72 Microseasons of the Pacific Northwest

Pacific Great Blue Herons (Ardea herodias fannini), a non-migratory subspecies found only along the Pacific Coast from British Columbia to northern California, begin returning to their nesting colonies as early as January in the Puget Sound region. Unlike their migratory counterparts, these birds spend their entire lives in the same coastal watershed. January marks the beginning of colony activity for the South Sound population, which breeds earlier than herons nesting farther north. Seattle's largest and most accessible rookery occupies big-leaf maple and cottonwood trees at Commodore Park on Magnolia's north side along Salmon Bay, with dozens of nests visible from the park's shoreline path. A second urban colony is active on the University of Washington campus. Other well-known rookeries include Padilla Bay near Bayview, a large colony in Everett near the waterfront, and multiple sites on the southern Gulf Islands of British Columbia. Herons arriving at colonies engage in elaborate display flights, bill-clattering, and loud squawking calls that carry hundreds of meters — the sounds of a rookery returning to life after winter silence. At this period, birds are establishing pair bonds and claiming nest platforms, often refurbishing old stick nests used for decades. The nests themselves — broad, flat platforms of sticks up to 1 meter across — are unmistakable in bare-limbed trees. Observers with binoculars can watch billing and bowing courtship displays. This is the beginning of a continuous breeding effort that will culminate in chicks fledging by late June.