In the wake of the Deepwater Horizon oil spill in 2010, disturbing photographs of Brown Pelicans coated in oily sludge played nonstop on TV news and ricocheted around the Internet. Now American White Pelicans, which migrate inland (unlike their brown relatives), seem to be revealing the far-reaching consequences of the disaster more than 1,400 miles from the Gulf, at Marsh Lake on the Minnesota River, where 12,000 to 14,000 pairs nest in May and June. Biologists from North Dakota State University and the Minnesota Department of Natural Resources have been collecting samples in the form of eggs and the odd-looking bill knobs, or nuptial tubercles, that pelicans shed after mating season. The scientists are analyzing the samples, looking for evidence of chemicals from both the oil and the dispersants used to clean up the spill. The latest tests show markers of contamination, particularly in the eggs. “We have documented evidence from the oil as well as the dispersant,”...