Naturalist’s Notebook
A BLUEBIRD DIARY
by Lindell Dillon
“A man’s interest in a single bluebird is worth more than a complete but dry list of the fauna and flora of a town.” – Letter, November 22, 1858, from Henry D. Thoreau to Daniel Ricketson, in The Writings of Henry David Thoreau, 1906.
This is a chronicle of a pair of Eastern Bluebirds (Sialia sialis) that is attracted to our nest box in Norman, OK. Because of their beauty and cheerful song, bluebirds have come to symbolize happiness, love and renewed hope. This pair of birds certainly starts our days with a burst of song and cheer.
The nest box was erected in August of 2009 in hopes that we might attract a pair of bluebirds the following spring. Surprisingly, a pair located it in only a few days and would visit occasionally.
During early 2010, the birds visited repeatedly on sunny days. The last couple of weeks in February, they were visiting several times daily and spending more time in the box. I think they spent some nights in it, though not all.
In March I moved a pink ceramic flower feeder from the front lawn and placed it directly under the nest box. I deposited a few mealworms in it and Daddy Bluebird spotted them immediately. He devoured the 6 worms I had placed in it. Over the course of the next few days, I moved it closer to the house and also fed them blueberries as well as mealworms. Although they eat the blueberries, they have a clear preference for mealworms.
March 15 The bluebirds have been feeding on the worms and going in and out of the house several times daily for a couple of weeks, but no sign of nesting activity. I check the nest box daily when I put out mealworms. Finally! Today there are signs of nest building.
March 19 Inspected the box today and some progress in nest construction is evident. Most of the grass is the native Little Bluestem from up on the hill. Bluebird nests are almost exclusively grass. Note there is one strand of blue ribbon. Bluebirds are attracted to the color blue.
Winter’s last hurrah in the form of a brief blizzard-like snowstorm came through over the weekend. The bluebirds were not around. I don’t know if they holed up in the box or down on the creek, but were not seen. I purchased some high-energy mealworm-flavored suet pellets and provided them for a boost, but they went uneaten.
March 22 The winter storm is gone and the sun is shining brightly. The bluebirds were at their feeding dish at first light for a breakfast of mealworms. Daddy fed his mate worms as they perched on the dish.
A short while after the mealworms were eaten the birds returned and each picked up a suet pellet and flew off with it. I don’t know if they took it somewhere else to eat or just wanted this offensive stuff out of the way of their mealworms.
Mama is spending time in the box today and Daddy is bringing her strands of dry Bluestem.
March 26 The nest is completely finished, but no eggs inside. The birds are getting used to me feeding them and don’t fly off now when I go out to place worms in their dish. Daddy is a pig; sometimes gathers 3 or 4 worms in his beak at once before devouring them.
March 30 Took some mealworms out early and the bluebirds came pretty quickly. Mama landed on the box and Daddy on the feeder. Mama started begging and Daddy would pick up a worm, fly to the box and feed her.
March 31 Checked the nest box this afternoon and was not surprised to find eggs. Mama is obviously pregnant. She is noticeably slower in flight and has a little difficulty hitting the hole when landing. Since bluebirds lay only one egg daily, it’s safe to assume she laid one after I checked the box yesterday and another today. Most eggs are laid during the night or the first two hours of daylight, so I refrain from checking the box until afternoon.
Bluebirds usually set a clutch of 4-7 eggs, laying only one daily. They may skip a day if the weather is cold. The eggs don’t start incubating until the female sets them and her body heat initiates incubation which takes 12-14 days. Interestingly, hatch success is better in cool weather than hot and northern bluebirds lay more eggs than those in the South; but southern bluebirds raise up to 3 broods a year, evening things out.
April 1 Checked the box around noon. I tapped on it to be sure Mama would leave if she were inside. No response, so I opened the box. To my surprise, Mama was sitting on the nest. I almost got a photo, but she flew when I raised the camera. As expected, there is a third egg.
We are leaving on an Easter trip to the Roulets’ in McKinney, Texas tomorrow and a week in the Texas Hill Country after that, so our observations are going to have some blank spaces. But an average clutch and average incubation time would put the hatch date around April 16, so we should be home for the big day. Before leaving I secured a baffle to the pole that supports the nest box to deter a snake or raccoon from reaching the nest.
Bluebird boxes without baffles may suffer predation losses of 30 percent or more.
April 12 Returned from the Hill Country to find 6 eggs in the box! I’m thinking we are going to have a large family. Mama and Daddy may need some help feeding this brood.
