Seasonal monitoring of arthropod abundance at Bylot Island, Nunavut

Monitoring seasonal variation in arthropod abundance above or near the soil surface primarily allows us to determine the interannual availability of food resources for insectivorous birds nesting on Bylot Island, Nunavut. Arthropod sampling begins as soon as the conditions allows it (when the snow melts in the first or second week of June) and continues until the end of the season (mid-August). Every summer, ten arthropod traps are installed facing the wind in the Qarlikturvik Valley. Modified pitfall traps with white tank (38 x 35 cm and 7 cm deep) filled with soapy water and surmounted by a mosquito net frame (40 x 40 cm) are used to trap arthropods. Five traps are distributed along a transect in a wetland (73.1595°N 79.9493°W) and five others along a transect in a mesic environment (73.1494°N 79.9785°W). Traps are emptied every 48 hours and samples are stored in 70% ethanol. The samples are then sorted, dried and weighed to determine the biomass. Because of their low importance in the bird diet and their large size, which can generate large variations in biomass, plant debris, bumble bees (Apidae: Bombus) and butterflies (Lepidoptera) are excluded. Mites (Acari) and Collembola are also excluded because of their non-significant contribution to the biomass and diet of birds.