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i i Wildlife No long-term or major impacts to terrestrial habitats (e.g., mule deer) are expected. Subsidence is expected to occur as a gradual, more or less uniform Lowering of the land form--formation of extensive or conspicuous surface irregularities (e.g., shears or slippage) is not predicted. Small areas of surface disturbance associated with well pad construction or sub- sidence (e.g., tension cracks) would eventually assume the character of adjacent habitats via weathering, natural plant reestablishment, or proper reclamation practices. Possible short-term inundation of palustrine vegetation due to subsidence (see Yegetation section) would not cause detectable redistribution oc dis- placement of associated wildlife due to the extremely limited extent of disturbance and rapid regenerative capacity of this poorly developed wet- land type. However, passing of a subsidence wave could topple larger cottonwoods in the vicinity of the lease and represent a loss of cavity or tree nesting habitat for species such as the kestrel and red-tailed hawk. Burrow or den-dwelling animals would be most susceptible to habitat loss or mortality. It is conceivable that subterranean burrow systems or dens could become damaged or destroyed from surface flex as a subsidence wave passes. In the experience of local BC,H and USFWS personnel, prairie dog populations and, ostensibly, their burrows remain unaffected when subject- ed to slight upheavals from seismic exploration activities, but it is unknown if these burrows would be capable of retaining structural inte- grity during subsidence. The degree of impact on individual animals would be dependent on variables such as timing of active subsidence, burrow depth, soil strength, and extent of burrow damage. Presumably, mature animals would readily escape from partially collapsed burrows or dens; dependent young of such species nesting or denning at the time of active subsidence would be most susceptible. Impacts of this nature would be expected to occur in stages overtime; con- fined to habitat directly overlying active mine panels or rooms. Based on the current mine plan, surface subsidence would affect an average of 25 acres annually, with no more than 15 percent of the lease (about 52 acres) being affected in any one year. Host species associated with this group are common and widely distributed in habitats represented throughout the region. These animals typically possess high reproductive and recoloniza- tion abilities and individual losses over a limited area would be rapidly compensated by adjoining populations. In the event subsidence proves detrimental to burrowing animals, impacts would be considered significant only in the case of sensitive species or those associated with endangered species (i. e., burrowing owl, prairie dogs). At this time, prairie dogs and burrowing owls do not inhabit the Lease area or other areas potentially affected by subsidence. If popula- tions are found or become established in areas influenced by Lease devel- opment, measures would be incorporated through the Section 7 process or revised mine plan to ensure appropriate protection of these species and their habitats. C~ 18