April 14 Checked the nest box this morning. As always, I knocked gently prior to opening so Mama can fly out if she is inside. When I opened the door, I was surprised to see Mama sitting on the nest. I took one quick pic, slowly closed the door and she never flew.
A Lark Sparrow decided to perch on the box and sing me a song, but Daddy dive-bombed him from the roof and sent him packing.
Then two starlings wandered through the back yard, foraging in the grass. A third joined them and a fight immediately broke out between the two males. Apparently Daddy didn’t like the disturbance. Although he is half the size of a starling, he immediately entered the fray and chased the interlopers from his territory.
April 15 Mama was in the box most of the morning. Daddy brought her a few bugs and some mealworms. I have been feeding them from a ceramic flower feeder, but it was recently blown over and broken. I glued the flower back together (mostly), but super glue wouldn’t stick it back on the pole. I just set the birds a plate at the breakfast table on the patio and Daddy joined me for breakfast. I had Bunches of Honey and Oats and he had his usual– mealworms.
April 17 A cool front came through yesterday. The temperature dropped back down into the fifties and it’s a dreary rainy day. All the birds at the feeders are soaked and haggard looking. Carolyn and I were talking about what a boring day it is when the bluebirds injected another ray of sunshine into our lives.
The young will fledge 16-21 days from today and will be strong flyers by 28 days.
I must be careful not to open the box after 13 days to prevent premature fledging.
April 18 Weather was cold and rainy again today. While I was curious about the goings on inside the box, I really didn’t want to open it and expose the babies to rain and cold air. I took one quick peek and saw 5 babies and 1 unhatched egg. I fed mealworms 3 times and Daddy did an excellent job of sharing with his family. Mama stayed in the box most of the day. Carolyn and I were gone in the afternoon, working the Oklahoma Master Naturalists’ booth at the Earth Day celebration in Reaves Park.
April 19 Fed the birds a couple of dozen mealworms at daybreak. Mama and Daddy were waiting and checking their dish. Waited for the light to get a little better and checked the box. All 6 chicks have hatched and the eggshell has been removed.
It’s difficult to get photos inside the box. I select a macro setting and have to place my camera against the top of the box, so I can’t see what I am shooting. I normally shoot about a half-dozen blind shots in hopes that one will be in focus and capture the babies. Daddy always keeps a nervous eye on me and is nearby when I have the box open. I’m amazed at how he and Mama have accepted me. They seem to know I’m not a threat to their young.
April 20 Catching bugs non-stop and feeding babies has become a full-time job for the bluebirds. I am in awe of their keen vision. They can spot a bug from across the yard. Not much change in the babies except they seem a little more hungry. Eyes are still closed.
I thought maybe Daddy was getting tired of eating at the Pink Diner every day, so we opened up another restaurant with a New Orleans décor. Menu is the same. Mealworms—breakfast, lunch and dinner.
April 23 The bluebirds’ days are filled with more of the same—catching bugs and feeding babies. It’s obvious that Daddy knows I’m the guy with the worms. When I go out on the patio he flies to a nearby tree and calls to me.
Mama has housekeeping chores as well as bugs to catch. A little box with six birds living in it could get pretty nasty if bluebirds and other cavity-nesting birds hadn’t adapted. Their young don’t defecate like most birds. Instead their poop is encased in a fecal sac. It’s a thick gelatinous membrane that allows the parents to remove the waste from the nest. I’ve seen Mama do it a few times, but haven’t been able to get a pic. She always drops it some distance from the nest. An accumulation under the nest would draw predators.
The babies continue to grow and get darker. Eyes are still closed.
April 25 Babies are growing fast and filling up the nest. I couldn’t wake them up for a pic this morning. Normally if I make cheeping noises, they open their mouths to be fed. Not today. I even touched them on the heads and they just slept. They are beginning to get real feathers.
April 26 Once again I was unable to rouse the babies for a pic. I can’t believe they just sleep as I cheep and poke them. Maybe I need to start taking pics before I put out mealworms and they have a full stomach. Daddy was a little cranky while I took pics this morning. I could feel the wind from his wings on my head as he dived and fussed at me.
April 28 The babies are growing even faster. They actually resemble birds more than hatchlings now. They aren’t going to be babies for long. The parents have been bringing in grub worms by the dozens the past few days. I’d like to see how they are catching them, but they are flying over the hill and coming back with them. They must have a good source located. I’ve observed Daddy flying off with some fecal sacs, so he is doing his share of the housework.
