Purple Martin Preservation Alliance
Synopsis: In June of 2007, the Purple Martin Preservation Alliance successfully transplanted one pair of breeding Purple Martins nesting in a T-14 at Moraine State Park in Portersville, PA (donor colony) to the property of Bob Allnock, Grant City Rd, Portersville, PA, (transplant site) a distance of 3.1 miles NW. This pair was moved at night, along with their five 11 day-old nestlings. When released at 6:15 AM, the pair left but returned four hours later and resumed feeding their nestlings. All five nestlings fledged and returned to roost at the transplant site along with the parents for four days. A series of stark associative cues placed at the donor site were moved to (or recreated at) the transplant site in order to allow the martins to recognize their nestlings in the new location.
According to an article that appeared in the scientific journal Wilson Bulletin over 100 years ago, in 1899, a man named Josiah Hoopes successfully transplanted a colony of Purple Martins from his property to the grounds of the Philadelphia Zoo. The Purple Martin house – parents, nests, babies, and all – had been transported to the new location where they stayed and raised their young. Titled “Purple Martins Removed to the Zoo” this fascinating article is actually just a newspaper clipping that had been sent to one of the leading scientific birding publications of the day; it gave no details about the transplant. While the newspaper clipping claimed that the transplant had been successful, no records or details could be located to verify that claim. I immediately began to search for clues and details about the man who conducted the transplant – a Quaker and businessman named Josiah Hoopes – as well as details about the transplant itself.. This search became an obsession, and ultimately inspired me to attempt to recreate Hoopes experiment. [It has since been discovered that the Hoopes transplant experiment did not succeed. -ed.]
Since one of the main goals of the Purple Martin Preservation Alliance is to develop techniques designed to achieve the establishment of new Purple Martin breeding colonies, I became excited about the prospect of attempting to learn if a new colony could be established using this unorthodox and little-known technique. Thus I began drafting a research proposal seeking permission to attempt a modern, scientific transplant. In March of 2007, a 25 page research proposal titled A Proposal to Establish Purple Martin (Progne subis) Colonies by Transplanting Nesting Pairs along with their Housing and Nestlings during the Breeding Season was submitted to both state and federal wildlife agencies, and the required permits were secured: U.S. Fish and Wildlife Permit # MB081548-0; Pennsylvania Game Commission Special Use Permit # 48-2007. The permits allowed us to move up to a total of eighteen pairs of breeding Purple Martins, along with their nest and nestlings, from three separate “donor” colonies (up to six pairs per colony) to three separate “transplant sites”. In the end, we only moved a grand total of seven pairs over the course of three separate transplant attempts. One pair was successfully transplanted! Only this one pair returned to the transplant site, continued to feed their young, and ultimately to fledge them. This article describes that remarkable event.
Ironically, the one transplant attempt that was successful was the one I thought least likely to succeed. I will refer to it as the Moraine-Allnock transplant, since we attempted to move three adult pairs nesting in T-14 compartments at Moraine State Park in Portersville, PA to a T-14 on the property of Bob Allnock – 3.1 miles northwest.. This was also the only transplant attempt that involved moving pairs that were nesting in a wooden martin house; the other two attempts involved martins nesting in large plastic gourds. The Moraine-Allnock attempt was initially planned so that an entire rack of gourds would be moved from the gourd rack at Moriane to the same-style gourd rack at Bob’s property, but the martins did not cooperate, refusing to nest in that gourd rack, and we had to modify our plan. Luckily, Bob Allnock also had a T-14 on his property. There were a total of nine pairs nesting in the T-14 at Moraine; we would attempt to move only the three earliest-nesting pairs. One reason for using the earliest-nesting pairs was the hope that, if the experiment succeeded, they might attract young, late-nesting pairs to the transplant site. In mid-June, some martins are still seeking out nesting sites in western PA.
One problem involved in moving just three of nine pairs was that we could not move the entire T-14, and the three pairs were all nesting in separate sections. Therefore, it was decided that Bob Allnock would build three nesting boxes specially designed to slide into the T-14 compartments at Moraine. On the night of the transplant, we would simply remove them and slide them into Bob’s T-14; these removable T-14 nestboxes are basically modified nest trays with walls, a back, and a ceiling. The nest contents would be transferred into these compartments after the eggs hatched, and the entire nest could be then be transferred into the T-14 at the transplant site at a later date. Both T-14’s (the one at Moraine and the one at Allnock’s) had to be further modified so that each compartment opened individually. Shutters were mounted on the front of the three transplant compartments in order to confine the parents inside on the night of the transfer, in a manner similar to Hoopes method..
