Purple Martins on Puget Sound

From: Stan Kostka, lynnandstan@earthlink.net, Arlington, WA, 2003
 

stan.jpg (32343 bytes)       My first season working with  Purple Martins (Progne subis) turned out  very different from what I had originally planned. The early weeks of spring in 1999  were spent clearing the flyway around a newly installed gourd rack near my residence in the Cascade foothills. Located only twelve miles from where martins nested in 1998, attracting them to my home seemed like a possibility. However, I soon came to learn this was not likely, since I'm twelve miles inland from that saltwater colony, and the marine shoreline is where just about all known martins have been nesting in the Pacific Northwest. In spite of this I persisted. Equipped with a loudspeaker, the gourdrack began broadcasting Dawnsong into the predawn darkness as  martin sightings were being reported in late April and early May. Evenings I checked http://birdingonthe.net/mailinglists/TWET.html  for reports of first arrivals, and mornings I watched dawn break behind the silhouette of  the gourds.  Spring of 1999 was unseasonably cold and wet, but Purple Martins were arriving into the region nonetheless.

          By mid May I had become obsessed with a bird I’d never seen. With binoculars and spotting scope, I drove out to Hermosa Point on Tulalip Bay, to investigate a reported sighting. There, after several evening visits to the beach, I finally heard and saw the purple bird, an adult male,  perched on and intermittently calling from a piling just offshore. As the light went out of the sky he flew to a nearby cavity where he was joined by a female of which I was previously unaware, and together they entered for the night.

          Hermosa Point is a residential area, with significant populations of House Sparrows, and some European Starlings. The old rotten saltwater piling in which the martins had roosted, and perhaps were attempting to nest, had a three inch entrance hole, was hollow and open to the sky. I figured these birds could use a little help. After a few days of frantic emails, phone calls, and nestbox construction, seven nestboxes were installed on nearby pilings at high tide on May 22 with the help of friends and their boats. Incredibly there were six martins there that morning, and they were in and out of the nestboxes before we even had them all up ! I was thrilled to say the least. Since active management seems to improve rates of reproductive success among martins, and since I couldn't very well be borrowing boats all summer, I bought a boat on my way home that afternoon.

          Nest building began immediately. Straw and pine needles were placed into some boxes before they went up, but into the wrong ones evidently, because the martins moved most of it into other boxes. Four more martins showed up and on June 6  more boxes went up, bringing the number of artificial cavities to eleven. A banded bird was sighted, so in an effort to read bands, perches were installed above each box. At one point, a martin briefly landed on one of the perch rods as I was installing it ! Three banded birds were sighted at the colony , but no band numbers were ever confirmed. The boxes are too far from the beach, and a spotting scope in a boat proved unworkable. House Sparrows were trapped out of a couple nestboxes and their nests pulled. Starlings were not a problem.

          The 1999 season started with a cold wet spring, so the martins were nesting late. Starlings had already fledged from  other pilings further off in the bay. A starling tried to enter the nestboxes once that I am aware of, but the rectangular starling resistant entrances worked. I held my breath as the 4th of July approached. It seems this martin colony is situated in the heart of fireworks country, and the bay was lighting up. In the end the martins stayed, perhaps reacting to fireworks as they would to a severe thunder and lightning storm. Who knows, maybe the fireworks kept predators away. The martins seemed more disturbed by the close-up clicks of my camera shutter than they did by the big booms of fireworks. Six nests were built. Eighteen eggs were laid in five of them in clutches of two to five. The first hatched between July 27 and 31, and by August 7, fourteen eggs had hatched. I became frustrated by the necessity of doing nest checks at a ten foot tide or better, when the boxes could be accessed by standing on the seats of the boat, and then only when weather was good during daylight hours. So on August 21, having previously noticed what I thought were blowfly maggots in one of the boxes, I loaded some extra rope along with an aluminum ladder into the boat , and headed out to check nests, without the benefit of a high tide.  Two nestlings, the youngest of the fourteen, were  dead, perhaps the result of inexperience on the part of their sub-adult parents. Most nests had the usual adult fleas, flea larvae, and mites. The apparent blowfly larvae, now pupated, were in only one box, along with a seemingly healthy and alert single nestling. All other nestlings seemed strong and alert. I am amazed how tolerant these birds are of our intrusions. For the most part the parents sat and watched as we did our work. Only one swooped and hissed at me. Hermosa Point is lined with waterfront homes and I was often watched doing nest checks. I can only imagine what those folks must have been thinking, as they watched me climbing a ladder out of a boat to look into birdhouses.

           Young were soon being fed at the nestbox entrances. The first confirmed fledging was August 27, and all twelve nestlings were confirmed out by September 12. The last observed feeding/fecal sac removal was September 8.  More martins arrived at the site as the season wound down, most notably an additional adult male.  On the morning of August 31 fourteen adult birds were perched at the colony following a cold rainy spell, with all twelve young confirmed in their respective nestboxes. On September 9, fourteen martins formed up over the colony at sunset and roosted, several into boxes that were unoccupied all season. On September 13, sixteen birds roosted.

