Flowers for Bats Campaign

Flowers for Bats Logo

The lesser-long nosed bat (Leptonycteris yerbabuenae) travels north from Mexico to Arizona each summer on a journey that can cover almost 1,000 miles. On this journey, the bats rely on nectar and pollen from agave and columnar cacti. These are also critical food sources for the bats when they arrive at their maternity roosts in Southern Arizona.

The endangered Mexican long-nosed bat (Leptonycteris nivalis) follows a similar long-distance migration from central Mexico to their maternity roosts in Texas and New Mexico, relying on agaves as their sole nectar source in these northern areas.

The US Fish & Wildlife Service, in partnership with the USA National Phenology Network, is seeking to better understand where and when nectar sources are available for these bats while they are in the northern portion of their range raising their young. This campaign also supports the efforts of Bat Conservation International to collect data on flowering phenology of Agave havardiana and Agave parryi neomexicana in West Texas, which will guide agave restoration efforts in the area.

You can help us document flowering of agave and columnar cacti during the spring and summer flowering periods. This information will be used by the USFWS to conserve and promote habitat for lesser long-nosed bats.

Read results from this campaign in our 2023 campaign summary email.

Read a poster about the campaign created by University of Arizona student Natalie Schwark.

Read 2023 results from Sands Ranch, a Pima County data collection site


How to Participate: 

1. Select one or more of the following species to track:

Interested in tracking agave? You can sign up to adopt one of our Agave trails to track flowering this summer! Check out the map here and then email [email protected] if you'd like to sign up for a Trail. 

2. Join Nature's Notebook. If you haven't already, create a Nature's Notebook account. See our specifics of observing if you need more details on getting started. You can set up a phenology monitoring site in your backyard or another location that you frequent. 

3. Take observations. We invite you to track flowering of saguaro and agave plants ideally 2-3 times per week during the flowering season. Remember, it's important to capture when your plants are not flowering as well as when they are flowering. Capturing that last "no" report prior to the first "yes" for flowers or flower buds and open flowers helps pinpoint when flowering first begins! 

4. Report your observations. As you collect data during the season, log into your Nature's Notebook account and enter the observation data you record. You can also use our smartphone apps to submit your observations! 

Sign up for Flowers for Bats updates

Download a flyer about Flowers for Bats

Download the full Flowers for Bats Monitoring Protocol, or the One-page Monitoring Guide

Agave Identification:

Agaves can be tricky to identify. Pay attention to the length and width of the leaves, the color of the leaves, and the overall size of the plant. If you see an agave blooming, you can consider it to be full size.

Agave palmeri leaf color ranges from pale green to dusty-colored light green, gray-green, or bluish green. Its leaf margins are straight, with small teeth regularly spaced along the margin with even smaller teeth often in between. It is a medium-sized to large-sized agave (3-4 feet tall) with leaves 3-4 inches wide and 14-29 inches long.

Phenophase Photo Guide »

Agave palmeri, Photo: Wynn Anderson 2016 CalPhotosAgave palmeri, Photo: Patricia Guertin

Agave parryi leaves are gray-ish to light green or light blue-green in color. It has a compact, dense rosette. Its leaf margins are straight or can have a slight undulation. Its leaves are mostly flat with a barely concave top surface. It is a medium-sized agave (12-20 inches tall) with broad-ish leaves 3-5 inches wide and 10-16 inches long.

Phenophase Photo Guide »

Agave parryi, Photo: Wynn Anderson, 2016 CalPhotosAgave parryi, Photo: Patricia Guertin

Agave deserti leaves are dusty-colored gray or gray-blue to green. Its leaf margins are straight in most forms of this species, with small regularly spaced teeth. It freqnetly has banding on its leaves. It is a medium-sized agave (12-19 inches tall) with leaves 2-3 inches wide and 6-16 inches long.

Phenophase Photo Guide »

Agave deserti, Photo: Aaron Schusteff, 2005 CalphotosAgave deserti, Photo: Patricia Guertin

Agave havardiana has a glaucous-grey to grey-green color. Its succulent leaves are arranged in a rosette and are 2-4 ft. in height. The leaves are typically 15-28 in. long and 6-11 in. wide. The leaves will have teeth on their edges. 

Phenophase Photo Guide (coming soon) »

Agave havardiana, Photo: Roy Morey

Agave americana, is often gray to gray-blue but can be dark green or varigated. This species has significant amounts of horizontal striping on the backs of the leaves. It is a very large agave (6-10 feet tall) with very wide leaves 6-10 inches wide and 3-6.5 feet long. This species is commonly planted as an ornamental in yards around Tucson.

Phenophase Photo Guide »

Agave americana, Photo: RJ Matthews

Contact: Erin Posthumus, USA-NPN Liason to the USFWS, [email protected], 520-621-1670

Download a handout with this information »