As the transplant proposal describes, this attempt involved far more than just moving the pairs from the donor site to the transplant site and hoping they stayed. A variety of visual and auditory cues were used to help the relocated pairs recognize their nesting cavities – and therefore their nestlings – at the transplant site. The porch and front of each transplant compartment was painted a unique, bright color. The ground underneath the T-14 was covered with two 6′ x 8′ bright yellow tarps. A string of pink pennants were strung around the perimeter of the tarps. The martins were given supplemental feedings, and a unique musical CD was played during the feedings. These stark, recognizable sights and sounds, known as associative cues, were put into place at the donor colony about one month prior to the transplant date, and were transferred to (or recreated at) the transplant site when the parents, nests, and nestlings were moved.. To gain a more thorough understanding of the nature of these cues and techniques, please refer to the transplant proposal.
As indicated in the transplant proposal, preparations for the transplant began months before the actual date of the move. One of the major associative cues that we employed was supplemental feedings. Also, whenever we provided supplemental feedings in the form of tossed crickets, egg, or mealworm, we wore fluorescent orange shirts and played a distinctive musical CD. There were actually three associative cues contained here – the toss-feeding, the orange shirts, and the music. The supplemental feeding cue may have been a key component in the success of the transplant, as I will explain later. Keep in mind that this colony had already been trained to accept supplemental feedings for several years. We toss-fed at Moraine on April 25, April 27, May 17, May 18, June 5, June 13, and June 14. Food was also placed on a raised platform feeder placed about 25 ft. from the T-14. Many martins ate from this feeder, and it was moved along with the martins on the night of the transplant and placed in the same location relative to the T-14 at the Allnock site..
On May 30, we laid the two yellow tarps under the housing and strung the pennant fence around the perimeter of the tarps. We painted the porches of the transplant compartments (WH-2, WH-5, and WH-10) a unique bright color on June 1 when all nests were at the late incubation stage. WH-2 was painted gold, WH-5 was painted orange, and WH-10 was painted purple. The paint used was quick-drying spray-paint, and the martins re-entered almost immediately when we raised the house after letting the paint dry. We painted the fronts of the compartments on June 5. The painting was done in two stages to avoid alarming the martins with a drastic color change. Each of the three compartments now had a unique, bright, color that the parents would hopefully associate with their nests and nestlings even in a new location. Meanwhile, the eggs had just begun to hatch.
On June 6, there were five 2 day old nestlings in WH-2, and five 1 day old nestlings in both WH-5 and WH-10. At this point in time we decided to insert the removable T-14 nesting compartments and transfer the nests and nestlings into them. I felt that the parents would be very unlikely to abandon their nests after the eggs had hatched. We were careful to keep the nests intact with the bowl formation to keep the tiny nestlings huddled together, allowing the mother to cover and brood them properly. This was a critical stage in the process; we worked as quickly as possible to install the modified compartments and transfer the nestlings into them. We had to modify the fronts of the T-14 so that the doors of the compartments opened individually. It was important that the parents accept this slightly altered, slide-in cavity. I was confident they would, since by the time nestlings have hatched, parents have invested a huge amount of time and energy in their reproductive attempt. After about 30 minutes, the nestlings were slightly cool to the touch on this sunny, 70 degree day, so I was impatient to get the house back up. It took longer than I would have liked to get the modified compartments installed and the nestlings transferred. This could have been avoided by modifying the T-14 to have individually opening compartments early in the season, had we known we would be using the T-14. In any case, the parents re-entered quickly, to our great relief. The female from WH-5 took the longest, probably because we had changed the color of the porch and front of the compartment from a dull orange, to a bright, fluorescent orange. The transplant was scheduled for about June 15, so the parents would have about 10 days to become accustomed to these slightly smaller quarters before being moved.
