Since 2018, the Vancouver Avian Research Centre has been involved in Bluebird Box Monitoring around the city of Merritt in south-central British Columbia.

Last weekend I finally had the opportunity to join a few compatriots to check nest boxes and band bluebird nestlings that were old enough.

Nest box and Mountain Bluebird eggs

An example of our nest boxes. Like the one pictured, most are located on fence-posts.

On the right, an active Mountain Bluebird (Sialia currucoides) nest with four eggs. Their nests are comprised of dried grasses beautifully woven into a cup, often with a few feathers mixed in. Their eggs are pale blue and slightly glossy.

Tree Swallow eggs and young nestlings

In addition to Mountain Bluebirds (and rarely Western Bluebirds (Sialia mexicana)), Tree Swallows (Tachycineta bicolor) are common inhabitants of these next boxes.

Somewhat similar to bluebird nests, Tree Swallow nests feature significantly more feathers in their construction. On the left is a nest with eight eggs. As you can see, they’re matte white and much smaller than the bluebird eggs (my fingers for scale give a sense of scale).

On the right is a nest with six very young Tree Swallow nestlings.

Tree Swallow nestlings

Another Tree Swallow nest with at least six older nestlings. Their eyes are still closed, and those comically large mouths is evolution adapting to draw as much attention from their parent as possible to ensure they get feed.

Northern House Wren nest and eggs

Another bird that occasionally uses these nest boxes is the Northern House Wren (Troglodytes aedon). They have a profoundly different style of nest-building, loading up nearly the entire box with twigs.

On the right, a peek into the nest revealing the feather-lined cup with seven eggs.

Mountain Bluebird nestlings

This is what we were looking for: Mountain Bluebird nestlings. These birds are 9-10 days old, making them old enough to band.

Mountain Bluebird nestlings

Two Mountain Bluebird nestlings I banded. The bird on the left is around 12 days old, while the one on the right is approximately 15 days old – almost old enough to fledge.

Helpers

Checking one of the nest boxes draw the attention of a handful of horses who decided to join me.

Not pictured is when I was banding some nestlings by a road and sat directly on top of an ant nest.

An unforgettable experience.

Until next time.

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