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We determined concentrations of selected trace elements in tissues of king and common eiders at three locations in the Canadian arctic. Renal and hepatic cadmium concentrations in king eiders at a location in the eastern arctic were among the highest ever recorded in eider ducks: there, they were higher in king eiders than in common eiders. Cadmium concentrations were lower in king eiders from the western arctic than in those from the east. In the western arctic, cadmium concentrations did not differ between species. Hepatic mercury and zinc were higher in king eiders than in common eiders. Zinc and selenium were higher in eiders from the western arctic than in those from the eastern arctic. Trace element concentrations in these two duck species were below published toxicity thresholds. Positive correlations in trace element concentrations in both species were found between total and organic hepatic mercury, renal and hepatic cadmium as well as hepatic zinc, copper, mercury, and cadmium. Body mass of common but not king eiders and spleen mass of both species were negatively correlated with mercury concentrations. In common eiders, the number of nematode parasites was positively correlated with total and organic mercury. Histopathological evidence of kidney or liver lesions that are typical of trace metal poisoning was not found. We did not find evidence to support the hypothesis that trace metal exposure may be contributing to adverse effects on the health of individuals of these species.

Summary 1.Many migratory birds are assumed to remain fairly stationary during winter. However, recent research indicates that mid-winter movements are evident in a variety of bird species, and the factors causing individuals to move are poorly understood. 2. We examined the winter movements of 95 individual king eiders ( Somateria spectabilis , L.) tracked with satellite transmitters in the Bering Sea between 2002 and 2006 to explore whether environmental factors such as day length, location, sea ice, and habitat quality could explain the occurrence of winter movements longer than 50 km. 3. We used a novel algorithmic random forest model to assess the importance of variables predicting whether a bird remained or departed from a wintering site. 4. We found extremely high individual variability in winter movement decisions by king eiders, and the individual bird was the most important variable followed by location, date, and sea ice concentration. 5. We conclude that individual strategies exist that interact with environmental conditions to form multiple movement patterns. 6. While a minor proportion of winter movements may be forced by environmental conditions, we propose that many winter movements may be of an exploratory nature where individuals aim to acquire information about alternative wintering sites that may enhance their survival probability at some point in time when environmental fluctuation renders their preferred wintering site unsuitable.

Adult Hyalomma truncatum Koch ticks were inoculated intracoelomically with Crimean-Congo hemorrhagic fever (CCHF) virus to examine tissue tropisms of this virus in ticks. Virus was recovered from all 185 ticks examined between 2 and 42 d after inoculation with CCHF virus. Titers or virus recovered from unfed male and female ticks were essentially the same (means, 10(2.4) and 10(2.5) plaque-forming units [PFU] per tick, respectively). Infection rates and titers recovered per gland for both salivary glands and reproductive tissues (ovaries and testes) were positively associated with blood feeding; average titers were 10-fold greater in organs from fed compared with those from unfed individuals. In contrast, neither the tick's sex nor feeding status (unfed or engorged) affected the titer of virus recovered from hemolymph (mean, 10(1.6) PFU/microliters). Although virus was recovered from Malpighian tubules, midgut, muscle, and nervous tissues from nearly all of the ticks tested, viral titers were consistently low. The increase in viral titer associated with blood feeding by ticks appeared to be due primarily to proliferation of tissue (e.g., salivary gland and reproductive tissues), rather than to increased replication in tissue already present.

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