April 29 After pouring myself a cup of coffee this morning, I walked over to the back door to survey the yard. Daddy was on the box and immediately spotted me. He flew to the feeder and began to chirp to me. He is much bolder than Mama, but she comes to the feeder as well. A Chipping Sparrow fed all around the box and the bluebirds didn’t seem to mind. They appear to have a dislike for starlings and cowbirds, but tolerate the finches and native sparrows. Fortunately we have only a couple of House Sparrows around and they are seldom in the back yard. House Sparrows are notorious killers of bluebirds. I’ve never heard of a bluebird winning a fight with a House Sparrow. Anyone attempting to attract bluebirds should have a plan to control House Sparrows.
April 30 Took the last pic of the babies in the nest today at 13 days old. Notice the foot of one and their feathering and beaks. It won’t be long until they fledge. I’m not going to open the box anymore until they do. Once bluebirds fledge they won’t go back into the nest, so I’m afraid I might make them jump out before they are prepared for the outside world. Just a few days makes a world of difference in their maturity. I’m amazed at the dedication and skill of the parents. They work constantly for their brood.
May 03 Babies still haven’t fledged. Mama flew in with a cricket today and spotted mealworms in the New Orleans Diner on her way to the box. She had to stop and pick up some more groceries before delivering the cricket.
May 06 The babies have spent a lot of time peering out of the box the past couple of days. Perhaps contemplating the big world outside. I had a friend over today and he wanted to see the bluebirds. I put worms out and called for Daddy. It took him longer than normal to show up. He gathered up his usual mouthful, but instead of flying to the box, he flew to the creek about 75 yards away. This was a clue that perhaps some of the babies had fledged, although one was peering out the hole in the box.
We watched while 3 more fledged. I was amazed that little baby birds could fly so well on wings that had never been tested. Two flew to the roof and then on to the creek; the third flew to the roof of a neighbor’s house on the creek where Mama came and led it to a tall pecan tree. They should be safe there. They were gathered about 30 feet off the ground when I Iast saw them.
I wish I’d gotten more pics of the babies, but it wasn’t in the cards. Now with a bad case of empty nest syndrome I conclude this chapter of my Bluebird Diary. I know there will be a sequel and I know I’ll continue to see Mama and Daddy regularly. When the fledglings are stronger flyers I suspect they will visit the back yard to eat mealworms with their parents. Daddy came for worms several times after the fledging and always inspected the box. Perhaps just to be sure he didn’t leave someone behind.
Maybe a second brood is in our future, maybe not. No guarantees in nature. One thing I know is that as surely as the sun will rise in the East tomorrow morning nature’s seasons don’t end, they just change with the winds. Carolyn and I feel privileged to have watched another generation of bluebirds take flight and make the world a brighter place. We hope you enjoyed our observations and we wish you bluebirds.
Summary:
March 15 First signs of nest building
March 26 Nest completed
March 30 First egg laid
April 04 Sixth egg laid
April 17 5 eggs hatched, 1 following day
May 06 Babies fledged
Today is a good day to put up a bluebird box. It is one of the easiest and most rewarding things you can do for the environment and yourself.
AVIAN WINDOW-COLLISION MORTALITY
An interview with
Tim O‘Connell, Wildlife Ecologist and OSU Associate Professor, Department of Natural Resource Ecology & Management
AG HALL— A dead hawk was found outside on a ledge right below our window mid-October. Dr. Tim O‘Connell, Associate Professor in the Department of Resource Ecology and Management identified the bird as a Sharp-shinned Hawk, from its bluish-gray wings and white belly covering its 13-inch frame. Its cause of death was deter-mined to be an in-flight window collision. Wanting to keep the hawk for his research, O‘Connell introduced us to some fascinating information about the growing problem concerning bird mortality rates. He noted that windows are a newly developed source of mortality for birds. “Everyone, whether into birds or not, can relate to the experience of find-ing a dead bird by a window”, O‘Connell said in a Q&A performed after the discovery, via email. As someone who is currently observing the correlation between bird migration and in-flight collisions on a daily basis, O‘Connell has collected various types of bird casualties on OSU‘s campus. He became interested in the issue 15 years ago during his residence in Richmond, Virginia. While jogging, he noticed several dead birds in the vicinity of various
“Everyone, whether into birds or not, can relate to the experience of finding a dead bird by a window.”
