Bluebird Diary

The bluebird, while symbolic of hope and happiness, is also a totem of the environmental movement, which is the chronicle of how adverse consequences too often stemmed from the uninformed actions of the well-intentioned.
– Jon Boone, one of the founders of NABS, designer of their first brochure, and former editor of the NABS journal Sialia.

The winter of 2020-21 was the coldest on record in Central Oklahoma and decimated Eastern Bluebird populations. We saw almost none last year. For the first time in eleven years we had no bluebirds in our box in 2021. It didn’t look like 2022 would be any better. No bluebirds around in early Spring and some Carolina Chickadees used our nestbox to fledge a brood of three.

But, a few days before the chickadees fledged a lone male bluebird showed up and was checking out the box. He would perch on it and peer inside, but made no effort to harm the chicks. On May 12 the chicks fledged and I immediately cleaned the box. The very next morning the bluebird was back and had a female with him. She started building a nest that same day! Yes. We were excited, but cautiously. Experience has taught me that a little bit of grass in the box is a long ways from fledging a brood.

Our new Mama Bluebird completed her nest on May 17 and laid her first little blue egg on May 18. She has laid on three consecutive days now. She will be our sixth female to use the nestbox. I may refer to her as Mama VI or just Mama. This male is our fifth and I may refer to him as Daddy V. I have five feeders in the yard and I’ve quit putting feed in the ones near the nestbox since Daddy gets so stressed when harmful birds are near the box. I’ve had several cowbirds in the yard and he chases them incessantly, but they seem to always return. They paratisized a cardinal nest in a big yew by our entry door. The cardinal eggs disappeared and a lone cowbird egg remained in the nest. The female cardinal seemed wise to the cowbird ruse and abandoned the nest. A Cooper’s hawk caught one of the cowbirds and I managed to get a photo of him dining on it. We are now down to four cowbirds daily. They are too large to enter the nestbox, but they stress the bluebirds who seem to know they are a threat to their nest.

I’ll chronicle the progress of this nesting. It sure feels good to be back in the bluebird business! Our nestbox has fledged 108 new bluebirds.

First brood 2022

First sign of nest building May 13

Nest completed May 17

First egg laid May 18

Second egg laid May 19

Third egg laid May 20

Fourth egg laid May 21

The bluebird, while symbolic of hope and happiness, is also a totem of the environmental movement, which is the chronicle of how adverse consequences too often stemmed from the uninformed actions of the well-intentioned.
– Jon Boone, one of the founders of NABS, designer of their first brochure, and former editor of the NABS journal Sialia.

I estimated that this brood would hatch on 13 June. But, this hatch is a bit chaotic and disappointing. The first chick hatched on 12 June, and two on 13 June. The fourth egg didn’t hatch and was removed. Three babies hatched, but a couple of days later, one was missing. I don’t think it was a predator, my best guess is that it died and the parents removed it. So that leaves us with two chicks.

Late Summer heat can be a killer of bluebird chicks.

According to Cornell, the optimal range for bird egg development is 96.8 °F to 104.9 °F (36 °C to 40.5 °C). If egg temperatures are lower, embryonic development slows. Higher temperatures can be lethal for the embryo. Bluebird eggs and nestlings cannot survive temperatures exceeding 107 °F (41° C). Prolonged excessive heat can severely impact nestling health due to dehydration and heat stress. Chicks only source of water is live insects. Never feed dried mealworms to chicks.

Temperatures inside a nestbox can reach 120 °F, and are often at least 10 degrees higher than the outside temperature. Some research indicates that if temperatures outside are 100-104 °F, the percentage of eggs that hatch drop, and nestlings under nine days old can die from heat stress or dehydration. (Up to 6-9 days old, the nestlings are as sensitive as eggs to cold/heat.)

Fortunately there are no 100 degree temps on the ten-day forecast and our box is shaded in the afternoon. Most of our broods have fledged on day seventeen. I’m estimating this brood will fledge on 30 July. This should be the final brood of 2020.

This nest site has fledged 108 new bluebirds.

