Endangered Species in Santa Cruz County - Species Account


Zayante Band-winged Grasshopper
(Trimerotropis infantilis)


This information was taken from the following publications, which are available for reference use at the Central Branch Library:


Recovery Priority 8 — indicates a species having a moderate degree of threat and a high recovery potential... .

Description and Taxonomy

The Zayante band-winged grasshopper (Trimerotropis infantilis) was first described from a sand parkland area near Mount Hermon in the Santa Cruz Mountains, Santa Cruz County, California (Rentz and Weissman 1984). The Zayante band-winged grasshopper is in the Order Orthoptera and Family Acrididae.

The body and forewings are pale gray to light brown with dark crossbands on the forewings. The basal area of the hindwings is pale yellow with a faint thin band. The lower hind tibiae (leg) are blue-gray, and the eye is banded. Males range in length from 13.7 to 17.2 millimeters (0.54 to 0.68 inch); females are larger, ranging in length from 19.7 to 21.6 millimeters (0.78 to 0.85 inch) (Otte 1984; Rentz and Weissman 1984). This species is similar in appearance to Trimerotropis occulans and T. koebelei; neither of these species is known from the Zayante sand hills region (Otte 1984; Rentz and Weissman 1984). Trimerotropis thalassica and T. pallidipennis pallidipennis have been caught nearby, but are not considered sympatric (i.e. they do not occupy the same or overlapping ranges) are morphologically distinct from the Zayante band-winged grasshopper (Rentz and Weissman 1984).1

Life History

The flight season for adult Zayante band-winged grasshopper extends from late May through October with peak activity during July and August (White, in litt. 1993; Morgan, in litt. 1994; Arnold 1999a,b). Specimens have been collected as late as November 4 (Arnold 1999a). When flushed, individuals generally fly 1 to 2 meters (m) (3 to 7 feet (ft)), producing a buzzing sound while in flight (Rentz and Weissman 1984). Band-winged grasshoppers often alight on bare ground, and are conspicuous in flight because of the color of the hind wings and the buzzing sound made by the wings (Borror et al. 1976).2

One Zayante band-winged grasshopper specimen was observed to be parasitized, most likely by a tachinid fly (White, in litt. 1993). However, the significance of parasitization on populations of this species is unknown. No additional information on the life cycle of this species is available.

Habitat Description

Habitat of the Zayante band-winged grasshopper was originally described as "sandy substrate sparsely covered with Lotus and grasses at the base of pines" (Rentz and Weissman 1984). Subsequent reports describe habitat as open sandy areas with sparse, low annual and perennial herbs on high ridges with sparse ponderosa pine. Such descriptions are consistent with those of sand parkland. Surveys also report that the Zayante band-winged grasshopper co-occurs with Ben Lomond wallflower (White, in litt. 1993; Morgan, in litt. 1994). The significance of such an association is unknown.3

In 1997, at the time of the listing of this species, all of its known locations occurred within 7 discrete areas of sand parkland habitat as characterized by Lee (1994). Recent studies indicated that the Zayante band-winged grasshopper occurs primarily in early successional sand parkland with widely scattered tree and shrub cover, extensive areas of bare or sparsely vegetated ground, loose sand, and relatively flat relief (Hovore 1996; Arnold 1999a, b). However, Zayante band-winged grasshoppers have also recently been observed in areas with a well-developed ground cover and in areas with sparse chaparral mixed with patches of grasses and forbs (Hovore 1996; Arnold 1999a, b), indicating that Zayanted band-winged grasshoppers are not restricted solely to sand parkland.4

Range and Distribution

The Zayante band-winged grasshopper is known only from Santa Cruz County, California. The species was described in 1984 from specimens collected in 1977 on sparsely vegetated sandy soil above the Olympia Sand Quarry. Between 1989 and 1994, Zayante band-winged grasshoppers were found at 10 of 39 sites sampled during two independent surveys near the communities of Ben Lomond, Felton, Mount Hermon, Zayante, and Scotts Valley, California (Hovore 1996; USFWS 1998).

