BLACK-CAPPED CHICKADEES ON VANCOUVER ISLAND?

The following was extracted (without references) from an article written by Sharon Godkin for “The Victoria Naturalist”, magazine of the Victoria Natural History Society. Sharon has been to Malcolm Island a few times and we were delighted to have her participate in our spring bird count last year. Many thanks for contributing to our blog Sharon!:

Black-capped Chickadees (BCCHs) are generalists that range widely across North America: from the Lower Mainland and interior BC to Newfoundland; from New Mexico to the Northwest Territories and Yukon; and into western Alaska. However, (BCCHs) have never been officially recorded on Vancouver Island.

The reasons suggested for BCCH absence from Vancouver Island are: strong reluctance to fly over water, the lack of any BCCH populations close to Vancouver Island to serve as irruption/emigration reservoirs; and relative lack of their preferred habitats (open deciduous, mixed deciduous/coniferous forests).

If BCCHs will not fly across water, they must have found some other way to colonize the water-isolated islands of eastern Canada. Perhaps the answer to this puzzle, for both coasts, is dependent on when they colonized these areas.

As the continental and regional ice sheets advanced and retreated, various types of tundra, herbaceous, shrub and forest habitats margined the ice. Lower sea levels and isostatic effects resulted in many coastal areas now isolated as islands being connected to each other and the continent by dry land.

There is also considerable evidence for the existence of multiple North American refugia during ice advances. Organisms which may have immigrated to Vancouver Island and other current islands prior to the last ice advance could have survived in refugia and recolonized from them. Any present populations of BCCHs would be successors of those established via peri-and/or post-glacial land connections.

Historically, there have been scattered reports of BCCHs being seen and/or heard on Vancouver Island, even on Christmas Bird Counts. None of these reports have been officially accepted due to their lack of documentation.

The past observations of BCCHs of which I have personal knowledge occurred on the northern portion of Vancouver Island. They were made by an Ontario birder participating in the Atlas, and by a friend in Port Hardy.

My observations of putative BCCHs on Vancouver Island occurred on the clear sunny afternoon of 18 July 2014 when I was photographing flowers and dragonflies around ‘9-km Bog’ on the flanks of Mt. Washington. I saw two birds flying in close tandem directly across the narrow meadow about eye height. They readily pished to within a meter from my face.

By comparing descriptions and images in multiple references to the birds’ physical appearance, sounds and behaviour, Sharon determined that the only description which fully fit the birds was that for black-capped chickadees. She posited that perhaps these BCCHs belong to a small, scattered, very mobile relict population, as encountering them seems to be purely by chance.