Two days later, on June 8, we banded the four adults who needed to be banded. The female from WH-2 was already banded, as was the male from WH-10. Each of the parents were given two leg bands – an aluminum federal band with a 9 digit number that is computer-indexed at the Bird Banding Lab in Laurel, MD, and a colored aluminum band with a 4 digit alpha-numeric code that can be read with a high-power spotting scope while the bird is perched on a porch or overhead wires. The parents were captured for banding by trapping them inside the compartment when they entered to feed the nestlings. The six parents had the following bands:
WH-2 ASY-F YELLOW T192
WH-2 ASY-M YELLOW K676
WH-5 ASY-F YELLOW K677
WH-5 ASY-M YELLOW K678
WH-10 ASY-F YELLOW K675
WH-10 ASY-M YELLOW M353
We continued to lower the house a little every day so that on the night of the transplant, it would be at a level where we could simply walk up and block the entrance holes to confine the adults inside, then slide the three boxes out for transplant to the Allnock site. We also tried to provide supplemental feedings every morning as the transplant date approached. And of course we prepared the Allnock site to receive the three pairs. These preparations included mounting decoys and mirrors on Bob’s T-14, painting it so that the color scheme matched (white with red trim), and cutting the fronts to accommodate the slide-in compartments. Bob already had an audio system to broadcast the dawnsong, and if fact had been playing the dawnsong to try attracting martins using the social attraction method. We also installed an extra audio system to broadcast the supplemental feeding musical CD audio cue. Incidentally, we had originally planned to conduct two transplants from Moraine to Allock: three pairs from the T-14, then three pairs nesting in horizontal gourds hung under the T-14. That is why there are brightly colored gourds hanging under the T-14. We eventually abandoned the second stage of the transplant, but an identical set of colored gourds was nonetheless erected at the Allnock site to help the martins orient to their compartments..
On the night of June 15th, at 9:00 PM, we drove to Moraine State Park to confine and transport the martins. When we arrived, we began loudly playing a thunderstorm CD on our car’s audio systems. We were parked near the housing. We hoped that the sound of thunder at dusk might cause any parents who would normally roost outside to think that a storm was approaching , and therefore sleep in their nesting cavity on this night. One of our overall concerns was that one or more of the ASY male parents might choose to sleep outside, and thus avoid confinement and transport. While females almost always continue to sleep with the nestlings for at least several weeks after hatching the males are less predictable, and sometimes sleep in trees or other compartments. We attempted to monitor WH-2, 5, and 10 as the martins came in for the night, but the darkness and high level of activity made it difficult to determine if all three pairs entered for the night. Sometimes an adult would enter, the exit again. After all activity had ceased, we waited 15 minutes, then, at 9:45 PM, we quietly approached the housing and blocked the entrance holes. We decided to block not only WH-2, 5, and 10, but all the cavities with nests, to avoid flushing parents that might be brooding small young or incubating eggs. We then slid all three removable compartments out of the T-14, loaded them into the vehicles, pulled up the tarps and pennant fence, and headed for the Bob Allnock property. We continued to play the thunderstorm CD loudly as we traveled back to the Allnock site, hoping to create the illusion of a thunderstorm rocking the T-14, and masking the semi-bumpy car ride back to Bob’s property. Perhaps when they discovered they were in a new location the next morning, they would think a tornado had blown the nest to the new location. We slid the compartments into the Allnock T-14, leaving it in the lowered position, just like the T-14 at Moraine. We then laid down the yellow tarps and strung the pennant fencing in the same manner that it had been in around the T-14 at Moraine. The feeder was also erected at the same distance it had been from the T-14 at Moraine..
At 6:15 AM the next morning (6/16/07), we liberated the pairs now at the Allnock site by pulling strings that were attached to pieces of pool noodle blocking the entrance holes. Although the house was at head level and we could have unblocked them by hand, we did not want to startle the martins by being very close to the T-14. We were also playing the dawnsong, as well as the musical CD that we played whenever providing supplemental feedings. Approximately five minutes later, the pair shot out of WH-2, about five seconds apart, followed shortly by the female from WH-10. It turned out that the male from WH-10 was not inside. At this point we counted five martins in the air, and we believe the other two martins were two subadult males that were already at the Allnock site. Bob had managed to attract a subadult pair (and an extra SY-M) using the social attraction method earlier in the season. The female was on eggs. There was considerable vocalizing among these martins as they circled the site for a few minutes, then disappeared in the direction of Moraine State Park. The female from WH-5 emerged approximately 30 minutes later at 6:45 AM, followed by the male from WH-5 about two minutes after her. Like the others, the slowly circled the site for several minutes then disappeared. They did not appear to leave together.
