This suggests that obtaining larger samples may improve estimates of lipid concentrations. Our initial results indicate that remote biopsy darts may not be suitable for quantifying lipid content, but we recommend future studies examine the potential for using wider and longer biopsy heads (Gauthier et al. 1997), rinsing samples in distilled water as soon as they are recovered, and, for comparisons with other studies, targeting the same area of the body from which samples are taken from immobilized polar bears (i.e., the rump). We found the painted orange PD darts easy to recover on land despite being smaller than the other darts we tested. Both the silver PC darts and green PC darts were difficult to spot and

recover on land, but the green

PC PF-01367338 supplier darts were generally easy to spot and recover on the sea ice. The red PX darts were the easiest to spot and recover on land given their bright color and large size. Dye marking prevented accidentally resampling 96% check details of the bears. Although we did not resample any bears in autumn 2010 when we did not dye mark bears, we struggled to keep track of which bears had been sampled when darting bears in groups and avoided sampling some bears because we were unsure whether they had already been sampled. In addition, our on-shore survey methodology (progressively flying from east to west) made it unlikely that we would have encountered the same individuals more than once. In the spring, we randomly searched the sea ice, so we had a higher probability of re-encountering previously sampled individuals. We resighted three bears that had been previously

sampled and marked earlier in the spring, and we resampled one individual whose mark was either undetectable or overlooked. We resampled a total of four bears in autumn 2011. Three of these occurred in August when we were marking with a Nyanzol dye. 17-DMAG (Alvespimycin) HCl This was likely in part because the Nyanzol dye marks looked similar to the mud or dirt marks on polar bears during the autumn. In addition, bears may have been molting (Kolenosky 1987) and bears frequently entered the water shortly after being darted, which may have reduced the intensity of marks. Bears marked with livestock solution or tree marking paint in September appeared to quickly lose their marks upon entering the water. The only bear resampled in September 2011 had been darted in the water and marked with tree marking paint, indicating that the paint is not effective at marking when bears are in the water. Neither the solution nor paint appeared to be suitable if marks are desired to last more than several minutes. We have subsequently tested five different dye/paint combinations of various colors, but these did not improve mark longevity (USGS, unpublished data). Further study should focus on finding appropriately colored, fast-fixing dye. The PC marking darts provided a larger and darker mark on bears than the PX darts (Fig. 5).