Why would the wool wear off on just one slipper? I wondered about this but concluded that particular slipper must have been made from a weak-wooled sheep.
The real explanation came a few days later. On warm spring mornings I leave my slippers on the deck and go barefoot. At lunch time, I looked out the window and saw a small bird, a titmouse, perched on my slipper. She was busily pulling strands of fleece out of the ruff. She’d bend down again and again, plucking the wool. Soon she had a large ball of fluff in her beak.
When she flew off, I tried to see where she was going with the wool, but she eluded me. I know that Black-crested Titmice build their nests inside cavities, usually in hollow limbs and tree snags. I never found her nest site though. She was clever enough not to go straight to the cavity while I watched.
Not long after this encounter I found a Verdin’s nest. I was walking in a thicket, and the nest was in a Blackbrush, just above my head. The nest was sturdily constructed of thorny twigs so well interlaced that I could not pull out a single twig. It was shaped in an oval ball. At one end there was an opening, about an inch across and projecting downward. I could see into the opening only a little way before the entrance curved up into the nest.
I couldn’t resist. I had to put my finger into the nest. It was unlikely that this nest was occupied. I hadn’t seen any Verdins around. This was probably an old nest, perhaps from last year.
I gently felt inside the nest. It was as soft as a baby’s blanket. The whole inside was lined with soft fur or milkweed floss. I pulled a little bit of the floss out and examined it. To my surprise, it was wool!
So, Verdins had been wool-gathering at my slippers, too. I guess I had been leaving those slippers out there in years past. (I knew they were getting old!)
The Verdin is a small bird related to the titmouse, so you might expect they would use similar materials to line their nests. Still, the two birds have quite different nest-building strategies. Titmice simply find a cavity and add lining to make it comfortable. Verdins, on the other hand, construct the tightly intertwined ball of thorny twigs; they then fill the hollow with a thick lining of feathers, fur and soft fibers. It is well padded and well insulated.
The padding and insulation are critical for the survival of the Verdin’s eggs. The Verdin is a bird of arid brush country and deserts. The thick insulation protects them from the desert heat. And the padding coddles the delicate shells of the eggs. Verdins have unusually thin-shelled eggs which break easily if bumped.
It seems that Verdins have evolved the strongest of nests to protect their fragile eggs. But Oberholser in his The Bird Life of Texas (1974) asks “Why not double protection—strong eggs in a strong nest?” He concludes wryly, “Apparently, nature, like most people, only does what it has to do and no more!”
Verdins are sweet little gray birds with yellow heads. As denizens of the brush they are not often observed. They move quietly among the scrubby branches gathering insects, caterpillars, spiders and occasionally small fruits and berries. A Verdin is more often heard than seen. It calls out a high, piercing “djeet” from the brush tops. The call is repeated every few seconds and soon becomes the only sound you hear. Follow the “djeet” and you will find a Verdin.
Because the Verdin’s nests are so sturdy and long-lasting, they may persist for years. Verdins also build sleeping nests, places where they can rest peacefully protected and warm on a cold winter’s night. This means there a lot of nests out there. And they are quite easy to find because they are usually only 2-10 feet above the ground. It can give a false impression of how many Verdins are in an area. Three or four nests may only represent one pair of Verdins.
The Verdin is one of those special birds that can only be found in the arid Southwest, from South Texas to California. If you have never seen a Verdin, make a point of looking for one this season. Just walk through brush thickets on a ranch or in a park and follow the “djeet!”