Habitat preferences of three Chorthippus species (Orthoptera: Acrididae)
in the Chelmsford area
TIM GARDINER, MICHELLE PYE & ROBIN FIELD
Centre for Environment & Rural Affairs (CERA), Writtle College,
Lordship Road, Writtle, Chelmsford, CM1 3RR
Abstract
This study investigated the habitat preferences of Lesser Marsh Grasshopper Chorthippus
albomarginatus, Field Grasshopper Chorthippus brunneus and Meadow Grasshopper Chorthippus
parallelus in grasslands in the Chelmsford area. The grasshopper populations of six study sites
were sampled in 2000 and 2001 using a simple comparative quadrat method.
Farmland sites were not favourable for either C. brunneus or C. parallelus, whereas densities
particularly of C. parallelus, were high on acid grasslands covered with fine-leaved grass species
such as Common Bent Agrostis capillaris. The authors suggest that these grasslands are favourable
due to microclimatic conditions because of the short, sparse sward, or that fine-leaved grass species
are preferentially selected as food sources. Agricultural sites may be unfavourable because the
swards are either too tall or too short and are comprised of tussock-forming grasses such as Timothy
Phleum pratense. However, C. albomarginatus was observed in high densities on a shorter area of
set-aside grassland and a disused farm track. The dispersal of this species to inland areas away
from its coastal strongholds may have been aided by the provision of grassland habitats such as
set-aside on farmland.
Introduction
Grasshoppers are insects of open grassland habitats. Marshall & Haes (1988) state that few British
species are able to exist in arable land, dense woodland and urban areas, although these habitats
combined constitute 50% of the land area of Britain. Approximately one-third of the remaining
land area is permanent pasture. These areas often support sparse populations of common species
(Marshall & Haes 1988), but can be unsuitable habitats for grasshoppers where grazing is intense.
Chorthippus species arc particularly affected by the use of insecticides on farmland with no
grasshoppers being recorded in an area after spraying in one experiment conducted by the Natural
Environment Research Council (1972). Clarke (1948) notes that grasshoppers may be found in
agriculturally derelict and disused areas where poor soil conditions have meant that the land has no
value for cropping. As a result of the detrimental impacts of fanning practices on wildlife, measures
have been implemented which aim to improve the biodiversity of farmland. Agri-environmental
schemes such as Countryside Stewardship have encouraged the introduction of grassy field margins
on fanns (Hill et al. 1995). Set-aside grassland, as introduced by the Ministry of Agriculture,
Fisheries and Food (now Department for Environment, Food & Rural Affairs, Defra), has facilitated
the removal of land from cereal production (to reduce surpluses) and the creation of habitats which
have some value for wildlife such as grasshoppers. However, research on farmland after the
introduction of such conservation and set-aside schemes is sparse.
Overall, less titan 20%i of the land area of Britain can be regarded as suitable or favourable habitat
for grasshoppers. This remaining land area consists of heathland, moorland and common land.
Most moorland is in northern England, Wales or Scotland. Lowland heathland in southern England
is relatively scarce, thus only a very small percentage of land in lowland England is favourable for
Essex Naturalist (New Series) 20 (2003)
JW