Wednesday, October 28, 2015

The Reappearance of the Bluebirds - Part I

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

As you might remember, my neighbor mounted a Bluebird nest box in our yard last spring.  By the first week of July, four Bluebird babies had hatched in the box.  On the morning of July 22nd, I knew that the babies were due to leave the nest soon. 

Fortunately, it was sunny and clear that morning; so I went outside and took numerous photos of the parents feeding the babies inside the box.  A couple of the photos even showed a baby or two peeking out of the nest box hole.

That evening, to my great dismay, there were no Bluebirds around the box or its vicinity!  I checked the inside of the box and found no babies there.  The nest was compressed and quite unsanitary looking. 

Apparently, the babies had left the nest box (fledged) some time that day.  I was unprepared for this because I had calculated that the following day would be fledging day and I would have one more day to photograph the babies peeking out of the box.

Prior to this past July, my experience with observing baby birds in a nest had been limited to Barn Swallows, as I have described in my book, Bonding with the Barn Swallows.

Unlike baby Bluebirds, Barn Swallow babies, once they fledge, remain in the vicinity of their nest.  In the days following the fledging of Barn Swallow babies, I have often seen them high in the air, quickly flapping their wings as they practice flying.  They will often line up on the utility wires to rest and wait to be fed by their obliging parents.

Also unlike baby Bluebirds, baby Barn Swallows who have fledged during the morning will often return to the nest that night in order to rest from their long day.  Below is a photo from page 102 of my book, showing two baby Barn Swallows after they had returned to the nest the evening of the day that they fledged.  They looked so worn out that I thought they were about to expire!

To my great relief, however, after an hour had passed, the babies were sitting upright in the nest, looking like normal baby Barn Swallows.  They left the nest for good the following morning. 

But baby Bluebirds are “here today, gone tomorrow”.  They do not return to their nest once they have left it.  Their parents usher them into the trees for safety from predators.  Unable to feed themselves, the babies must depend on their parents to bring them insects for at least the next two weeks, just as the parents do while the babies are still in the nest.

I would have liked to have witnessed the fledging of the baby Bluebirds as an assurance that all four babies had made it out of the box safely.  We have a number of roaming, feral cats around here, and I was quite concerned that one or more of the babies had landed on the ground, making them vulnerable to predation.

A couple of mornings after fledging day, still not having seen any Bluebirds around, adult or young, I cleaned and sanitized the nest box. I had read that Bluebirds can raise two or three broods per season and that it might not be too late in the summer for the parent Bluebirds to start another brood.  I had also read that a pair of Bluebirds likes to have their box clean and their old nest removed before they re-nest in the same box.
But the parent Bluebirds did not return to their nesting area.  In fact, I did not see them anywhere!

I began searching the grounds of the property where I live for any sign of Bluebird fledglings.  But they were nowhere to be found.  Then I remembered, as previously stated, that parent Bluebirds take their newly-fledged babies into the woods to hide them from predators.  I had also read that, if the mama Bluebird decides to build a new nest, she will proceed to the nesting site and do so, leaving the papa to feed the young birds and teach them how to hunt.

In an intense desire to find out how many babies had made it safely to their new home in the woods, I continued to search the property, paying close attention to the trees that border it.  Finally, on the morning of July 31st, nine days after fledging day, I spotted a Bluebird on the wire above the neighbor’s property across the road.  It appeared to be an adult male, but all I could get was a blurry photo, as shown on the left.

July turned into August, but still, no Bluebirds.  Where were they?  By August 6th, the two-week period of the fledglings’ dependence on their parents for food had passed.  Had the fledglings survived?  Were they now learning to hunt on their own?

At long last, on the morning of August 21st, 30 days after the Bluebird babies had fledged, I spotted a couple of Bluebirds on the fence at the far corner of the property. They were perching several feet from one another, apparently searching for insects on the ground.

One of the birds (see photo on right) had a considerable amount of blue on its back, along with a rust color on the side of its breast. However, its plumage was visibility mottled with small patches of white, showing that the bird was losing some of its feathers in preparation for growing new ones.  This process is called "molting".

The bird looked like it might have been a juvenile in the process of gaining its adult plumage.  However, if indeed a juvenile, it had not been hatched in our nest box because it appeared to be too mature.  Perhaps it was an older juvenile that had fledged from another nest, possibly in early June.  It displayed too much solid-colored plumage to have been be young enough to have been one of our babies.

