All About Purple Martins At Union Bay

Here is a recent post from the Union Bay Watch Blog published by Larry Hubbell, long-time local photographer and birder.

Here also is an in-depth article about Larry and his work.

Purple Martins

In mid-June, David O. Wilbur sent in this exquisite photo of a female Purple Martin. He captured the photo near the osprey nesting platform at the Union Bay Natural Area (UBNA). In short order, I heard from multiple sources, that Purple Martins were nesting in Wood Duck Box #3 - just to the west of the osprey platform.

When I visited the area, I spotted one of the Purple Martins peering out of the Wood Duck box, while a Great Blue Heron lurked overhead.

When the martin flew, the heron raised its wings, as if hoping to strike. However, the martin was gone, before the heron could execute its plan.

Foiled by the martin, the heron chose to investigate the opportunity from below, but could not find any access to the nest. To those of you who helped to build the Wood Duck boxes, Thank You! Our product has passed the Great Blue Heron test.

In July, Connie Sidles sent a message which said as far as she knew, "...this is the first nesting record of Purple Martins at the Fill..."(e.g. UBNA). None of us who built the Wood Duck boxes had the slightest clue that this box would one day become a Purple Martin nest.

The heron moved back to the top of the box and proceeded to go through a lengthy grooming process. It was quite picturesque, but that is a post for another day.

A few days later, I spotted one of the martins on the perch above the Osprey Platform. The elevated location makes a natural hunting site from which they can capture airborne insects. This particular time, the martin was interacting with a female House Finch. 

I found the size difference very interesting. Purple Martins are the largest North American swallow species. Their size can be difficult to estimate if all you see is a single martin in flight. However, since they are often chased by smaller birds, making the size comparison is easier than one might expect.

This year, sadly, the Osprey chose not to use the nesting platform and the Wood Ducks failed to use Box #3. However, since the Purple Martins are using both, it feels like a nice consolation prize.

Last May, my friend Rick Matsen sent in this photo which he captured near the Orcas Ferry Terminal. It is an excellent side-by-side comparison of a pair of Purple Martins. The male is on the right.

I have photographed males before, like this one at the Port Townsend Marina in 2018. However, so far this year, I have yet to catch a photo of a male at the UBNA. The first-year birds flying around the nest indicate that a male was here, at least long enough to fertilize eggs. I wonder if adult males head south earlier than the females and their young?

Earlier this week, I noticed the adult female on top of the nest box. Suddenly, she abandoned her perch. 

The logic of her action became clear when I saw the flash of a passing Cooper's Hawk. The female martin swiftly chased the hawk away.

After a time, the family members returned to the nest. I soon deduced that the light grayish bird, with its wings raised, was one of the younger family members.

The older siblings tended to fly more often. I suspect they were hunting for themselves, although I was unable to capture conclusive evidence.

Every time a more mature bird landed, the youngster's mouth gaped open and provided a brilliant yellow-rimmed target. The young bird was living in the past and hoping someone would provide food.

It was willing to accept food from any passing martin. However, I never saw the young one get fed. However, I do believe I saw the adult perch at the opening to the box and provide food to an internal occupant. 

Ignoring the youngster on the roof looked like a case of tough love. While I could hear the loud, liquid calls of the martins I had no way to determine their meaning. I can imagine the adult female saying to the youngster, "Since you can fly, it is time for you to find your own food."

Later, three different martins abandoned the nest at the same time. Obviously, something was up. My friend Bill pointed out the culprit, who had just rushed the nest site.

Similar to the Great Blue Heron the young Green Heron inspected the box from below. It also failed to find a feeding opportunity. I have never seen a Green Heron eating a bird but I suspect they would not turn down a defenseless nestling.

Slowly, the hungry heron retracted its neck and seemed to shrink to a less formidable size.

Soon, the adult female flew in and sent the young heron packing. Protecting the young and defending the nest is truly a full-time job.

I have read that along the east coast Purple Martins generally nest in multi-stored nest boxes. On the west coast, they are more likely to nest in natural tree cavities or gourds provided by humans. In Port Townsend, I have also seen them utilizing small nest boxes. Often multiple nest sites are placed quite close together. Purple Martins are colony nesters. This winter, after the family has gone south, I am thinking about subdividing or adding on to Next Box #3. Next year, it would be wonderful to have a whole colony of Purple Martins nesting on Union Bay.