Monitoring Populations

Some of the more conspicuous plants and animals are observed and counted annually by coordinated efforts across wide geographic areas. The July 4th butterfly counts in North America, organized by the North American Butterfly Association (http://www.naba.org/counts.html), are a good example. These are usually carried out by small teams of volunteers, each led by at least one expert in the local butterfly fauna. Each team designs a transect within a 15-mile diameter count circle and counts and identifies all butterflies observed from the transect, usually once per year on or about July 4th. In 2006, 483 counts were held in the U.S., Canada, and Mexico. The data are published annually and provide a wealth of information on population trends and geographical distribution of the species. Species diversity and abundance vary, of course, with location. The all-time record for most species on a California count was 78 species in Yreka, California, in 1991. Some species have population booms in some years and busts in others, making long-term trends difficult to document.

Our local counts (Upper Newport Bay, Orange County, California) have been taking place since 1987 and are unfortunately showing a dis-

322 / Peter J. Bryant turbing decline in both numbers of individuals (4-500 in the late 1980s and early 1990s, but 1-300 since 1994) and number of species (over 20 in the late 1980s and early 1990s but 4 or less since 2004).

Butterfly counts in Northern California have also shown a serious decline. In 2006, Dr. Arthur Shapiro at UC Davis reported fewer butterflies in Northern California, particularly in the Central Valley, than at any time since he started counting them 35 years ago. At most of his study sites, he found only about half, or less than half, the number of species present in an average year. Near Vacaville in 2005, he found 378 individuals of 21 species, but in 2006 there were 43 individuals of 10 species (Kay, 2006).

Headlines like "Where have all the butterflies gone" are showing up in newspapers and journals in many other countries, including India (Khanna, 2005), Japan (Inoue, 2005), Canada (Science Daily, 2007), Australia (http://www.samuseum.sa.gov.au/butterflies/butterfly.htm), New Zealand (New Zealand Herald, 2007) and Britain (Butterfly Conservation, 2007a). The reasons for butterfly decline are usually not known, although pesticide use, genetically modified crops, climate change, habitat destruction, drought, and excessive collecting for trade are among the known causes or suspects.

In Britain, with a long tradition of public engagement in wildlife observation, over 10,000 volunteer recorders participate in assessing the distribution and abundance of butterflies over a network of over 750 geographic sites (http://www.butterfly-conservation.org/text/36/ recording_monitoring.html), using a combination of weekly transect counts and single-visit timed counts. The comprehensive 2007 report (Fox et al. , 2007) shows that many of Britain's butterflies are, unfortunately, in a rapid and alarming decline. The Large Blue became extinct in 1979 and has been successfully reintroduced, but 76% of the 54 remaining resident species have declined. A related moth monitoring program including a National Moth Night assesses the distribution of moths throughout the country. Moths are much more diverse than butterflies, with about 2,500 species, and are not as well known but their numbers have also dropped, by about a third since 1968 (Butterfly Conservation, 2007b). Some moth species are seriously endangered and a few are thought to have gone extinct. British insect species that have disappeared in the past 50 years include 88 beetles, 56 butterflies and moths, 20 bees, 17 flies, 14 bugs and hoppers, and 12 wasps (McCarthy, 2006) making a total of over 200 extinctions. Three bird species and 20 plants have also been lost.

Sightings of butterflies by hundreds of volunteers are contributing to our understanding of climate change. This was seen most clearly in Britain, where April 2007 was the warmest April on record ending the hottest 12 months ever recorded. Associated with this climate change, 11 species of butterflies made their earliest recorded appearances and of 59 resident 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.

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