The distribution and extent of heavy metal accumulation in song sparrows along Arizona's upper Santa Cruz River

Environmental Monitoring and Assessment
By:  and 



Heavy metals are persistent environmental contaminants, and transport of metals into the environment poses a threat to ecosystems, as plants and wildlife are susceptible to long-term exposure, bioaccumulation, and potential toxicity. We investigated the distribution and cascading extent of heavy metal accumulation in southwestern song sparrows (Melospiza melodia fallax), a resident riparian bird species that occurs along the US/Mexico border in Arizona’s upper Santa Cruz River watershed. This study had three goals: (1) quantify the degree of heavy metal accumulation in sparrows and determine the distributional patterns among study sites, (2) compare concentrations of metals found in this study to those found in studies performed prior to a 2009 international wastewater facility upgrade, and (3) assess the condition of song sparrows among sites with differing potential levels of exposure. We examined five study sites along with a reference site that reflect different potential sources of contamination. Body mass residuals and leukocyte counts were used to assess sparrow condition. Birds at our study sites typically had higher metal concentrations than birds at the reference site. Copper, mercury, nickel, and selenium in song sparrows did exceed background levels, although most metals were below background concentrations determined from previous studies. Song sparrows generally showed lower heavy metal concentrations compared to studies conducted prior to the 2009 wastewater facility upgrade. We found no cascading effects as a result of metal exposure.

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Publication type Article
Publication Subtype Journal Article
Title The distribution and extent of heavy metal accumulation in song sparrows along Arizona's upper Santa Cruz River
Series title Environmental Monitoring and Assessment
DOI 10.1007/s10661-014-3737-2
Volume 186
Issue 8
Year Published 2014
Language English
Publisher Springer
Contributing office(s) Southwest Biological Science Center, Contaminant Biology Program
Description 13 p.
First page 4779
Last page 4791
Country United States
State Arizona
Other Geospatial Santa Cruz River
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