The second bird (photo, below left) had a familiar look to it. At first I thought it was a juvenile because of the white spots on its breast. But, again, the bird definitely looked too mature to have been one of the babies that had left our box on July 22nd.

The familiar look was not from the bird's plumage. Rather, the bird’s fierce stance and alert personality jogged my memory. The bird was acting exactly as our mama bird had acted while her babies were in the nest – proud, yet vigilant, and seemingly prepared to attack anyone who would dare to venture close to her nest.

Could this possibly have been our mama bird in molt?  The white spots could be indicating that she had been shedding her summer coat in preparation for gaining her winter plumage. 

Suddenly, the bird left the fence and quickly flew to the utility wire on the other side of our building. I walked around the building to get a better view of it. The bird allowed me to get a couple of photos but remained in an alarmed and vigilant state, as you can see from the photo below:

Yes, this was definitely our mama bird!  It had the same slate-colored head and upper back as our mama.  In addition, her beak was relatively long in Bluebird terms.  Mama had apparently recognized me while I was photographing her on the fence and must have become alarmed that I might be a threat to her young ones.  It was as if she had flown up to the wire to get a better view of me to be certain that I was not there to harm her or the other Bluebirds. 

So the mama was still alive!  I was extraordinarily relieved and hopeful that she had done a good job of protecting her young.  Given my observations of her personality over the summer, I assumed that she had done just that! 

On the right is a photo of Mama Bluebird that I had taken on July 16th while her babies were still in the nest box.  She was holding a worm in preparation to feed the babies, and you can see how long her beak was. She was exhibiting the same stern and vigilant stance as exhibited by the bird on the wire. Her plumage was a little more colorful in this photo because she still had her summer coat.

The next evening (August 22nd), I noticed some birds perching on the distant wires across the hay field from my driveway (see photo below).  The wires extend from a prominent, yet distant, telephone pole.  My best count was seven birds. Although the birds looked like black dots to my naked eyes, my binoculars soon revealed that they were Bluebirds!

One by one, a Bluebird would occasionally leave its perch on the wire and quickly swoop down to the ground, far below, to gather an insect.  Having harvested its prey, it would usually return to the wire to devour the insect.  Once in a while, however, I would see a bird carry its insect from the ground to the top of the telephone pole to smash the insect and make it more digestible, just as our mama and papa Bluebirds had done this past summer in order to prepare food for the youngsters.

The birds on the wire whose plumage patterns I could discern appeared to be adults.  But, were some of the birds juveniles?  I wondered if the visual acuity of a immature Bluebird would be sharp enough to allow it to be able to see an insect on the ground from the distance of a high utility wire.  I did not witness any of the birds feeding another bird, which made me assume that, if juveniles were included on the wire, they were old enough to feed themselves.

The questions remained:  Did all four chicks fledge successfully from our nest box and were they still alive?

The next day, August 23rd, I again ventured to the far corner of the property to see if I could find any juvenile Bluebirds.  It had been one month and one day since the babies had left the nest, and I had not yet seen a bird that could have been one of them. 

Well, it must have been my lucky day because, as I approached the fence, I was delighted to see a bird perching there, and yes, it proved to be a young Bluebird!  And it appeared to be the age that one of our babies would have reached by that time.

The photo at the above right shows the bird's "pin feathers", revealing it to be a juvenile.  And, judging by the bright blue feathers on the edge of its wing and part of its tail, it appeared to be a male.

The following day (August 24th), during the late afternoon, I was still determined to find more juvenile Bluebirds, if possible.  And I was not to be disappointed!

This time I spotted a juvenile female, as shown on the right side of the photo above. This particular juvenile appeared to be a female because her plumage lacked the blue that the previous day's juvenile male had displayed. You can see that the Bluebird on the left side of the photo is much more brightly colored.

As for the brightly colored Bluebird on the left side of the above photo, I could not discern its age. Despite the rich hues of its plumage, there were white spots throughout, indicating that the bird was molting. This bird was most likely the same bird I had seen on August 21st. Again, I could only guess that it was an older juvenile that fledged in June from another nest.

That same morning, I was able to get another photo, shown below, of the brightly colored bird. this time perched on a high fence post.  What a beautiful bright blue was on its wings and back!

