North they go

It is that time of year again. Across the northern hemisphere the poleward procession of the snow-line is giving way to a swarm of migratory birds. We are reminded of that fact every time we see a bird, or hear a sound, that seems out of place. Migrants have been passing through Catalina since mid-April and have been doing so in waves. We had one such wave today, bringing with it Townsend's Warblers, Hermit Warblers, Black-throated Gray Warblers, Western Tanagers, and plenty of other species that I'm sure we missed. Over the years we have caught many of those migrants and, before releasing them unharmed, have had them pose for a few photos.

Hermit Warbler

Warbling Vireo

Townsend's Warbler

Wilson's Warbler

Orange-crowned Warbler

Ok, so I know what astute readers out there must be thinking: "Aren't you there studying a breeding population of orange-crowned warblers? Why is that last photo lumped in with the other migrants?" Well, believe it or not - on this same day last year - we caught a few orange-crowned warblers of the Alaskan/Canadian race that were migrating through Catalina (the above bird is smaller and has duller plumage than our local breeders). We don't know where those birds ended up, but they do serve to highlight just how delayed the northern breeders are. Here most orange-crowned warblers have raised a batch of young (i.e. a brood) by early May, but the Alaskan birds have just started to make their way north. In a few short weeks we will catch up with some of those birds in Fairbanks, and will start studying them just as their migratory journey ends and their breeding season begins. Until then, we will continue to enjoy the passing of migrants on Catalina Island.