Behavior of Purple Martins Captured in Pre-nesting Compartments
Ken Kostka
Purple Martin Preservation Alliance
http://www.purple-martin.org
Pittsburgh, PA
01/29/06

 

    On May 28, 2005, as I was conducting nest checks at the Saxon Golf Course colony near Saxonburg, PA, I trapped and banded a small number of Purple Martins that had claimed compartments in a wooden T-14 but not yet built nests. (I am a licensed bird bander.) I wanted to test whether the ordeal of being captured, confined, and released several miles away would cause them to abandon the colony and, if so, to determine where they relocated.   I captured 4 martins - an adult male (ASY-M) that was already banded with Yellow K279 (I was trying to capture his unbanded mate), a subadult male (SY-M) that was already banded with Yellow K370 (I was also trying to catch his unbanded mate), and two subadult females (SY-F) - both unbanded - that were given Yellow K477 and yellow K478. These four martins were trapped in four separate compartments using  T-14 insert traps. K279 ASY-M was captured in WH-17, where he was just beginning to build a nest with an unbanded adult female. He had been banded as a nestling at the Saxon colony in 2003, and resided as a subadult at the Saxon colony in 2004.  K370 SY-M was banded at the Saxon colony as a nestling in 2004; he was now just beginning to build a nest in WH-16 with an SY-F. The two unbanded subadult females, that I banded K477 & K478, had fledged from unknown colonies last season. They had paired with SY-M's and had just begun bringing nesting material into WH-15 and WH-22 respectively. There were only trace amounts of nesting material in each of the four compartments.

    The weather that afternoon was warm and sunny, and the four martins were held for less than one hour before being released seven miles away, within the same ten minute block, in nearby Freeport, PA. (see map below)  I chose this location because it is within 5 miles of four uncolonized sites. Dawnsong was being broadcast at two of the sites and decoys were deployed at all four. The martins were released in two groups of two, in the middle of a large open area, next to the Allegheny River. In both releases, the two martins gained altitude, began circling, and, after reaching a height of about 500 feet, moved off together in a westerly direction. Interestingly, although none of the four martins were pair-bonded with each other, K370 SY-M  and K477 SY-F began calling to each other when released. 

    I didn't return to the Saxon colony that evening.  I thought it likely that the martins would return temporarily. Purple Martins, as with most songbirds, have an excellent homing ability, and usually fly immediately back to their point of capture after being trapped, transferred, and released. The males, at least, would probably attempt to rejoin their mates, since there is always a shortage of females in the breeding population. However, I predicted that the females would eventually seek out a new breeding site after the negative experience of being captured and banded in their nest compartment. Perhaps they would escort their mates to a new site, or choose new mates.  Not so! On May 30, four days later, I returned to Saxon Golf Course at 7:22 PM to read bands with my spotting scope and saw 3 of the 4 martins - sitting on their porches and later entering the same compartments they had been captured in. On June 1st, I saw the fourth martin - K478 entering WH-22. On June 5th, I conducted another nest-check, and confirmed that all four martins had resumed nest-building and almost completed their nests!

Discussion

    These four martins showed a great deal of site loyalty indeed. They were captured in their nest cavity before even having invested the time and energy of building a nest. Three of the four martins were SY's and had never nested at the site before. They were handled, banded (with one band on each leg), confined for 1 hour in a dark box, transported approximately seven miles, and handled again for release. Despite this ordeal, these four martins returned to their original nesting compartment and built complete nests within five days. Wow!

    I would certainly NOT encourage anyone with a new, small colony to have their adult (breeding) martins trapped and banded. The Saxon colony is a large, long-established, and therefore highly desirable colony that probably gives the martins residing there a strong sense of site loyalty and a degree of confidence high enough to overcome the negative experience of being trapped, banded, and transported. Additionally, the martins at this colony have been trained to accept supplemental feeding, perhaps making the site even more valuable to them.  But this experiment should demonstrate to novice landlords that once martins have chosen a site to nest, the landlord need not be paranoid about lowering the housing to do nest-checks. Doing so will NOT cause their martins to abandon the site!