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In the Light of Evolution: Volume II—Biodiversity and Extinction
and regular migrant species, at least 36 emerged earlier than they would have done 10 years ago (McCarthy, 2007).
In the U.S., the Audubon Society’s Christmas Bird Count is the world’s longest-running uninterrupted bird census, engaging hundreds of volunteers every year. The complementary Breeding Bird Survey is a standardized count of birds along roadsides from May to July, carried out by volunteers and organized by the U.S. Geological Survey. Data from these two efforts were recently analyzed to discern 40-year population trends of all common North American bird species, and unfortunately the analysis revealed alarming declines of many of our most common birds. Some species declined by 80 percent, and 20 species lost at least half their populations over the study period.
For some declining bird species, some of the contributing factors can be identified. For example, meadowlarks favor farmland habitat, and this has been declining with changes in land use and the intensification of farming. Greater scaup and other tundra-breeding birds are suffering from loss of their permafrost breeding habitat and the arrival of predators from more temperate areas in association with global warming. Forest-dwelling birds, notably the boreal chickadee, are losing habitat due to various forms of deforestation.
Upper Newport Bay’s Back Bay Science Center (Mallett, 2006) has developed a regular Marine Life Inventory program, carried out each month with the help of many volunteers. Otter trawls, plankton tows, beach seines, and mud grabs are used to collect both vertebrates and invertebrates from the bay, and the catches are brought ashore for species identification, measuring, and counting.
Captain Dave’s Dolphin Safari (http://www.dolphinsafari.com/), based in Dana Point, Orange County, California, has been making use of volunteer dolphin and whale spotters on short cruises off the coast. During the 2007 season, large pods of bottlenose dolphins, common dolphins, Risso’s dolphins, as well as surprisingly large numbers (up to 20 during a half-day trip) of blue whales were documented.
In addition to early appearances, several species are extending their distributions northward, according to data collected largely by volunteers. In Britain, the Essex skipper, the comma, brown argus, orange-tip, peacock, speckled wood, and ringlet are all expanding their ranges northward, consistent with the predicted responses to climate change (Briggs, 2006). In Orange County, California, the giant swallowtail first arrived in 1997 and has now been recorded from several cities in the county. The brown widow spider first appeared in 2005 and has been spreading to other cities