I think one of the biggest misconceptions people have about birds is that just because they can fly, they’re “free”. In reality, it’s hard to be a bird. In the winter, they either brave the cold or fly thousands of miles to somewhere warmer, where they’ll have to compete with all the birds who had the same plan. It can blow my mind to realize that in the time between when I see a hummingbird at a feeder in the fall and when I see it again in the spring, it’s flown over the Gulf of Mexico and back. After winter is over, they get to work. They have to compete for territories and nesting spots, find a mate, lay some eggs, and then raise the babies before getting ready for winter again. It sounds exhausting.
This year, I’m getting to witness some of this amazing lifestyle firsthand as I monitor Tree Swallow and Eastern Bluebird boxes. I decided that I would dedicate a post to outlining an Eastern Bluebird’s life during the breeding season, from building to soaring.
Step one is simple: find a mate and set up camp. Male birds sing to defend a territory and attract a mate. Females will judge the territory and the male himself, including his singing skills, to decide if he’s a good mate. In some species, the males arrive a couple of weeks before the females to stake out a spot. Eastern Bluebirds tend to like open areas with short grass where it’s easy to find and grab the insects they’ll feed their young. It’s not unusual to see a male alone waiting for a female to come his way. When he’s managed to score one of my luxury nest boxes, they usually oblige.
Once pairs have formed, the work of building a nest begins. Males are dirty liars when it comes to how much nesting effort they’re willing to put in. When trying to attract a mate, males of many species will show off to her with nesting material in his beak as though he wants nothing more than to start building. But when it comes down to it, females will do most of the nest building.
Once the nest is complete, the female begins to lay eggs. She only lays one egg a day, and Eastern Bluebirds typically lay 4-5 eggs before calling it quits. Once all the eggs are in, it’s incubation time. Females have a spot on their breast called a brood patch, which is an area with no feathers. She uses her other feathers to cover it when she isn’t brooding, so you normally don’t see it. This brood patch allows heat to be transferred from her skin to the eggs without the insulating feathers getting in the way. She spends over half her time incubating, keeping the eggs at a high enough temperature to promote growth of the chick inside. The male spends his time defending the territory and feeding the female.
After about two weeks of incubation, it’s hatching time. Since the female doesn’t begin to incubate until all the eggs are laid, they hatch at about the same time. These babies are born featherless, blind, and completely helpless. They can’t even maintain their own body temperature until they’re about eight days old, so the female continues to sit on them periodically to keep them warm, which is called brooding. However, they grow up fast. Within a few days their eyes are open and their feather tracts, the spots where their first feathers will grow, are visible. They also gain size at an almost alarming rate. Within three weeks they are about the size of the adults and ready to fly. Throughout this entire time, both parents are feeding the young multiple times each hour, finding insects that will provide lots of protein for this fast growth. Pictures tell the story better than I ever could. These aren’t all from the same box, but together they capture the some of the stages a typical nest goes through.
Once they’re out of the nest, their parents will continue to look out for them and feed them for several days. After that, they’re on their own. They’ll spend their time getting better at foraging, eating, and when spring comes they’ll start the breeding process themselves.
You would think that would be the end of raising babies for the parents. Nope! Bluebirds will have up to three broods in a single season. This means doing everything except finding a territory all over again. They even build new nests over the old ones rather than reusing the soiled one.
So next time you see a bluebird, take a moment to appreciate how much work it took a couple of birds to raise it, and how much energy they’re using to raise their own young. If you want to give them a little help, consider putting up your own nesting box. The North American Bluebird Society has nest box plans for free online, or you can find one for sale if you aren’t the DIY type. If you’re really into it, install a nest cam and watch the young grow up yourself! I can tell you from my experiences that it’s a pretty amazing thing to witness.