It is prime time to look for bird nests now that leaves have fallen and heavy winter snow has not arrived. Nests such as this Mourning Dove nest are visible and still in fairly good condition. Much can be learned from examining the habitat, exact location, size, shape and construction material of these avian nurseries. But the nests must be left where they are, for possession of not only a bird, but of a bird nest, egg or feather of most migratory birds, even for scientific research or education, is illegal if you do not have a Federal Migratory Bird Scientific Collecting Permit.
Ninety-seven years ago the Migratory Bird Treaty Act (MBTA), one of our oldest wildlife protection laws, was created. Basically it is a law that protects birds from people. It was made in response to the extinction or near-extinction of a number of bird species that were hunted either for sport or for their feathers. According to the United States Fish & Wildlife Service (USFWS), “The MBTA provides that it is unlawful to pursue, hunt, take, capture, kill, possess, sell, purchase, barter, import, export, or transport any migratory bird, or any part, nest, or egg or any such bird, unless authorized under a permit issued by the Secretary of the Interior.” A list of the species this law pertains to can be seen at http://www.fws.gov/migratorybirds/RegulationsPolicies/mbta/MBTANDX.HTML.
Not all North American bird species are protected under the MBTA. (Passenger Pigeons were not protected, and they no longer exist.) Birds that are considered non-native species such as the House Sparrow and the European Starling are not protected, and many hunted or game birds, including ducks, geese, doves, and many shorebirds are subject to limited protection and can be hunted in season.
The U.S. Fish and Wildlife Service is currently working on strengthening this bill to better protect birds from modern-day threats (windmills, cell phone towers, etc.). According to USFWS estimates, power lines kill up to 175 million birds a year. Communications towers account for up to 50 million kills, and uncovered oil waste pits account for up to another 500,000 to 1 million deaths. Data on wind turbines are harder to come by, but current estimates are around 300,000 bird fatalities a year. A number of companies in the oil and power-line sectors have already developed and implemented best practices to protect birds. Let us hope that this trend continues.
The mournful lament of the male mourning dove is often one of the first songs heard in the early spring. The frequency of this call builds to a peak from mid-May to mid-June. As in many other pigeons and doves, the Mourning Dove’s main call, or “perch coo” (coo-oo, OO, OO, OO) is an advertising call, sung in order to attract a mate. Unmated males often establish perches within their territory from which they repeatedly sing.
A shorter nest call is used by a paired male to attract his mate to a potential nest site. The male then gathers nesting material and presents it to the female while standing on her back. While she constructs the nest, he continues to use the nest call to maintain a bond with his mate. Once the nest is built, this call diminishes. You can hear Mourning Dove calls at http://www.allaboutbirds.org/guide/mourning_dove/sounds, although to my ear, it’s hard to distinguish the perch call from the nest call in these recordings.
Seeds, including cultivated grains, grasses, weeds and berries, make up 99 percent of a Mourning Dove’s diet. Because they can find enough food to sustain themselves, Mourning Doves are permanent residents, remaining year round, even in northern New England.
These birds feed on the ground and in the open, consuming 12 to 20 percent of their body weight per day, or 71 calories on average. Mourning Doves swallow the seeds and store them in an enlargement of the esophagus called a crop. Once their crop is filled (the record is 17,200 bluegrass seeds in a single crop), they can then fly to a protected area where they can safely digest their food.
As opposed to humans, who use the entire bottom of their feet for support, birds stand and walk only on the ball of their foot and with their toes. When you look at a bird’s leg, what appears to be its knee, bending backward instead of forward as it does in humans, is actually its heel.
Most birds have four toes, arranged differently according to the life style of the bird. Songbirds, as well as most other birds, have three toes pointing forward and one pointing back. Most woodpeckers, being active climbers, have two toes pointing in each direction, which provides added clinging support. The outer toe (of the three forward toes) of ospreys and owls is reversible, so that they can have two toes in back should they need to get a better grasp on slippery fish or other prey. Some birds that do a lot of running, such as sanderlings and most plovers, have only the three forward toes. (Photo: Mourning Dove tracks)