Wildlife Feature Part II: On Being a Gourd Lord

Part II of a blog series by Troy Clark, CSWC Board Member

A male purple martins purchases above its gourd nest. Photo by Matt Tillett.

When I first got involved with purple martin housing, all I knew about purple martins was that they were migratory and in the swallow family. Yet they established a hold on my imagination because I could not figure out why they weren’t nesting in the Smith and Bybee Wetlands Natural Area. The habitat seemed just right for martins. For over five years, this question surfaced sporadically. When I retired from Portland Audubon in 2012, a nice contribution was made to Portland Audubon in my name and I was approached with the idea of using part of the money on a project at Smith and Bybee. When asked if I had any ideas, I responded, well yes, I had purple martins on my mind. This led me to contact Dave Fouts, who had established several purple martin colonies in the Portland area.

Dave had come up with a very sturdy martin housing design and he graciously let me copy his setup. The design involves lengths of pipe, some conduit, a winch, various eye bolts, wire, screws, nuts, and eight plastic nest gourds. It’s quite a lovely design and far superior to the martin housing kits that can be found online. The primary feature is the brilliantly conceived plastic gourds.

Purple martin hotel, as illustrated in “A year with the birds” in 1917. New York : Gibbs & Van Vleck.

When the first colonists came from Europe, they found Native villages with hollowed out natural gourds on posts to attract purple martins. The Indigenous peoples had discovered the benefit of martins feeding on mosquitoes. Later, people built “martin hotels,” wooden boxes with multiple nest cavities, or used natural gourds hollowed out and shellacked for strength. These natural gourd and wood boxes required a lot of maintenance. Then the Purple Martin Conservancy out of St. Louis came up with a nifty molded plastic gourd design with a squash-like neck, a clean out lid and a martin sized entry hole. I ordered my first eight gourds from the Conservancy and, copying Dave’s pole design, set up my first installation in 2012 with the one question, “If I build it, will they come?”

As I did research on martins, I learned that their nemesis is the European starling, an abundant invasive bird species that outcompetes martins for cavity nest sites. The western population is in decline because of starlings, and there are very few martin hosts (aka “gourd lords”) west of the Rockies. The eastern purple martin population, however, is almost completely dependent on human-supplied nest cavities. So, when I put up my first pole, I had no idea what to expect.

That first year, all eight gourds were occupied with purple martins. We were on our way. The next year, I put up a second pole with eight gourds some 40 yards from the first pole. These two poles were very successful, with full occupancy every year.

Five years later, I put up two more poles (16 gourds) in a sedge meadow at Smith and Bybee. Last year, I had to move the older colony to join the newer colony because five of the 16 gourds had not been used. Trees had grown up near the poles and were making the martins nervous. The trees supplied perfect launching pads for Cooper’s hawks, a bird-eating raptor who might fancy a purple martin now and then. Now the four poles and 32 gourds are together, making maintenance of the colony a bit easier for me.

One of the gourd poles Troy maintains at Smith and Bybee—home to 8 martin families each year!

Normally, about mid-October, I go out to winterize the gourds. The martins will have left mid-September for their 5,000-mile journey back to the Amazonian rainforest for winter. The fall maintenance involves winching down the gourd assembly, removing the nest material in the gourds and scouring the inside of the gourds with bleach water to kill mites and fungus. This is also when I will find any dead chicks or unhatched eggs. In fact, I just winterized the colony yesterday. It took five hours. I found no dead birds or eggs. The wonderful thing is that 31 of the 32 gourds had been used this year. I have only lowered and opened the gourds twice when the kids were in the nests. I felt their terror when suddenly the lid was removed and a huge beast peered into their little bedroom.

When the gourds are cleaned up, I put roofing nails in the seven drain holes that are in the bottom of each gourd. I found out the hard way that if I don’t block every access into the gourds, wasps will make themselves at home through the winter. That first spring, I came out to prep the gourds and to add alder shavings (a bit of staging and not necessary), only to find them full of wasps, which I had to remove. The wasps were in torpor and not dangerous, but it was not enjoyable for either of us.

Once the roofing nails are in place, I must cover the entrance hole. This I do with an old CD, a 4” dowel, a tongue depressor and a zip tie (just imagine). Once the gourds are winterized, I winch the assembly up the 21’ pole, where they will sit protected from wasps and starlings until martin time.

The CDs covering the entrance hole are critical. I keep them on the gourds until the first martins show up. The non-migratory starlings start nesting a month or more before the martins come and would use the nest gourds for themselves if accessible. So far, I have had no starling intruders. It is fun in the spring when the first martins arrive and are waiting for me to open the gourds, to imagine their chatter, “Don’t worry baby, the gourds will be open. Trust me.” It’s amazing: while I winch down the gourd assembly and remove the CDs, the birds are flying all around, excited. I cannot even get the gourds winched into place before they are checking out every gourd. I wonder how they choose which gourd. The gourds are all the same, the only difference being the direction the entrance hole faces. I guess it depends on if you prefer the morning sun or evening sunset.

Peeking into a martin nest inside a Conservancy gourd. Photo by Oakley Originals, Flickr.

A fascinating thing I have observed is that every martin will check out every gourd (32, mind you) multiple times. The literature says that the male chooses the nest site, but I bet she has something to say about it. Another interesting colonial habit is that all the adult martins work together to mob an intruding hawk or suspected threat. This past summer, I walked out to check on the birds and as I walked from pole to pole, about 50 martins followed me, swooping and diving and hoping that by sheer numbers I would be frightened off. They obviously didn’t suspect that I really enjoyed their voices and flight displays. I joked with them, “Be nice or I’ll raise the rent.”

Even though it involves quite a bit of work twice a year to manage the colony, the presence of purple martins at Smith and Bybee has satisfied my initial pondering of “why no martins”. Along the way, I have had numerous moments of serendipity. I have also learned a lot about the birds and their conservation status. The west coast martins are rather vulnerable to the vicissitudes of seasonal weather. In 2008, for example, there was a significant decline in the western martin population due to unseasonably cold spring weather. This inhibited bug hatches, causing some martins to starve and few to nest successfully that year. Their vulnerability inspires me to maintain this particular colony with love and diligence. Now that the martins are here, I want their presence to be a permanent summer feature out at Smith and Bybee.