Thursday, April 15, 2010

Starting Life in a Sock!


Baby Bushtits spend their early life not unlike the children of the Old-Woman-in-the-shoe, except in this case it’s more like a hanging sock!

The classic image most of us have of a nest is the ‘shallow bowl’ style nest typical of American Robin and many other birds. A certain number of North American species however build more complicated nests that completely enclose or surround the eggs. Most are nearly round, with entry holes for the parents to enter and exit. They are constructed of a variety of materials: We’ve seen round Bullock’s Orioles nests made up of horsehair and baling twine; big, round American Dipper nests all of green moss and football shaped verdin nests in the desert of dried leaves and twigs. The ‘dangling stocking’ nest constructed by the diminutive bushtit though, made largely of spider web woven together with small leaves and moss is perhaps the most impressive display of creative home-building.

Liam and Alita and I filled an hour yesterday afternoon walking the perimeter of Teichert Pond. Our first sighting of note was about a dozen Canada Geese goslings, chaperoned by 6 adults, picking among the domestic lawn on the fringe of the nearby mall parking lot. Given the date and recent wind direction (from the south) I hoped to find some newly arrived migrant warblers among the pond-side riparian. We stopped along the north side of the pond where a lone olive tree often produces large numbers of birds. Instead of warblers, Liam pointed out two nests, one the traditional bowl shaped nest of a northern mockingbird at the top of the tree, the other, just above eye level, the pendulous basket of the bushtits.

I use the plural bushtit(s) because these tiny birds, their gender told apart only by the color of their eyes, collaborate on all aspects of the construction. Choosing a height anywhere from “6 to 35 ft.” above the ground they weave the ‘pocket’ up to 12 inches long of “mosses, lichens, leaves, cocoons, grasses” with spider silk to the twigs and branches of a tree or bush. The feat takes them 13-51 days – longer than it takes the eggs to incubate! Both expectant parents brood the eggs and spend the night in the nest.

Hopefully we hadn’t scared the parents off, bushtits are known to abandon nests too closely scrutinized by predators during construction. With this in mind we only stayed long enough to snap a photo and then departed.

Selected information for this post from Hal Harrison's Western Birds' Nests (Peterson Field Guide)

3 comments:

  1. Saw this strange sock-like nest in the large Pepper Tree in my front yard last week. On Sunday finally saw one of the occupants come home. Your posts helped me identify this newcomer to my neighborhood. This is the first of it's type that I have seen here in the San Joaquin Valley.

    ReplyDelete
  2. I have one in my grapefruit tree in San Jose, CA. Found one last year in the orange tree. Thank you for your information.!

    ReplyDelete
  3. Thank you for posting the photo and the information. I discovered our robin's nest had been abandoned, so I got to trimming the tree. When a sizeable branch hit the ground and rolled over, I saw the hanging nest. I hadn't seen much bird activity, but seeing it made me nervous that I had become a home wrecker. I snipped off the branch above the nest and cable tied it back into the tree next to where it had been. I am happy to say, they have moved back in! Do you know the likelihood they'll use the same nest again next year?

    ReplyDelete