Monitoring the pulse of the desert through avian monitoring in the Pinacate Biosphere Reserve
By: Aaron Flesch, Miguel Grageda García
Monitoring the status and distribution of wildlife and vegetation are fundamental aspects of conservation and sustainable management of biodiversity and natural resources. Without solid baseline information on these and other parameters, individuals, habitats, and potentially entire populations or species can be lost before they are documented and protected. When properly designed, ecological monitoring efforts can help trigger focused management and protection actions needed to ensure that species and resources persist for the enjoyment of future generations, to ensure essential ecological functions and ecosystem services, and for their own intrinsic and inherent values.
Ecological monitoring is especially important in regions that face the gravest threats from climate and land-use change and other stressors, which include arid regions. These stressors could have especially severe and compounding impacts on wildlife and habitats in arid environments because resources are often limited, weather events are often unpredictable, and small changes in precipitation and temperature can have major effects on abundance and vital rates of species that are often living near ecological tolerance limits. In fact, a century of monitoring in the Mohave Desert of North America shows the virtual collapse of bird communities over this period due to climate change, even in a protected area (see A, B).
Figure 1: View northwest from the northern high point in the Pinacate high peaks region showing cinder cones emerging from the volcanic shield and in the distance the dunes of Gran Desierto.
The El Pinacate and Gran Desierto de Altar Biosphere Reserve is a UNESCO World Heritage Site managed by the federal government of Mexico occupies a hyperarid region of the central Sonoran Desert and is a place of exceptional natural beauty and biodiversity. The eastern portion of El Pinacate that is the subject of our efforts is dominated by a massive, dormant volcanic shield and an immense area of sand dunes that form the largest dune network in North America. It includes a small shield-type volcano, reaches elevations of ~1,200 m above sea level just north of the coast of the Gulf of California, extensive black and red lava flows, hundreds of cinder cones of all shapes and sizes, and 10 enormous and almost perfectly circular Maar craters, which are formed by steam explosions as a result of magma superheating underground water (Figure 1). Such a rich and complex geological history and broad elevation gradients have helped create a multitude of wildlife habitats and promoted high biodiversity and conservation value.
Importantly, El Pinacate is also in CEDO Intercultural’s “backyard”, which makes it a valuable setting for ecological study, environmental education, and local efforts to protect resources and promote sustainable uses of Sonoran Desert environments for the human communities that depend on them. In Mexico, lands that comprise Natural Protected Areas such as El Pinacate are often owned by individual people or communally in the form of ejidos, rather than by the federal government as in the U.S. Thus, sustainable use of natural resources within protected areas is fundamental for conservation. Such arrangements make environmental education and development and demonstration of sustainable management practices, essential for the protection and enhancement of natural resources, which highlights an important role of CEDO in the region.
In 2021, we began a partnership between the University of Arizona’s School of Natural Resources and the Environment, CEDO, the National Commission of Natural Protected Areas in Mexico (CONANP), and the U.S. National Park Service (NPS). Our efforts, funded by NPS’ Southwest Resources Border Protection Program, focused on:
- Ecological monitoring of bird communities in El Pinacate,
- Linking monitoring with similar efforts in Organ Pipe Cactus National Monument in neighboring Arizona that began in the early 1980s, and
- Educating local people in Mexico in the region surrounding the reserve about the ecology of Sonoran Desert environments, local bird communities, and how they can contribute to conservation.
Birds are an important focal group for monitoring because each individual species is linked to a broad array of specific resources and conditions on which they depend, because they can be surveyed more efficiently than other vertebrate groups, and because birds have broad economic value and appeal to the public. Here, we summarize our efforts, review some preliminary findings from analyses that are still ongoing, and discuss future activities for the CEDO community.
Over three past years (2015-2017), then CONANP staff biologist at El Pinacate, Miguel Grageda García established up to eight transects and conducted point counts for birds. Transects were initially established in areas with representative habitats for the birds across the reserve and in significant natural areas. These efforts provide some initial baseline data and spanned the Agua Dulce reach of the Río Sonoyta that supports the only free-flowing perennial water in the El Pinacate region, areas near Papago Well where natural hard-rock tanks or tinajas support surface water and riparian woodlands, and areas of dense saguaros, sand dunes, desert scrub and other resources. Efforts in 2021 added two new transects and the authors and CEDO staff completed two to three visits to complete point counts between February and May. Moreover, we also surveyed special status species such as Golden Eagle and Prairie Falcon across the El Pinacate shield. In this region, most raptors including both of these species depend on sheltered, often north-facing cliffs to place nests that are rare and distributed locally in El Pinacate. Hence, surveys for these species focused on large craters and on significant cinder cones that harbored cliff faces.
Over four years of effort, we detected approximately 84 species of birds across the 10 transects during point counts, and several additional species incidentally or during surveys efforts for special status species. In 2021, we observed 70 species during point counts and found that species richness (e.g., total number of species) was highest (40-45 species) along the Río Sonoyta and near Papago Well, which is not surprising given these are the only areas in El Pinacate where surface water is typically found. Richness was lowest (12-15 species) in desertscrub on the east side of Pinacate Peak and on sand dunes, which support habitats of lower structural diversity. Nonetheless, several species of conservation interest including LeConte’s Thrasher and Sagebrush Sparrow were observed on dunes making these areas significant for bird communities.
Figure 2: Field training lead by University of Arizona staff attended by CEDO and CONANP staff and collaborators in the dunes region of El Pinacate.
During survey efforts for special status species, we observed evidence of nesting by Prairie Falcon on cliffs at two large Maar craters and observed a sub-adult Golden Eagle, which could have been a migrant or breeder, at one large Maar crater. Numerous nests of Red-tailed Hawk and Great Horned Owl were observed at the more than 15 cinder cones we surveyed, and were often using cliff faces. Importantly during and just before the 2021 field season, we also helped train CEDO staff and collaborators in field methods for this work and in bird identification (Figure 2). Ongoing efforts will compare baseline data from earlier years with results of the 2021 field season, and provide all data to CEDO and CONANP for future applications.
Environmental education efforts linked to our project are also still ongoing and curricula are now being developed by CEDO staff that will be implemented this fall and winter. Initial education efforts included a kickoff event at El Pinacate in mid-February 2021 that was attended by approximately 25 people including numerous children and young adults (Figure 3). During this event, we gave presentations on bird communities and habitats in El Pinacate, and on field methods for avian ecology. Field methods were then implemented by University of Arizona and CEDO biologists during field work.
Our efforts represent a multifaceted approach to ecological monitoring and environmental education in support of landscape conservation and sustainable use of natural resources in an important biodiversity hotspot in northwest Mexico. Collaborative efforts between local non-governmental organizations such as CEDO working together with researchers, local people, and government management agencies are essential for realizing landscape conservation across broad areas. It is our hope that further integrating monitoring efforts across this binational landscape will help foster conservation and sustainable management of what is one of the largest protected areas in North America, and the crown-jewel of more than a century of binational conservation efforts in the U.S.-Mexico borderlands.