Bluebird Egg Incubation in Progress!

Text and photos © 2015 Adele Wilson, author of Bonding with the Barn Swallows

Wonderful news!  The female Eastern Bluebird is still incubating her eggs.  That's a good thing because our temperatures have been cool for the last couple of days.

This morning, from a distance of about 20 feet (6 meters), I was trying to photograph the nest box with the female Bluebird inside.  Suddenly, unbeknownst to me while I was pressing the shutter, the male Bluebird landed on the top of the box with a worm in his beak!  If you look carefully at the photo on the upper right, you might be able to see a hint of the female Bluebird's head inside the box.

Apparently, the male Bluebird trusts me.  This does not overly surprise me because he often stations himself in one spot and watches me for quite a long time.  The other day, he perched on the fence and observed me the whole time while I was refilling the bird feeders.

Below is a close-up of the male Bluebird holding the worm.  In the background you can see blooms on a mimosa tree.

The male Bluebird had not flown to the box just to feed himself.  As the photo on the right shows, he flew to the entrance hole of the box and proceeded to feed his mate, who was still inside the box.

So far, so good!  I am hoping that this nesting attempt will be successful without the female abandoning her eggs as the first female did.

I do not know how many eggs are currently in the nest, but on Sunday, June 21st, there were four eggs.  Once I feel that it is safe to check the inside of the box without scaring the female Bluebird away, I will find out how many eggs she has laid.  From that information, and assuming that she laid one egg per morning (as is usually the case), I should be able to calculate approximately when the eggs should start hatching.

A female Bluebird is said to begin full-time incubation of her eggs either on the day she lays her last egg or on the preceding day.  So, once I find out how many eggs are currently in the nest, I can calculate the approximate date on which the eggs should begin to hatch.  In the following paragraphs I shall describe how this calculation is performed.

For instance, if I find that there are currently five eggs in the nest, knowing that the female laid her fourth egg on June 21st, and assuming that she laid one egg on each successive morning, I can assume that she laid her last egg on the morning of June 22nd.  If there are six eggs currently in the nest, the assumption would be that she laid her last egg on June 23rd.  The average number of eggs in a Bluebird clutch is five, but that number can sometimes be as high as seven.

In the former case (if there are five eggs currently in the nest), the female would have begun incubating her eggs either on June 22nd or on the preceding day.  In the latter case (six eggs currently in the nest), the female would have begun incubating either on June 23rd or on the preceding day.

The final bit of knowledge required in order to estimate the hatching date is that the average incubation period for Eastern Bluebirds is fourteen to fifteen days.  Therefore, assuming that there are no more than six eggs currently in the nest, the eggs should begin hatching sometime between July 5th and July 8th.

To the right is a photo of what Eastern Bluebird eggs look like.  I took this photo on June 6th after the first female had abandoned the nest.  She had not been in the area or inside the nest box for several days.  The eggs were due to hatch soon, but she had not incubated them.  These eggs disappeared within a few days after the new female arrived on June 12th.  My assumption at this point is that the new female removed them.

All of the eggs in a Bluebird clutch are said to hatch within one or two days of each other.  Once the hatching date(s) are known, the ages of the nestlings can be calculated, and that is the most important thing to know in the monitoring of Bluebird boxes.

It is important to be able to track the ages of the nestlings in order to avoid opening the box when the chicks are twelve or more days old.  Opening the box during this time period can cause the premature fledging of one or more of the chicks, which could result in their demise.

All for now!  You can follow this blog by entering your email address in the upper right corner of the top of this page.

If you have found this story interesting, you might want to check out my book, Bonding with the Barn Swallows.  Its 117 photos include closeups of the baby Barn Swallows that were hatched on my porch during 2011 and 2012.  There are also photos of the parent swallows guarding the nest and feeding their young.  As an extra bonus, the book includes photos of five different juvenile Barn Swallows, just ten days after fledging.  You will be amazed at their varied markings.  The book describes how one special male Barn Swallow communicated to me by his body language on the utility wire and how, only two days later, I discovered what he was trying to tell me.  To find out more about the book and read a preview, just click on the image to the right. 

I've got the Bluebird Blues ...

Text and photos © 2015 Adele Wilson, author of Bonding with the Barn Swallows

For several days now, the female Bluebird has not been on, around, or in the nest box.  The five eggs are still in the nest, intact and undamaged.

So it seems quite likely that she has abandoned the nest.  This situation is very sad to me, and I’ve got the “Bluebird Blues”.

This spring has marked my first experience with Bluebird nest boxes.  I purchased the boxes, and my neighbor mounted them on poles.  We put up Box #1 on April 24^th, and a pair of Tree Swallows arrived and claimed it a week later, on May 1st.  The female Tree Swallow even started building a nest that very day!

But nine days later, on May 10^th, a pair of Bluebirds arrived and hijacked the box from the Tree Swallows.  The photo to the right, taken that same day, shows the female Bluebird checking out the size of the hole on the box, with the male guarding her from the top.

Over the next week, the female added grass to the Tree Swallow nest inside the box, heightening the sides of the nest.  By May 23^rd, the female had laid five eggs.

In the meantime, we felt sorry for the Tree Swallows who had been driven out of their nest.  So we mounted another nest box on May 19^th about 75 feet from Box #1.  We began to refer to this second nest box as Box #2.

