Thursday, July 11, 2013

Update on Purple Martins at Knox Preserve

Back in June, we reported that we had erected a 12 unit SuperGourd System at the Knox Preserve. This was funded by an Audubon IBA ( Important Bird Area) grant.

By April 28, we had our first serious investigators into the new real estate in the area.

By early June, there was a lot of activity around the houses, but it was hard to tell who was serious about nesting. Apparently this is normal behavior for Martins. There was a lot of chasing, swapping, and peeking into multiple cavities. Nest-checks at this time revealed several gourds with extra nest material added-a hopeful sign. The following week we noticed an unusual pattern to the Martins behavior; they were landing in a cherry tree and ripping off leaves and carrying them back to the nests. This is a sign that egg-laying is very imminent. There are theories that some green leaves, especially those of Wild Cherry, have a type of toxin that is released when they wilt and which may act as a deterrent to bird mites which are parasites on young birds. Too many mites, which suck blood from helpless, featherless nestlings, can weaken the young and cause death.

We conducted a nest check on June 16 by lowering the whole system and peeking into each cavity. Eureka! Success-several nests contained eggs, all nestled in among the green leaves!
A clutch of five Purple Martin eggs nestled on
cherry leaves to protect against mites. 
 Martins lay one egg daily, at dawn, until the clutch is complete. A clutch can be anywhere from three to eight eggs. Five is average. By assessing eggs and clutch size, we estimated that first hatching could be around the last days of June to July 1.

On June 21, we checked again, and each of the four nests had completed clutch sizes of five lovely pale cream white eggs. Another newer nest had green leaves added but no eggs yet.
By June 30th we were anxious to see what would await us. Hatching! One nest had one baby and still four eggs. Two nests had five small, pink, helpless looking hatchlings, probably only out of eggs within 24 hours. I felt like a first time grandmother! The parent birds keep the nest immaculate. There were no old eggs shells, and the adults remove fecal sacs constantly.

One hatched-four to go.
Full house-five hatchlings.

The following week was the brutal heat wave, baking sun, and high humidity. I feared for the colony, but there was nothing to be done to get them through it.

We gathered our supplies to make a check and also to change out the nest material on July 7th . It is recommended that “landlords” remove old nest material when the birds are about a week to 10 days old. By this time, infestations of mites can reach serious levels. Research shows greater success in those colonies where the nests are monitored and changed.

I am thrilled to report that we lost no young to the heat and even added a few babies!
Three nests had a total of 11 young, all about 10 days old. One other nest contained five new hatchlings.
A 10 day old clutch, riding out the heat.

Another clutch of newborn hatchlings.

Changing out the nests was a challenge at first. But it all proceeded quickly. The young were removed to a clean basket. Old nest material was removed, and yes...there were mites all over inside, outside, on my arms, everywhere! No, they don’t harm people, but they sure make you feel crawly! We cleaned out the gourds, replaced new pine needle nest material, and I decided to add a few new green cherry leaves. I did notice that the nest that had the fewest leaves had the most mites. The nest that had dozens of leaves had far fewer mites. Maybe there is something to the theory.
When the process was completed, all in about a half hour, we raised the nests, and the adult Martins flew in immediately. Apparently they have no problem readjusting the new material and settling in.

Hatchlings on their first trip out of the nest.
Hatchlings waiting while their nesting materials are changed.

We will plan on doing a Federal Banding of all our nestlings and possibly a DEEP color banding for study purposes. This will occur before the young fledge and are about 10-20 days old.
Parents return to their nests.

We will keep you updated!

Written by Beth Sullivan.
Photography by Beth Sullivan and Rick Newton.

For more detailed information about Purple Martins please visit The official site of the Purple Martin Conservation Association.

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