Part II will include a description of a special event that occurred in September and a revelation about the identity of one of the Bluebirds I spotted in August. You can follow this blog and be notified of the next post by entering your email address in the upper right corner.
If you have found this story interesting, you might want to check out my book, Bonding with the Barn Swallows. Its 117 photos include close-ups 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.

Sunday, August 16, 2015

The Barn Swallows had me fooled!

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

This past spring, on April 22nd to be exact, our Barn Swallows returned from their distant wintering quarters in Central and South America.  I saw only five of them that day, and their photo appears below.  I was concerned that there were only five, significantly fewer than during previous years.

I eagerly anticipated the nesting season that was about to commence.  If there were only five Barn Swallows showing up this year, we certainly needed their population number to increase.  As the days went by, however, I was disappointed that I could not find any Barn Swallow nests on this property.  Memories of Barn Swallows nesting on my porch in 2011 and 2012 as described in my book seemed distant and vague.  Besides, who was going to catch all the flying insects this summer?  Many flying insects are regarded as pests by humans, and Barn Swallows have been valued for centuries as natural forms of pest control.

Barn Swallows are adorable birds.  They are amazingly intelligent, agile, and comfortable in the presence of humans, at least in the presence of humans who do not threaten them.  What I like most about Barn Swallows, however, is their relatively egalitarian social structure as compared with many other songbirds.  In the Barn Swallow species, both the male and female build their nest and feed their young.  The male even helps incubate the eggs.  

As the days passed, I began seeing Barn Swallows swooping under the eave of the lower corner of the building where I live.  In fact, the swallows would periodically swoop at me during the mornings when I was in the yard refilling the bird feeders on the nearby tree.

Why were the swallows swooping at me, and what were they trying to protect?  I walked around the building and inspected all of its eaves, searching for Barn Swallow nests.  The photo on the right shows what a typical Barn Swallow nest looks like.  After thoroughly inspecting all four walls of the building, however, I did not find any nests. I then decided to investigate the corner of the building where I had seen the swallows swooping.

I ventured under the eave and carefully inspected the wall and the ceiling of the overhang, but saw no trace of a Barn Swallow nest, or at least the type of cup-shaped nest that Barn Swallows build.  What I did see, however, intrigued me to no end.

A drainage pipe protrudes from the lower back wall of the building.  I discovered that the top of the pipe, which is at a height of about eight feet (almost 2.5 meters) from the ground, was covered with mud and straw.  The inside pipe perimeter also seemed to be lined with mud and straw, leaving an opening in the center of the pipe.  To the above left is a photo of the pipe that I took on May 10th.

Can Barn Swallows nest inside a pipe?  No, that seemed impossible.  The pipe would have to lead to an open space inside the building where they could build a nest.

Each day I kept wondering if a nest was being built on top of the pipe.  From my second-story porch, I was unable to see the pipe itself, which protrudes from lower level of my building and is obscured by the roof that overhangs it.  

The photo to the right shows the view from my porch as I am looking toward the location of the pipe.  The red arrow points to the location where the pipe is hidden underneath the eave.  Therefore, in order to check the pipe each day, I had to venture down the stairs of my porch and then turn back toward the building.  Once I approached the overhang, I could see the pipe.

A few weeks later, I decided to be a bit more proactive.  Just in case the swallows were in the process of building a nest above the pipe, I fabricated a ledge on which they could build it.  I took a small rectangle of corrugated cardboard and covered it with duct tape.  I then attached the rectangle to the side and above the pipe, again with duct tape.  A little sloppy, but it was the best that I could do!  You can see in the photo at the above left, taken July 17th, that the swallows eventually applied a little mud to the ledge.

Early one morning, I approached the pipe to find out if a nest was being built on top of it.  To my surprise, three birds suddenly came flying out from under the eave and away from the building!  They flew out so quickly that I surmised that they must have been perching on the cardboard ledge I had affixed beside the top of the pipe.

After the three birds flew out and away from the eave, I ventured closer to the pipe.  Upon my inspection of it, I found nothing different … just a pipe covered with mud, the inside of the pipe lined with mud and straw, and a little mud on top of the ledge.

Intermittently over the next few weeks, as I watched from my porch, swallows were flying to and from that corner of the building.  One morning there were two swallows coming and going, each spending only a few seconds under the eave and then departing again.

This made me wonder if the swallows were arriving at the pipe with mud to build a nest on the duct-tape-covered ledge that I had set up.  But no, my checking of the ledge did not reveal any additional mud on top of it.

