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HIGH TEMPERATURE CAN AFFECT BLUEBIRD NESTING SUCCESS

Jul19

        Georgians are well aware of the fact that during the summer the temperature soars into the high 90s and above. However, this year the thermometer seems to be reaching these lofty numbers more often than ever before.  While these temperatures put us under a lot of stress, they are especially harmful to eastern bluebirds trying to nest during these difficult times.

       Bluebirds nest in Georgia from February into September.  During this time, bluebirds can produce up to three broods.

      Consequently, there is a good chance untold numbers of bluebirds are currently trying to nest during these torrid temperatures.

       For many of these birds, one factor that will play a key role as to whether or not these nesting efforts are successful is the color on the exterior of the nest box they are using.  Let me explain.

       The temperature inside a nesting box can reach 120ºF or more.  In addition, these temperatures can 20º higher than the air outside a box.   One way you can moderate the temperature in inside a box is to paint the outside of the box a light color.  Boxes painted white and other light colors absorb less light than those than darker colors such as brown.

       This is critical to the success of the nesting attempt because eggs develop best in temperatures ranging from 96.8 to 104.8º. In addition, bluebird’s eggs and nestlings simply cannot survive when the temperatures rise above 107º.

     

      

DO EASTERN BLUEBIRDS USE THE SAME BOX FOR MORE THAN ONE YEAR?

Mar12

        If you erect bluebird boxes, more than likely you have wondered if bluebirds return to nest in the same nest box they used the year before. 

       As it turns out, banding studies demonstrate anywhere from 26-44% of the bluebirds that nested in box last year will return to nest there this year. 

       One factor that determines if bluebirds use the same box from year to year is whether their nesting efforts the previous year were successful.  As you might imagine, they are more likely to use the same box if they successfully raised young in that box the previous breeding season.

NEST BOXES FOR PILEATED WOODPECKERS?

Jan8

       One of the most difficult birds to attract to backyards in Georgia is the pileated woodpecker.  The truth of the matter is most of us have little chance of attracting one of the birds to our yards unless we live close to mature woodlands. 

       However, since this, the third largest woodpecker in the world, has such a large home range (1.5 to 3 acres), if you home is located with the home range of a pileated one just might show up to dine at your feeders.  (If you want to see if you are putting out the right foods for pileated woodpeckers, read the blog I wrote some time ago that addresses this issue.  You can access it by typing the words pileated woodpecker in the Search bubble on the right side of the blog page.)

       This begs the question, “Can I attract a pileated woodpecker with a nest box?”  The answer to this question is, “Probably not.”  Almost invariably, those that have erected nest boxes for pileated ended up providing a nesting site for birds such as the eastern screech owl, American kestrel or wood duck.

       It seems pileated woodpeckers customarily nest in dead trees.  However, even then after they spend upwards of 60 days chiseling out a nesting cavity, they will not reuse it a second year.

PILIATED WOODPECKER PHOTO CREDIT: USFWS

       Since dead trees are at a premium, the pileated woodpecker faces a housing shortage of epic proportions.  With that in mind, if you own a woodland, one of the best things you can do to encourage pileated woodpeckers to your yard to leave dead and dying trees standing whenever possible.

       I live on a bit less than three acres.  One-third of the property is wooded.  When one of the large trees growing on the backside of my land died, I left it standing.  After several years, a pair of red-headed woodpeckers nested in it.  I was hoping the tree would also be used by a pair of pileated woodpeckers too; such was not the case.  The tree eventually fell to ground and is being routinely visited by wild critters seeking ants, beetle grubs and other juicy foods.

       To date, the only pileated woodpeckers I have seen where I live have been flying overhead. Perhaps this will be the year one will drop down and dine on some of my suet.  You never know.

BEST TIME TO CLEAN BARN OWL BOXES

Sep18

         If you erect and maintain nesting boxes for birds in your yard, you realize the need to annually repair and clean them during a time when birds are not nesting.  This is easy to do because the nesting dates of most birds that nest in our backyards are well known.  However, if you have a barn owl nest box on your property, you have a problem.  It seems that biologists know surprisingly little about when barn owls nest in Georgia.  

       Such is not the case in California.  Researchers at the University of California, Davis combed through almost 100 years of banding and other records to determine when barn owls nest in California.

       The biologists found that the median egg laying date in California is February 20.  Consequently, the lead author of the study Ryan Bourbour says, “We want to reduce disturbances to breeding pairs prior to egg laying.”  Based on the findings the researchers recommend boxes need to be erected, repaired, and cleaned in the fall.

