Population fluctuations of 13 rodent species were monitored for 21 years in the central Negev Desert,Israel,in a 110 km2 area in different habitat types including sand dunes,open gravel plains,rock cliffs,loess hills and dry river beds.Analysis of factors affecting population dynamics of 9 common and abundant species demonstrated that densities of most rodent species in the late summer,after the end of reproduction,were determined mainly by total precipitation during the previous rainy season.Rodent densities in the winter,before the reproductive season,were determined mainly by their densities in the previous (late summer) season.Rodent populations in dry river beds (wadi) demonstrated either no or negative correlations with total rainfall,suggesting episodes of population crash due to flash winter flooding.For all species occurring in more than one habitat,densities,at least in some habitats,were correlated with their contemporary densities in other habitats.For these species,processes of density-dependent habitat selection were indicated using isodars analysis.Interspecific competition affecting species distribution at the micro-habitat scale has no effect on population dynamics at the macro-habitat scale.Generally,population dynamics of desert rodents were determined by the complex interactions of extrinsic (rainfall) and intrinsic mechanisms but were modified by density-dependent habitat selection.In most cases,population dynamics can be explained as processes acting at equilibrium around fluctuating levels of habitats carrying capacities.However,especially high environmental fluctuations result in significant deviations from equilibrium.