The swallow activity calmed down for a while, but a few weeks later, I noticed it again.  I began to do some Internet research on whether Barn Swallows ever nest inside a pipe.  The only reference I could find to such an activity was on a website forum where RV and camper owners were complaining that Barn Swallows were starting nests inside the exhaust pipes of their parked vehicles.  The comments indicated that the vehicle owners considered the swallows to be a nuisance.  To rid the swallows and their nests from the pipes, they would start their vehicle engines, causing the exhaust to blow the nesting material away.  Indeed, I found that the diameter of the drainage pipe on my building was approximately the size of the diameter of the exhaust pipe on my car.

On the morning of June 22nd, there had been a whole flock of swallows swooping toward the corner of the building and under the eave.  The swallows seemed to be intent upon raiding the area where the pipe was located.  Through binoculars, I observed that some of the birds seemed to be Cliff Swallows.

It made more sense to me that the pipe would be appropriate for a Cliff Swallow nest rather than a Barn Swallow nest, especially if the pipe led to a wider opening inside the building.  This is because Cliff Swallows build nests with small entrance holes and tunnels leading toward the inside of their nests.  A pipe, if it indeed led to a wider space, would seem to serve that purpose. 

To the right is a photo of a Cliff Swallow nest.  In fact, it is the nest on my porch that was originally built by Barn Swallows but modified by Cliff Swallows two years later.  The entrance hole is part of a passageway that leads to the more open part of the nest. 

Cliff Swallows, who usually nest in colonies, are known to raid their own nests.  In the Cliff Swallow species, there seems to be great competition for nests, supposedly because some Cliff Swallow nests are built so poorly that they end up being destroyed by harsh weather conditions.  Consequently, Cliff Swallows who have built a faulty nest are often forced to usurp the nests of other Cliff Swallows.

Another reason that Cliff Swallows highly value other Cliff Swallow nests is that they have a habit of removing an egg from their own nest and placing it into another nest.  Sometimes they will first remove an egg from the other nest first.  I have read that both the male and female Cliff Swallows engage in this type of activity.

Yet on most mornings, the birds flying around the pipe were Barn Swallows.  And on only one morning was there such a large number of birds flocking toward the corner of the building. 

As the summer progressed, I would sit on my porch each morning.  I continued to see a pair of Barn Swallows, one-by-one, visiting the area of the pipe.  Again, I could not see the pipe itself from my porch because it was obscured by the overhang (see previous photo). 

In the late afternoons and evenings I would again inspect the pipe, but it continued to look the same as it previously had, with no nest visible.  I never actually saw a bird fly in or out of the pipe.  In order to do so, I would have to approach the pipe so closely that it would have given the birds ample warning not enter or leave the pipe.

There were several swallows on the roof of my building on the morning of July 16th, as shown in the photo below, which I took from my porch.  This is the upper roof of the building not shown in the photo, not the lower overhang under which the pipe is located.  Since this upper roof is near the same part of the building where the lower overhang and pipe are located, these birds could have fledged from the nest inside the pipe, assuming, of course, that there was indeed a nest inside the pipe!

The birds on the roof were definitely Barn Swallows, not Cliff Swallows.  One of them is shown in the photo to the right.  Although the breast color looks light, the lack of a white patch on the forehead shows it to be a Barn Swallow.  It is a juvenile, as shown by the continuous breast band.  Unlike European Barn Swallows, our Barn Swallow adults have "broken", or discontinuous breast bands.

On July 17th, while I was sitting on the porch, a male Barn Swallow flew toward the corner of the building, but landed on the nearby fence when he saw me.  I was able to take a photo, which appears below.  The discontinuous breast band, along with the rich colors on the rest of his plumage, shows him to be an adult male.  He didn’t look too happy that I was in his presence!

On the morning of July 18th, there were numerous swallow fledglings on the utility wire.  After observing them closely through binoculars, I noticed that some of them were Cliff Swallows!  The photo below shows a fledgling Cliff Swallow on the left.  The three birds to the Cliff Swallow’s right are fledgling Barn Swallows.

Where did all of these babies hatch?  Had they fledged from a nest on my building?  Or perhaps their parents had directed them to perch on that wire because the wire’s location gives a nice, wide view of our valley, enabling the fledglings to more easily spot their parents flying toward them to feed them.

Just eight days later, on July 26th, there were even more swallows on the wire.  Four of them are shown in the photo below.

