56 BR. J. ENT. NAT. HIST., 7: 1994 



where extensive areas of such turf are present (often with a mixture of sparse grass 

 tussocks or heather bushes). Areas dominated by heather (Calluna vulgaris (L.) Hull 

 and Erica cinerea L.) and western gorse (Ulex gallii Planchon) were occupied, but 

 densities appeared to be lower than in more open grassy areas. Densities were 

 particularly high in short maritime turf on the Arches, and along the shore south 

 of the lighthouse at Dreswick Point. Towards the centre of the peninsula densities 

 were greatest around slate outcrops (and especially near the Powder House). At 

 Sandwick the grasshopper occupied an area of short turf, again with only a scattering 

 of grass tussocks. 



The floristic composition of the vegetation occupied by S. stigmaticus differed 

 greatly between Sandwick and the peninsula, yet its distribution in relation to sward 

 height appeared to be similar. Information on sward structure is difficult to convey 

 without quantitative data. In these circumstances, the distribution of S. stigmaticus 

 can perhaps be described most effectively via comparison with the better known habitat 

 preferences of the two co-occurring species, M. maculatus and C. brunneus. The 

 former species is known to occur exclusively within areas of very short turf (Marshall 

 & Haes, 1988), while the requirements of C. brunneus are more complex. The early 

 juvenile stages of C. brunneus occur predominantly in areas of short turf, while the 

 later stages are associated with tussocky grass (Richards & Waloff, 1954; Atkinson 

 & Begon, 1988). In comparison with these two species, S. stigmaticus was observed 

 to be intermediate in its habitat preferences. Thus, while S. stigmaticus was associated 

 with patches of short turf, this relationship was not as pronounced as that exhibited 

 by M. maculatus. Conversely, S. stigmaticus was rarely found in the taller vegetation 

 occupied by adult C. brunneus. 



If my interpretation of the species' habitat requirements is correct, the species' 

 absence from short turf on the golf course requires explanation. The most likely cause 

 is the disturbance associated with maintenance of the fairways and playing activity. 

 It is possible that an intensive search of the 'rough' would reveal small colonies 

 surviving on remnants of heath, but the golf course as a whole appears to offer a 

 sub-optimal habitat for S. stigmaticus. 



Threats to the species' survival on the Isle of Man 



In 1990 a proposal for the extension of the existing Langness golf course into 

 the seaward section of the peninsula was rejected at public enquiry. Whilst many 

 long-established golf courses are valuable wildlife refuges (NCC, 1990), the applicants' 

 submission that wildlife may actually benefit from the further development of Langness 

 peninsula (RPS Clouston, 1990) gained little credence. Despite this judgement, the 

 future of the lesser mottled grasshopper is yet to be secured unequivocally. By the 

 time the inspector's decision was given, the owners of Langness had already ceased 

 livestock grazing on the peninsula several years previously. At the time of my visit 

 in August 1993, this traditional means of managing the vegetation of the peninsula 

 had not been reinstated with the result that many areas of turf, which supported 

 S. stigmaticus in 1990, now appeared to be too tall for the species. Unfortunately, 

 poor weather in 1993 prevented a direct reassessment of the species' distribution. 



At Sandwick, and along the rocky shores of Langness peninsula, environmental 

 conditions alone may be sufficient to maintain an open sward of low growing plants. 

 Towards the mid-line of the peninsula, however, S. stigmaticus appears vulnerable 

 to shading from unchecked growth of the vegetation. In the continued absence of 

 grazing, the build up of dead plant material presents an additional risk from 

 uncontrolled heath fires. 



