from their food. Free-standing water is consumed when available, but their range is not limited to areas with available surface water. Where surface water is not available, squirrels appear to be physiologically adapted and get sufficient water from food, dew and rains. They probably make use of water that temporarily collects in tree cavities.
Limiting Factors
Flying squirrels have been known to live 13 years in captivity, but seldom live five years in the wild. A variety of predators and internal and external parasites can affect them. Predators include owls, domestic cats, hawks, snakes, bobcats, raccoons, weasels and foxes. Predation is probably no more significant for flying squirrels than it is for other tree squirrels. External parasites reported from flying squirrels include fleas, lice and mites, and internal parasites include nematodes and protozoans. None of those parasites are known to be substantial limiting factors. Few diseases have been reported in flying squirrels, and none are thought to be significant.

The amount and quality of habitat are probably the most important factors limiting flying squirrel populations in Nebraska. The range of the southern flying squirrel coincides closely with the range of several species of oaks and hickories. Eastern Nebraska is near the western edge of distribution of several oak and hickory species and the southern flying squirrel. Because many of the mast-producing trees produce nut crops irregularly, a diversity of tree species is needed to assure an ample supply of nuts each year, and the lack of diversity of mast-producing trees may be a limiting factor for flying squirrels.

Although Nebraskans have little control over the natural diversity of mast-producing trees, the loss of habitat can be controlled. The primary reason the southern flying squirrel is threatened in Nebraska is the loss of deciduous timber habitat and the potential for this loss to continue. Habitat has been lost for several reasons. The conversion of forest to cropland and the use of forested Missouri River bluffs for homesites are the two most significant. Researchers from Peru State College found that 42 percent of the timber in Nemaha County was lost from 1856 to 1977. Most of the loss has occurred since 1955, primarily through conversion to cropland.

Changes in the remaining forested areas can be detrimental to flying squirrels. Logging removes mature oak timber that is important to flying squirrels as a food source and for the cavities the trees contain. Removal of trees for firewood can be detrimental because dead trees containing cavities are often cut, and the best mast-producing species are also the best species for firewood.
Management and Outlook
Because flying squirrels are nocturnal and are not valued as a game species, they have not been studied as extensively as other tree squirrels. Much of our knowledge about flying squirrels has been gained from observing them in captivity. Flying squirrels are doing well without human assistance in areas of their range where habitat is abundant. Management practices have rarely been implemented specifically to benefit flying squirrels.

Flying squirrels readily use nest boxes placed for their benefit or for other species. Nest boxes have been used in Nebraska and other areas in attempts to determine the status and distribution of flying squirrels. By periodically checking nest boxes and capturing and tagging the inhabitants, considerable information can be gathered. The number of squirrels using an area and their survival can be estimated, and movements can be monitored. Nest boxes can be used as a management tool when a shortage of cavities exists. Such a situation can occur in a young timberstand where trees are old enough to produce mast, but cavities are in short supply.

Nebraska can never expect large populations of flying squirrels unless the loss of habitat is dramatically reversed and forested areas are expanded. However, flying squirrel populations could increase. First, wholesale conversion of eastern Nebraska woodlands to cropland would have to cease. The effects of commercial logging or firewood cutting can be moderated by leaving a few large dead trees. The effects of homesites might not be serious if tree removal is minimized. Homeowners should consider erecting nest boxes and feeders and should keep pets from ranging freely If the loss of mature deciduous timber in southeastern Nebraska can be reversed, natural plant succession will eventually replace some of the lost habitat. Through natural succession, remaining woodlands and pastures would eventually become mature oak-hickory forest-just what the flying squirrel needs. The future of the species in Nebraska would then be brighter