According to the passage, the long-billed shorebird is expected to be more likely than the short-billed shorebird to have trouble migrating because A. it is more vulnerable to the effects of organochlorines B. it typically is unable to differentiate between a foreign ecosystem and a familiar one C. it stops feeding before it is fully satiated D. it grazes in parts of the mudflat in which the surface is known to have a higher concentration of organochlorines E. it digs deeper into the earth and is therefore more likely to encounter toxins