Male Tree Swallow guarding Box #2

Only four days later, on May 23rd, to our great delight, a pair of Tree Swallows claimed Box #2!  The photo on the left shows the male Tree Swallow on top of Box #2 the following day.

The female Tree Swallow has now laid at least five eggs, and the male stands guard duty most of the day while the female incubates the eggs inside the box.  Sometimes the male takes over incubating duty while the female leaves the box to feed on flying insects.

Unfortunately, there is not nearly as much activity around Box #1, the Bluebird box.  It seems that Ms. Bluebird has “flown the coop.”  We don’t know why she is no longer around.

Perhaps she didn’t like my checking her nest, or perhaps she didn’t think the male was taking very good care of her.

I would sometimes see the female Bluebird peeking out of the nest box’s hole, which made me assume that she was incubating her eggs.  The male would occasionally fly to the box and feed her through the hole.

However, the male did not seem to be feeding the female very often.  One day the male came to the box, fed the female through the hole, and then quickly flew from the box.  To my surprise, the female immediately flew out of the box after him!

It is said that in the Eastern Bluebird species, the female does all of the egg-incubating.  If that is true, the eggs are not currently being incubated.  My neighbor, however, has seen the male entering the nest box during the daytime.  He therefore thinks the male is incubating the eggs.  But I tend to think otherwise.

At any rate, as of this date, the male is still looking for his mate.  He has been perching on top of the high fence post in the vicinity of the box, singing his beautiful song.  Sometimes he flies to the utility wire and does the same.  The photo to the left shows him on the fence post yesterday evening (June 8th).

The song of the Eastern Bluebird is the most beautiful bird song I've ever heard.  It consists of a soft, subtle, melodious warble of several notes.  If I were a musician, I would be able to describe it more fully, but the notes and rhythm remind me more of chimes than of vocal singing.

This evening (June 9th), Mr. Bluebird was again perching on the fence post.  I slowly approached him, and then sat down on the grass about 25 feet away.  He posed for me and allowed me to take numerous pictures of him.  It was actually too dark to get a good shutter speed; so I had to brighten this photo.

After perching on the fence post, Mr. Bluebird flew toward his nest box that still contains the five eggs.  Midway between the post and the box, he did something that I never would have expected.  He hovered in the air to get a better look at me!

After Mr. Bluebird hovered for a few seconds, he landed on top of the nest box to see if I was still looking at him.  Again, he obliged me by allowing me to take a couple of pictures of him.

Mr. Bluebird then flew to the front of the box and appeared to go inside for a second as if to look for his mate.

Or, was he going inside the box to tell me his mate wasn’t there?  Although it can’t be proven, I think that he was telling me so.  He knew that I had been watching him from the time he was on the post until the time he landed on the box.  I interpreted his hovering as his special way of getting my attention and confirming that we were communicating.

It has now been 17 days since Ms. Bluebird laid the last of her five eggs.  With the average incubation period for Bluebirds being 14 to 15 days, the eggs should have hatched by now – that is, if the eggs had been properly incubated.

In a case like this, it is recommended to leave the eggs in the nest for a while in case the female returns and begins incubating them.  But given the fact that I have not seen the female in a few days, I am thinking she is probably gone for good.

I wonder if Mr. Bluebird will find a new mate or if a new pair of Bluebirds will become interested in the nest box.  Bluebirds are known to raise more than one brood per season.   After they raise their first brood in the spring, they will usually start a second nest in June or early July.  

I was halfway planning to clean out the nest box tomorrow evening in case Mr. Bluebird finds a new mate, but this evening, I received a “no” answer from him.

Just as I have been doing for the past few days, Mr. Bluebird still seems to be hoping that Ms. Bluebird will return.  By the fact that he was perching on top of the box while looking at me, and then quickly entering and exiting the box, I think he was telling me that he wanted his mate back.

He might have even been telling me to go find his mate and bring her back to the box! 

So it seems that Mr. Bluebird is still protecting his precious eggs, and they are precious to me, too.  For these reasons, it does not seem like the proper time to clean out the box.

Poor Mr. Bluebird!  He is obviously mourning for his mate, just as I have been.

But Mr. Bluebird is teaching me something.  As depressed as I’ve been feeling about the eggs not hatching, my heart goes out in deep compassion to Mr. Bluebird.  After all, it is he who has lost his beloved mate.

In the meantime, the Tree Swallows in Box #2 seem to be doing great.  I am thinking their eggs will start hatching around the time of the summer Solstice or shortly thereafter.

You can follow this blog to find out what happens with both the Bluebird box and the Tree Swallow box.  Just enter your email address at top of the page on the right.  That way, you will not miss the next episode!

I first began having intimate encounters with wild birds when Barn Swallows nested on my porch during 2011 and 2012.  During those encounters, I became convinced that humans and birds can develop meaningful rapports, communicate with each other, and enjoy mutually beneficial relationships.  You can read about how one special Barn Swallow communicated to me in my book Bonding with the Barn Swallows, available at Amazon at:   http://www.amazon.com/gp/product/1494481464/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=1494481464&linkCode=as2&tag=barnswalfrie-20&linkId=5WME3VAHNSX3EXHH