REPRODUCTIVE SUCCESS OF BARN SWALLOWS NESTING NEAR A SELENIUM-CONTAMINATED LAKE IN EAST TEXAS, USA

Reproductive success and contaminant levels in 1986 and 1987 were comp ared between Barn Swallows nesting at selenium-contaminated Martin Lak e, Texas, USA, and swallows nesting at a reference site. Nests were in itiated about the same time or earlier at Martin Lake than at the refe rence site and clutch size was similar between the two locations. Nest success was significantly higher at Martin Lake than at the reference site and no embryo or chick deformities were documented Selenium conc entrations in 14 of 20 eggs from Martin Lake were above background (>3 ppm, dry weight); two of 20 eggs contained >5 ppm, a concentration as sociated with a 20% embryo mortality/deformity rate in some bird speci es. Selenium concentrations in the kidneys of adult swallows were high er at Martin Lake (mean = 14 ppm dry weight) than at the reference sit e (5.8 ppm). DDE, the only detected organochlorine compound, was in tw o of 10 eggs from Martin Lake; these concentrations were below those a ssociated with chronic poisoning and reproductive problems. The maximu m mercury concentration in livers of adult Barn Swallows (0.83 ppm, dr y weight) was within the range for background levels (<5 ppm).