| OCR Text |
Show Ecological sk Assessment Northern ...l.rrh Mountains There was no measurement of CoC concentrations in insectivorous birds or quantification of survival and of birds during the 1995 field project. Chronic risks to birds reproduction may be less than for mammals because many avian species observed in the northern Oquirrh Mountains are migratory and are present only as summer residents or during migration. Many species nesting in the Oquirrh Mountains arrive shortly before the nesting period, so their prenesting exposure to CoC would be limited. There are no data to determine how dietary exposure to CoC may affect the developing young of insectivorous birds. Several chukars (Alectoris chukaf), a gallinaceous species with insectivorous young like the Chukars are Japanese quail, were observed in Kessler and Black Rock Canyons. nonmigratory species that are more omnivorous as adults. The 1995 field work occurred Nevertheless, chukars were frequently observed or heard during both the 1994 and 1995 field seasons. too early in the year to observe juvenile chukars. The highest risk quotients for all insectivores were observed for Se, especially in Kessler Canyon. The Se concentrations in herbivorous foliar invertebrates were found to be significantly correlated to the mean concentrations of Se in forbs weighted by the relative cover estimate of each species from the Releve sampling (r=0.69, p<0.05, N=11). However, the Se concentration in herbivorous foliar invertebrates in Pine Canyon were among the lowest measured and were not related to forb concentrations (Le., herbivorous invertebrates ranged from 1.4 to 1.6 ppm while the weighted mean of forbs ranged from This may be related to the dominance of mulesears (Wyethia 1.2 to 12.7 ppm). amplexicaulis) in Pine Canyon. In the four canyons from Coon to Black Rock Canyon, the correlation between concentrations of Se in herbivorous foliar invertebrates and the weighted mean of forb species was highly significant (r=0.94, p<O.OOOS, N=8). The relatively high concentrations of Se in invertebrates in Kessler Canyon seemed related to the dominance of whitetop, which had the highest Se concentration of all plants, whitetop was the most abundant plant on KC2 (25% of total ground cover) and ranked third on KC1 (20% of total cover) behind cheatgrass and stinging nettle. In BR1, whitetop had the highest Se concentration of aU plants sampled and accounted for 9% of the total plant cover. Whitetop was much less dominant in the other sampling sites and lower in Se concentration. Consequently, the concentration of Se in herbivorous invertebrates seems to be driven by the presence and dominance of Se-concentrating forbs, such as whitetop. concentrations in surface-dwelling invertebrates (a mixture of herbivorous and camivorous species) and carnivorous foliar invertebrates were significantly related to herbivorous foliar invertebrates. The Se concentrations in carnivorous foliar invertebrates The (Coccinellidae) and spiders] were highly correlated with (r=0.93, p<0.0004, N=11). The relationship between invertebrates herbivorous foliar invertebrates was more complex. and surface-dwelling [primarily ladybird beetles herbivorous foliar invertebrates Selenium concentrations in surface-dwelling invertebrates were higher than in herbivorous foliar invertebrates when the surface-dwelling invertebrate sample 'was dominated by carnivores [e.g., ground beetles (Carabidae) and spiders], but lower when dominated by [e.g., darkling beetles (Tenebrionidae), lepidoptera larvae, and grasshoppers Even with variation in the surface-dwelling invertebrate samples on the based species composition of the samples, the Se concentrations among the surface-dwelling and foliar samples varied less within sampling sites than among sampling herbivores and 'crickets (Orthoptera)]. ecological planning and toxicology, inc. 77 |
