Colony Farm: distant birds

A hot summer's afternoon is the worst time to go birding. Colony Farm is one of the best places. Combining the two works, sort of; the light is good, the birds mostly in hiding, but the music is wonderful.

The river through the Farm is bordered with stands of red elderberry and impenetrable thickets of hardhack; beyond this are the grasslands. Deep in the shade at this time of day, unseen red-headed blackbirds sing to their mates, joined at intervals by other birds that we are incapable of identifying by sound. Assorted chirps, tweets, whistles, gurgles (Gurgles? What makes that sound?), twitterings ... Ah, those we recognize!

Bridge over the Coquitlam River, with hardhack thicket and lathyrus.

Swooping over the river, sometimes touching the water with the tip of a wing, sometimes soaring high above, the swallows dance, twittering as they go. "Good mosquitoes here!" "And here, too!"

Swallow in the distance, pausing on a dead elderberry branch.

At the wooded end of the farm, where the river exits, swallow nest boxes stand on pilings.

One of the pilings, and hardhack in bloom.

High in a distant tree, a different bird was singing loudly. His song was one or two notes, a pause, then a trill. Pause and repeat, over and over. I didn't recognize the song at all.

The photo, taken against the light, zoomed and cropped, then lightened so that we could see more than just the silhouette.

What is this bird? It has a dark head and neck, a greyish breast, white at the base of the tail, then another white patch at the end. It mostly resembles a female Evening Grosbeak, but its song doesn't match the sound clips I've found. Black-headed grosbeaks are known to nest here in Colony Farm, but I find no mention of Evening Gs.

The photo above, cropped even more.

Same bird, facing front.

Help! Can you name this bird?

Next: Bright colours.

UPDATE: It's a spotted towhee (see the comments below), and here's its song, the third recording on Cornell's Spotted Towhee page.