Purple Martins are colonial nesters. When I first read that fact as a young Boy Scout in my earliest days of birding, I wondered what Purple Martins nesting in the pre-Revolutionary War American Colonies had to do with their then current nesting habits. Not too long after that I learned that “colonial nesters” meant that Purple Martins nest in colonies in close proximity to each other.
And now, many years later, we are maintaining a good-sized Purple Martin colony of our own: 144 gourds in a combination of natural and plastic gourds configured just the way Purple Martins like them, with long necks and spacious round bowls. (top of page) There are six poles with racks containing twenty-four gourds each, with perches on top of the poles where adult Martins relax and watch all the surrounding activity. (photo 2) Each pole has a cranking system so that racks can be lowered regularly, every five days during the breeding season for nest monitoring, and for removal and cleaning out of the gourds for winter storage at the end of the summer.
Purple Martin landlords have three main avian problems with which they must contend: Cooper’s Hawks by day and Great Horned Owls by night consider the Purple Martin colony to be a smorgasbord set up just for them; and European Starlings will kill Martins and take over their gourds for their own nesting purposes. While we have had problems with Cooper’s Hawks in past years and had to personally spend considerable amount of time being present around the colony serving in effect as live human scare crows, this year has been different in that we have not seen any Cooper’s hawks around the colony. However, we have constantly had problems with Great Horned Owls at night.
On three consecutive nest checks this year we found evidence of Great Horned Owl predation as baby Martins had been completely removed from gourds, and in one instance an adult had been killed right in the gourd. We learned that the “dancing scare crow,” a waving, constantly moving balloon-like figure resembling a person, similar to those often seen during promotions at car dealerships, running from just after dark until just before dawn, would deter Great Horned Owls. Since our “dancing scare crow” has been set up we have now had six successive nest checks with no baby Martin losses whatsoever.
The dancer can be seen in the photo of the complete rack set-up. It was operated for only a few moments for this photo opportunity. The Martins do not like the dancer and completely left the area while he was doing his thing. We never run it during the day. As for the Starlings, we have installed Starling proof entrances to most of the gourds, which work well, and by next year expect to have all gourds completely converted.
Our Purple Martins arrive back at the colony on our farm in Pennsylvania in early April (mid to late January at our condo complex in Florida) and keep arriving for the next six weeks. We begin our nest checks in mid-May and it is exciting to find new nests with eggs, or newly hatched babies. (photo 3) Because the Martins nest at different times, during a nest check we can find eggs still being incubated; babies about three or four days old with eyes not yet open; (photo 4) babies seven to 10 days old with eyes now open and just beginning to develop feathers; (photo 5) or babies almost ready to fledge watching us very closely. (photo 6)
An older baby, placed on its back is quite docile and allows examination of the belly fat to determine if the bird is well fed. (photo 7) Sometimes we find dragonflies beneath the gourd racks that the parents have dropped. (photo 8) The always hungry baby birds ravenously gobble down the dragonflies, wings and all, when we deliver the dropped food to them. (photo 9) (Note: all of these photos, except No. 1, were taken during the same nest check on July 8 of this year.) Purple Martins tolerate the nest checks quite well, patiently waiting on the nearby gourd racks as their particular rack is lowered and flying back into their gourds even while the rack is being cranked up to its full height.
This year we expect to fledge 129 baby Purple Martins. While that may sound like quite a few, it is well below our top year, 2016, when we fledged 346 young Martins. That year Martins laid eggs in 98 of the 134 gourds we provided. This year, only 48 gourds of the 144 available housed Martins that laid eggs and raised young. 2016 was a perfect year for the Martins, weather-wise, and we had not yet been discovered by the Cooper’s Hawks or Great Horned Owls. Hopefully, now with the “dancing scare crow,” future years will once again be more productive. Unfortunately, in 2019 our area of Pennsylvania suffered a wet cold spring and Martins had difficulty finding food which discouraged nesting and breeding activity.
Purple Martins rely almost exclusively on housing provided by humans. On only one occasion have we ever found a pair of Purple Martins attempting to nest in a natural tree cavity, (several years ago at Orlando Wetlands Park) and they were under severe pressure from European Starlings. Whether they were successful or not is not now known. Many well intended prospective Martin landlords mount housing but then fail to follow through with monitoring that housing to keep out Starlings and House Sparrows, both of which will kill the Martins to take over the nesting site.
In Florida, houses installed on poles above docks along rivers seem to work well as the invaders appear not to like being over the water. Certainly in Florida, with more Purple Martins, we see many more nesting colonies, often small, containing only one house of four to eight nesting units, than are found in more northern states such as Pennsylvania. But every bit of housing provided is critical to the survival of the Purple Martin population.
We humans are colonial nesters also, if you consider apartments, high-rises, condominium complexes and shoulder to shoulder residential developments as forms of “colonies.” Purple Martins, like humans, will also explore many potential homes before selecting the one they want to raise their “children” in. For example, during nest checks we find that the Martins have formed cups and added material to the pine straw that we supply in almost every gourd, but then only select a certain specific preferred gourd for their own. And like many of us “Snow-birds,” when the cold weather arrives, Purple Martins have long since migrated south, primarily to Brazil.
It is truly amazing the similarities in raising families by birds and humans. Oh yeah, they sometimes squabble with their neighbors too.