We were not disappointed by the martins rather quick departure, but by 8:30 AM, when none of the martins had yet returned, we grew increasingly concerned. It should only have taken the martins a few minutes to travel back to Moraine, a few minutes to realize their nests were gone, and a few more minutes to fly back to Allnock’s site. I decided to travel to the Moraine colony and use my spotting scope to look for the banded parents. I did see the male that we failed to capture in WH-10 (Yellow M353). He was sitting on the porch of WH-9 with a large dragonfly in his mouth. I also saw the female from WH-10 (Yellow K675). She was sitting on the T-14 also. I didn’t see any of the other banded martins, but assumed that they too were here. At 8:45, I decided to do conduct some supplemental feeding I donned my fluorescent orange shirt, turned on the musical CD, and began tossing mealworms. Even though it was a warm, sunny morning, the martins fed heartily! I went through several hundred worms, and probably could have gone through all of them, but I decided to save some and headed back to the Allnock site at 9:30 AM.
Back at the Allnock site, I put the musical CD on the loudspeaker and turned the volume up as high as possible without distortion. By this time we had raised the T-14 back to full height in order to give the martins more confidence if they returned. At approximately 10:00 AM, the pair from WH-2 returned and landed on the T-14. We confirmed their identity by reading the leg bands. They landed almost immediately on their gold-fronted compartment. The pair did not land on any other porches. The ASY male entered almost immediately and removed a fecal sac. He did this several more times. The female landed on the porch but would not enter at first. We did not hear any begging. About 20 minutes after they arrived, I decided to try feeding them some mealworms, hoping it would stimulate them to feed their nestlings. My van was parked in the same position relative to the T-14 that it would have been at the Moraine colony. Wearing my orange shirt, I started the musical CD, slowly approached, and used a spoon to start flinging mealworms. To my amazement, they went after them almost immediately and started eating the mealworms themselves. Within an hour, the male began carrying mealworms inside, and an hour after that, the female began carrying them inside as well. A short time later, the female brought in a large dragonfly, and by 12:30 PM, both parents were feeding well, bringing in large dragonflies quite regularly. The male began hauling in large numbers of mealworms that we had placed on the feeding platform; he made constant trips between the feeder and his cavity. In fact, the pair fed almost exclusively from the feeder for large chunks of time. They continued to use the feeder until the nestlings fledged.
Almost from the time the pair returned, the female was intermittently harassed by the unattached subadult male that was resident at the Allnock site. He would land next to her on the porch, causing her to fly off or to land on the top perch of the T-14. This went on for some time, without any reaction from her ASY mate. Eventually, this behavior subsided, but not before causing us extremely high levels of anxiety. This subadult male would follow the female intermittently right up until the nestlings fledged. In the photo to the right, the three real martins are indicated with red lines. The ASY-M is on the porch, his ASY-F mate is to the upper left, and the bachelor SY-M is in the upper right. The rest are decoys.
At 5:00 PM, we returned the other two nests to Moraine, and the parents landed and entered almost immediately. They resumed feeding within 20 minutes. Apparently they had been back at Moraine almost the entire time. At dusk, Bob observed the transplanted male fly back towards the Moraine colony, but he was back on his porch at the Allnock site at first light. The feeder was stocked daily with mealworms every day until several weeks after the young fledged. Three nestlings fledged on July 4th, and the remaining two the next day. All seven martins came back to roost at the site on July 5th, 6th, 7th, and 8th, 2007. And several came back until the 11th.
Two days after the first transplant, we attempted to re-transplant the pairs nesting in WH-5 and WH-10, but discovered that the parents were no longer sleeping in the cavity, probably as a result of their capture on the first transplant attempt.
