Sunday, April 4, 2010

Verdins: Avian Architects of the Desert

Photo by Richard Halliburton

One amenity you may have on your list of considerations when buying or building a new home is energy efficient construction. Long before the notion of passive solar architecture emerged in modern lexicon, one of our local avian architects, the Verdin, has been creating “green” housing for centuries, if not millenia. No, they haven’t figured out how to install solar panels, but these birds do utilize the most important components of passive solar strategies: site selection, structural orientation and insulation.

Unlike most birds, Verdins build nests year round. During the breeding season, between March and June, nests are used to protect eggs and rear their young. The rest of the year, they are used as shelters from the weather. Depending on the season, the nest will be built in a location that is best suited for keeping warm or cool. In winter months, a south-facing sunny location is chosen, with the entrance oriented away from prevailing winds to keep warm. During warmer months, they will move to a north-facing shady area with the entrance oriented towards cooling winds. The amount of insulation can also be adjusted by type and thickness to suit the season.

Working together, mating pairs build hollow oval-shaped homes about the size of a cantaloupe. Males build the outer shell using thorny twigs and grasses. Females take care of interior design, lining the nest with a soft inner layer of leaves, feathers, fur and spider-webbing. Usually the nest is attached among the outer branches of a large tree or shrub with an easy flight path to the entrance. Look closely at one of these balls of sticks, and you’ll see a small hole near the bottom of the nest. Verdins prefer to build along washes where food is more abundant, but are also common in landscaped suburban neighborhoods. A busy pair may build more than ten nests over the course of a year!

You are more likely to notice a Verdin nest than the actual bird, even though they are among the top ten most abundant species in annual regional bird censuses in the Sonoran desert. On a typical sunny morning, the loud whistles and chirps of Verdins are some of the dominant bird calls echoing across washes and green belts around Deem Hills. If you follow your ears to find the song’s source, you might be amazed to see how tiny they are, less than five inches long with a wing span just over six inches.

If you’ve never noticed them, that is not surprising, since Verdins are also listed in Sibley’s Guide to Birds as one of the eight “Drab Gray Birds of the Arid Southwest.” Of all the DGB’s, however, adult Verdins are one of easiest to recognize, since the heads of both males and females look like they have been dipped in greenish yellow paint. The juveniles are the drab ones, being dull gray all over. In Spanish, verdin (pronounced “ver-deen”) means “green stain” or “green pond scum.” Not a very flattering description, but apparently that is what some early desert ornithologist was reminded of! A closer look will reveal rusty red shoulder patches. When not tending nests, Verdins spend their days flitting about in trees and shrubs, pecking at seed pods, fruits, flowers or branches to glean insects, spiders, seeds, berries and nectar.

If you are lucky enough to have a Verdin build its nest near you, let it be an inspiration to make your own home more energy efficient and perhaps a little more comfortable!


  1. Great story about the Verdin. I also love your plant list. I would love some background stories on how those non-native plants arrived here. That Chamomile seems be taking over everywhere. Have you seen the fields of it at Thunderbird Park?

  2. Yes, the Chamomile (Oncosiphon) is an African native that is reputed to have imported for horticultural purposes by the Desert Botanical Garden. Now is is invading everywhere! It is also called "Stinkweed" because when it flowers, it starts smelling like rotting meat, probably to attract pollinating flies. Yucky stuff. I'm actually on the brink of developing a whole separate blog on invasive plant species. Stay tuned!

  3. Hi. I'm in Yuma and have two Verdin just a few feet away from my window industrially building what must be a breeding nest in my backyard screwbean mesquite brush. Sure enough, the nest is in the brush periphery, 6 feet high off the ground, opening from the bottom, to the south. Very cool – I have a front row seat.