Date of this Version
The central Platte River Valley provides crucial staging habitat for the endangered whooping crane (Grus americana) and the mid-continent population of sandhill cranes (Grus canadensis). Platte River flow depletions and the conversion of native wet meadows for agriculture and other purposes has decreased the cranes natural habitat in the central Platte River Valley, and waste corn now makes up most of the cranes diet while they are in the Valley.
The purpose of this research was to measure organochlorine, elemental contaminant, and pesticide exposure to sandhill cranes from the central Platte River Valley, and to evaluate their reproductive condition. Pesticides and organochlorines were measured in soil and waste corn samples collected from cornfields where sandhill cranes foraged. Elemental and/or organochlorine contaminants were measured in sandhill crane carcass, liver, brain, muscle, and kidney tissues. Reproduction in sandhill cranes was evaluated by measuring sex steroids in blood plasma and by histological examination of gonads.
Sandhill cranes collected from the central Platte River Valley in 1999 and 2001 appeared to be in normal reproductive condition and concentrations of organochlorines in their tissues were not at levels considered harmful. In addition, pesticides in corn and soil from cornfields were all below detection. Elemental contaminants measured in crane tissues also were generally low, with the exception of boron. Concentrations of boron in sandhill crane livers (n = 7) averaged 43.60 ± 3.59 mg/kg dw and exceeded reproductive toxicity thresholds established for mallards. Boron concentrations also were detected at higher concentrations than previously reported in sandhill crane livers analyzed ten years earlier in the same study area. More research is needed to identify sources of boron in the area and further evaluate whether boron exposure to sandhill cranes may be adversely affecting their reproductive potential.