Tree Swallow Nestbox Monitoring

Ongoing Project

Tree Swallow Nestbox Monitoring

Tree Swallow Monitoring

Since the late 1990’s, several research studies have been completed on tree swallows using nest boxes in the Fort McMurray region to understand if these birds are experiencing elevated stress due to oilsands development. Founding members of the WBWRI began monitoring the tree swallows in 2011, continuing the research begun by others. Currently, the tree swallow boxes are being monitored for productivity.

"Banding tree swallow nestlings is an excellent opportunity for our volunteers to be introduced to bird banding under the guidance of our professional bird banders."

Tree Swallow

Tree swallow colonies synchronize their nesting activities and arrive in the Fort McMurray region about early to mid-May to begin building their nests. The nests are built quickly and within a few days the females will lay one egg per day, with most of the nests in our nest boxes containing between 5 and 8 eggs. After about two weeks, the nestlings will hatch. Starting in May, our volunteers monitor the timing of nestling hatching and nestling growth so we can band them at the appropriate age.

Nestling banding normally occurs between June and July. The nestlings will leave the nest and fledge when they are between 16 and 20 days old. Banding tree swallow nestlings is an excellent opportunity for our volunteers to be introduced to bird banding under the guidance of our professional bird banders.

Tree Swallow Nest

Tree Swallow Nestling

Sometimes we can also band the adult tree swallows when they are found in the nest boxes with the nestlings. Many of our banded adults are recaptured when they return the next year to nest again.

After the tree swallows have migrated away from Fort McMurray in the fall, or prior to their return in the spring, our volunteers assist with the removal of the old nest material to minimize the transmission of parasites that can overwinter inside the nest boxes.

2024 Project Results

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Nest Boxes Occupied

Nestlings Banded

Adult Females Banded

Adult Males Banded

Did you know?

Prolonged periods of cold and rain or extreme heat, nestling diet, and asynchronous hatching are all important factors that affect tree swallow hatching success and nestling growth. Sometimes nests will fail if bad weather over many days prevents the parents from being able to feed their young.

Tree swallows will eat both terrestrial and aquatic insects, including beetles, parasitic wasps, flies, mayflies, and damselflies.

Some of our recaptured adult female tree swallows have been found occupying the same nest box that they used in a previous year. We have also recaptured females that returned to Fort McMurray but occupied our nest boxes up to 12 km from where they nested previously, and where we banded them originally.

The research on tree swallows over the last decade has found that the reproductive success of tree swallows that breeding near Fort McMurray was not influenced by their proximity to the oilsands mine operations.

The number of eggs that a tree swallow will lay is related to how far north they are nesting. More eggs can be laid farther north because of the longer day length that allows the birds more time to forage and feed their young.

Tree swallow nestlings will hatch over 24 hours, and the smallest nestlings are the ones that hatched last. Tree swallows will begin to incubate their eggs after the second to last egg is laid, which contributes to this asynchronous hatching of the nestlings as the last egg laid needs the extra day before it will hatch.

Male nestlings are larger than female nestlings when they are less than 9 days old, but both male and female nestlings are about the same size when they are old enough to leave the nest and fledge.