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Literature Review

Coachella Giant Sand treader Cricket

Macrobaenetes valgum

USFWS: Federal Species of Concern (no official status)
CDFG: No official status

Background

Distribution, Abundance and Trends. The Coachella Valley giant sand treader cricket occurs exclusively in the active sand hummocks and dunes in the Coachella Valley. They are most abundant in the active dunes and ephemeral sand fields at the west end of the Coachella Valley, west of Palm Drive at least to Snow Creek Road, adjacent to the Whitewater River and San Gorgonio River washes. Suitable habitat also occurs within the Whitewater River Floodplain Preserve and at the Coachella Valley Preserve, on the main dunes and the Simone dunes. Despite the low numbers reported below from pit-trap samples at the Coachella Valley Preserve, burrows of these crickets are commonly observed in the main dunes (Barrows, pers. comm.). The east end of the Indio Hills also includes suitable active blowsand habitat, but this species has not been observed there; their apparent absence at this location may relate to moisture regimes where they occur in lower numbers in the drier eastern portion of the Plan area. Their preferred habitat in windblown environments is dominated by perennial shrubs including creosote bush, burrobush, honey mesquite, Mormon tea, desert willow, and sandpaper bush. Stabilized sand areas appear to be avoided.

LOCATION	NUMBER OF CRICKETS
	JANUARY 1998	JANUARY 1999	FEBRUARY 1999
SNOW CREEK (West valley)	5	95/732	28
WHITEWATER RIVER FLOODPLAIN PRESERVE (West valley)	28	–	–
COACHELLA VALLEY PRESERVE - Main Dunes (Central valley)	2	1	–
COACHELLA VALLEY PRESERVE - Simone Dunes (Central valley)	3	–	–
EAST END OF THE INDIO HILLS (East valley)	0	0	0
1 Results are from Cameron Barrows (personal communication and CNLM 2000); except as noted (see 2 ) data represent one sample of 20 pit traps (500 ml cups) placed within 0.50 to 0.25 ha area of active aeolian sand hummocks at each location.
2 Two different samples are reported.

The historic range of this species is entirely within the Plan area, from Fingal's Finger east to the sand dune areas in the vicinity of Indio. Tinkham (1962) describes them as occurring on "sand dune ridges to two miles west of Indio"; this description would include portions of the Big Dune area. Information on the occurrence of this species in the remnants of the Big Dune, from Palm Springs east to La Quinta and Indio, is limited as most of the land is privately owned and has not been accessible for surveys. The species distribution model indicates that potential habitat occurs on the Big Dune, however, the active blowsand areas apparently preferred by the Coachella giant sand treader cricket are no longer present. The occupied range has been greatly reduced as a result of development and sand stabilization.

The giant sand treader cricket has its primary period of activity during the spring. They are nocturnal, coming to the surface to forage on detritus blown over the dunes, or to look for mates. During the day they conceal themselves in self-dug burrows from five to twenty meters deep in the sand. These burrows are often associated with the roots of perennial shrubs or under boards, rocks, and other hiding places. The life history of these insects is not well known. The adult and juvenile instars disappear during the warm months of the year, perhaps spending the summer in the egg stage. Activity of small juvenile instars begins in the late fall through early winter. By mid to late spring the adults have disappeared.

Threats and Limiting Factors. The most significant limiting factor for this species is the availability of the aeolian sand ecosystem and the sand sources and corridors that maintain it. Threats to this species include cumulative habitat loss and degradation of the existing habitat as a result of development, in particular where sand transport processes are disturbed. Off-road vehicle activity is a threat to the habitat of this species as their shallow burrows can be crushed and the sand compacted. Any human activity that results in sand stabilization is also a concern. Non-native species including Saharan mustard (Brassica tournefortii) and Russian thistle (Salsola tragus) can significantly stabilize active sand habitats.

Special Considerations. This species is strongly associated with wind-blown, active sand dunes and fields. Sand sources, sand corridors, and dune hummocks must all be connected and protected.