On August 1st, I was out in my yard refilling the bird feeders on the tree.  A Barn Swallow came flying from the corner of the building and landed on the fence behind the tree.  He allowed me to photograph him, and the photo on the right proves him to have been an adult male.  He could have well have been the same male as in the previous photo taken on July 17th, with the sunlight hitting his feathers differently.

On the morning of August 3rd, I counted 13 swallows on the wires.  There was a group of seven on one wire and a group of six on an adjacent wire.  By observing the birds through binoculars, I surmised that they were all juveniles.  The photo to the left shows two of them.  These are both Barn Swallows.

I began to assume that Barn Swallows had indeed nested in the pipe earlier in the summer.  And perhaps there had been not just one, but two nestings – two broods of swallow babies who had fledged from that nest.

By August 12th, there were no more swallows on the wires.  But, on both the mornings of August 13th and 14th, I observed a solitary swallow circling high over the property.  Although swallows are generally flocking birds, I wondered if this lone swallow had been a male fledgling from the pipe nest who was viewing the nest’s location one more time in order to claim the nest upon his arrival next spring.

Yes, a young male Barn Swallow will sometimes do this.  He will return the following spring and claim the nest in which he was hatched.  He will then proceed to attract a female to the nest, and if the female approves of both him and the nest, the pair will mate, and the female will lay her eggs in that nest.

I experienced this very phenomenon by observing my porch nest during the summers of 2011 and 2012.  It sounds unbelievable that a young Barn Swallow could fly to South America, only to return in the spring and find the very nest in which he was hatched, but this has proven to be true!  You can read a detailed narrative of it in my book.

As of this date, all of our swallows have departed for their long journeys south for the winter.  The photo to the left shows the way the pipe looked on August 16th.  Again, you can see that, although the swallows had applied mud and straw to the top of the ledge that I had installed for them, they had not build a nest there.

It still remains a mystery as to how Barn Swallows could have nested inside the pipe.  Even if I assume that they did so, how did they do it?  I do not own the building and therefore do not know if the pipe leads to an open space.  If the pipe had not been a nesting place for swallows, why else would I have experienced swallows swooping at me while I was walking around the yard near the corner of my building?  And why did we have so many juvenile swallows perching on the nearby utility wire?

Perhaps the mystery will be solved next spring.  I plan to carefully observe whether any of the returning swallows show interest in that corner of the building and the pipe that protrudes from it.
In Bonding with the Barn Swallows, you can read about the unexpected location where one special male Barn Swallow perched all night and why he perched there.  You can also read about how that same Barn Swallow communicated to me on two occasions, once through typical Barn Swallow twittering, and again by his body language on the utility wire while perched next to two other Barn Swallows.  Two days later, an event revealed what he was trying to tell me.

Just click on the image to the upper right to find out more about the book.  You can click on "Look inside" to see the Table of Contents and read the first few pages of the book.  Or, you can click on "Surprise me" and read other pages!


Tuesday, July 28, 2015

Bye-bye Baby Bluebirds!

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

I don’t know why I get so attached to baby birds, but I’ve been that way all my life.  The baby Bluebirds left the nest box on Wednesday, July 22nd, and I haven’t seen them since.

I really didn’t see the babies at all except for their little heads peeking through the nest box hole the last few days during which they were in the box.  During that time, the parents had been extremely busy feeding larvae and full-grown insects to the babies through the box's entrance hole.

From my observations during the times that I had opened the nest box, I knew that the female had laid her last egg on June 21st.  The day the last egg is laid is generally said to be the day that the female begins incubating her eggs.  According to Cornell Lab of Ornithology, the average incubation period for Eastern Bluebirds is 14 days, but I had read that this period can be anywhere from 12 to 14 days.  The day that the first egg hatches is said to be the end of the incubation period.

Again, according to Cornell, the average number of days that Eastern Bluebird nestlings stay in the nest is 17 days, but I had read that it can be anywhere between 17 and 21 days, most likely 18.  When the babies leave the nest, they are said to “fledge”.  Therefore, the number of days that the nestlings stay in the nest is called the “fledging period”.

Also, in some cases, the female might begin to incubate on the day before the last egg is laid.  That would hasten the hatching date by one day.

Using all of this information, including the variability of the day that incubation begins, the length of the incubation period, and the number of days that the young stay in the nest (the fledging period), I had estimated that the babies would leave the nest (fledge) on Thursday, July 23rd, when they were 18 days old.