       Unfortunately, the only nesting records for Peach State barn owls are largely anecdotal.  Only a dozen barn owl breeding records surfaced during The Breeding Bird Atlas of Georgia Project.  Although most records came from central Georgia, breeding was corroborated from the mountains to the coast. Undoubtedly, barn owl nesting is more common and widespread in all parts of the state.

       In Thomas Burleigh’s book Georgia Birds, the author noted that nests have been located from March to December.  However, biologists do not have enough data to develop a median egg laying date for Georgia.

      Since we know there is a need to provide more nesting sites for barn owls in Georgia, we all need to check our barn owl boxes during each season of the year.  When we conduct a check, if no nesting is currently going on, we need to repair and clean it.  If nesting has or is taking place since the last check, record it too.  Over time, we should be able to determine when nesting takes occurs in our part of the state.

       If you don’t have any barn owl nesting boxes on your property, consider erecting one.  Once you have one in place, follow the procedure outlined above.

       It would be great if landowners knew when it is the best time to conduct an annual barn owl nest box check.

       Let me know what you find.  I will forward your information on to the Wildlife Conservation Section biologists trying to restore nongame wildlife throughout Georgia.  Hopefully, your information will enable them to establish a median egg laying date for Georgia and recommend the best time to check barn owl nesting boxes.

BIRDS WERE TESTED BY A MARCH FREEZE

Mar13

       The last thing we needed was extremely cold weather during the second weekend in March.  It would not have been so bad if one of the coldest days of the winter had not followed days upon days of temperatures hovering in the 70s and 80s. However, when I awoke on the morning of Sunday, March 13 the thermometer at my house read 24º F.  Not only did the late winter freeze threaten plants that had already begun blooming and/or sprouting leaves, it also endangered the lives of many birds.

       When the nighttime temperature drops this low untold numbers of birds face a life and death struggle to survive. A factor that often determines whether a bird survives to see the light of dawn is whether it is able to spend the night in a site that offers insulation from cold winds and low temperatures.  The warmer the site, the less energy it needs to burn simply to stay warm.

       For example, one of our common winter residents is the American goldfinch.  This gregarious bird roosts in dense vegetation.  If they are fortunate enough to roost is a location where the foliage and branches form a thick barrier against the wind and cold, they will burn about a third less energy than they would have expended had they been forced to roost in a more open site.

      All to frequently during extremely cold, windy weather birds roosting in unsuitable roost sites will literally starve to death during the night. For this reason, when you are trying to transform your yard into a haven for wildlife, do not overlook supplying your feathered backyard neighbors an abundance of suitable winter cover.

     Cavity nesting birds such as woodpeckers, nuthatches, Carolina chickadees, tufted titmice, and eastern bluebirds roost in natural cavities, nesting boxes, and roosting boxes.  The problem is, in most locales, the demand for these precious sites far outstrips their availability.

       The situation is often more dire for birds that roost in dense vegetation and brush piles.  The roster of these birds includes mockingbirds, yellow-rumped, and pine warblers, kinglets, sparrows, cardinals, dark-eyed juncos, blue jays and many others.  These birds roost in places such as evergreen shrubs and trees, as well as dense thickets and even brush piles.  Such sites are either woefully missing or in short supply in many neighborhoods.  Just a handful of these plants serve as safe havens for dozens of roosting birds. 

       Facing a paucity of places to escape the cold, birds will often attempt to find refuge in some odd places.  For example, when my daughter took the dog out a few hours after midnight on the 13th, she flushed a yellow-rumped warbler that had found refuge in the welcome wreath hanging on her front door.  Birds have been found roosting in other places such as inside open garages, barns and other buildings, above security lights, and on the limbs of Christmas trees.  

     A few of the native plants that address this need are red cedar, viburnums, wax myrtle, American holly and pines.

    With that in mind, if your yard lacks enough roosting cavities and/or evergreen trees and shrubs, make a point to add them to your landscape before our next cold front sweeps down from the north bringing with it freezing temperatures.  Hopefully, that will not happen until next winter.

    If you are looking for plans for a roost or nesting box, contact Melissa Hayes at the Georgia Wildlife Conservation Section (melissa.hayes@dnr.ga.gov).

IT IS TIME TO REMOVE VINES AND TALL PLANTS GROWING NEAR NESTING BOXES

Feb20

        Before we know it, spring will be here, and birds will be nesting in the nesting boxes we have erected for them.  Among the chores we all need to tackle in preparation for this year’s nesting season is trim back the vines, saplings and shrubs growing close to each of our nesting boxes.

