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Lucy’s Warblers and Nestboxes

Just four inches long and very active, Lucy’s Warbler has been known in the past as the Mesquite Warbler due to their close ties to these trees. Being one of the two cavity-nesting warblers we have in United States, they choose old woodpecker holes as well as peeling bark crevices as their nesting sites. Lucy’s Warblers are in population decline and listed as a Species of Conservation Concern by Arizona Game and Fish – primarily due loss of available nesting sites which occurs most commonly in dense mesquite bosque along major waterways. Even in an urban environment, Lucy’s Warblers seek out mesquite trees, which leads us to our two major projects with these birds. Image by Jeremy Hayes

To learn more about this little warbler click here: allaboutbirds.org/guide/Lucys_Warbler/overview

Unlike many other species that are limited by lack of available nesting sites which have been helped by the creation of appropriate nestboxes, no one yet knows exactly what type of nestbox Lucy’s Warblers would prefer – so much so that even literature says that they do not use nestboxes. Over the last few years Tucson Audubon has received reports of Lucy’s Warblers nesting in small decorative boxes and gourds as well as various other small cavities. Knowing that there’s an opportunity to make a big conservation effort and to increase the state of scientific knowledge on this species, we’ve undertaken a project to better understand Lucy’s Warbler nesting and to develop nestboxes that they’ll readily use.

These study efforts aim to determine the nesting preferences of Lucy’s Warblers with the ultimate goal of increasing Lucy’s Warbler populations by creating functional habitat especially via viable nestboxes in Tucson’s urban areas.

Experimental Nestbox Set Up on 7B Ranch Trail by Jennie MacFarland

Experimental Nestbox Set Up on 7B Ranch Trail by Jennie MacFarland

After studying their natural nests one thing stood out the most: the apparent preference of two points of exit in the natural nests located in peeling bark of mature mesquite trees. Thus we created 8 different designs of nestboxes to suit Lucy’s Warblers and placed them in the three experimental locations are:

  1. 7B Ranch on the San Pedro River
  2. Along the Santa Cruz River in Tubac
  3. Tanque Verde Wash in Tucson

Each box was installed in the same conditions (same tree, height, and direction) with order varied randomly to know that Lucy’s are going for a specific design box and not its placement on the tree.  With the help of numerous volunteers and staff who built, installed and monitored these boxes, we have collected a lot of valuable data.

In 2018, a total of 62% of the experimental sites had a Lucy’s Warbler nest (37/60). With each field site having 20 locations, we had 14 nests in the Tanque Verde Wash, 16 on the 7B Ranch Trail, and 7 on the Anza Trail. In addition to the experimental locations, we’ve had over 800 participants from the public install boxes in their own yards, creating a community of citizen scientists. We estimate that over 200 Lucy’s Warbler young have fledged from our boxes in 2018 alone. A whopping 75% of the used experimental boxes were either a small or a large triangle. A clear winner, the triangle box is a success.

So what’s next? We are continuing our project to gather more data and eventually publish our findings to contribute to the scientific knowledge about this species. We are planning on expanding our project to more locations in southeast Arizona and beyond, turning stands of young mesquites into suitable nesting habitats with the help of nestboxes. We live in the center of the Lucy’s breeding range, so there is no better place to study their nesting behavior. We want to see a Lucy’s Warbler nestbox in every eligible yard.

Put up a Lucy’s Warbler Nestbox in Your Yard!

  • You can purchase a Lucy’s Warbler nestbox at our Nature Shop or construct your own using this plan.
  • Fact sheet and mounting directions can be found here.
  • Please register your nestbox to help us learn more about this secretive species: tucsonaudubon.org/lucyboxregister

If you are already involved in this project in any way, thank you! You make it possible to have a citizen science effort
that yields such significant results.

For more information contact Olya Phillips: ophillips@tucsonaudubon.org

Foraging Study

Tucson Audubon has set out to study how Lucy’s Warblers use native and non-native types of mesquites as a food source. This is part of our larger effort to determine what Lucy’s Warblers need to successfully nest in urban Tucson which includes our nestbox experiment. We would love your help in watching Lucy’s Warblers forage for insects in locations where both types are present. Tucson Audubon has found a few such locations but you may know of one as well. It only takes a few minutes and we have lots of great information for you including how to tell native mesquites from non-native mesquites. We need your help with this urban conservation! Image by Joan Gellatly

Do you know of a place that should be added to our map of locations that have both native and non-native mesquites? This could be in your own neighborhood! Fill out our survey here: https://goo.gl/forms/fktzqantBlstQNjH3

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Tucson Audubon Society
300 E University Blvd. #120 Tucson, AZ 85705

Mason Center
3835 W Hardy Rd.
Tucson, AZ 85742

Paton Center for Hummingbirds
477 Pennsylvania Ave.
Patagonia, AZ 85624
520 415-6447

color_square_face_right

Tucson Audubon Society
300 E University Blvd. #120
Tucson, AZ 85705

Mason Center
3835 W Hardy Rd.
Tucson, AZ 85742

Paton Center for Hummingbirds
477 Pennsylvania Ave.
Patagonia, AZ 85624
520 415-6447

color_square_face_right

Tucson Audubon Society
300 E University Blvd. #120
Tucson, AZ 85705

Mason Center
3835 W Hardy Rd.
Tucson, AZ 85742

Paton Center for Hummingbirds
477 Pennsylvania Ave.
Patagonia, AZ 85624
520 415-6447