The lesser long-nosed bat (Leptonycteris curasuae yerbabuenae) feeds exclusively on the fruit and nectar of agave and night-blooming cacti such as saguaro and organpipe, pollinating flowers in the process. Photo Courtesy of Bruce Taubert.

Authors: Sophia Ruger, ASU Undergraduate Student Researcher, and Kelli L. Larson, Professor of Geography and Sustainability at ASU, with input from Andrew Trgovac.

Sophia Ruger is completing her Sustainability degree and a certificate in Geographic Information Science. She hopes to provide applicable solutions for significant environmental and health-related issues in cities across the globe. If she’s not busy at school, she is out rock climbing, wakeboarding, or sewing at home. She is searching for internships or professional experiences, so feel free to connect with her through LinkedIn.

Kelli Larson is a Professor at Arizona State University who moved to the Sonoran Desert in 2005 and regularly engages students in her research. Her work focuses on how people interact with nature and manage urban landscapes and the environment. When she is not working, Kelli practices yoga and loves to hike, paddle, and otherwise explore nature and different places throughout Arizona and elsewhere. She also enjoys spending time with her dogs, going to plays, and cooking. You can learn more about Kelli or contact her through ASU.

The story begins in 1972 when the first wildlife habitat in Arizona was certified in Prescott on August 21st. This was the year before the National Wildlife Federation (NWF) officially launched their wildlife gardening program. Since then, thousands of properties have been certified statewide, although the frequency of certifications remained low until the 2000s. When our team at Arizona State University started analyzing data on certified wildlife gardens from the NWF in May 2024, over 4,000 properties—including residential yards and other types of properties—had been certified in Arizona to provide shelter, food, water, and places for wildlife to raise their young. 

The Arizona Wildlife Federation (AWF) is one of the 26 state affiliates active in promoting gardening for wildlife through the Certified Wildlife Habitat® program. Our team is collaborating with both AWF and NWF to understand: how and why have wildlife-certified gardens expanded over time, and who and where are these gardeners? 

As seen in the chart below, the years 2006 and 2023 saw the most certifications in the state, with a peak of 296 in 2023 alone. Mary Phillips, who leads the national Garden for Wildlife/Certified Wildlife Habitat® program, explains: “The national program celebrated its 50^th anniversary in 2023, and both AWF and NWF received high levels of media attention and engaged in outreach that year, resulting in more awareness and certification applications.” Although we do not yet know what caused the peaks prior to 2015, when Mary started working with NWF, we are exploring the factors underlying the rise and decline of wildlife-certified gardens over time. The mortgage crisis of 2007-2010 may be one factor leading to declines since the number of certifications between 2011 and 2016 decreased dramatically. With the emergence of the COVID-19 pandemic around 2020, we later saw a surge. Mary adds, “With people at home, gardening, and sustainable practices surged nationwide as they were inspired to do something positive that generated visible increases in butterflies, birds, and bees to support and enjoy where they live. In Arizona, the use of drought-tolerant native plants is an added appeal to residents in their quest to conserve water and support AZ wildlife.”   

Just as we see temporal patterns in the rise and fall of certified habitats in the state, interesting geographic patterns are also evident in the data. Across 190 cities and towns in Arizona with at least one or more certified properties, the top 20 (highlighted in the map below) contain 72% of the total (at around 3000 habitats), and the top 10 contain 50% of the certified habitats in the state.

Larger circles represent more community gardens per resident.

With 976 gardens, Tucson contains the most (23%) Certified Wildlife Habitat® in the state; this translates into approximately 18 gardens for every 10,000 residents in Tucson. Coming in second, Phoenix — as the largest city in the state — has 11% (470), which amounts to fewer than 3 gardens per 10,000 residents. Along with these large cities in the top 20 are other municipalities in the metro Phoenix area including Scottsdale, Mesa, Tempe, Glendale, Chandler, and Gilbert. Other top towns are Prescott, Sedona, and Flagstaff to the north and Bisbee and Ajo to the south. 

It is not surprising that cities and their suburbs with some of the largest populations in the state have the most gardens, but what is happening in smaller towns like Ajo, Bisbee, Sierra Vista, and Hereford? Perhaps conservation initiatives around the San Pedro River or the birding culture in the region contribute to the cluster of garden efforts in southeastern Arizona. With further research, our team aims to identify the factors leading to certifications in particular places across the state.

Ajo and Bisbee are two small towns in Arizona with around 100 recorded habitats, which amounts to more than 1% of their residents gardening for wildlife (compared to only 0.03% in Phoenix). The high Certified Wildlife Habitat® count among these relatively small towns indicates a significant effort to provide wildlife habitat in these communities. With Bisbee’s population of 5,008 residents and 104 gardens, the town hosts two gardens per 100 residents (or 2% of the community). With Ajo’s population of 2,922 and 96 gardens, they host the highest number of gardens per capita at 3% (or three gardens for every 100 residents). 

So, why do Ajo and Bisbee have a relatively large number of Certified Wildlife Habitat® relative to their populations? One reason is that both towns have been certified through the NWF’s Community Wildlife Habitats®, which requires a certain number of habitats. This community-level program extends the gardening for wildlife effort beyond individual properties by bringing together committed gardeners to expand habitat for wildlife in their municipalities. As Keith Ashley, the Deputy Director of the Arizona Wildlife Federation explains, “When you take a close look at the data like this, you can really see the impact that a small group of changemakers like "Project Wildlife Bisbee" can have. When they decided to get their community certified, they inspired so many people to get involved with habitat creation and maintenance. Imagine what a difference it would make if we had a few Arizona communities becoming certified each year for the next few decades!”

Finally, we are exploring: who are the people behind Certified Wildlife Habitat®? Specifically, based on the data we have available from NWF (as shown in the pie chart below), which landowners are certifying their properties as wildlife habitat across the state? Mostly, so far, they are residents like you. That is, more than 90% of all habitats certified since 1972 (3,448 total) were established by residents at their homes, and 40 additional habitats are located in community gardens.   

Among the other 7% of non-residential habitats (227; see the pie chart below), 34% are located in schoolyards (represented by teal), especially at K-12 institutions. Certified Wildlife Habitat® at schoolyards makes good sense because many people visit schoolyards, and these habitat gardens can be educational for students learning biology and other subjects. Additional habitats are managed by private entities (in yellow) including farms (23% of non-residential property) and churches (18%) are the next most common types of property. Relatively few certified habitats are on other types of properties, as shown in the graph. 

In moving forward with our research, our ASU-based team hopes to better understand the reasons for designing and maintaining Certified Wildlife Habitat® in residential yards and other types of property. By identifying barriers or challenges with gardening for wildlife, moreover, we can provide information and other resources to overcome them. By doing so, we hope to expand wildlife habitat across Arizona and the U.S. in collaboration with the National Wildlife Federation and our state chapter. As we learn more, this information could help NWF and AWF, among other organizations, to support habitat gardeners. Based on previous research, we know that certified habitats make a real difference by increasing biodiversity by hosting a larger variety of vegetation and bird species. 

To get certified or learn more, visit https://certifiedwildlifehabitat.nwf.org/.

Learn about the biodiversity impacts of Certified Wildlife Habitat®

Read more about constraints to wildlife gardening and associated tips

Be sure to sign up for Arizona Wildlife Federation’s E-News to receive regular updates on Gardening for Wildlife in Arizona!

Meet the ASU Team