For those who are bluebird landlords, it's time to prepare properties for the migratory tenants.
Early nesting behavior among eastern bluebirds that call our region home is ready to break out nowadays. Bluebird couples will be home shopping any day now if they haven't started already â “ picking out new quarters or checking on previously used facilities for nesting purposes in coming weeks.
Folks who have bluebird nesting boxes placed from past seasons consequently should do a clean-out to ready them for the occupants they hope to serve this year. People who'd like to get into hosting bluebirds should get their hands on appropriate boxes right away and get them placed where they ought to go as soon as possible.
Bluebird boxes are not just a novelty. They can add to the bluebird population by providing a real helping hand. It takes a little history to see that.
Research and biology suggests that bluebirds were probably as plentiful as, say, robins during times of early North American settlement. But people unintentionally started stacking the deck against bluebirds as early as the 1800s.
A brutal blow was dealt by the importation of non-native house sparrows and starlings from Europe. Both have no natural checks and balances in America, and they compete directly with bluebirds.
As America grew up, we started cleaning up and eliminating bluebird habitat. Bluebirds are secondary cavity nesters, using holes gouged out of trees (by woodpeckers mostly) and naturally formed cavities in dead trees, etc., in which to house their nests and raise broods of young. They nest along fields, meadows, lawns and any sorts of open areas where they gather insects that make up the biggest part of their diet.
People eliminated standing dead trees as a matter of clearing and property development. Eliminating cavity sources and the edge type habitats for human housing and commercial developments knocked out places for bluebirds to reproduce. Later, the elimination of many fence rows and the conversion from wooden fence posts to metal ones in the fence rows that remained rubbed out many more likely nest spots.
Increasing use of pesticides in modern times seems to have been another deadly factor. DDT alone (finally banned in 1972) may have been major in pushing the bluebird population to a perilously low level.
After everything else, those severe winters of 1976-77 and 1977-78 â “ extreme cold and lots of snow and ice â “ killed off many of the struggling survivors.
It's said that by the 1980s, many people under the age of 40 had never seen a bluebird. In those days, bluebirds were pretty scarce.
DDT had been banned, and nature was trying to flush those poisonous effects away. But concerned people stepped in and invigorated the movement of placing bluebird nesting boxes to provide spaces in which the birds could raise young. Often, these nesting boxes provided the only suitable nesting sites in areas that otherwise offered suitable bluebird habitat.
Multiplied many times over, man-made bluebird boxes began having a real effect. Lots of people put out lots of boxes. And with nesting habitat restored to places otherwise void of it, bluebird numbers turned around and over the next 30 years or so relatively proliferated again.
Workable, safe-for-tenants bluebird boxes come in a variety of designs. They can be obtained ready-made or plans for building your own are abundantly available. (For a few versions, see the North American Bluebird Society website www.nabluebirdsociety.org.)
Keys to a good box include an entrance hole that's not so big as to allow or encourage house sparrows or starlings to enter (and destroy eggs or kill bluebirds, which they will do if possible). A round, 1Â½-inch hole is preferred by many. An oval hole 2Â¼ inches high by 1 3/8 inches wide is recommended by others.
The hole should not be accompanied by a perch. Bluebirds don't need one. And a perch is prone to attract house sparrows and/or starlings.
A nesting box should be vented in the upper portion to reduce heat build-up that can kill nestlings. Insulation to reduce heat transfer is a plus. Placement in a partially shaded location is best.
A roof to deflect the rain â “ but a drain hole in the floor to let out any influx of precipitation â “ is important to nestling survival.
A predator guard like metal flashing on a mounting pole or tree trunk location will help to prevent lethal access to the nest and nestlings. Slithery predators like rat snakes or bigger critters like raccoons will get at eggs or chicks if they can.
Location is much of the deal in real estate, and it's likewise crucial in bluebird real estate.
The nest box should be no closer than 100 yards from another box or active bluebird nest or the neighboring birds will clash territorially.
A bluebird nest box should be located in or adjacent to an open area, preferably a sizable one, for best food-gathering habitat. The box itself should be placed relatively low â “ four to six feet is plenty high.
Done right and placed appropriately, a nesting box has good prospects to attract bluebird tenants that will raise youngsters there. Thanks in large part to these human-offered boxes, bluebirds are back in business.
If you haven't seen one, you're not looking in many of the right places.
Steve Vantreese , a freelance outdoors writer, can be contacted at firstname.lastname@example.org.
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