of you who have put up houses, thanks for your help securing a better future for the Eastern bluebird.