| Artificial Barn Swallow Nests |
A. To entice a pair of barn swallows who have chosen a site unacceptable to humans to relocate. One site considered unacceptable by many homeowners is directly over the front door, where droppings fall on the entrance. This frequently happens because the outdoor light fixture above the door is one of the few sites where the swallows can anchor their mud nest. Also, the front yard is often a virtual wasteland of 2" tall grass, seemingly uninhabited. The humans leave early in the morning via the automatic door of the attached garage and return in early evening via the same route. The front door may not be opened for days at a time and the swallows feel they have found the ideal safe nest location, of little interest to predators and apparently deserted by humans, compared to a busy farm yard. Another often unacceptable site frequently reported to me is inside a horse barn or other outbuilding. This can be a problem to the humans either because this requires always leaving a window or door open in the building during the nesting season or because the human activity in the building will not be compatible with the swallows nesting, or because the interior of the building and its contents must be kept clean.
B. To attract barn swallows to a new site. Nest cups placed in desirable locations. are the best bet to attract barn swallows for the first time. Whether this is because the swallows may think a pair previously nested there or because the nest cup saves them the major job of nestbuilding is not apparent.
C. To allow an existing colony to grow. Where limited nest sites exist due to a lack of suitable surfaces for building mud nests, the addition of artificial nest cups allows additional pairs to nest.
If your nest cups are hard to reach, it is not necessary to climb up and remove and replace them each year. However, if you can, it may be very beneficial to empty and wipe out the nests immediately after each brood fledges. This will remove the accumulation of nest parasites, especially mites.
In August, 2001, when I discovered that the last four nests in our colony were deserted due to heavy mite infestations, I looked at the teaming mass covering the rim of one of the nests under a stereo dissecting scope. In the very first field that I viewed was a spider busily wrapping up several mites, still kicking, while hundreds of other mites were rather rapidly crawling around and over each other. After a moment I realized that this spider was tiny - less than 1/10 inch long, as measured in the eyepiece micrometer. Did all of the mite infested nests harbour these spiders? How wonderful! When the barn swallow young fledge (or die), the mites lose their host. The hungry mites then become phototactic, and, in the process of crawling toward the light, end up on the rim of the nest, in a perfect position for attaching themselves to the foot of any adult swallow that may land on the nest. Some manage to grab a new swallow host, others leave the nest, probably expiring before reaching another nest, others remain in the nest, most dying in winter, but some surviving to await the returning swallows the following spring. But, what of the tiny spider? He has an almost unlimited food supply. He is, as they say, in hog heaven. If a human should poison the nest, in the name of "helping the birds", the mite will be reintroduced by the swallows, themselves, but will the spider? Is this species a common inhabitant of the swallow room, crawling all over the walls and floors? Or, is it rather uncommon and confined mainly to the swallow nests, in which case, it may take a very long time to repopulate this nest. And, does it play a roll in limiting the extent of swallow nest infestations? Maybe not, but it suggests to me yet another reason to not use insecticides to "help nature".
The minimum requirements for nest placement are adequate protection from rain, safety from predators, and privacy. In busy yards, privacy can be accomplished by height of the nest. The swallows would probably feel comfortable nesting under the eaves of a two story house, even with constant foot traffic on the ground below. However, they may not want to nest at half that height in such a busy location. Placing the nest cup high under the gable end of a single story house in such a location would better suit their need for privacy. Where heavy foot traffic is uncommon, nest heights of 8 ft are fine. This allows easy nest checks with a mirror on a stick and easy nest changes using a small ladder.Barn swallows frequently nest under porches, under elevated decks, and under carports. These locations should be checked for nest level temperature before installing nest cups. If the site receives afternoon sunlight and the roof has no insulation or ventilation, the air trapped just below the roof can rise well above the ambient air temperature. Please review the shelter page for more info on selecting or building a swallow shelter.
Richard Van Vleck
richard@americanartifacts.com
Testing artificial nests for barn swallows