So, based on my estimation of the fledging date, I went out early Wednesday morning, July 22nd, to take pictures of the nest box.  Hopefully, I would get some photos of the babies’ heads peeking out of the box, and, if I didn’t, I would have 24 more hours left to do so.

The morning of July 22nd was beautiful and sunny.  The sunlight coming from the east was hitting the nest box nicely, and I had a full, clear view of what going on at the box.

Both Mama and Papa Bluebird were busy bringing insects to the box to feed their babies through the hole.  Mama and Papa, usually one by one, would first land on top of the box with a grasshopper, a grub worm, or some other type of live insect in their beaks and await clearance to fly to the hole of the box and feed the babies inside.

And I wasn’t disappointed in my hopes of being able to see the babies’ faces peeking out of the hole!  It was a memorable and gratifying experience.

But I don’t think it was so gratifying to the parent Bluebirds to have me out there taking pictures of the box when the babies were so hungry.  So I took as many pictures as I could during a 30-minute period while the angle of the Sun was almost horizontal to the nest box.

At one point, I realized that I was holding up the feedings.  Both Mama and Papa were perched on top of the box at the same time, both holding insects to feed to their young, as the photo below shows.

The babies were eagerly awaiting their breakfasts.  Most of the time, I would see only one baby’s face through the nest box hole.  Perhaps this was the first-hatched, and therefore the most fully developed, nestling, the one with the most strength to beg for food.

On one occasion I was able to photograph, through the hole, what seemed like the heads of three of the nestlings.  I was rather disappointed that I couldn’t see all four because Mama Bluebird had laid four eggs and I had observed four nestlings in the box a week previously, on July 15th, which was the last time I had opened the door of the nest box.

On that day, July 15th, I had estimated the nestlings, or at least the oldest nestling, to be 10 days old.  All of the Eastern Bluebird information sources say not to check the box after the nestlings are 12 days old for fear that it will cause them to fledge early and decrease their chances of survival.  So I chose not to open the nest box door again after July 15th.

My calculation of the oldest nestling being 10 days old was based on the assumption that Mama began incubating her eggs on June 21st and did so for 14 days until the first egg hatched, which would have been on July 5th.

I had read that Bluebird eggs generally hatch within 24 hours of each other, but there might be a straggler that takes a little longer than that to hatch.  Yet, the eggs are said to all hatch within no more than 48 hours of the first egg hatching.

So, if the first egg had hatched on July 5th, the babies, at least the oldest one, would have been 10 days old on July 15th, the last day that I had opened the door of the box.  I did not photograph them on that day, but I tried to remember what they looked like.  I remembered how I could see their light-colored pin feathers and began searching on the Internet for photos of Eastern Bluebird nestlings.

Yes, according to the photos that I found of Eastern Bluebird nestlings of different ages, the nestlings did indeed look much like 10-day-old nestlings on July 15th!  That meant that on July 22nd they would be 17 days old and on July 23rd, 18 days old.

At the time, I was not giving a great deal of attention to Cornell’s exact estimation of incubating and fledging time periods.  Instead, I was trying to assess an average of the time periods given on different websites.

Most of the websites said that baby Eastern Bluebirds fledge when they are 18 days old, which would be on July 23rd.  Therefore, on the morning of July 22nd I would have at least another 24 hours before the 17-day-old babies would leave the nest.

Wrong I was!  On the evening of July 22nd, there were no parent Bluebirds anywhere near the nest box.  If the babies were still inside, they would be starving because 17-day-old babies need to be fed several times an hour.

I checked the box on the morning of July 23rd and found a crumpled-down nest that looked gross and unsanitary.  I had read stories about having to remove dead babies from the nest box, but, fortunately, I did not find any.

That meant that all four babies had been alive at the time they exited the box.  I would love to have seen the fledging of the babies, but I don’t think the parent birds would have permitted their babies to leave the box with a human in sight.

There is a chance that a predator (mainly a cat) could have attacked the babies while they were flying from the box, but I am having faith that did not occur given the parents’ defensiveness and vigilance that I had witnessed over the past two weeks.

On the morning of July 24th, just before I put out my trash for our weekly pickup, I removed the nest from the box and sealed it in a plastic bag to put into my trash.  I then proceeded to scrape out the debris from the box, sprayed the inside with a 10% bleach solution, and scrubbed it with a brush.  By the time I had again sprayed, scraped, and brushed several times, the box was as clean as a new box. 