Ten days later, on June 26, we attempted to transplant six pairs nesting in a gourd rack at the Shelocta colony to Crooked Creek State Park. We were extremely optimistic in light of the semi-successful Moraine-Allnock transplant. In fact we had an even higher degree of confidence because, even though the transplant distance was longer – 10.4 miles as opposed to 3.1 – we would be transplanting an entire nesting structure (gourd rack), not just a few nests; there would be nothing for the martins to land on at the Shelocta site when they returned (except for nearby martin housing), because even their gourd pole would be removed. We only captured three complete pairs, since three males were not roosting in their gourds. None of the transplanted individuals stayed at, or returned to. the Crooked Creek site. When the gourds containing their nestlings were brought back to the Shelocta site at 6:00 PM that evening, and the gourd rack re-erected, all six pairs resumed care of their nestlings within one hour.
On July 4th, we transplanted two complete pairs from the Zeglin Dairy Farm colony near Mt. Pleasant, PA, to a site near Beaver Run Reservoir, a distance of 19.3 miles, but neither of these pairs remained at the release site. They did resume care of their nestlings when the gourds were returned to the donor colony.
Why did only one of the seven pairs transplant successfully when all seven pair were subjected to the same set of associative cues? I will discuss seven possible key factors that may have contributed to this one pair’s successful transplantation.
- Distance. This may be the most critical element. The successfully transplanted pair was moved only 3.1 miles, as opposed to five other pairs that were moved either 10.5 or 19.3 miles. The transplanted martins may have been very familiar with the transplant area because of its proximity to the donor site, especially since the landowner was broadcasting the dawnsong on a loudspeaker in the direction of the park for several months prior to the transplant in an attempt to attract breeding martins. This pair may have visited the site at some point. The relatively short distance may have more easily allowed the pair to relocate their nests and nestlings after homing to the donor site on the morning of the transplant.
- Age of Parents. The two pairs that were moved from Moraine State Park were two of the oldest three pairs breeding at the colony. ASY individuals are generally experienced breeders and their increased parenting skills may have accounted for a stronger than average nestling-parent bond that allowed them to overcome the traumatic event that a transplant must be for a pair of nesting passerines.
- Supplemental Feeding. Both parents were well trained to accept supplemental feedings in the form of tossed egg, crickets, and mealworms, as evidenced by their taking of tossed mealworms upon their return to the transplant site. In addition, this pair was trained to eat these same food items off of a stationary platform feeder, as demonstrated by their frequent use of the feeder at the transplant site. This pair may have been especially well-trained to take supplemental feedings since their compartment faced the spot of ground from which we usually tossed food items at the donor site. Additionally, their compartment faced the platform feeder at the donor site. 3a) Feeding Auditory Cue. This pair was also well-conditioned to associate the supplemental feedings with the musical CD cue. And in associating the musical CD with their food, they may also have come to associate the CD with their nestlings. This series of associations may have allowed them to recognize their nestlings when the musical CD was played at the Allnock site, where their nestlings were present.
- Simultaneous Departure from Transplant Site. Both parents emerged one after the other from WH-2 and left the site together. The male and female of the other pair (WH-5) left approximately two minutes apart. Perhaps there is some positive dynamic at work when the pair leaves together and travels back to the donor site together. However, two of the three pair from the Shelocta-Crooked Creek transplant also left together, and none of those pairs returned to the Crooked Creek site.
- Female Not Captured for Banding. The female from WH-2 at Moraine (the only successful transplant) was the only female from the seven pairs that was not captured for banding in the week prior to the transplant. She had been banded as a nestling and therefore it was unnecessary to band her. Perhaps the capture of the other females twice within the period of about one week had a negative impact.
- Nearby Housing in Same Configuration. While the same compass orientation was maintained in all three transplant attempts, only in the Moraine-Allnock transplant was nearby housing serendipitously located in the exact same position relative to the transplant structure. While we could position the feeder and other associative cues in any desired location, it was not possible to erect or relocate other housing structures at the transplant sites, so that the housing configuration matched the donor site.
- Breeding Martins Present at Transplant Site. In a unexpected development, Bob Allnock attracted one pair of subadult martins to the gourd rack at his site in early June. The female of this established subadult pair was incubating eggs when the Moraine-Allnock transplant occurred, and there was also an extra subadult male present at the Allnock site most of the time. When the transplanted Moraine pair exited WH-2 during their release at the Allnock site, both of the Allnock subadult males greeted them and cavorted with them while vocalizing. This interaction may have contributed to the successful return of the pair from WH-2. The bachelor subadult male appeared to harass the female of the transplanted pair upon their return, but this may actually have had a positive effect.