Little is known of the historical distribution of the species. A review of museum specimens yielded Zayante band-winged grasshoppers from "Santa Cruz Mountain, no date", "Alma, 1928", "Felton, 1959", and "Santa Cruz, 1941" (Rentz and Waissman 1984). No subsequent collections have been recorded that substantiate the existence of a population in the vicinity of Alma. Furthermore, the town of Alma is currently beneath a reservoir, and the cited specimens cannot be located in the listed depository for verificatio (D. Weissman, California Academy of Sciences, pers. comm. 1994, 2000). Therefore, because no specific location or habitat descriptions accompanied these historic specimens, they were not considered in our assessment of the current range and status of the species.

The Zayante band-winged grasshopper occurs in association with the Zayante soil series (USDA Soil Conservation Service 1980). The Zayante soils in the vicinity of the communities of Ben Lomond, Felton, Mount Hermon, Zayante, and Scotts Vally are dominated by maritime coast range ponderosa pine (Pinus ponderosa) forest and northern maritime chaparral (Griffin 1964; Holland 1986). The distributions of these two plant communities overlap to form a complex and intergrading mosaic of communities variously referred to as ponderosa sand parkland, ponderosa pine sand hills, and siler-leafed mazanita (Arctostaphylos silvicola) mixed chaparral. These communities are collectively referred to as "Zayante sand hills habitat" and harbor a diversity of rare and endemic plant species (Thomas 1961; Griffin 1964; Morgan 1983). A unique habitat within the Zayante sand hills is sand parkland, characterized by sparsely vegetated, sandstone-dominated ridges, and saddles that support scattered ponderosa pines and a wide array of annual and perennial herbs and grasses.5

The Zayante band-winged grasshopper is narrowly restricted to sand parkland habitat found on ridges and hills within the Zayante sand hills ecosystem in Santa Cruz County. Approximately 200-240 hectares (500-600 acres ) of sand parkland existed historically (Marangio and Morgan 1987). By 1986, only 100 hectares (250 acres) of sand parkland remained intact (Marangio and Morgan 1987). By 1992 sand parkland was reportedly reduced to only 40 hectares (100 acres) (Morgan, pers. comm. 1992). A more recent assessment revised that estimate up to 78 hectares (193 acres) because of identification and inclusion of additional lower quality sand parkland (Lee 1994). Evaluation of sand parkland quality was based on vegetation structure and species composition.

Population Status

Between 1989 and 1994, Zayante band-winged grasshoppers were found at 10 of 39 sites sampled during two independent regional surveys (White, in litt. 1993; Morgan, in litt. 1994). All 10 collection locations were on Zayante series soils (Hoekstra 1994b). The habitat at these sites was consistently described as a sparsely vegetated sandy substrate or sand parkland (White, in litt. 1993; Morgan, in litt. 1994). The association and restriction of the Zayante band-winged grasshopper to sand parkland was further corroborated by an overlay of collection locations on maps delineating sand parkland habitat (Marangio 1985; Morgan, in litt. 1994; Lee 1994). All 10 collection locations fell within 7 discrete areas of sand parkland habitat (Hoekstra 1994b).6

Current Threats

The primary threat to the Zayante band-winged grasshopper is loss of habitat. Historically, approximately 2,533 ha (6,265 ac) of Zayante sand hills habitat occurred in Santa Cruz County. Over 40 percent of the Zayante sand hills habitat, and 60 percent of the sand parkland within that habitat, is estimated to have been lost or altered due to human activities. These activities include: sand mining, urban development, recreational activities, and agriculture (Marangio and Morgan 1987; Lee 1994; R. Morgan, pers. comm. 1992).

The disruption of natural landscape-level processes may also be resulting in shifts in plant communities, which has reduced the extent and quality of habitat available for the Zayante band-winged grasshopper. For example, active suppression of fire has resulted in the encroachment of mixed evergreen forest into ponderosa pine forest (Marangio 1985). Increase [sic] shading from the mixed evergreen forest appears to restrict the use of areas by the Zayante band-winged grasshopper and results in lower population numbers. (Sculley, USFWS, pers. observation 1999). Historically, fire would have burned in this area and resulted in areas with more exposure to sunlight. In addition, nonnative plant species, including Portuguese broom (Cystisus striatus) and sea fig (Carpobrotus chilensis), are out-competing native species and encroaching on sites occupied by the Zayante band-winged grasshopper (Rigney 1999). Pesticides and over-collection are also recognized as potential threats to the Zayante band-winged grasshopper (USFWS 1998).7

