Creating Homes for Our Unique Lucy’s Warbler

By Bob Bowers

Lucy's Warbler adult and chicks in Tucson Audubon-designed nestbox by Paula Redinger

Compared with some other states, bird-rich Arizona comes up short when you look at nesting warblers. There are about fifty members of the wood warbler family in North America, and only eleven of these nest in Arizona. Nevertheless, we have some special warblers that are found only in the southwest part of the country.

Four of our nesting warblers are only found in Arizona and its neighboring states: Grace’s Warbler, Red-faced Warbler, Painted Redstart, and Lucy’s Warbler. Each of these are impressive birds deserving their own article, but perhaps the most special is Lucy’s. If you are familiar with these four, you know how beautifully colorful the other three are, and may wonder why I would choose Lucy’s, a black-eyed tiny creature that’s gray above and off-white below. Granted, it has rarely-seen rufous color on its crown and rump, but in no way is this comparable to the other technicolored species. 

Subtle beauty: Lucy's Warbler in mesquite by Hemant Kishan

What is so appealing about Lucy’s? At give-or-take four inches, this hummingbird-sized warbler is smaller than all other U.S. warblers. In addition, this is only one of two warblers in North America that nest in cavities, and the only one in the west. Although they will nest opportunistically in an unoccupied Verdin nest, a Gila Woodpecker-drilled saguaro hole, or even in a clay bank crevice, their favorite spot may be a narrow wedge between the bark of a mesquite tree. Here’s how Herbert Brandt described one of these nests in his 1951 classic, Arizona and Its Bird Life: “I found myself at one of the daintiest creature homes it’s been my pleasure to visit. Skillfully tucked down in a fold behind thick, rough bark was an artistic, silvery cup which held four wreathed gems of eggs. Within this ancient skin-wrinkle on the mesquite’s brawny arm, snuggled a Lilliputian cradle, the natal home of the smallest of all our many warblers.” Brandt measured this nest at 1.75 inches in diameter and just .75 inch deep. Despite their size, Lucy’s Warblers face problems in and around Tucson as mature mesquite bosque habitat is not as plentiful as it once was.

The Birds of the World website (Cornell Laboratory of Ornithology) wrote in 2012, “Unlike many cavity nesting species, Lucy’s Warbler will not use nest boxes, and no direct management actions specifically targeting this warbler have been taken.” Beginning in 2015, Tucson Audubon began a series of nestbox experiments that resulted in finding that Lucy's will in fact utilize boxes and seem to prefer the triangle design that the conservation department created. Currently, Tucson Audubon has placed 2,167 nestboxes with more being added every season. Most nests we've recorded have contained 3–5 eggs, and all of the nestboxes have a potential of raising multiple Lucy's Warbler broods in a single season. When Tucson Audubon publishes these results, it might be time for Cornell to update their Lucy’s Warbler section!

NOW is the time to get your nestboxes up! Lucy’s Warblers will be back in March. Come to a special Birds ‘n’ Beer event at Tucson Hop Shop on February 24, 2022 where we’ll have nestboxes for sale.

If you can’t make it, we still sell boxes online or in person at our Nature Shop. Learn more at tucsonaudubon.org/lucy.

Bob Bowers is a birding photographer/writer who has published articles in the Vermilion Flycatcher as well as newspapers and magazines in Arizona, Colorado, and Mexico. He and his wife Prudy lead Tucson Audubon field trips and volunteer for the Tucson Bird Count and Catalina State Park's Nature Program.