and pan traps can be used to provide reliable population estimates (Russell et al., 2005). Light traps, which attract insects with mercury vapor lamps (visible and ultraviolet light) or various short- and long-wave ultraviolet lights, are also used to sample insect pollinators (some nocturnal bees, beetles, flies, wasps, moths) in diverse temperate and tropical habitats.
Because direct long-term monitoring studies are so rare, population patterns over time must be ascertained in other ways. Biological databases—taxonomic and genomic databases and information collected from conservation-related enterprises—can often be mined for data on historic patterns of pollinator distribution and, in some cases, abundance.
Specimen databases contain the information associated with vouchers in museum collections. At a miminum, the records show when, where, how, and by whom particular specimens were collected as well as their presumptive identifications. Specimen databases also can hold information about field observations. Museums capture information associated with the specimens in their collections, usually processing information on the best known and most widely studied groups first and then moving on to groups that are less well characterized. It is so widely assumed that mammal and bird species have been described that discovery of an undescribed primate genus (Rungwecebus) makes worldwide headlines (Davenport et al., 2006). In contrast, some groups with greater relevance to pollination, such as flies, are so diverse that experts cannot even venture a guess as to what proportion of genera remain to be described.
Specimen databases may be accessible online, and software applications grant access to all available databases together. The Global Biodiversity Information Facility (GBIF) provides a single interface that queries all online specimen databases that conform to community standards and protocols. The GBIF portal provides access to 90 million records from more than 700 collections (http://www.europe.gbif.net/portal/index.jsp). Sample queries for the honey bee returned 6,362 records from 9 data providers; most records were from Costa Rica (INBio, 5,920 records). The ruby-throated hummingbird, in contrast, returned 15,912 records from 9 data providers. Although specimen databases are optimal sources for trend information, few museum collections have digital databases of their specimen holdings, particularly of insects.
Character databases document the characteristics that taxonomists use to distinguish groups of organisms, primarily for specialists. The information also can be used to construct interactive identification aids for parataxonomists and citizen-scientists. There are three principal character databases: MorphBank (http://www.morphbank.net/) and MorphoBank (http://www.morphobank.org/)