The Secret Life of Bluebirds

- [Danielle] Hello, my name is Danielle Williams.

I'm a master's student in the Department of Ecosystem Science and Management.

Today I'm gonna be telling you a little about one of the species I study, the eastern bluebird.

Eastern bluebirds are a species often admired by the public for their bright plumage, warbling song, and tendency to nest in manmade homes.

However, few people get a behind-the-scenes look at what it really takes to survive and reproduce as a bluebird.

Today we will go past the nest box walls and into the secret life of the bluebird.

The first step in any bluebird's nesting cycle is finding a place to raise their young.

They are secondary cavity nesters which means that they nest in holes in trees but do not create the holes themselves.

Instead they use cavities that were originally created by woodpeckers or formed when a tree limb fell.

Nest boxes provide a space that is similar to a natural cavity, allowing humans to attract them to their yards and fields.

Once they've found a box, nest building begins.

The first signs of a bluebird nest are a few pieces of grass scattered on the bottom of the box.

Though males often display to females by carrying nest material in his bill, this is all for show.

In reality, the female does the majority of the work during building.

From there, grass is added in a circular pattern until there is a thick layer with a small cup in the middle for the eggs.

Then it's time to lay eggs.

Bluebird eggs are blue, ranging from bright blue to almost white.

Bluebirds usually lay four to five eggs.

However, they don't lay them all at once.

Instead the female lays one egg each day until she has a full clutch.

Eggs are normally laid in the morning.

Once all of the eggs have been laid, the female begins incubating.

Once she begins incubating, the female spends about 60% of her time on the nest.

She incubates for approximately two weeks, providing the heat that allows the chicks inside the eggs to develop.

Though 60% of her time is the average, the actual amount of time spent incubating each day depends on temperature.

She must keep the eggs at a steady temperature, about 99 degrees Fahrenheit, to keep development going.

After two more weeks of incubation, hatching day arrives.

Since the female begins incubating all the eggs on the same day, they develop synchronously and usually hatch within hours of one another.

Bluebird chicks are born tiny, helpless, and blind.

They can't even control their own body temperature, so the female must continue to sit on them to keep them from getting too cold.

From here on out, feeding is the name of the game.

Parents must try to get as much nutrition to their chicks as they possibly can.

Parents visit every few minutes to provide insects to the young.

Both the male and female feed the young, as we see in this video clip.

Sometimes parents get a little carried away.

However, chicks are able to eat insects that are nearly the same size as them, and still beg for food the next time a parent drops by.

Chicks prompt their parents to feed them by begging.

They call loudly and open their mouths to accept the food items their parents bring to the box.

These frequent feedings allow the chicks to grow at almost alarming rates.

In less than two weeks, these chicks went from tiny and helpless to nearly the size of their parents.

All this eating and growing creates a lot of waste.

Bluebird parents must keep the nest tidy and free from pests by removing waste as it is created.

Here, a male bluebird takes his young chicks' waste from the nest box.

They fly far away with the waste rather than dropping it nearby to prevent attracting nest predators such as mammals, snakes, and other birds.

Bluebirds care for their young in the nest box for anywhere from 16 to 25 days, depending on the time of year.

By the time they're ready to leave the nest box, they often weigh more than their parents and are able to fly short distances.

A young bluebird's first flight is the distance from its nest box to the nearest tree or shrub.

Flying from the nest box is referred to a fledging.

Parents encourage fledging by exchanging a distinctive too-wee call with their young.

This young bird is leaving for the first time as his siblings look on.

You might think fledging spells the end of the breeding season.

In fact, bluebirds will usually have at least one more brood, raising another round of chicks after their first round has left.

This means doing everything over again, even building over the old soiled nest.

They often return to the same box year after year, raising dozens of chicks in their lifetimes.

The nest box walls hide an amazing series of events that leads to future generations of bluebirds.

If you're interested in putting up your own box, check out these great plans and monitoring tips from the North American Bluebird Society and the Pennsylvania Game Commission's eastern bluebird page.

And when you get a bluebird in your yard, take a moment to appreciate all the unseen effort they are putting in to raise their young, and thanks for watching.