I left the box open to dry in the sun for the remainder of the day.  By evening, the box was dry and fresh, smelling like natural wood (the box is made of cedar), with no trace of the scent of bleach remaining.  So I closed the door of the box to prevent it from getting saturated with dew overnight.

After thinking that the babies had fledged one day early and that perhaps I had caused them to do so by my photographing the box on the morning of July 22nd, I reviewed Cornell Lab of Ornithology’s timetable for Bluebird nesting.  To my surprise, I discovered that the babies had fledged RIGHT ON TIME!

As previously stated, Cornell gives an Eastern Bluebird incubation period of 14 days and a fledging period of 17 days.  Since 14 plus 17 equals 31, and 31 days added to June 21st equals July 22nd,, in light of Cornell’s average incubation and fledging periods, the babies fledged on the exact day that they were supposed to.  Excellent work, Cornell!

Bluebird babies are said to be unable to feed themselves for the first two weeks during which they are out of the nest.  The parents are said to take the babies into trees to protect them from predators, with the parents continuing to feed insects to the babies for the next two weeks.  Eventually, the parents teach the babies to hunt for insects by themselves.  The photo to the left shows what a baby Bluebird looks like when it is out on its own.  I took this photo during the summer of 2013 when I first observed baby Bluebirds near my yard.

So, perhaps by August 5th or so, I will see the babies around, perching on the fence with their eyes on the ground, hunting for insects in the manner that their parents have taught them.  In the meantime, I am wondering if the Bluebird parents will nest again this summer.  Will they use one of our two now-clean nest boxes to do so?  Time will tell.

You can stay tuned to discover whether I see the babies again and whether their parents nest again in one of our boxes.  To follow this blog, you can enter your email address on the upper right of the 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 close-ups 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 juvenal 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.

Friday, July 17, 2015

Nesting Bluebirds -- Bugs for the Babies!

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

The Bluebird eggs have hatched!  My estimation is that the hatching date was July 5th.  That would be the date of the hatching of the first egg.  Bluebird eggs are said to hatch within twenty-four hours of each other, although the last-laid egg might take a little longer.  The general rule is that all of the eggs will hatch within 48 hours of the first egg hatching, unless any of them are infertile. 

If you are interested in knowing how I estimated the hatching date, you can read the Technical Section below.

There were four eggs in the nest, and now there are four Bluebird babies.  I do not check the inside of the box very frequently for fear of stressing the parent Bluebirds.  The last time I checked, which was on Wednesday, July 15th, the babies had light-colored “pin feathers” on them.  Assuming a hatching date of July 5th, the first-hatched baby was ten days old at that time.

I have not photographed the babies, but if you go to the following site and look at Figure 5, you can see approximately what the babies looked like on July 15th  Here’s another photo of 10-day-old Bluebirds:

As the babies grow larger, they need increasing amounts of food and higher frequencies of feeding.  Their food consists of bugs, more technically called insects, that the babies’ parents bring to the nest box.  On the right is a photo of Mama Bluebird with what might be a grasshopper in her beak.  She is preparing to feed at least one baby through the nest box hole when she feels that it is safe to do so.  The blossoms in the background are on a Mimosa tree.

Both parents have been diligently hunting for insects and bringing them to the box to feed to the babies.  The insects that Bluebirds eat are largely those that live on the ground.  A Bluebird will perch on a fence, a utility wire, or a building's roof and focus on the ground below.  Once it sees an insect, it will quickly swoop to the ground, capture the insect, and immediately return to its higher post to either digest the insect or save it to feed its youngsters.

The parent Bluebirds closely guard the nest box and for good reason.  We have roaming, feral cats around here that eat birds.  The parent Bluebirds probably also consider me to be a potential predator because they are extremely cautious about feeding their babies when I am taking pictures of them.

The photo on the left shows both Mama and Papa Bluebird on top of the box with insects in their beaks.  They are awaiting a safe time to feed their babies.

Mama Bluebird is more cautious than Papa Bluebird and likes to wait until I am out of the way before she feeds her babies.  I have very few photos, if any, of Mama feeding the babies though the nest box hole.

Finally, after a few minutes of both Mama and Papa Bluebird perching on top of the nest box, Papa Bluebird deemed it safe enough to feed his insect to the babies inside the box.  Mama stayed on top of the box awaiting her turn, as shown in the photo below.

