In the Pacific Northwest, last year was a long, wet winter that morphed into a long, wet spring. It was looking like it would be a wet summer as well, until the skies finally cleared in July. Across most of the United States, the situation was very different. Drought conditions prevailed, and in many areas, plants and animals are still pining for moisture. What’s an animal to do in a shifting climate? In the summer of 2012, studies out of the University of California Berkeley’s Initiative in Global Change Biology examined the ability of species to adapt to changes in climate. They examined the factors that drive species out of regions, and they looked at how species are able to shift their range. They also looked at the animals that don’t move; can they adapt, or are they simply dying out?
Climate Change: Too Hot to Handle?
While a hot climate might seem like the main reason that an animal would move, there are other factors at play as well. Although many species move predictably in response to temperature changes, the studies found that changes in rainfall also force them to move. Climate changes can make areas get hot and dry, but they can also make other areas get cool and wet. In hot weather, birds go up to cooler places. In rainy weather, they tend to move down. If adjacent locations have very different changes, then populations could move in different ways.
What About the Migrants?
Alison Moran of the Rocky Point Bird Observatory specializes in hummingbird migration. The migratory abilities of these tiny, jewel-like birds are amazing. The Rufous Hummingbird (Selasphorus rufus) breeds in the northern United States, Canada, and Alaska, then embarks on a huge 1500-kilometer migration that takes it as far as Mexico. On the way back up, the birds follow the nectar trail to their summer breeding grounds. As the nectar-rich flowers open, the hummingbirds arrive to drink and to pollinate.
Moran’s organization bands hummingbirds and watches their migration. She says that hummingbirds show “an amazing site fidelity.” That means that the bird that visited your feeder last year may well be the same one that’s at your feeder this year. Not only that, but the birds may even show up in the same order, unless something changes.
In 2011, the Pacific Northwest suffered from an extremely cold spring. The flowers that the hummingbirds drink from did not open on time, since it was so cold and wet. Around the same time, the Sonoran Desert experienced a snap freeze killed off many of the flowers, that the hummingbirds pollinate. In the Pacific Northwest, the banders waited for hummingbirds but the migrants did not arrive. In fact, sites that once had thousands of birds saw only one or two arrive on time.Decoded Science
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