|We should be hearing the vibrating buzz of the Savannah Sparrow any day now. They return to Vashon in the first week of April. Usually about the third note of their song contains a sub-sonic trill that one can feel shimmering one's eardrums like the thrumming of a Ruffed Grouse. That part of the song is almost more felt than heard.
Savannah Sparrows look very similar to a light brown Song Sparrow. They possess a lot of streaking on the breast like a Song Sparrow. They can be told apart by the presence of a small amount of yellow in between the brown streaks going over the eyes. Their bills appear yellow to tan in contrast to gray for the Song Sparrow.
The Savannah Sparrow breeds in wet fields with tall grass around the island. Good areas to look for breeding birds include the wet fields adjacent to the monument on Monument Road, the fields in Paradise Valley and the fields along Westside Highway in the Colvos and Cove areas. Savannah Sparrows fare better in Western Washington than most field and open area birds because they use relatively small patches of weedy lots to breed. However, on Vashon, this specie's breeding population needs watching as the forest reclaims more fields and residential area sprawls.
Several sub-species/forms of the Savannah Sparrow move through western Washington, with the small Brooks form being the breeding form. Others such as the large Aleutian form are spring and fall migrants. Migrants on the islands show up very visibly at KVI Beach and Pt. Robinson. It would be interesting for birders to take note of the size of birds seen along the shoreline areas to see if both Brooks and Aleutian forms pass through Vashon.