in the forest-tundra ecotone. Typical plant life in the breeding grounds consist of white and black spruce (Picea glauca and P. mariana) and American larch (Larix laricina), dwarf birch-willow, and wet sedge meadow and shrubby tundra with dwarf ericad/lichen plant life. The species migrates mainly through tallgrass prairies to winter in open woodlands, woodland edges and clearings, hedgerows, dense riparian thickets and around brush piles. The Harris's sparrow regularly occurs at feeders in suburban and rural gardens during the wintertime. They typically avoid dry shortgrass prairies and dense woods during winter. Migrating sparrows may be attracted to marsh elder (Iva annua) and giant ragweed (Ambrosia trifida). Behaviour Migration Spring migration commences around late February with birds arriving on breeding grounds by May. Sparrows arrive on their wintering grounds as early as late October, though mostly during November and early December. Records from Banff National Park suggest Harris's sparrows use mountain valleys as migration routes. Apparently, fall migration is less strict than spring migration as Harris's sparrows regularly wander about prairie provinces in Canada until harsh weather forces them south. Feeding ecology The Harris's sparrow generally feeds on the ground, scratching vigorously in the leaves and soil for food. Observed foraging during nesting was 85% ground-gleaning. During the breeding season individuals typically forage alone or with a mate. Primary in the diet (66% of stomach contents of breeding birds) are seeds, largely of Carex sedges, grasses and Scirpus bulrush. Also important in the breeding season diet are fruits, largely black crowberry (Empetrum nigrum), mountain bearberry (Arctostaphylos alpina) and various Vaccinium species. Pine needles, flower buds and blossoms are eaten supplementally. Larval invertebrates are important from June to September in the diet, as available prey becomes more common at this point. The principal preferred animal prey includes beetles, flies, bees, ants, moths, butterflies, spiders, cicadas, aphids and leafhoppers. The diet of wintering Harris's sparrow is less well-known and has not been quantitatively studied. Sociality Males of this species often group together to sing at dusk. In winter flocks, Harris's sparrows maintain linear dominance hierarchies that determine access to food and roost sites. The most dominant birds are the oldest males which usually also have the largest bibs. "Jump fights" between males occasionally occur, consisting of birds facing off, then leaping at each other, pecking, clawing and beating each other with wings. Testosterone alone does not affect the dominance status of winter birds.