Reports on nesting activity tell us where and when breeding is occurring, and how successfully Barn Swallows are producing young. This information helps us determine what factors may be contributing to the population decline.
Barn Swallows nest in and around barns, sheds, and boathouses; under bridges; and in culverts. Nests are often adhered to vertical surfaces near the ceiling, or under eaves on the outside of buildings. Barn Swallows also build nests on horizontal beams, or on top of ledges, light fixtures, cables, etc. which provide additional support for the nest.
To find nests in a barn or shed, use a flashlight to scan rafters and other areas near the ceiling that could be used to support a nest. In two-storey barns, the majority of nests are usually found in the lower level.
PLEASE NOTE: Permission from property owners must be obtained before searching for nests on private property.
IMPORTANT: If you are interested in monitoring Barn Swallows using the BSC Project NestWatch protocol, please contact firstname.lastname@example.org to obtain a copy of the Canadian Wildlife Service Scientific Permit from Bird Studies Canada.
You may find Cliff Swallow nests near Barn Swallow nests. Cliff Swallow nests are easily identified by their shape, which is rounded and enclosed except for a small tunnel entrance. Cliff Swallows sometimes take over Barn Swallow nests by building domes on top of them, even if they are occupied.
Barn Swallow colonies should not be disturbed too early in the nesting season. The risk of nest abandonment is higher during the early stages of nest building and laying. Start checking nests when you think the birds have begun incubation (usually late May in southern Ontario).
Do not check nests too early in the morning or in inclement weather when eggs and young are more vulnerable to exposure. Avoid disturbing nests when it is cold or during heavy rain, when birds may already be stressed due to reduced foraging ability and/or insect availability.
Because Barn Swallow nests are usually very close to the ceiling, roof, or overhang of a structure, it is often impossible to observe nest contents from above. Use the methods described below to check nests at different stages of development.
Nests with eggs
Nests with young
NOTE: Please use extreme caution with the mirror and do not touch the nest! Nests can be fragile, and may fall if disturbed. For nests that are more than 12 feet above the ground, do not attempt to use a mirror on a pole - use your observational skills to gather information about these nests from a distance.
Gather information about nesting stage by watching the adults and looking for other clues around the nest. Keep in mind that if the adults are disturbed by your presence, they may leave the nest during any stage. Here are some clues to look for:
The young will usually flutter to the ground and quickly try to hide. It is unlikely they will survive unless returned to the nest, since they are very vulnerable to predators on the ground. If it is safe to do so, retrieve the young and place them back in the correct nest carefully. Place your hand over the nest, gently holding the young in the nest and wait for them to settle before slowly moving your hand away and leaving the area.Do not attempt to return the young to the nest if there is no safe way for you to access the nest!
If you are monitoring more than one nest, it is very important to label the nests. In a barn, consider affixing a small piece of flagging tape below each nest using tacks. Write a number, or nest code, on the flagging tape in permanent marker to keep track of your nests even if there are changes in the colony throughout the season (e.g., new nests being built).
Check Barn Swallow nests every 5-7 days throughout the entire nesting attempt (i.e., from the first visit until the nest fledges or fails). Do not visit more frequently, as this could have a negative impact on Barn Swallow nesting success. The recommended frequency of nest visits is less often than for other species because there is some indication that more frequent visits may negatively impact nesting success for Barn Swallows. After the nesting attempt is complete, check the nest one last time to see if any unhatched eggs remain. If you find a Barn Swallow colony, try to monitor all the active nests throughout the breeding season. Remember that some pairs of Barn Swallows raise two broods. Please submit your data even if you only visit a nest or colony once over the season.
More on the Information you're collecting
|Eggs & young||Try to start monitoring your nest(s) once incubation has begun. This allows you to collect data on clutch size (the number of eggs laid) and brood size (the number of young).|
|Nest outcome||Did the nest fledge or fail? Monitoring the nest regularly until the end of the nesting attempt will help you determine its outcome. Counting the number of young up until they leave the nest will help you determine the number of young that fledged.|
|1st clutches, 2nd clutches, and re-nests||After 1st nests fledge, some Barn Swallow pairs start a 2nd nest. Re-nesting is also common if a nest fails. Once the nest you are monitoring is finished, be sure to check back in about 10 days to look for 2nd clutches. Pairs may raise a second brood in the same nest, build a new nest, or use a different old nest. Because many Barn Swallows raise two broods the Barn Swallow breeding season is long; in southern Ontario there are still many active nests in August.|
Although Barn Swallows have a high rate of nesting success, nest failures (i.e., no young surviving to the stage of fledging) can occur for a number of reasons. If all the eggs disappear, or the young are gone before they should have fledged, you'll know the nest has failed. Possible causes include:
Please submit data on all nests you monitor, even if they do not succeed, or the final outcome is unknown.
If a nest you are monitoring fails, make note of the conditions of the nest and if any contents remain (e.g., broken eggshells), as this may provide clues about the reason for nest failure.