Monday, July 15, 2019

Purple Martins 2019

By Beth Sullivan
This is our sixth year monitoring and stewarding the purple martin colony at Knox Preserve. I always start off the year with so much optimism and high hopes. The season started out great, with reports of scouts in the area as early as April 11th. We took the hint and got the first set of gourds up on April 14th. There were birds on the pole as soon as we pulled up the gourds. The second set went up soon after. The first days and weeks are all about scouting, with mature birds returning first, to territories they are familiar with and often taking first choices on their nest sites. We were enthusiastic and guardedly hopeful.
The adult males are usually the first scouts and arrive early to stake out their favorite spots.

Nests are complete with a cup of green leaves ready for the beautiful eggs.

A wet Spring

Those last weeks in April and early May were really wet. It was cloudy, cooler than average with frequent rain, and often even when it wasn’t raining, it was foggy and damp. That was not good. The insects that are the staple of the martins’ diets were not flying. Martins tend to feed at higher altitudes than other birds so maybe those closer to the ground and tree tops were doing ok, but the high flying dragonflies and butterflies were just not there. This had at least two bad effects. Many martins simply kept moving north. If it was too cool and damp at the shore, apparently inland sites were more acceptable, so they settled there. Lack of food weakened the birds, and their attempts to find mates, make nests, and establish themselves were less than successful in many cases.
In mid-May I like to try and check the gourds, to see if there is sign of nest building. This is simply extra material added to the pine needles I supplied. I was happy to find several enhanced nests and see birds in the area. However, we also found a pair, dead, inside one of the gourds. The female was actually banded and identified as one who had been born there at Knox several years earlier. When I reported to DEEP, they confirmed that it was likely due to the cold and wet. They likely had taken shelter together in the gourd and just starved. I was devastated.
Over the next weeks we watched and waited. The weather improved. A number of the gourds were filled with nesting material, but not nearly as many as in previous years. One sign I always look for is the addition of green cherry leaves to the central part of the nest. There are several thoughts about why the birds do this. Some believe they are insecticidal and deter mites. Out of our 24 gourds, we had 11 nests completed with green leaves, less than half occupancy. Meanwhile, reports from friends with inland colonies in Ledyard and Norwich, seemed to have an overflowing abundance-full houses.
Our first eggs were laid around the very end of May. The female will lay one egg a day until her clutch is completed. The average number of eggs is five, but occasionally six or seven can be found. There are instances of a second female sneaking an egg into an established nest. This will result in one hatchling being of a noticeable difference in size. Hatching begins about 15 days after the last egg is laid. Our nests were created over quite a wide span of time, and thus the eggs were laid over quite a long period within the colony.
We also had a few mysterious and sad occurrences. On two separate occasions, a nest was discovered completely empty of eggs. After being full on one check, a week later all were gone. We have predator guards against snakes and raccoons, so this predator may have been another bird. We have had problems with house sparrows ousting martins. This may have been the case.
In the other gourds, hatching began mid-June and has continued. We even had one new nest full of eggs at my last check July 8. I wonder if it was from a pair who lost their eggs early on.
They go from pink and helpless at hatching to feathered and alert in just a couple of weeks.

One of these birds is several days younger than the rest. It may have been an egg from another female.

Between two and three weeks of age, when the shiny blue-purple begins to appear on their feathers, they become more active and I stop monitoring them.

Egg to flying in 21 days

We are nearing the end of the time for checking nests. As the young ones go from pink and helpless, they grow rapidly with noticeable changes on a daily basis. The feathers emerge in predictable patterns so we can estimate age more accurately. Once they get to about 21 days old, they can become quite jumpy and could leave the nest before they are ready, so we do not peek as often. Usually though they are tolerant of disturbance and have gotten used to the intrusion and behave quite calmly. The parent birds always stay near, often waiting with an insect meal in its mouth.
At last count we had nine successful nests with a potential of 35 young. While I am a bit disappointed, I know that some of the inland colonies did very well this year. CT Audubon and DEEP report that due to caring stewardship of purple martin colonies, the birds are faring far better than they have for decades.
There are numerous online resources about purple martins, including one on the CT DEEP website. Check them out. You might get hooked.
This was just an off year, but I am happy with my small success. There will be next year, and hopefully these little ones will return and give me some full houses.
The Martins fly high to catch dragonfiles and butterflies to feed their young.

When the nest is jostled a bit, the young respond by opening their beaks, expecting a meal.

Photographs by Mariano Librojo and Beth Sullivan.

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