       One of the main reasons why this should be done is it helps protect the birds nesting in our boxes from arboreal snakes (those that climb trees).  Snakes such as the rat snake are capable raiding nesting boxes erected on poles.  For that reason, it is always best to mount nesting boxes on poles equipped with predator guards.  However, even the best predator guards cannot protect a nest if vines encircle the pole or tall vegetation is growing nearby.  Such plants create a veritable superhighway for snakes trying to raid a nesting box.  Even if vegetation is not actually touching a box or pole, a snake can circumvent a predator guard and gain access to adults, eggs and/or young birds by simply climbing up nearby vegetation and then extending their body the distance between their head and the box.

       For this reason, we need to make every effort to cut back tall vegetation in a wide circle around each nest. While we are creating this protection zone, any branches growing close to the top of the box should also be trimmed away.  Snakes are also capable of using a canopy of branches to gain access to a nesting box.

       Taking a little time to perform this simple task can give the birds nesting in our boxes a better chance of being successful.

 

 

A NOVEL WAY TO KEEP FIRE ANTS OUT OF NEST BOXES

Feb16

       Here in Georgia fire ants can threaten birds that nest in nesting boxes.  These pesky ants will enter nesting boxes and actually kill hatchlings.

       Several decades ago Jackson, Mississippi resident R.B. Layton came up with a novel way to keep these dreaded imported insects from reaching his nesting boxes.  Layton soaked either wood thread spools or sweetgum balls with the oil additive STP and placed them between the boxes and the poles that held them aloft.  Supposedly, this formed a barrier over which the ants would not pass.

       If you decide to try this technique, since thread now comes on plastic spools, you will have to find them at a craft store.  They are available in a variety of sizes.  I would imagine that you need to buy spools that are unpainted; an unpainted spool would probably retain more STP than those that are painted.  As for sweetgum balls, they can be located beneath sweetgum trees across the state.

       Since I have never had a problem with fire ants entering my nest boxes, I have never tested this technique.  However, if you try it, I would love to know if it worked for you.

BLUEBIRDS NEED WINTER ROOST SITES

Nov3

        Since the weather has abruptly changed from being more like autumn than summer, my wife and I have been seeing eastern bluebirds inspecting some of our nesting boxes.  I am certain the birds are not checking out potential nesting sites–it is much too early for that.  The birds may be just curious, or perhaps the onset of cold nights has triggered a search for suitable roost sites.

       In addition to the bluebird, a number of familiar backyard birds also roost in cavities and nesting boxes including screech owls, woodpeckers, tufted titmice, brown-headed nuthatches, and Carolina chickadees.  In the case of the bluebird, they typically roost alone in warm weather.  However, when temperatures dip below freezing, a cavity or nesting box might harbor anywhere from a couple to more than 20 bluebirds. 

       The advantage of nesting together is the birds share their body heat.  During an extremely frigid night, the additional heat offered by a group of roosting birds may spell the difference between life and death.

       With that in mind, as we enter the harshest portion of the year, keep an eye on your nest boxes.  There is a good chance one more bluebirds or other cavity-nesting birds are roosting in a box erected to provide a place for them to nest.

       The best times to look for such activity is late in the afternoon when the birds are going to roost, or first thing in the morning when they are leaving for a day of foraging.

       You can also peek inside a box.  If you see some downy feathers scattered about the bottom of a box, chances are birds are roosting there.

BLUEBIRD BOX COLOR IS IMPORTANT

Mar30

        Cavity nesting birds have a difficult time finding a place to nest.  In fact, there simply aren’t enough suitable cavities to meets the needs of the birds that need them.  Throughout Georgia a wide assortment of birds nest in tree cavities including the eastern bluebird, Carolina wren, house wren, house sparrow, tree swallow, European starling, purple martin, barn owl, tree swallow, screech owl, great crested flycatcher, Prothonotary warbler, and wood duck.  In an attempt to offset the shortage of natural cavities, for more than eleven decades folks have been building and erecting nesting boxes.  Beyond a shadow of doubt more nest boxes have been built for bluebirds than any other species. They have been so successful they have played a large part in the recovery of this beautiful bird.

       While the majority of bluebird nesting boxes look pretty much the same, some provide better nesting sites for the birds than others. Often the only thing that determines whether or not a box is better than another is its color.

       Bluebird nesting boxes are painted in a rainbow of colors. In fact, I once saw a black bluebird nesting in a blue bluebird box. I would like to know how many red and black See Rock City have been erected across the south. Some folks paint nesting boxes in the colors of their alma mater or favorite football team. Others leave boxes unpainted. With this bewildering array of colors to choose from, you might be wondering what works the best. In truth, bluebirds don’t seem to show a preference for any color.  However, studies have shown that year in and year out more bluebirds fledge from boxes painted certain colors over all others.   Let’s take a look at what’s best for the birds and your pocketbook.

