DRAGONFLIES (ODONATA) OF CYPRESS HILLS PROVINCIAL PARK, ALBERTA AND THEIR BIOGEOGRAPHIC SIGNIFICANCE

Abstract

AbstractThe Cypress Hills consist of a hilly elongate plateau straddling the Alberta–Saskatchewan border. They are mostly covered in a foothills-type vegetation but are surrounded by short-grass prairie and lie about 250 km east of the Rocky Mountain foothills. The upper 95 m remained unglaciated as a nunatak during the Wisconsinan glaciation. Dragonflies were collected at various times during May–August in 1982–1984 at 24 localities in Cypress Hills Provincial Park, Alberta. Thirty-one species were obtained, 3 of which (Aeshna multicolor, Gomphus graslinellus, and Libellula pulchella) are new records for Alberta. The dragonfly fauna of the Cypress Hills consists of species with the following Canadian distributions: 22 transcontinental (13 boreal, 7 southern, and 2 widespread), 4 southwestern, 2 western boreal–northwestern, 2 cordilleran, and 1 primarily prairie. An analysis of this fauna indicates that, following northward retreat of the glaciers, 22% of the present species came from cordilleran regions and 42% were derived from the boreal fauna. This corroborates the boreo–montane forest connection that is considered to have extended along the retreating ice front before the climate became too warm and resulted in the forest being replaced by grassland.