Southwestern Avian Community Organization in Exotic Tamarix: Current Patterns and Future Needs

Abstract

Tamarisk (saltcedar: Tamarix), an invasive exotic tree native to the Eastern Hemisphere, is currently the dominant plant species in most southwestern riparian ecosystems at elevations below 1500 m. Tamarisk alters abiotic conditions and the floral composition of native southwestern riparian ecosystems and, in turn, affects native southwestern animal communities. However, information on the overall effects of tamarisk on avifauna is somewhat conflicting and incomplete. This paper attempts to resolve conflict in the literature by addressing several questions: (1) Are there consistent broad geographic patterns in avian species richness and abundance in tamarisk?; (2) Which groups of birds use tamarisk?; and (3) Which attributes are most useful in predicting avian use of tamarisk? A survey of published literature found that overall avian species richness and abundance in tamarisk are not consistent across broad geographic scales, but vary consistently between the Rio Grande and the Pecos and Colorado Rivers. Examination of geographic variation in food and nesting resources provided by tamarisk-dominated vegetation did not fully explain overall geographic patterns; most groups of birds show consistent use of tamarisk across geographic locations. However, use of tamarisk by cup nesting breeding birds does vary with geographic location. Since most research on avian use of tamarisk has been completed on breeding birds, patterns in breeding birds appear to drive the documented geographic patterns. Overall, avian use of tamarisk is best explained by species-specific nesting and foraging requirements, which in turn covary with vegetation structure and floristics, and are mediated by climatic influences. Since large gaps still exist in the knowledge base, especially for wintering and migrating birds, more research should be completed on both local and regional avian use of tamarisk and a classification system of tamarisk vegetation types should be developed to aid in defining which types of tamarisk are most useful or detrimental to wildlife.

Parent Publication

• Monitoring Science and Technology Symposium: Unifying Knowledge for Sustainability in the Western Hemisphere

Citation

Walker, H. A. 2006. Southwestern Avian Community Organization in Exotic Tamarix: Current Patterns and Future Needs. In: Aguirre-Bravo, C.; Pellicane, Patrick J.; Burns, Denver P.; and Draggan, Sidney, Eds. 2006. Monitoring Science and Technology Symposium: Unifying Knowledge for Sustainability in the Western Hemisphere Proceedings RMRS-P-42CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 274-286