Buildings shielded with mirrored-glass. O‘Connell took notice of two things. One, the species were migrants, which probably died while passing through the area. Two, he thought the birds would be valuable additions to the collections at Virginia Commonwealth University where he knew its museum‘s bird curator. It was then that O‘Connell decided to find some way of quantifying the bird mortalities. So, he spent a year searching for birds around the same location, and keeping records of all his findings. He has been keeping track of relevant information ever since, and has developed his own methods that has led to his current conclusions about avian window-collision mortalities. The following information will contain summaries further looking into this topic, mostly incorporating O‘Connell‘s input about his own studies concern-ing this newfound phenomenon.
How Big of a Problem is This? Biologist Daniel Klem from Muhlenberg College in Pennsylvania was one of the first people to conduct experiments that explored the topic of birds striking windows. O‘Connell often uses Dr. Klem‘s findings to illustrate the severity of the issue. According to a fact sheet on Muhlenberg College‘s Acopian Center for Ornithology Web site, an estimate for the annual window-collision mortality in the United states ranges from 97 million to 975 million. O‘Connell shares that there are about 20 billion birds total in North America each autumn when annual populations peak. ―If the number killed by windows actually approaches a billion birds, then this one source of mortality is far greater than the number killed by cats, hunters, auto collisions, and pollution, and other factors,‖ he said. About 75% of bird-window collisions end up fatal for birds, Klem estimated. Even if a bird is merely stunned from the collision and attempting to recuperate, they could become an easy prey for predators, such as cats.
Examining the Problem O‘Connell‘s search for birds mostly revolves around the Noble Research Center roughly every morning. He tries to find birds that have died while migrating the night before. Getting to NRC as early as he can reduces the chances for any predator, or he adds, “some other well-meaning ornithologist on campus”, to remove the bird before O‘Connell ever gets the chance to record it. O‘Connell guesses he records about 90% of the total mortality at the building, despite the fact that there are some animals that do end up scavenging for the dead birds, such as cats, raccoons, opossums, skunks, or foxes. ―But the rate seems to be low, he said. After a bird has been collected, it is placed in a freezer with a card indicating the date and location the bird was found, as well as the bird‘s species, age, sex, and manner of death. O‘Connell also lists the fat scores of the birds. The fat score is an estimate of the bird‘s health and readiness for migration at the time of its death. Although window collision mortality is a minor component of O‘Connell‘s research program, he frequently reviews studies and proposals from other people doing similar work.
The Interest in Avian Window-Collision Mortalities
O‘Connell suspects that some species are more susceptible to this kind of mortality than others, reflecting the amount of urban development that has occurred along certain migratory routes. Although windows might be one of the primary dangers for migrating birds, it is difficult to determine what sort of broad impact this mortality might have on any one species‘ population. To estimate the relative influence of window-collision mortal-ity for a species would require reliable estimates of the total population of the species, a coordinated effort among multiple sites to estimate all sources of mortality, and some complex statistical modeling. For now, O’Connell is just trying to test the feasibility of regular monitoring to see if it would make a good research project for his undergraduate students. Discussing window-collision mortality on bird-related listservs is one of O‘Connell‘s ways of spreading the word about conservation issues that affect wild birds. Another way he expresses his findings is through his new blog, started last August, titled, “Avian Window Kills.” The blog serves as a regular online record of the window collisions that have occurred at the NRC. “Blogs are an exceedingly simple and uncluttered place online where people can go to obtain information on this phenomenon, and track the regular progress‘ of my findings”, O‘Connell said.
Conclusion One compelling fact that prompts O‘Connell to say that this issue is a “big deal”: birds have always had to deal with predators, rough weather, and food shortages during migration. However, it has barely been 200 years that they have had to deal with windows during their trek. “There probably hasn‘t been time for birds to evolve in their behavior for complete avoidance of human structures while on migration—especially considering they‘ve had eons of evolution shaping their behavior to follow those exact routes where we‘ve put up a bunch of buildings”, O‘Connell said. His original plan was to survey the NRC for window-killed birds from August to October, but an increase in casual-ties has him extending his searches, perhaps for a full year. A possible alternative based off of his findings recorded on his blog would be building a database to share his analyses. He said while it is important to analyze these data for publication in scientific literature, information in journal articles is not nearly as accessible or timely as in a free, daily blog.
To visit Dr. O’Connell’s blog, go to http://birdsmack.wordpress.com