Selenium Poisoning in Birds
Photos and article by Alex Lees
Alex Lees is an undergraduate in Biological Sciences from UEA, England and is currently studying at UCI in California.
A least one Red-winged Blackbird (Agelaius phoeniceus) with a deformed bill was present with a large mixed icterid flock in a private intensive agricultural area of the Prado Basin, San Bernardino County California. Found in early January 2001 by Larry Tripp and Bettina Eastman, the bird’s advanced plumage indicates it has survived a considerable time with its handicap. Such a deformity might occur occasionally in a population but such mutations appear to be occurring at an increasing frequency. Genetic deformities in birds are often associated with environmental pollution such as PCBs and have been demonstrated in Double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Sterna caspia) (Ludwig et al 1996).
Perhaps, more likely would be poisoning by seleniferous agricultural drainage wastewater, which has become a major source of pollution in the world. In the USA, large areas of farmland in 17 western states generate contaminated salinized drainage with Selenium concentrations much higher than 5 mu g/l, the US Environmental Protection Agency water-quality criterion for the protection of aquatic life (Kharaka et al 1996). Reproductive success and contaminant were measured in Barn Swallows (Hirundo rustica) nesting at a selenium-contaminated site in Texas, USA. Selenium concentrations in 14 of 20 eggs were above background, two of 20 eggs contained >5 ppm, a concentration associated with a 20% embryo mortality/deformity rate in some bird species. (King et al 1994). It is likely that the increasing need for irrigation in agricultural lands will have further detrimental effects of populations of birds and other wildlife.
References
Kharaka YK, Ambats G, Presser TS, Davis RA (1996) Removal of selenium from contaminated agricultural drainage water by nanofiltration membranes, APPLIED GEOCHEMISTRY 11:797-802
Ludwig JP, KuritaMatsuba H, Auman HJ, Ludwig ME, Summer CL, Glesy JP, Tillitt DE, Jones PD (1996) Deformities, PCBs, and TCDD-Equivalents in double-crested Cormorants (Phalacrocorax auritus) and Caspian Terns (Sterna caspia) of the upper Great Lakes 1986-1991: Testing a cause-effect hypothesis, JOURNAL OF GREAT LAKES RESEARCH 22: 172-197
King KA, Custer TW, Weaver DA (1994) Reproductive success of Barn Swallows nesting near a selenium contaminated lake in eastern East Texas, USA.
ENVIRONMENTAL POLLUTION 84: 53-58
