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Title: Projecting avian responses to landscape management along the middle RIO GRANDE, New Mexico

Author
item Brand, A. - University Of Arizona
item Dixon, M. - University Of South Dakota
item Fetz, T. - Hawks Aloft, Inc
item Stromberg, J. - Arizona State University
item Stewart, S. - University Of Arizona
item Garber, G. - Hawks Aloft, Inc
item Goodrich, David - Dave
item Brookshire, D. - University Of New Mexico
item Broadbent, C.d. - University Of California
item Benedict, K. - University Of New Mexico

Submitted to: Southwestern Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2013
Publication Date: 6/15/2013
Citation: Brand, A., Dixon, M.D., Fetz, T., Stromberg, J., Stewart, S., Garber, G., Goodrich, D.C., Brookshire, D., Broadbent, C., Benedict, K. 2013. Projecting avian responses to landscape management along the middle RIO GRANDE, New Mexico. Southwestern Naturalist. 58(2):150-162. https://doi.org/10.1894/0038-4909-58.2.150.
DOI: https://doi.org/10.1894/0038-4909-58.2.150

Interpretive Summary: Freshwater ecosystems, and the habitat they support are relatively rare in the semi-arid southwest and significant effort and expense is being directed at restoration of these systems. In the Middle Rio Grande, the lack of flooding due to river impoundments has contributed to the spread of exotic vegetation with dense understory fuel loads. Restoration has focused on understory vegetation thinning but it is unclear how these actions impact bird populations. We quantified densities of five guilds of birds (canopy, midstory, and understory nesting birds; water-dependents; and spring migrants) across 12 vegetation composition-structure types. We then estimated bird population changes expected from restoration scenarios for three possible management options (mechanical clearing, hand thinning, and wetland restoration). The estimated projections of bird population changes will help managers evaluate biological impacts of restoration measures being applied on the Middle Rio Grande. This study is part of a larger effort to link science with valuation of non-market ecosystem services in semi-arid riparian systems.

Technical Abstract: Lack of flooding due to river impoundments on the middle Rio Grande has contributed to the spread of exotic vegetation with dense understory fuel loads. Restoration has focused on understory vegetation thinning but it is unclear how these actions impact bird populations. We quantified densities of five guilds of birds across 12 vegetation composition-structure types. We then estimated bird population changes expected from restoration scenarios for four possible management options. One management option, mechanical clearing of cottonwood understory, had severe detrimental impacts for the three nesting guilds and spring migrants. A hand-thinning method to remove most exotics but retain native shrubs and the ground layer also negatively impacted understory nesting birds, but had positive or no effect on the other four bird guilds. Application of a “no management” option over the short-term would increase the proportion of native and non-native understory vegetation and generally increase bird abundances. A wetland restoration scenario that converted 25% of open habitat to wetland increased understory nesting birds slightly and water-obligate birds substantially. Quantitative projections of bird population changes will help managers evaluate biological impacts of restoration measures being applied on the middle Rio Grande. This study is part of a larger effort to link science with valuation of non-market ecosystem services in semi-arid riparian systems.