Summer in the tundra reveals not only a rapid growth of plants and fungi, but a sudden flourishing of arthropods as well. Thick black clouds of flying creatures rise from the waters and hover like smoke over the tundra landscape. The mosses and lichens are, for a few short months, alive with scurrying beetles, springtails and mites. Such a harvest of food cannot fail to bring in flocks of arthropod-eating birds, and huge formations can be seen swooping and diving above the lakes and bogs in the summer.One particular bird has abandoned its powers of flight, leaving the clouds of flying mosquitoes, midges and caddis flies for the airborne hunters, and has concentrated its feeding to the arthropod life on the ground. Large ground-scurrying flocks of whiffles follow the tromble herds, pecking here and there in the stunted vegetation with their long beaks. Through the weight of their passage, the trombles cause such a disturbance to the soil and moss, churning up the mud and crushing down the vegetation in deep footprints, that the insects and other arthropods that live there are sent scattering for new cover. The whiffles following behind are quick to snap them up. Each tromble, representing a huge mass of flesh, is prey to warble flies, fleas and all manner of other parasites which are also eaten by the whiffle flocks.