West Mojave Plan FEIR/S - Desert Managers Group

distance-sampling data indicate that 12 of the 14 (86%) crushed carcasses were of adult tortoises,1 (7%) was a subadult, and 1 (7%) was unknown.Aboveground Tortoise Activity in Response to Wet versus Dry Years: Sign count anddistance-sampling data indicated within a give year, tortoises are more likely to be aboveground(i.e., active) in the spring and in burrows (i.e., inactive) in the summer-fall. The distancesampling data suggest that increased activity patterns occur on a regional scale, not just on alocal scale. This may the first evidence that increased tortoise activity patterns in response torainfall occur on a population level instead of at the individual level.These observations are significant for the following reasons:• Heightened activity in wetter years may put more tortoises at risk to being crushed byvehicles, both on and adjacent to designated routes. This impact is more likely to occurin higher density areas where operators are more likely to encounter tortoises.• Illegal activities that are facilitated by roads (i.e., poaching, pet collection, inter-regionaltranslocations, intentional vandalism, etc.), may occur more frequently in wetter years,given that tortoises are substantially more visible aboveground than in burrows.Increased law enforcement in higher density areas during such conditions may minimizethese impacts when and where they are most likely to occur.• Vehicles traveling in washes in wetter years may impact relatively more tortoises than indry years. It has been suggested that vehicle travel in washes during drought periodswould result in more impacts. This may not be true if tortoise activity in washes occursat reduced levels (i.e., although tortoises in burrows would still be affected by vehicletravel in washes).Locations of Tortoises: There were 491 sign count and distance sampling tortoisesobserved between 1998 and 2002. Their locations and other information are given in Table 3-24.Distance sampling tortoises for 2001 and 2002 are given in the middle two rows of the table.Arrows show the directions to which percentages apply; the two middle rows are relative to“Distance Both Years” shown in the fourth row of data.Chapter 3 3-124