Terrestrial Invertebrate Surveys

Background

Terrestrial Invertebrate Survey reports and mitigation plans are required for development projects that could affect protected species, as part of obtaining planning permission or a mitigation licence, and for conservation projects. Surveys need to show whether protected species are present in the area or nearby, and how they use the site. Mitigation plans show how you’ll avoid, reduce or manage any negative effects to protected species.

EMEC invertebrate ecologists offer a broad range of services to meet your needs, examples of which are:

• Scoping surveys (single visit) surveys to determine whether a site has the potential to support invertebrate populations of significance.
• Multiple visit surveys to determine the species composition of a given site. Recent survey work has involved regular surveying of a brownfield site prior to redevelopment, with recommendations made for sympathetic redevelopment to mitigate loss of favourable invertebrate habitat.
• Common Standards Monitoring (CSM) for designated sites including Sites of Special Scientific Interest (SSSI) and Special Areas of Conservation (SAC). Recent work for Natural England has included the assessment of ancient woodlands for their assemblages of saproxylic fauna, a season’s fieldwork on an acid mire in the north of England to help formulate an action plan for its maintenance and enhancement as an area for invertebrates, and several smaller studies on the prevalence of invertebrate scrub edge communities throughout the United Kingdom.
• Individual species identification of key taxonomic groups.
• Invertebrate surveys for Wildlife Trusts to measure impacts of land management on the invertebrate fauna of sites, and to provide useful and realistic management recommendations for the future.

Timing

The optimal period for terrestrial invertebrate surveys is May to mid-September. Surveys can be carried out in April and late September to early October, but the adults of many species will not be present at this time so additional surveys within the optimal period are generally required to provide a complete picture of the invertebrate species present.

Methodology

Terrestrial Invertebrate Scoping Survey

A scoping survey for terrestrial invertebrates of habitats on site is used to assess the potential for a site to support an important invertebrate assemblage, and to determine the need for further survey to fully assess the invertebrate assemblages present. The scoping survey will involve an assessment of habitat suitability for invertebrates and recording of casual observations.

Terrestrial Invertebrate Full Survey

A full terrestrial invertebrate survey is undertaken if the scoping survey determines the site as suitable for an important species assemblage. Suitable habitats within the survey area considered favourable for invertebrate collection will be targeted during the visit. Every attempt will be made to make the site visit in weather conditions conducive to invertebrate surveying.

Methods for surveying and sampling terrestrial invertebrates include:

• Direct observation. Active and visible species such as butterflies, dragonflies and bumblebees may be observed and identified in the field during a walk-over of the site.
• Suction sampling where ground material including invertebrates are ‘hoovered’ into a collecting bag for later identification.
• Hand searching. A search of important invertebrate habitats, including dead wood, bare ground, beneath stones and discarded objects, and common invertebrate host-plants.
• Sweep-netting of flying insects and herbaceous vegetation.
• Beating of woody vegetation. Dislodged invertebrates are caught on a large fabric tray and quickly collected.
• Trapping. A variety of traps can be used, including pitfall, malaise, flight intercept, sticky and light traps. Bait traps can be used for butterflies and other insects attracted to fruits and sugar.
• Sieving of leaf litter.
• Extraction of insects from leaf litter using Kempson extractors or water funnels.

The following invertebrate groups will be targeted by the sampling:

• Araneae – spiders (larger spiders, Linyphiidae will incur extra fees)
• Coleoptera – beetles
• Heteroptera, hemiptera – true bugs and leafhoppers
• Orthoptera – grasshoppers, crickets, earwigs etc.
• Odonata – dragonflies and damselflies
• Hymenoptera – bees and wasps
• Lepidoptera – butterflies and day-flying moths
• Larger Diptera (the Brachycera and Syrphidae), a full Diptera list will incur extra fees.

Specimens collected will be retained in iso-propyl alcohol for later identification (except those where definite identification in the field is possible). All collecting methods are in line with Natural England’s collection protocols. The survey will be undertaken by a suitably experienced entomologist, with an assistant for health and safety when working near water.

EMEC invertebrate ecologists carry out all their survey work to best practice following methods developed and recommended by Natural England.

Following the Survey

Following the invertebrate survey, a report would be produced detailing specific advice suitable for the proposed works and the species found. This may include advice on suitable planting schemes in order to encourage specific species, or specific management regimes and timings of the work to promote diversity.

Examples

Saproxylic Invertebrate Fauna of Bredon Hill, Worcestershire
EMEC Ecology was commissioned by Natural England to conduct an intensive season long survey on the Saproxylic Invertebrate Fauna of Bredon Hill, Worcestershire.

Invertebrate Assemblage of Northumberland’s Lampert Mosses Site of Special Scientific Interest (SSSI)
EMEC Ecology was commissioned by Natural England to conduct an intensive whole summer survey on the invertebrate survey of the notified Invertebrate Assemblage of Northumberland’s Lampert Mosses Site of Special Scientific Interest (SSSI). The primary objective of the study was to identify the assemblage of invertebrates intricately associated with sphagnum bog habitats typically found in upland areas of northern England.