|ROACHO-ESTRADA, J. OCTAVIO|
Submitted to: Ecosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2011
Publication Date: 5/23/2011
Citation: Peinetti, H.R., Fredrickson, E.L., Peters, D.C., Cibils, A.F., Roacho-Estrada, J., Laliberte, A. 2011. Foraging behavior of heritage versus recently introduced herbivores on desert landscapes of the American Southwest. Ecosphere. 2(5):Article 57.
Interpretive Summary: Large herbivores use of landscapes not only affects their well-being and productivity, but the future capacity of landscapes to support large herbivores, such as livestock. A problem with most studies that monitor livestock use of rangelands is the usefulness of the observations are often site specific, being limited to a narrow set of rangeland conditions similar to those occurring during the study. To increase the value of these studies we developed two mathematical approaches designed to allow us to predict how two different beef cattle breeds use a variety of arid landscapes over time. One model uses observations of cattle movement to generate a map using Multi-Criteria Evaluation algorithms, a decision making process used in geographic information systems, while the other used statistical logistic procedures that uses key variables of a site to assign probabilities of a animal’s likely use of a particular area in the landscape. The breeds include Angus crossbred cows representing a beef cow breed common to arid regions of the U.S. and Mexico during the last 100 years, and criollo cattle that were first introduced into North America in 1521 and spread throughout most arid regions of North America by the late 1500’s and 1600’s. This later breed represents grazing pressures prior to introduction of British breeds in the late 1800’s and 1900’s. When forage conditions were favorable, both breeds used the landscape similarly; however, when forage conditions declined criollo cattle used a greater area and more diverse habitat types. Both models provided similar results. These models will assist researchers to reconstruct historic changes in vegetation patterns, and develop ecologically appropriate grazing management approaches for the future. In addition, this research indicates that criollo cattle may be a useful breed in nutritionally limiting arid environments.
Technical Abstract: Since the 1800s managed grasslands and shrublands of the arid American Southwest have been grazed predominantly by cattle originally bred for temperate climates in northern Europe. A heritage breed, the criollo cattle, has survived in northern Mexico for more than 400 years under desert-like conditions of low and variable rainfall, hot temperatures in the growing season, and both spatially and temporally scarce levels of primary production. We tested the hypothesis that the heritage breed has a broader spatial foraging distribution under harsh environmental conditions, and that its distribution is driven by environmental variables which differ from those that control the distribution of the introduced European breed. Movements of individual criollo and Angus breed animals were monitored autonomously in the northern Chihuahuan desert of southern New Mexico, USA. Georeferenced foraging locations acquired at 5-minute intervals for each animal were fit to a logistic regression using environmental factors as predictors. In the spring, when forage availability was high and more uniformly distributed across the landscape, animal foraging patterns were similar for both breeds. In the fall when forage availability was low and non-uniformly distributed, the two breeds exhibited very different foraging patterns: heritage animals foraged across a much larger spatial extent whereas their domestic counterparts remained in close proximity to the permanent source of water. These differences in foraging behavior driven by environmental variables have important implications for sustainability of rangelands in spatially and temporally variable environments. Heritage breeds of animals that are generalist foragers during unfavorable conditions can reduce environmental impacts compared to more recently introduced breeds.