English

While the decline of B. franklini in southwestern U.S.A. and B. affinis in eastern North America have been well documented and quantified, there are few baseline data for comparing previous and current abundances of B. occidentalis, the Western Bumblebee. Here we provide a comparison of the relative abundance of B. occidentalis after 20 years in the Fraser Valley of British Columbia, Canada. Bombus occidentalis was the second most abundant bumble bee in blueberry fields in 1981 (27% of collected bumble bees), and it was the second most common Bombus species, overall, collected in berry fields and natural vegetation (approx 22%) in 1982. In 2003–2004, this species represented less than 1% of the Bombus collected (26 individuals of the 2738 total). Likewise B. occidentalis was the most abundant bee (55% of bumble bees, 312 individuals) in cranberry fields in 1982 and second most abundant bee in 1981 (41% of bumble bees, 104 individuals) but was represented by 2 individuals (0.3% of bumble bees) in cranberry fields in 2003 and was absent from cranberry fields in 2004. Bombus occidentalis was also very low in abundance in urban habitats adjacent to this region in a survey performed during the same time period (2 individuals, 0.1% of bumble bees). These results provide quantitative evidence that wild populations of B. occidentalis have declined in western Canada.

House Sparrows (Passer domesticus) were introduced to North America after 1850, increased and spread up to 1920, and stabilized or decreased thereafter until 1960. In the Maritimes (and perhaps some other areas), a further decline set in after 1970, continuing to the present. Now the species is rare to absent in much of the Maritimes, except around farms with livestock. Decline here since 1970 probably approaches 90 per cent in most other areas of human settlement except south of 45°N.

Anthropogenic habitat loss is usually cited as the most important cause of recent species’ extinctions. We statistically compared areas in Canada where imperiled species currently occur, versus areas where they have been lost. Using multiple regressions, we relate the numbers of species that had suffered range reductions in an ecoregion to variables that represent present habitat loss, pesticide use and human population density. We find high losses of imperiled species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. The relationship between species losses and area treated with pesticides remains significant after controlling for area in agriculture. Our results are consistent with the hypothesis that agricultural pesticide use has contributed significantly to the decline of imperiled species in Canada. Habitat conversion per se may be a less important cause of species declines than how that converted habitat is used.

Two systemic neonicotinoids, imidacloprid and thiamethoxam, are widely used for residual control of several insect pests in cotton (Gossypium spp.), vegetables, and citrus (Citrus spp.). We evaluated their impact on six species of beneficial arthropods, including four parasitoid species—Aphytis melinus Debach, Gonatocerus ashmeadi Girault, Eretmocerus eremicus Rose & Zolnerowich, and Encarsia formosa Gahan—and two generalist predators—Geocoris punctipes (Say) and Orius insidiosus (Say)—in the laboratory by using a systemic uptake bioassay. Exposure to systemically treated leaves of both neonicotinoids had negative effects on adult survival in all four parasitoids, with higher potency against A. melinus as indicated by a low LC50. Mortality was also high for G. ashmeadi, E. eremicus, and E. formosa after exposure to both compounds but only after 48 h posttreatment. The two predators G. punctipes and O. insidiosus were variably susceptible to imidacloprid and thiamethoxam after 96-h exposure. However, toxicity to these predators may be related to their feeding on foliage and not just contact with surface residues. Our laboratory results contradict suggestions of little impact of these systemic neonicotinoids on parasitoids or predators.

We quantified the relative value of native and long-established plant species as forage (nectar and pollen) resources for bumblebees by collating visitation data from 14 field sites across Britain. Twentieth Century changes in range and frequency of these forage plants were assessed using data from the New Atlas of the British and Irish Flora (1930–1969 to 1987–1999) and the Countryside Surveys of Britain (1978–1998). Forage plants declined in both large-scale range and local-scale frequency between the two survey periods. These changes were of greater magnitude than changes in other native plant species, reflecting serious reductions in quality of foraging habitats for bees as well as a general decline in insect-pollinated plants. Seventy-six percent of forage plants declined in frequency within 1-km squares, including those (e.g. Trifolium pratense) of particular value for threatened bumblebee species.

Changes in summer numbers of adult Corn Buntings Emberiza calandra in a large sample of study areas holding discrete localized populations were measured. Singing cocks and hens paired with them were counted in early summer at 30 study areas on farmland from south Angus to central Aberdeenshire. Although 22 study areas held birds in 1989 and 25 in 1990, this fell to 10 in 1999, seven in 2005, and four in 2007 (the only areas that held birds in all years). On all areas combined, cock numbers fell by 83% between 1989 and 2007.

From 2005 onwards, butterflies have been adopted as Governmental biodiversity indicators in England, Scotland and for the UK as a whole. The indicators are compiled using butterfly abundance data collected through the UK Butterfly Monitoring Scheme, at a network of site established from 1976 onwards. The indicators show significant long-term declines in each country since the 1970s. In spite of large amounts of investment since 2000 to improve the habitat condition of protected areas, the trend for butterfly populations is no different in protected areas compared to elsewhere. Analysis by policy sector in England, shows that butterflies are declining rapidly in both forestry land and farmland.

We used point counts to conduct systematic quantitative surveys of Darwin’s finches and other land birds on Santa Cruz Island in the Galápagos archipelago between 1997 and 2010. The temporal analysis revealed that six of the nine species investigated declined significantly and that this decline was most pronounced at higher elevations in humid native forest and agricultural areas; the highland areas have been most affected by introduced species or direct human impact. Five of the six declining species are insectivorous, which suggests that changes in insect abundance or insect availability are a critical factor in the declines. Other factors including habitat alteration and introduced parasites or pathogens may be contributing to the observed declines.