Monday, June 15, 2015

Purple Martins 2015

By Beth Sullivan
Those of you who have followed this blog for the past years know that I am the grandmother to a nice colony of Purple Martins on Knox Preserve. Actually I share custody with all of Avalonia, but as the landlady and nest checker, I feel pretty possessive.

Purple Martin condominiums 

In 2013 we erected one super gourd system. You can read that post here. We applied for a grant through Audubon CT, and they were eager to help us establish a colony on our perfect coastal site. Martins need open space and fields around, necessary for catching all the aerial insects that make up their diets. They also like to be near a water source as they will use mud in their nests. Ponds and wetlands also attract insects to feed hungry young. They also want to be near people! It is the only species of bird that truly depends on humans now to provide nesting sites. We placed the first set of houses close to a couple of homes and a barn and also close to a neighbor’s exiting colony of Martins-a recipe for success! From that season forward we have hosted increasing numbers of pairs of Purple Martins which are species of concern here in CT as their numbers have greatly diminished. Last year we added a second set of gourds, also funded by Audubon CT, and we doubled our real estate offerings and our residents.
Adults do not mind disturbance and seem to enjoy watching our activities.

This year I have had some challenges. Non-native and aggressively invasive House Sparrows have invaded the colony. Each time I lower the nests to check on them, I remove large messy wads of grasses that entirely fill the cavity. As they are considered a danger to the nesting success of several species of native birds, the House Sparrows are not protected by federal laws as our native birds are. Martin Landlords, as well as those that monitor Bluebird houses, are encouraged to remove nests and prevent any future generations of House Sparrows. This species is known to not only take over good sites, but also aggressively fight native birds such as Martins, Bluebirds and Tree Swallows, remove eggs, kill nestlings, and even kill adult birds on the nests. Then they just create their own nest right on top!
A perfect view for a Purple Martin, fields full of insect habitat and open sky.

Martins return home

Martins are quite tolerant of human interactions and frequent nest checks do not disturb them. Frequent checks help keep an eye on the stages of nesting and egg laying and anticipate hatching dates. This year we had two pairs of more mature birds arrive early, one even sporting bands indicating he was born at this spot probably in 2013. They got right down to nest building, and their eggs were already present when I checked on May 28. That means that they will be hatching probably by the time this is posted!
Purple Martins are often found near people and their buildings.

Other pairs are taking their time. The nests are created using the base of pine needles I had provided. They don’t add much other material. Just before they begin to lay eggs, they bring in many green cherry leaves which are believed to help chemically deter mites which can be harmful to nestlings. Eggs are laid, one a day until the clutch is complete, and then the female begins incubation and they all hatch on the same day.
By the time this is posted, we will have hatchings.

Right now we have 9 active nests with 46 eggs. But there are four more lined with green leaves! Our hatching dates will span from June 13 to possibly later than June 23rd. I will keep checking, keep records, and let you know how things progress and when the DEEP will come to band them.
The green leaves are placed in the nest right before egg laying.

Photographs by Beth Sullivan

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