At the altitude of the refuge, spring starts late. It's almost summer before the snow starts to melt here. Spring starts our seasons because it is the start of new life on the refuge. The winter has covered the refuge with snow and starting in April and May it begins to melt. By May, many of the migratory birds have arrived. Many of these birds make nests, mate and start to give birth to their chicks. Gestation time in these birds is short. Trumpeter swan cygnets hatch. The elk, deer, pronghorn and moose mated last fall and now give birth to calves between May and June. Willows and aspen grow their bright green leaves by mid-May to early June. Early wildflowers begin to bloom.