A Five-Year Change in an Assemblage of Wood Rat Houses

Abstract

The house of the dusky-footed wood rat ( Neotoma fuscipes ) in California is an impressive structure compared with the small size of the animal that makes it. The owner of a house assembles sticks, bark, plant cuttings, and miscellaneous objects that it deposits in a conical heap, which may tower six feet or higher above the ground and have a basal diameter of eight feet. Passageways penetrate the interior and one or more chambers contain a soft nest for the repose of the occupant. Old and dominant individuals generally maintain and control several houses from which they exclude all other members of the colony. A mother and her young may occupy a house, but otherwise a single rat lives in a house. Long residence in the same house is rare. More often a rat shifts its headquarters frequently to a different dwelling within its sphere of influence. Occasionally, too, abandoning its own property, it may make a major move to a new area where it takes over a group of houses that belonged to an animal that died or moved elsewhere. As a rule only established rats build new houses. When young rats leave the maternal abode, they must find unoccupied dwellings in which to live, for construction of new homes is time consuming, and homeless rats cannot survive long enough to make a new shelter. Increase of a population of rats, therefore, is dependent in part upon the frequency with which established animals build houses and the vigor with which they maintain old houses. Most houses are occupied by a succession of tenants that persist in the upkeep of the structure, which then represents the work of many generations of rats. If a house is vacant for a considerable time, it loses its rat sign, such as deposits of feces …