By Scott Shalaway
For The Register-Herald
While I was perusing the notes on the Pa-Birds list serve last week, a subject line from Feb. 17 caught my eye. It was posted by a friend of more than 20 years, and it read, “My annual dove!”
Kermit Henning of Mechanicsburg, Pa., a town located just west of Harrisburg, reported that for the fourth consecutive year, he had an active mourning dove nest in his carport. Furthermore, Henning wrote that the nest contained two eggs Jan. 15. In a recent phone conversation, Henning told me the eggs had hatched about a week ago.
“I can’t be certain it’s the same female because she isn’t banded,” he told me, “but a dove has nested at eyelevel just a foot from the back door in my carport for four years now. In 2010 she raised five broods, and last year she raised six.”
According to the online edition of The Birds of North America, mourning doves typically live about one year, so Henning’s bird is either getting old, or perhaps one of her kids or grandchildren continues to use the carport. Birds often return to the area where they were hatched, so it’s not unreasonable to think that the carport has become a family tradition. On the other hand, I did find one record of a wild mourning dove living more than 19 years, so it’s possible this female has lived four years.
Henning’s backyard is surrounded by mature conifers, a preferred nesting habitat for mourning doves. “I guess she likes the protection the carport provides,” Henning said. “Whenever I walk by, she sits tight and watches me. The nest itself is protected from wind, rain, and snow. It sets between two mallard decoys on top of a shelf. In 2009, the nest was on top of a ladder.”
Nesting close to the house also may ensure protection from predators. Average mourning dove nest success ranges about 35 to 60 percent, but so far every nest in Henning’s carport has been successful. And he said about one-third of the nests have contained three eggs rather than the typical two.
I asked Henning how long the nesting season lasts for his carport dove. “It’s usually been late October or November when she fledges the final brood,” he said. That means, if the same female is responsible for all these nests, she gets about eight weeks each year free from nesting responsibilities. I doubt that few tropical species keep this busy.
Near year-round nesting by mourning doves is not unusual in southern latitudes. From the Gulf coast to southern California, doves often nest year round. However, an active nest in central Pennsylvania in mid-January seems almost miraculous.
Normally the first birds to nest are great horned owls and bald eagles. Great horns are usually incubating eggs by late January, and bald eagles follow shortly thereafter. These large predators time their nests so the eggs hatch just as young cottontails and migrating ducks and ice-free water become available to feed the nestlings.
Mourning doves cope with feeding their nestlings by regurgitating “pigeon’s milk,” which is sometimes called crop milk. Adult doves eat primarily seeds. As incubation comes to an end, both sexes manufacture a nutritious milky liquid in their crops. Fatty cells slough off the inside of the crop and are fed exclusively to nestlings for the first five or six days after hatching. Thereafter, the “milk” is mixed with an increasing amount of seeds as nestlings transition to an adult diet.
At higher elevations in coniferous woods, pine siskins nest in late winter when there is a bumper crop of conifer seeds. Siskins build well-insulated nests, and females incubate almost constantly. The male brings her food so she rarely leaves the nest to allow the eggs to cool.
But most song birds wait for longer, warmer days to nest. This coincides with the emergence of protein-rich insects, spiders and other invertebrates, which most birds feed their nestlings.
If you have any active bird nests right now, I’d like to hear about them. Egg and hatching dates would be especially useful. My earliest backyard nesters are usually Carolina wrens in early March.