Third brood 2020

First sign of nest building 20 June

Nest completed 25 June

First egg laid 26 June

Second egg laid 27 June

Third egg laid 28 June

Fourth egg laid 29 June

Incubation begins 30 June

First egg hatches 12 July

Two eggs hatch 13 July

Fourth egg did not hatch

Two babies fledge 31 July

You begin by sharing with your friends and neighbors and before you know it they pass on the information to a wider circle. It takes time for you to see the results because the seed you plant today may take a decade or more to mature.
– Keith Kridler, Bluebird_L, 2007

Mama V started the third nest of the season this week. She is a young bird and I suspected she would raise a summer brood. Recall that our first brood was laid by Mama IV and with five eggs in the box, she disappeared. Daddy V found a new mate and they fledged a brood of five prior to this one.

Heat can be a problem with summer broods, it can addle eggs and kill chicks. I have my box mounted to a piece of electrical conduit that I slide over a piece of steel rebar. I can easily move it to keep the box in afternoon shade as the sun changes positions.

House Sparrows are always a threat to bluebirds and I can’t stress this danger enough. They will destroy eggs, kill babies, build a nest on the corpses and even kill adult bluebirds if they attack them inside the box. I always advise people in suburban habitat where HOSP’s live that if they can’t trap and euthanize these little murderers, they shouldn’t put up a bluebird box. I’ve trapped sparrows for a decade and have very few currently. Hadn’t seen one in the yard for a year until recently. Just as Mama began this nest a male HOSP showed interest in the box. I attached the Sparrow Spooker and problem solved.

I also provide plenty of water in the yard. We have two blue ceramic bird baths– one low one and one pedestal type. The bluebirds drink from both. Heat is also hard on adult bluebirds raising a summer brood. They get thin and haggard looking.

Hosting bluebirds for over a decade is one of the most rewarding things I’ve done. It’s one of the easiest and best things you can do for Nature. Our beautiful world, pass it on.

This nest site has fledged 106 new bluebirds.

Third brood 2020

First sign of nest building 20 June

Nest completed 25 June

First egg laid 26 June

Second egg laid 27 June

Third egg laid 28 June

Fourth egg laid 29 June

Incubation begins 30 June

“The love of wilderness is more than a hunger for what is always beyond reach; it is also an expression of loyalty to the earth, the earth which bore us and sustains us, the only paradise we shall ever know, the only paradise we ever need, if only we had the eyes to see.”   ― Ed Abbey

In my last post, I detailed how Mama IV disappeared with four eggs in the box.  I removed them and the nest, took down the sparrow spooker and hosed out the box in anticipation of Daddy IV finding a new mate.  This was in late March.

Daddy would come to the box every morning to call and call for Mama to no avail.  This went on for weeks.  Then one morning I saw him fly into the yard with a lovely looking female.  Just as they entered the yard, the local mockingbird took after the female!  Daddy fell in behind the mockingbird, nipping at his tail.  I hoped that wouldn’t be the end of her.  But she returned with Daddy in a few minutes.

Daddy did an enormous amount of courting this lady.  Chattered and wing-waved incessantly to her.  Showed her the birdbaths, fed her a mealworm from the feeder and went in and out of the box.  Eventually he picked up a piece of grass and took it in and out with the female watching.  She has been in the yard with him every day since.  Bluebirds have strong bonds with their mates.  They are always together.  Photos are Mama V.

Whenever I lose one of the bluebirds, I always wonder if I’m out of the bluebird business.  Will the remaining bird bring in a new mate, or just move on looking for one? I know people who have erected boxes and never attracted bluebirds.  I’m extremely lucky that back in 2009 I erected a box and two weeks later a pair moved in.  Since that time, I’ve never been without bluebirds.  Mama V and Daddy IV have an active nest and the first egg in the box.

Total chicks fledged from this site is 101.

Second Brood 2020

• First sign of nest building                                                23 April
• Nest completed                                                                   01 May
• First egg laid                                                                       03 May
• Second egg laid                                                                  04 May
• Third egg laid                                                                     05 May
• Fourth egg laid                                                                   06 May
• Fifth egg laid                                                                      07 May