SEASONAL OCCURRENCE OF ARTHROPODS AS A SOURCE OF FOOD FOR BIRDS IN FINNISH LAPLAND

The seasonal occurrence in arthropod abundance was studied in Utsjoki, northernmost Finland, from the viewpoint that arthropods form an impo rtant food resource for birds. On ground surfaces, Araneae was the mos t abundant taxon. The abundance peak of spiders occurred in June. Dipt era, which was the dominant taxon in samples collected from dwarf shru bs, had their dominance peak in July. In birch foliage, Homoptera and Coleoptera were most common in June, but lepidopteran and symphytan la rvae dominated in late summer. The larvae in pines (Symphyta; Diprioni dae and Pamphiliidae) also had their abundance peak in autumn. The rol e of predation in the seasonality is discussed from the point-of-view of both birds and arthropods.