Conservation Efforts

Only 20 ha (49 ac) of sand parkland habitat are publicly owned--1.2 ha (3 ac) of high quality and 2.4 ha (6 ac) low quality habitat are protected within the Quail Hollow Ranch, owned by the County of Santa Cruz; 8 ha (20 ac) of low quality sand parkland are protected in the Bonny Doon Ecological Preserve, managed by the California Department of Fish and Game (Lee 1994); and approximately 8 ha (20 ac) of low quality habitat occur in Henry Cowell Redwoods State Park (Steinmetz, Henry Cowell Redwoods State Park, pers. comm. 1993). The Zayante band-winged grasshopper does not occur in the Bonny Doon Ecological Preserve or Henry Cowell Redwoods State Park. The remaining 58 ha (143 ac) of sand parkland are privately owned and at risk of loss to sand mining and urban development (Hillyard, California Department of Fish and Game, pers. comm. 1993; Lee 1994).8

Two HCPs (Habitat Conservation Plans) have been completed within the range of the Zayante band-winged grasshopper. Both HCPs are for sand mining operations and both provide take authorization for the Zayante band-winged grasshopper. The Revised Habitat Conservation Plan for the Quail Hollow Quarry owned and operated by Granite Rock Company provides for the permanent protection and management of three conservation areas known to be occupied by the Zayante band-winged grasshopper and that total 26.3 ha (65.8 ac) in area (Granite Rock 1998). The Habitat Conservation Plan for the Felton Plant owned and operated by Hanson Aggregates provides for the permanent protection and management of two habitat set-asides known to be occupied by the Zayante band-winged grasshopper and that total 8.5 ha (21.3 ac) in area (Hanson Aggregates 1999). In addition, both HCPs provide minimization measures to reduce the potential impacts of the sand-mining operations on the Zayante band-winged grasshopper.9

Needed Recovery Actions

The general strategies discussed in the Overall Recovery Strategy section are appropriate for this species. In particular, this species would benefit from:

  • HCPs (Habitat Conservation Plans) with quarry owners that minimize the loss of habitat from sand mining and urban development
  • HCP with County of Santa Cruz that minimizes the loss of habitat from sand mining and urban development10
  • Development and implementation of management plan for State- and County- owned unit (Quail Hollow Ranch County Park)
  • Protection of habitat through acquisition or establishment of conservation easements, and
  • Conduct research focusing on habitat requirements for long-term survival.11

Footnotes

1U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon." The Service, 1998, p. 21.

2Federal Register: July 7, 2000 (Volume 65, Number 131). "Endangered and Threatened Wildlife and Plants; Proposed Designation of Critical Habitat for the Zayante Band-Winged Grasshopper," p. 41918.

3U.S. Fish and Wildlife Service. Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon. The Service, 1997, p. 21.

4Federal Register: July 7, 2000 (Volume 65, Number 131). "Endangered and Threatened Wildlife and Plants; Proposed Designation of Critical Habitat for the Zayante Band-Winged Grasshopper," p. 41918.

5Ibid., p. 41918.

6U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon." The Service, 1998, p. 23-24.

7Federal Register: July 7, 2000 (Volume 65, Number 131). "Endangered and Threatened Wildlife and Plants; Proposed Designation of Critical Habitat for the Zayante Band-Winged Grasshopper," p. 41918.

8U.S. Fish and Wildlife Service. Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon. The Service, 1997, pp. 22-23.

9Federal Register: July 7, 2000 (Volume 65, Number 131). "Endangered and Threatened Wildlife and Plants; Proposed Designation of Critical Habitat for the Zayante Band-Winged Grasshopper," p. 41923.

10U.S. Fish and Wildlife Service. Draft Recovery Plan for Two Insects (Polyphylla barbata and Trimerotropis infantilis) and Four Plants (Chorizanthe pungens var. hartwegiana, Chorizanthe robusta var. hartwegii, Erysimum teretifolium, and Polygonum hickmanii) from the Santa Cruz Mountains, California." Portland, Oregon. The Service, 1997, p. 23.

11U.S. Fish and Wildlife Service. "Recovery Plan for Insect and Plant Taxa from the Santa Cruz Mountains in California." Portland, Oregon." The Service, 1998, p. 25.