Purple Martins are colonial cavity nesting swallows. Native Americans fist attracted martins to artificial houses (gourds) and began a long relationship between Purple Martins and humans. Now the martins are completely dependent on the houses that human landlords put up.
Martin populations have been declining since the mid-twentieth century due to competition for nest sites from more aggressive non-native House Sparrows and European Starlings. In Connecticut the bird was state listed as threatened.
Since 2005 Menunkatuck Audubon Society has been monitoring the two Purple Martin colonies at Hammonasset Beach State Park, one at Chase Pond (Swan Pond) with five houses and 76 compartments and one near the Meigs Point Nature Center with three houses and 48 compartments. In 2009 we installed a martin house at the Guilford Salt Meadow Sanctuary hoping to establish another colony and in 2016 five martin pairs successfully nested. Since then the colony has grown to two gourd racks with 48 compartments. We are now trying to begin another colony at West River Memorial Park in New Haven with a gourd rack installed in 2018.
Purple Martin monitoring involves frequent checking on the nest cavities. House Sparrows and European Starlings are discouraged from using the cavities by removing their nests. (The Migratory Bird Treaty Act which protects all native birds in the North America permits removing the nests of non-native birds.)
As we learned lessons from the monitoring, new techniques were employed to compensate for the condition which occurs when one or more of the chicks is significantly smaller than its nest mates. For example, if six eggs are laid over the course of six days, many times not every egg will hatch on the same day. This is known as asynchronous hatching.
As with most behaviors there are both advantages and disadvantages. One advantage is that if adverse weather were to occur during the time the eggs are hatching or brooding, some of the chicks may perish while others are still protected within the egg. The disadvantage is that the last chick to hatch can be at a serious disadvantage when it comes to competing for food with nest mates that are one or more days older. In the most extreme examples of varying development within a brood of chicks, some chicks are transferred to a different nest cavity with chicks that more closely matched their weight as a temporary foster home.
Depending on their rate of growth, sometimes the adopted chicks are returned to their original nest mates or other times they would stay with their foster family. Fortunately, Purple Martins don’t seem to be bothered by one more hungry mouth to feed for newly introduced chicks.
Using this new technique, we are able to decrease the number of martins that would have certainly died during the nestling phase for no other reason than they were in the last egg that hatched and were not able to compete with their older nest mates. This results in an increase in the overall number of martins that fledge.
These efforts and the work of other Purple Martin landlords in Connecticut has resulted in the DEEP down listing them from threatened to special concern.