Tamarix as Habitat for Birds: Implications for Riparian Restoration in the Southwestern United States

Abstract

Exotic vegetation has become a major habitat component in many ecosystems around the world, sometimes dramatically changing the vegetation community structure and composition. In the southwestern United States, riparian ecosystems are undergoing major changes in part due to the establishment and spread of the exotic Tamarix (saltcedar, tamarisk). There are concerns about the suitability of Tamarix as habitat for birds. Although Tamarix habitats tend to support fewer species and individuals than native habitats, Arizona Breeding Bird Atlas data and Birds of North America accounts show that 49 species use Tamarix as breeding habitat. Importantly, the relative use of Tamarix and its quality as habitat vary substantially by geographic location and bird species. Few studies have examined how breeding in Tamarix actually affects bird survivorship and productivity; recent research on Southwestern Willow Flycatchers has found no negative effects from breeding in Tamarix habitats. Therefore, the ecological benefits and costs of Tamarix control are difficult to predict and are likely to be species specific and site specific. Given the likelihood that high-quality native riparian vegetation will not develop at all Tamarix control sites, restoration projects that remove Tamarix but do not assure replacement by high-quality native habitat have the potential to reduce the net riparian habitat value for some local or regional bird populations. Therefore, an assessment of potential negative impacts is important in deciding if exotic control should be conducted. In addition, measurable project objectives, appropriate control and restoration techniques, and robust monitoring are all critical to effective restoration planning and execution.

Endangered species management and ecosystem restoration: finding the common ground

“…Because of this conflict, salt cedar eradication has been delayed while other control strategies are devised (U.S. Fish and Wildlife Service 1997). Without restoration efforts that assure the re-establishment of native riparian vegetation and restoration of ecosystem function, the removal of invasive salt cedar will result in a loss of nesting habitat for the endangered flycatcher (Zavaleta et al 2001, Dudley and DeLoach 2004, Sogge et al 2008, Dudley and Bean 2012.…”

Riparian trees and aridland streams of the southwestern United States: An assessment of the past, present, and future

“…Nonnative trees do not break down into pieces as large as native trees, so course woody debris would eventually be absent from the forest floor. Loss of habitat for imperiled riparian species including the southwestern willow flycatcher could occur in response to loss of Goodding's willow and boxelder, though additional research is needed to determine if they will successfully use other woody species as habitat throughout their range (Sogge et al, 2008).…”

The Biology of Invasive Alien Plants in Canada. 11. Tamarix ramosissima Ledeb., T. chinensis Lour. and hybrids

“…and the desert cottontail (Sylvilagus audubonii); however, mammal numbers are generally lower in saltcedar than in other vegetation types (EngelWilson and Ohmart 1978). Sogge et al (2008) reported that as many as 49 bird species use saltcedar for breeding habitat in North America. Brown and Trosset (1989) reported that the black chinned hummingbird (Archilochus alexandri Bourcier and Mulsant) nested only in saltcedar in the Grand Canyon, Colorado, because its native habitats were no longer present.…”