Each year, purple martin “landlords” anxiously await the loud, throaty chirps and rattle songs of purple martins (Progne subis). That includes our bird team here at the Smithsonian Conservation Biology Institute in Front Royal, Virginia. It means the birds have returned from their South American wintering grounds!
Purple martins are important native birds that help control insect populations by eating bugs. They have experienced a steady decline over the last several decades due to the widespread use of pesticides and competition from invasive species. But dedicated purple martin landlords have likely slowed the rate of this decline by helping the birds thrive during the breeding season.
Martins make their way to Virginia in mid-March and start nesting in May. In preparation for their arrival, we clean plastic nest gourds and hang them on metal nesting tree racks. We also set up predator safeguards to deter raptors and snakes. The first birds to arrive are often called “scouts.” Contrary to popular belief, they are not sent ahead to scout nesting sites on behalf of their group. Scouts are simply older birds returning to the places where they successfully nested before.
This year, our first scout (a lone adult male) arrived March 25. Over the next few weeks, 180-200 more birds moved into the colony at the center of our campus. The colony has 108 nest cavities and was first erected in the 1980s by Smithsonian biologist Gene Morton, who led many research projects on martins over the years.
In 2018, we set up a second purple martin tower with 24 more nest cavities. This smaller colony is about 2 miles east of the first, in an area of SCBI that houses rare and endangered ungulates (hoofed animals), like Persian onagers and Eld’s deer. It can take anywhere from a few days to a couple of years to attract martins to new housing, and no birds moved in for the first few years.
Hoping to attract them this year, we added a “dummy” bird (a plastic bird that looks like a purple martin) and played recordings of purple martin calls. Purple martins prefer to nest together, so the dummy bird and songs entice young martins flying by to stop in and investigate the housing. On April 21, we finally had our first arrival. A few more young martins soon followed. We hope these 12 birds will return next year — and bring some friends along with them!
We monitor our purple martins from their arrival in March through the end of August. We check all 132 nest cavities once a week to record signs of nests, the number of eggs laid and how many chicks hatched. Martins can have up to seven eggs in a clutch, laying one egg every 24 hours. The chicks hatch after about 15 days, and both parents feed them for four to five weeks until they fledge (leave the nest).