The Condor 109:199–205 # The Cooper Ornithological Society 2007 POTENTIAL ECOTOXICOLOGICAL SIGNIFICANCE OF ELEVATED CONCENTRATIONS OF STRONTIUM IN EGGSHELLS OF PASSERINE BIRDS MIGUEL A. MORA 1,3 ,ROBERT J. TAYLOR 2 , AND BRYAN L. BRATTIN 2 1 U.S. Geological Survey, Columbia Environmental Research Center, c/o Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843-2258 2 Trace Element Research Laboratory, Texas A&M University, College Station, TX 77843 Abstract. We investigated the occurrence and potential ecotoxicological significance of elevated concentrations of strontium (Sr) in eggshells of nine passerine birds from four regions in Arizona. Concentrations of Sr in eggshells ranged from 70 to 1360 mgg 21 dry weight (overall mean 5 684 6 345 SD mgg 21 dw) for the four regions. 23% of the eggshells had Sr concentrations greater than 1000 mgg 21 dw. To our knowledge, these are among the highest levels of Sr that have been reported in bird eggshells in North America. Of the nine species, Brown-headed Cowbirds (Molothrus ater) had the greatest concentrations of Sr. There was a significant positive correlation between Sr and calcium (Ca), and between barium (Ba) and Ca. Ca, Sr, and Ba interact with each other and can exert similar chemical and pharmacological effects. Mean (n $ 3) eggshell:egg ratios for Sr varied with species and ranged from 6.1:1 to 40.2:1; ratios for individual eggs reached 92.7:1. Mean Sr/Ca values ranged from 1.3 3 10 23 to 3.0 3 10 23 and mean eggshell thickness ranged from 83 6 6 to 120 6 9 mm for all species. Eggshell thickness was not significantly correlated with Sr for any species but tended to increase with Sr concentra- tions. We postulate that high concentrations of Sr in the shell could affect later-stage embryos by possible Manuscript received 7 February 2006; accepted 17 August 2006. 3 E-mail: miguel_mora@usgs.gov SHORT COMMUNICATIONS 199 Downloaded from https://academic.oup.com/condor/article-abstract/109/1/199/5563729 by guest on 08 June 2020