Purple martins, the largest of the swallows in North America, are totally dependent on man-made housing and faithfully return to the same locations each year, so it's understandable that human "landlords" anxiously await the return of the birds from wintering grounds in South America.
Purple martins, the largest of the swallows in North America, are totally dependent on man-made housing -- often a rack of gourds or multi-compartment birdhouse --- and faithfully return to the same locations each year from wintering grounds in South America.
It's understandable that human "landlords" anxiously await their return. Reports of "scouts" with dates/locations are made almost daily on an online data base (purplemartin.org) maintained by the Purple Martin Conservation Association, a nonprofit conservation organization.
The earliest reported purple martin this year was in East Prairie on Feb. 25. A martin had returned to Boonville by March 1 and to Joplin by March 12.
While purple martins begin returning to Missouri after about March. 1, migration is drawn out. Most new arrivals are not seen in the northern half of the state until after about April 1.
The first wave consists of senior martins -- three or more years old -- followed in a few weeks by two-year-olds. Martins two years or older are called "adults," with adult males sporting full dark-purple color. Females are a bit drab, with a gray breast.
One-year-old martins -- called "sub adults" -- arrive 10 to 12 weeks later than the older birds. These younger birds -- males lack full purple dress -- are more easily attracted to new housing locations, which they may not choose until early June.
The term "scout" actually is a misnomer. These are simply older experienced birds that are eager to reclaim their housing.
Some arrive dangerously early and may perish when cold temperatures clear the air of flying insects.
Fortunately for the martins, some landlords today offer supplemental feeding of thawed crickets, live mealworms or even small bits of scrambled eggs flung into the air from a plastic spoon and placed on elevated platforms and in compartments.
Purple martins prefer to nest in colonies in housing offered in open yards.
As a species, purple martins are relatively common throughout Missouri, with the greatest numbers found in the southern half of the state, according to North American Breeding Bird survey.
A few Missouri colonies host more than 100 pairs each season -- a number hobbyists often refer to as a "super" colony.
The PMCA recently analyzed long-term data from the North American Breeding Bird Survey, which has maintained records dating to 1966, and found that -- thanks to devoted men and women who erect and maintain housing -- purple martin populations overall are holding steady in North America. Purple martins are declining in two border states -- Illinois and Iowa -- but appear to be stable in Missouri.
Most urban residents lack the necessary open space to successfully erect purple martin housing, but not all martins are rural birds.
Thriving colonies have recently been established in Forest Park, in the St. Louis area, and rebuilding of colony sites is under way, with new housing erected at the nearby Missouri Botanical Garden, a haven for the creatures..
But attracting purple martins to new housing isn't always easy. Even in areas that where the birds are present, many people may try for years without success, or their colonies disappear.
Hobbyists may be unaware that problems such as competition from invasive non-native birds -- European starlings and house sparrows -- or predation from raccoons or rat snakes caused abandonment.
While generations of Missourians have hosted purple martins -- the custom adopted from Native Americans who hung out nesting gourds -- specific techniques to help a colony thrive emerged in the past decade, based on research conducted by the PMCA and landlords in the field.
Among innovations are: deeper compartments to protect nestlings from rain and aerial predators such as owls; specially-shaped entrance holes designed to admit martins while excluding starlings; and special pole guards to thwart rat snakes and raccoons.
Because purple martins are birds of the open sky -- catching insects on the fly -- the PMCA's number one tip: place housing in the most open space available, but where the colony can be enjoyed and monitored.
More information about purple martins can be obtained from the Purple Martin Conservation Associa-tion online at www.purplemartin.org.