Wilson’s Warbler (Cardellina pusilla ssp. chryseola) had a baby

(Written on June 10, 2017)
On the first Wednesday of June, a foggy morning, we heard cha-cha-cha-cha-chchchch and spotted a Wilson’s Warbler singing on the branch of a Western Red Cedar (Thuja plicata) as we were about to enter Pacific Rain Forest from Sea Bluff.

All of a sudden a Wilson’s Warbler landed on the trail next to the wooden bridge by several Yellow Skunk Cabbages (Lysichiton americanus). The bird was on the ground for less than a minute, then a second warbler appeared. Both flitted in the lower branches of conifers. Their plumage looked identical to each other; both had a dark cap, olive-green upperparts and bright yellow underparts (an exception to the description in most field guides about female having a lighter cap). We were sure that they were a mated pair because they were amiable to each other, not chasing the other away as happens often in territorial defense in breeding season. Soon their couple-hood was confirmed: one stood on the bridge fence briefly before going down to feed a baby on the mossy bank behind skunk cabbages.

No sooner had the short feeding session done than the adult flew up, leaving the young bird sitting in a small Heuchera. The tiny chick was brown and dark, quiet and motionless. It would have been invisible if we had not seen it being fed earlier.

We stayed about 30 feet away to look at it with our binoculars, then walked quietly past it. It turned its head to look at me as I crossed the bridge. Seeing its large pink beak was a thrill—this is my first time seeing a pink-billed chick of any warbler!

Tips on watching Wilson’s Warbler:
1. Learn its songs, and they will be the best clue to its presence. (Go to Macaulay Library. This is one example.)
2. 2015 and 2016 surveys of botanic garden show that they arrive in late March and are gone in early August.
3. Leave them a lot of space when you see nesting pairs and young birds. Please go quietly past them after you have viewed them no more than 5 minutes. I learned from Jon Young’s book What the Robin Knows that animals take many cues from observing our behavior. I wouldn’t want to interfere with Jays’ hunting of eggs and chicks of smaller birds; nor would I want to aid them.

If you want to know more about Wilson’s Warbler, some online resources about our local subspecies are below.
A study of female singing in Tilden, 1999
Photo of a banded bird in Tilden, 2015
Three subspecies may turn out to be two species, 2015
Why coastal Wilson’s Warbler subspecies chryseola declines, 2016

Parking lot of Regional Parks Botanic Garden, May 4, 2016, by Minder Cheng.

Juvenile Spotted Towhee (Pipilo maculatus)

(Written on July 5, 2017)
At the border of the Franciscan and Canyon Sections, there is a tributary that flows down by the greenhouse and joins Wildcat Creek under the bridge. Near the bridge there grow red elderberry (Sambucus racemosa) and California pipevine (Aristolochia californica). This rushing side creek becomes a trickle or disappears altogether in the dry season. In July, instead of water, there is lush vegetation on the canyon floor. This is the favorite habitat of brush-loving birds.

Walking up the steep trail from the bridge to the greenhouse, we saw, on the right slope, a dark brown bird with thick beak and a sparrow-like streaky pattern on its underside. It was larger than a sparrow, approaching the size of a thrush. Then we saw its very long tail. Near the tip on the underside of the tail, two distinct white almost rectangular marks stood out from the ground of gray tail feathers.

Three outer tail feathers.
Evolution of the Colors of North American Land Birds by Charles A. Keeler. 1893

The white tail spots told us right away that it was a juvenile Spotted Towhee. Lacking the adult’s rufous flanks, lines of white spots on the sleek black back, or red iris in the eye, this young bird did not at all resemble its parents in plumage; but in body shape it was very much a towhee. Towhees (Pipilo) are a genus of New World sparrows. The adults do not share the intricate brown and black streaks that we commonly associate with sparrows. However, in the developmental stage of the young birds, a remarkable resemblance to sparrows is apparent.

When we stood under the valley oak (Quercus lobata) near the grind stones, an adult Spotted Towhee started singing its fast dry trills from a low manzanita. It sounded a little agitated. Soon a juvenile flew out and went on to walk on a horizontal branch of coast redwood (Sequoia sempervirens) trying out its balance beam skills. Another adult showed up by the path toward the greenhouse and repeatedly called out “wrang-ng” loudly. Then the second juvenile appeared.

Based on their proximity to one another, we believed they were one family. The parents were chaperoning their children’s foray into the world!

Juvenile Spotted Towhee, probably from the second brood of the year.
Southern California Section. September 10, 2015. By Wen Hsu.