In the birding world, few species generate more excitement than the Purple Martin, the swallow that is now arriving in Tennessee. How do we know this? Because a devoted community of scouts including those in southern, middle Tennessee log in daily to report sightings.
Purple martins, the largest of the swallows in North America, are totally dependent on man-made housing east of the Rockies and faithfully return to the same locations each year, so it’s understandable that human landlords anxiously await the return of their birds from wintering grounds in South America.
Some of the earliest arrivals to Tennessee trickle in by late February, and dates/locations are watched by martin enthusiasts nationally on an online database (www.purplemartin.org) which is maintained by the Purple Martin Conservation Association (PMCA), a nonprofit conservation organization.
The earliest arriving martins recorded in Tennessee this season flew in on Feb. 17 in Adamsville and in South Pittsburg. Among other early arrivals were Walnut Log on Feb. 23 and Knoxville on March 3.
The first wave of arrivals consists of so-called adult martins – those two or more years old – 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 six to eight weeks later than the older birds – well into May. These younger birds sometimes are more easily attracted to new housing locations.
Purple martins prefer to nest in colonies in gourds hung from large racks and in multi-compartment birdhouses. The birds nest throughout Tennessee with the greatest populations west and central, with substantial but fewer colonies in the mountainous east.
Purple martins feed on the wing – taking insects from the air – and early arrivals sometimes face the prospect of starvation when cold snaps clear the air of insects. However, hobbyists have learned to supplemental feed purple martins during cold spells.
Information about supplemental feeding – the techniques are still new to many hobbyists – can be found on the website. Although once believed improbable, it’s been shown that purple martins – when no other food is available – will learn to accept crickets, mealworms and even bits of scrambled eggs flipped high into the air or placed on high platform feeders or inside nest compartments.
The PMCA recently analyzed long-term data from the North American Breeding Bird Survey (BBS) and found that – thanks to devoted men and women who erect and maintain housing – purple martin populations overall are holding steady in North America – with exceptions in some states – and appear to be slowly increasing in Tennessee.
A rural Amish community, Ethridge in central Tennessee, may well have the most martins in the state, with colonies located on many of the farms, as well as in many yards in nearby Lawrenceburg.
Purple martin colonies can be found in several Tennessee parks and nature reserves, including Warner Parks Nature Center and Shelby Bottoms Nature Center in Nashville, and Lichterman Nature Center, Memphis.
Sighting have already taken place this year in Tullahoma, Decherd, Wartrace, Pulaski and Lawrenceburg.
Purple martins gather in massive roosts in late summer in preparation for fall migration. One of the largest in North America is on an island in Dale Hollow Reservoir, which straddles the Tennessee, Kentucky line. Some martin enthusiasts who have visited the roost believe it may contain upwards to 100,000 birds in early August.
The roost can be viewed at sunset – when massive numbers of the birds descend into the trees – from Lilydale Campground. Nearby Willow Grove Resort also hosts a large colony in traditional wooden houses.
Despite relative abundance of purple martins in Tennessee, many people try for years to attract them 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 caused abandonment.
While generations of Americans 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 restricting starlings – and unique pole guards to thwart climbing predators: 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 Association – which is focused on aiding martins and landlords – including an information and supplies booklet, with advice on attracting and managing a colony, and data sheets to participate in a citizen science program called Project Martin Watch, a national effort in which participants monitor nests and mail information to the PMCA at season’s end.
To obtain the booklet, contact the PMCA at (814) 833-7656 or online. The website also has an active forum, and many hobbyists participate in the group’s Facebook page.