The photo on the right, taken early in the morning, shows Papa Bluebird on top of the box holding an insect, a large one at that!  Since I was there with my camera, he was watching me to be certain that I would not interfere with his feeding of the babies.

I wondered how many babies that large insect would feed.  Interestingly, male Bluebirds are said to show preference for feeding the female babies instead of the males.  It is speculated that the Papa Bluebird would rather have the females grow up and be healthy because, unlike the males, they will not interfere with his breeding territory next spring.  Instead, the females will go off with their own mates into another territory.  In short, male Bluebirds compete for breeding territories, which are usually five or six acres in size, but they can sometimes range up to twenty acres.

Much of this information presented here can be found in the delightful book, Eastern Bluebird by Gary Ritchison, which I heartily recommend if you would like to find out more about Eastern Bluebirds.  The book is well illustrated with superb photos and contains a great deal of information.

After perching on top of the box and holding the huge insect in his beak, Papa Bluebird proceeded to feed the babies.  As the photo to the left shows, Papa landed on the front of the box and fed the insect to the babies inside. 

Immediately afterward, Papa actually went inside the box.  I was wondering what he was doing inside of the box, but a moment later I discovered what it was.

Papa Bluebird stayed inside the box for a short time and then exited from the box, flying away to hunt for another insect.  The photo below shows him flying from the box.  As to what Papa had been doing inside the box, the answer is shown in the photo.

If you look closely at the photo, you will see that Papa had something white in his beak.

Something white?  It was actually a form of a diaper.  It is called a “fecal sac” and is from one of the baby Bluebirds.  When the babies reach a certain age, it becomes the job of the parents to remove these sacs from the nest.

A parent will take the sac from the nest box and fly far away from the box.  The parent will drop the sac in a place where predators will not be able to associate the scent of the sac with the location of the nest box.  And that is what Papa Bluebird did.  I watched him fly across the adjacent field and out of sight with the sac still in his beak.

Technical Section

Estimating Eastern Bluebirds’ hatching dates is based on observations of the nest and certain knowledge of Bluebird behavior and breeding patterns.  It is necessary to know how many eggs are laid and when the female finishes laying them.  Here are my observations:

Afternoon of June 17th – no eggs in nest
Afternoon of June 21st – four eggs in nest
Afternoon of June 29th – four eggs in nest

Ornithological observations have shown that, once a female Bluebird starts laying eggs, she will lay one egg each morning.  This is also true of many other birds.  Bluebirds tend to lay their eggs well after sunrise, often between 8 and 10 a.m.

Also from observations, it is known that the female will usually start incubating her eggs either on the day that she lays her last egg or on the previous day.

Since no eggs were in the nest on the afternoon of June 17th, the female had not yet laid any eggs.  However, on June 21st there were four eggs in the nest, indicating that she had laid her first egg on June 18th, her second on June 19th, her third on June 20th, and her fourth on June 21st.

Since there were still only four eggs in the nest on June 29th, the female stopped laying after she laid her last egg on June 21st.  She therefore began incubating her eggs either on June 21st or on June 20th. 

For the purpose of my calculation, I assumed that the female began incubating on June 21st. That is because I did not notice the female peeking her head out of the nest box prior to the morning of June 21st. Peeking her head out of the box would have indicated that she had been in the box all night keeping the eggs warm. Instead, early each morning prior to June 21st, between about 6 and 7 a.m., I observed the male landing on top of the box, the female flying from the fence to the top of the box to join him, after which the male would enter the box with the female following him. The male would then fly out of the box, leaving the female inside. I interpreted this behavior as the male escorting the female inside the box to make sure it was safe to lay an egg.

Since the average incubation period for Eastern Bluebirds is fourteen days, I assumed that the eggs began hatching on July 5th, which was fourteen days from June 21st.

Based on the assumption that the oldest baby was ten days old on July 15th, I estimate that babies will start fledging (leaving the nest) sometime around July 23rd. This is based on the average fledging date for Eastern Bluebirds being the date when they are eighteen days old. However, this can vary up to twenty-one days. On the other hand, the material that I have read about Eastern Bluebird nesting in this region of the U.S. has indicated an average of 18 days.

Stay tuned to discover the fate of the babies!  And please pray with me that they will be safe once they leave the nest.  To follow this blog, you can enter your email address on the upper right of the 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.