      Most store-bought bluebird boxes are unpainted.  Typically, they are made from finished pine boards.  If you take such a box home and hang it out without doing anything to it, chances are it will rot in a season or two and end up lying on the ground. Consequently, if you want the box to last a lot longer, coat it with a good quality exterior paint or stain before you put it up.  When you treat a box in this manner, it will last several years.  With most bluebird boxes costing anywhere from $10-$25 or more, this is a significant savings.

       However, boxes made from cypress or cedar should not be treated. These woods naturally resist decay.  It is not unusual for a well-made cypress box to last up to 25 years.

       Here in the South, it is best to paint boxes a light color.  Any light color is suitable. Bluebirds don’t care if a box is white, gray, light pink or pale blue.  However, whatever you do avoid using dark colors.  The reason for this is simple, pastel colors absorb less heat than boxes coated in dark colors.

       Here in the Peach State during the spring and summer (the bluebird’s nesting season), the thermometer often soars above 90°F.  However, when air temperature reaches only 87°F, the temperature inside a nesting box painted a dark color can soar to 107°F or more.  When eggs are exposed to such intense heat, developing bluebird embryos can be killed.  Bluebird eggs seem to develop best when temperatures inside a box are no higher than 99°F. 

       When painting a box, I prefer using an oil-base exterior paint. You will find it will last longer than other exterior paints.  I ALWAYS avoid lead-based paints since there is always the potential that birds and other wildlife can ingest paint chips containing lead.

       It is always best to paint a box before it is erected. Use a medium-sized flat brush. Apply at least one coat of paint to all exterior surfaces. If the bare wood absorbs a lot of paint, apply a second coat.  I would recommend that you apply 3 or more coats of paint to the back of the box. Since this surface will be in direct contact to a tree, post, or metal pole, as such it will be exposed to water much longer than the other surfaces of a box.  The extra paint provides an added barrier to water.

       Under no circumstances should you paint the interior of box or its entrance hole. In fact, I recommend that you avoid using spray paint since there is always a possibility that paint can be accidentally sprayed inside the box.

       Isn’t it amazing how a little dab of the right color paint can be so important to such a gorgeous and popular bird?

SHOULD I CHECK MY BLUEBIRD BOXES?

May2

       With bluebirds now nesting across the state, I am often asked, “Should I check my bluebird boxes?”  When this question is posed I always tell folks that, if it done properly, checking bluebird nesting boxes can actually be beneficial to the birds.  Let me explain.

       Unlike many birds, the eastern bluebird is more tolerant of human activity around their nests than many other birds.  This tolerance allows the close monitoring of the success of the birds’ nesting efforts.  By so doing we can help thwart situations that can lead to the failure of a nesting attempt. 

       For example, we can keep house sparrows from taking over a box by tossing out the sparrow’s bulky nesting materials.  If this is done enough times, the aggressive, unprotected, invasive house sparrows will finally give up and leave the box alone.

       (Never remove the nest of a native cavity-nesting bird.)

       Also, wasps will occasionally attempt to build a nest on the underside of the top of a box.  If wasps are allowed to build a nest inside a box, bluebirds will abandon it.  With that in mind, if you find a small wasp nest, remove it. 

       If you plan to monitor a box, make sure the box can be easily opened.  Too often boxes are made in such a way that the box cannot be opened from the top or side.

       Make every effort to make nest box checks as brief as possible.  In addition, it is always best to check boxes when temperatures are mild, winds are calm, and it is not raining.

       Checks can be safely performed weekly up until the hatchlings are 12 or 13 days old.  Checks made after that time can result in the youngsters prematurely bailing out of their nests.

       If you monitor you boxes on a weekly basis, you will know when a nest is built, when a female lays all of her eggs (females lay one egg a day until the clutch is complete), incubation has begun, the approximate age of the hatchlings, and how many young bluebirds successfully fledge.

       Here are some facts that will help you understand what you will be observing.  Typical clutch size is 4-5 eggs; Incubation lasts 12-14 days; Time of fledging: anywhere from 17-21 days.

       The North American Bluebird Society recommends the nest be removed after the young fledge.  If a bluebird wants to use the box later, a new nest will be constructed in short order. 

       However, dispose of the old nesting materials some distance from the nest site.  This will help keep potential predators from discovering the location of the nest.

       Keep in mind, eastern bluebirds will nest up the three times a year.

       If you have additional questions about checking, please let me know.