Today’s batch of photos comes from Kevin Krebs, who’s been busy banding birds in south-central British Columbia. Kevin’s captions and IDs are indented, and, as always, you can enlarge the photos by clicking on them.
Since 2018, the Vancouver Avian Research Centre (VARC) has been involved in Bluebird Box Monitoring around the city of Merritt in south-central British Columbia.
Like almost all birds, bluebird numbers have been declining, and we’ve recruited many volunteers to maintain and monitor over 400 nest boxes.
A few weeks ago, I had the opportunity to join some compatriots checking nest boxes and banding bluebird nestlings.
Mountain Bluebird (Sialia currucoides)
Mountain Bluebirds (Sialia currucoides) are found throughout Western and Central North America. The males are a brilliant cerulean blue that is almost impossible to capture in a photograph. Imagine a small piece of the most vibrant blue sky you’ve ever seen growing wings and flying free.
They’re medium-distance migrants, with some breeding into Alaska, and wintering down into Northern Mexico. They are cavity nesters and rely heavily on old woodpecker holes, often facing significant competition. North American Breeding Bird Survey (BBS) data from 1970–2014 shows an estimated overall population decline of 21%. Recent research suggests a more complex picture, with some populations declining, some stable, and some increasing.
Next box and Mountain Bluebird eggs
On the left, an example of our nest boxes. Most are located on fenceposts, while a handful are placed on trees and stumps.
On the right, an active Mountain Bluebird nest with four eggs. Their nests are made of dried grasses beautifully woven into a cup, with a few feathers often mixed in. Their eggs are pale blue and slightly glossy.
Tree Swallow (Tachycineta bicolor) eggs and young nestlings
In addition to Mountain Bluebirds (and rarely Western Bluebirds (Sialia mexicana)), these nest boxes are frequently used by Tree Swallows (Tachycineta bicolor).
Somewhat similar to bluebird nests, Tree Swallow nests feature significantly more feathers in their construction. On the left is a nest with eight eggs — matte white and much smaller than the bluebird eggs (my fingers give a sense of scale).
On the right: a nest with six very young Tree Swallow nestlings.
Tree Swallow nestlings
Another Tree Swallow nest with at least six older nestlings. Their eyes have yet to open, so they’re probably only a few days older than those pictured above. The comically large and bright mouths are selected to draw as much attention from their parents as possible, ensuring they get fed.
Adult Tree Swallow
An adult male Tree Swallow (Tachycineta bicolor) who started out as one of those little eggs.
Northern House Wren (Troglodytes aedon)
Another bird that occasionally uses these nest boxes is the Northern House Wren (Troglodytes aedon). There’s no mistaking their nests as they have a profoundly different style of nest-building, packing nearly the entire box with dozens of twigs.
On the right, a peek into the nest revealing the feather-lined cup with seven mottled 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. We can’t band them when they’re much younger as they store fat in their legs, making them too large for the metal bands we use.
Banded Mountain Bluebird nestlings
Two Mountain Bluebird nestlings in the hand.
Before anyone panics: yes, I am trained to do this and am operating under a permit! I don’t think I need to tell any of you not to try this yourself.
The bird on the left is around 12 days old, while the one on the right is approximately 15 days old — probably within a few days of leaving the nest.
Note that we use federally numbered bands, anodized with a different colour for each year. This allows us to identify adult birds to the year they were banded, even if we can’t get the band number.
Banding in progress
A photo of me in the process of banding some nestlings. The bags on my lap contain birds to be banded and that have been banded. Once they’re all completed, we carefully and quietly place them back in the nest box.
Not pictured is when I sat directly on top of an ant nest while getting ready to band…