Grassland birds have declined more than any other group of North American birds. The causes for most of the declines are poorly understood but likely stem from changes in the quantity and quality of grasslands across their migratory range.
Two-thirds of the Chihuahuan Desert lies in Mexico. Less than 15 percent is grassland and less than half of that is suitable for species that require ample grass cover and little or no shrub cover. Many Chihuahuan Desert grasslands have been destroyed or radically altered through conversion to cropland, inappropriate grazing, urbanization and invasive species. The ongoing loss of wintering habitat is likely a principal factor in population declines among species wintering here.
Of 34 grassland-obligate bird species breeding in the western Great Plains, 85 percent overwinter in the Chihuahuan Desert. Only the three prairie grouse species do not depend on the Chihuahuan Desert grasslands for at least part of their life cycle. Because so many of North America’s grassland bird species concentrate in the limited grasslands of the Chihuahuan Desert, suitable habitat in this region is critical to their conservation. However, conservation efforts on the wintering grounds have lagged far behind those to the north.
Unfortunately, the loss of desert grasslands is accelerating, especially in Mexico where the expansion of center-pivot irrigated agriculture has converted more than 100,000 acres in Chihuahua alone since 2005. This recent surge in land conversion is threatening to extirpate the last desert-dwelling Aplomado Falcons and the Mexican Pronghorn, while severely impacting other grassland species.
Bird Conservancy of the Rockies is working with partners in Mexico and the U.S. to conserve Chihuahuan Desert grasslands and the birds that depend on them. Until recently, little was known about how grassland birds are distributed among the grasslands of the region and what affects their abundance and survival. The Bird Conservancy is leading the way to fill these critical information gaps, while developing a platform for broader conservation. We are producing the scientific knowledge and tools needed to advance strategic habitat conservation, while building international partnerships, local capacity and public support for grassland conservation throughout the region.
Wintering Grassland Bird Surveys
Since 2007, the Bird Conservancy has been leading a bi-national effort to inventory and monitor wintering grassland bird populations in the most important grasslands in the Chihuahuan Desert. This project has produced, for the first time, rigorous information on the distribution, density and habitat use of nearly 30 grassland species throughout most of the desert. We have used this information to redraw the map of priority conservation sites and develop conservation tools for this region.
We have also developed a bi-national network and partnership of organizations with increased capacity to address grassland bird conservation. To learn more about this project, see our latest reports at the bottom of this page or on the Bird Conservancy’s Reports page.
Winter Grassland Bird Survival Research
The Bird Conservancy began a pilot investigation in 2009 into the winter survival and daily movements of grassland birds to better understand if populations are limited during the winter and what factors affect their survival.
We focused our initial efforts on Vesper Sparrows, using radio-telemetry, and in the winter of 2012-2013 extended this research to Grasshopper and Baird’s Sparrows. Results from the Vesper Sparrow study suggest grass height has a strong effect on survival, with at least 30 cm of standing cover needed to provide effective protection from predators. This need for tall standing cover is also desired by many range managers, highlighting the great compatibility of bird conservation and range management objectives in the Chihuahuan grasslands. See the reports and publications from this project on the bottom of this page or on the Bird Conservancy’s Reports page. Data from the Grasshopper and Baird’s Sparrow study is currently being analyzed for publication.
Education and Outreach
The Bird Conservancy has developed education and outreach tools for people living and working in grasslands. Our “Guia de Bolsillo para Aves de Pastizal del Desierto Chihuahuense” (Pocket Guide to Chihuahuan Desert Grassland Birds) has successfully engaged landowners and increased their awareness about birds. Our manual “Compartiendo Sus Agostaderos con Las Aves de Pastizal” (Sharing Your Rangelands with Grassland Birds) provides best management practices to help landowners and range managers understand bird conservation needs and incorporate bird-friendly practices into their management and extension services. We also produced a video, with support from Habitat Seven, Cornell Lab of Ornithology and others, to engage ranchers in northern Mexico in conservation efforts and highlight options for them to enhance production.
Since 2012, the Bird Conservancy has been working to implement habitat improvement efforts for grassland birds on private lands. We aim to create a network of private lands that support a mosaic of grassland conditions to benefit a range of priority species with differing habitat needs, as identified by our monitoring and research. Through rotational grazing, shrub removal, prescribed grazing and other techniques, we are restoring habitat conditions needed in winter by species such as Sprague’s Pipit, Chestnut-collared Longspur and Baird’s Sparrow, while reducing sources of mortality and other limiting factors on private ranches and ejidos through simple conservation efforts. By working with ranchers, we can both keep working ranches viable and increase the carrying capacity of the land to support more birds.
We are currently expanding our grassland bird demographic research to include survival and productivity on the breeding grounds. In 2015, we began efforts to monitor these demographic rates in Baird’s and Grasshopper Sparrows breeding in western North Dakota, and hope to soon expand this research to other key populations in Montana and beyond. Our goal is to examine these vital rates in context of other key demographic rates throughout the full annual life cycle to explore the influence of each life-cycle stage on population growth from year to year.
2011 Chihuahuan Desert Wintering Grassland Birds Report
2010 Chihuahuan Desert Wintering Grassland Birds (Technical Report)
2010 Chihuahuan Desert Wintering Grasslands Bird Survival Phase II (Annual Report)
View more reports on the Bird Conservancy’s Reports page.
The Bird Conservancy thanks its partners that have helped implement these projects; in the U.S., the Bureau of Land Management in New Mexico has been an important partner, and special thanks to our international partners in Mexico, including the Universidad Autónoma de Nuevo Leon, Universidad Juarez del Estado de Durango, Universidad Estatal de Sonora, IMC-Vida Silvestre, A.C., The Nature Conservancy, World Wildlife Fund-Mexico, Profauna-Coahuila, A.C., Profauna-Chihuahua A.C., Pronatura Noreste A.C., Pronatura Noroeste A.C., Sul Ross State University, Universidad Nacional Autónoma de Mexico, CONANP, CONABIO, Cuenca Los Ojos Foundation and numerous private and communal landowners .
Major funding for these programs has come from the Neotropical Migratory Bird Conservation Act, U.S.D.A. Forest Service International Program, National Fish and Wildlife Foundation, The Nature Conservancy, Commission for Environmental Cooperation, Rio Grande Joint Venture, American Bird Conservancy, Rio Grande Research Center, National Park Service, Texas Parks and Wildlife Department, Rio Grande Joint Venture, Sonoran Joint Venture, Colorado Parks and Wildlife, Colorado State Land Board, Arizona Game and Fish Dept., New Mexico Dept. of Game and Fish, The Association of Fish and Wildlife Agencies – Southern Wings Program and the City of Fort Collins, Colorado.