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During 2010-2014, tree swallow (Tachycineta bicolor) reproductive success was monitored at 68 sites across all 5 Great Lakes, including 58 sites located within Great Lakes Areas of concern (AOCs) and 10 non-AOCs. Sample eggs were collected from tree swallow clutches and analyzed for contaminants including polychlorinated biphenyls (PCBs), dioxin and furans, polybrominated diphenyl ethers, and 34 other organic compounds. Contaminant data were available for 360 of the 1249 clutches monitored. Markov chain multistate modeling was used to assess the importance of 5 ecological and 11 of the dominant contaminants in explaining the pattern of egg and nestling failure rates. Four of 5 ecological variables (female Age, Date...
Egg production by desert tortoises was estimated at two sites in San Bernardino, California: Ivanpah Valley in 1980 and 1981 and Goffs in 1983, 1984 and 1985. Mean clutch frequencies were estimated for 1980 (1.60) and 1981 (1.10) from mass changes observed among sexually mature females weighed every 1-2 wk. Mean clutch frequencies in 1983 (1.89), 1984 (1.57) and 1985 (1.75) were estimated from periodic X-rays of females. Clutch sizes were also determined from radiographs. Tortoises at Goffs typically laid 1-2 clutches during May and June, but one female failed to lay eggs in 1984 and single tortoises laid three clutches in 1983 and 1985. If tortoises laid two clutches, the second was faintly visible in X-rays within...


    map background search result map search result map Reproductive success and contaminant associations in tree swallows (Tachnycineta bicolor) nesting in the U.S. and Binational Great Lakes' Areas of Concern data Reproductive success and contaminant associations in tree swallows (Tachnycineta bicolor) nesting in the U.S. and Binational Great Lakes' Areas of Concern data