Swallows are amazing aerial insectivores, catching insects while flying. Many of these insects are mosquitoes. They can catch up to 850 mosquitoes a day, that’s great natural mosquito control!
Conflicts with Barn Swallows occur when these birds nest close to humans, primarily because of the droppings and other debris they deposit. When swallows first hatch, the parents eat their droppings, which keeps the nest clean and insect free. After a few days, the adults carry the droppings away from the nest to prevent detection by predators. Barn swallow chicks stay in the nest for 18-23 days. Around day 12, the chicks start to defecate over the edge. That means that you only have to deal with the mess for 6 to 11 days a year! Maybe twice that if the birds have a second brood in the same nest.
Instead of destroying the nest which is illegal under the Migratory Birds Convention Act (and also Species at Risk Act if the species is listed as being at risk like the Barn Swallow), here are some simple solutions that should be implemented quickly to reduce disturbance to the nesting birds:
1. Place newspaper or some similar material under the area of droppings. Since most of the mess falls directly down onto the paper below, the problem is solved. The paper and droppings can be added to a compost pile, dug into the ground (droppings make wonderful fertilizer), or put in the garbage.
2. If an active nest is above a car or something else where you do not want a mess, a blanket or sheet can be used to cover a car or structure and moved when needed.
3. Install a board under the nest(s) to catch the droppings. Due to its close proximity to the nest, the board should be cleaned as needed to prevent infestations of insects and mites that may live in the accumulated debris.
4. If the nest is messing up a window on your house, put a black plastic bag or a board beneath the nest to catch droppings. This will be very temporary (about 2 weeks or less) and can be disposed of after the young fledge (leave the nest).
5. Hang a board under the nest using screws or string/wire, or a piece of cardboard flat under the nest using string/wire and screws/tacks. A longer board/device could be used under a group of Cliff Swallow nests. The board/device should be a couple of feet below the nest and not so wide as to interfere with the bird’s comings and goings.
https://www.cornwall.gov.uk/media/0azjdwic/accommodating-swallows-swifts-and-house-martins.pdf
Ideally, any of the strategies that involve approaching the nest at a close distance should be done ahead of the breeding season, which can be done at pre-existing nest sites (Barn Swallows can re-use their nests). If that is not possible, these strategies should be implemented as quickly as possible so as to reduce disturbance to nesting birds. Also, nests should not be approached when chicks are large as they can jump out of the nest early which can lead to death.
For questions or help with these strategies for co-existence, please contact swallows@wildsight.ca.