          1999 was a great year thanks to the martins. Thanks also to  everyone who helped and advised me, and all the people who have done Purple Martin recovery work in the Pacific Northwest region of the US and in British Columbia in previous years.

          The Hermosa Point colony, in Snohomish County,  has grown over the past 4 seasons to 17 pairs in 2003, 15 in nestboxes, and 2 in piling cavities.  The banded birds from 1999 showed up again in 2000, presumably the same three, based on their color bands and leg sequence.  All were trapped in order to recover their band numbers.   They came from nestbox colonies in the South Sound, near Olympia and Tacoma (WDFW, unpublished). These colonies were started in the mid 1980s,  not long after the nestbox recovery of Purple Martins began in Washington’s Southern Puget Sound in 1976 (J Davis, unpublished).

          The Hermosa Point piling cavity where the initial May 1999 sighting  occurred was eventually used by breeding martins in 2003.  In all likelihood,  martins were breeding in this and other piling cavities on the bay prior to 1999.

          Another nestbox colony now exists on the opposite end of Tulalip Bay at Mission Beach. Begun with 2 pairs in 2000, it has grown to 12 pairs, so that this year the bay had 29 known breeding pairs of Purple Martins. 

          As a result of similar nestbox installations  in 2000 thru 2003,  martins have successfully bred in Island, Skagit, Whatcom, and San Juan counties to the north of Hermosa Point, counties where breeding martins had not been observed for many years. Since 1999,  190 nestboxes have been installed at 29 sites in five North Sound counties. At the end of 2003, nine of those sites had a total of 55 breeding pairs of martins.  While these numbers may seem small by Eastern standards,  consider that the estimated population in the Puget Sound Basin in 1999 was about 300 pairs (WDFW unpublished data), nearly all in the South Sound.   By 2003 , the number of breeding pairs of Purple Martins in The Sound was estimated to be about 400 (unpublished data).

          In addition to installing nestboxes,  I’ve been traveling around the Sound, visiting other nestbox colonies, attempting to read leg bands,  as well as searching for colonies unknown to me, especially incidental nesting sites. These incidental nesting sites include the spaces under conical caps on both wooden and concrete pilings, ledges under piers and navigation markers, rot pockets in the ends of horizontal timbers and the ends of horizontal pipes on various marine shoreline structures, and in woodpecker holes and other cavities in dead trees.

          Experiencing a significant population of Purple Martins nesting in these unusual situations “in the wild”,  has altered the perception I originally had of these birds back in 1999.  While I remain an advocate of artificial cavities (nestboxes and gourds) for the benefit of martins,  I’ve become convinced that not all martins belong in these birdhouses. Western martins differ from their Eastern cousins, slightly in appearance and song, and often greatly in nesting behavior.  The behavioral differences the birds currently display need to be preserved.        Here are two examples:

1.     A pair of martins were found nesting in the end of a horizontal pipe, part of some derelict and abandoned maritime hardware on one of several pilings.  After observing the birds, and closely inspecting all the pilings, it was determined there was only one potential nesting cavity at this site. The nearest known martins were 30 miles to the west, also a solitary pair, and a 12 pair colony over 35 miles to the south.   Therefore,  several nestboxes were installed on pilings nearby the newly discovered pair, and this year the site supported four pairs of martins.  The general locality is a historic martin breeding area, but no breeding martins had been noted here in over two decades. Nestboxes enabled their return, since most of their original nestsites were either gone or being used by starlings.

2.     Martins were found nesting on small ledges under an abandoned pier. Observations at this site indicated that four pairs were nesting, three on the ledges, and one in a rot pocket in a horizontal timber.  Many suitable ledges and apparent rot pockets were not being used, thus a surplus of nesting opportunities were available.   Also,  the next county hosts a healthy and apparently growing population of martins in several nestbox colonies, the nearest only 7 miles away. In the case of the pier nesters,  nestboxes were not installed. Nestboxes may well have increased the number of pairs at this site, but the opportunity to further observe and document the characteristics of this unique and spontaneous colony would have been lost.

 

          Prior to the arrival of the European Starling into the Puget Sound region , martins were more common than they are today.  A roost at Green  Lake in Seattle in 1945 was estimated to contain 12,500 birds (Larrison 1945). By the time nestboxes were being installed in the mid 1970s, in an attempt to rescue a perceived remnant Purple Martin population, recovery pioneer Jack Davis was able to locate only 12 pairs of martins in the Southern Puget Sound (Davis 1995 unpublished). Although a few records exist of martins using nestboxes west of the Rocky Mountains prior to the 1970s, the centuries old Eastern tradition of supplying martins with birdhouses did not exist.   So, virtually all the birds that congregated in Seattle in 1945 bred in incidental nestsites, and a significant number of martins continue that tradition to this day. We must be careful, that in our zeal to help the Purple Martin, we do not inadvertently put an end to these diverse nesting behaviors.

 

© 2003. Stan Kostka. lynnandstan@earthlink.net Arlington, Washington