- Natural Intelligence. One or both of the individuals from the pair that was successfully transplanted may have possessed above average intelligence This may have allowed them to solve the problem of what had happened to their nestlings.
We attempted to transplant 12 breeding pairs, but failed to capture the male in 5 of these attempts (they were not sleeping in their nest cavities on the nights of the captures), so there were only 7 true transplant attempts, although it would not have been impossible, one would think, for the female to lead the male to the transplant site after returning to the donor colony. Perhaps the male could have been captured separately the next morning and taken to the transplant site. Any method or technique that would enhance the likelihood of capturing both parents on the night of the transplant would be a plus. We gradually lowered the Moraine house over the course of the week leading up to transplant, in order to easily plug the entrances on the night of the move, and later thought that this lowered height may have prevented the male from sleeping in WH-10, but the housing at the Shelocta-Crooked Creek transplant was not lowered at all (we used fishing line to pull shutters), and we still failed to capture 50% of the males, so capturing the male at night may remain a wildcard. Perhaps transplanting the pair earlier in the breeding cycle would enhance the chances of capturing the male, (for example, when the nestlings are 5-6 days old) but then the problem of the nestlings not yet being thermoregulatory becomes an issue.
Any technique that would enhance the propensity of both parents to leave the nesting cavity “together” might also lend to more successful transplants. Four of the seven transplanted pairs left the cavity one or minutes apart, meaning they likely traveled back to the donor site independently, which may have had a negative effect Any technique that would minimize the stress of capture, transport, and release might lend to increased transplant success, since these events are certainly stressful to the transplanted pair. Any technique that would allow the parents to spend more time with their nestlings and at the transplant site might enhance the likelihood of success, since the parents are confined in semi-darkness prior to their release, and have not yet fed them in the morning.
The supplemental feeding cue appears to have played a major role in the success of the transplant. I suspect that the pair was lured back to the transplant site by the musical CD auditory cue. Recall that we conducted an impromptu feeding session back at the donor site several hours after all three pairs were released and were believed to be present back at Moraine. Thirty minutes later, the musical CD feeding cue was loudly broadcast back at the Allnock transplant site, and the pair returned and began accepting tossed mealworms. Remarkably, they calmly ate tossed mealworms, even though they had just endured a very stressful, disorienting event. Eventually, they began to feed the mealworms to their relocated nestlings, helping them to re-bond with them at the transplant site. Additionally, this was a warm sunny day, when martins typically would not accept supplemental feedings. Were the mealworms relatively good tasting – a real treat – or were they just too easy of a meal to pass up? The pair continued to use the feeder to feed themselves and their nestlings for the nest two to three weeks.
Did the pair which returned to the Allnock site recognize their compartment by color or compass orientation? They never looked into any other cavity, landing almost immediately on WH-2, the gold-painted cavity, and my feeling was that they did recognize the color. It would be interesting to test this by painting a number of gourds or cavities, then spinning the housing and thereby changing the orientation, to see if they could relocate their cavity by color alone.
Will this transplanted pair return to the transplant site in 2008? Or will they go back to the donor colony (Moraine State Park), assuming they survive their off-season migration to Brazil and back? Purple Martins generally return to breed at the site from which they successfully fledged nestlings, but this is a highly unusual circumstance, and it will be interesting to see what happens.
In all three transplant attempts, only a fraction of the nesting pairs were moved. Could the fact that other breeding martins and nesting structures remained at the donor colonies have contributed to the failure of some transplants? When the pairs returned to the donor colonies, could the presence of the non-transplanted breeding martins going about their business have been a distraction that prevented the transplantees from returning to the release site? What if all of the pairs were moved and no housing remained at the donor site? A transplant in which all the breeding pairs and housing were moved might be more successful.
Conclusion: In June and July of 2007, PMPA staffers moved a total of seven pairs of breeding Purple Martins a distance of 3.1, 10.4, or 19.3 miles in southwestern Pennsylvania. A variety of visual and auditory associative cues were also transferred along with the adults, nestlings, nests, and nest cavity in order to allow the parents to recognize their nestlings in the new location. Only one pair stayed at the transplant site and continued to feed, and ultimately to fledge, their nestlings.
We must walk consciously only part way toward our goal,
then leap into the dark to our success. -Henry David Thoreau