Invertebrates are classified as animals without backbones and include species ranging from insects and spiders to worms and snails. Invertebrates form a major component of biodiversity, both nationally and globally. In the UK alone there are over 30,000 different invertebrate species – that is more than all other UK animal and plant species put together.

As with vertebrates, some invertebrate species are very rare, or have severely declined in recent years. The decline and extinction of invertebrate species is reason for concern due to the vital part these organisms play in maintaining healthy ecosystems. They provide invaluable services, such as plant pollination and nutrient cycling, in addition to being important food sources for many birds and mammals.

Invertebrates are found in nearly all habitats in the UK. Some of our rarest species have very particular habitat requirements or have evolved specialist relationships with other species on which they have become dependent. Therefore changes in land management practices and habitat structure have had profound effects on many of these specialist species which may now only exist in very discrete and fragmented populations.

Consequently, conserving biodiversity is now an important planning consideration. Where a proposed development is likely to impact upon biodiversity, the developer will often be required to carry out a survey to ascertain the biodiversity interest of the site. Should the proposed development be shown to impact upon biodiversity, effective mitigation plans have to be implemented.




The majority of UK invertebrate species are not protected by any legislation. However, 69 invertebrate species, including the White-clawed Crayfish (Austropotamobius pallipes) and the Large Blue butterfly (Maculinea arion) are currently listed on Schedule 5 of the Wildlife and Countryside Act 1981. This means (with certain exceptions and exemptions) that it is an offence (without a license) to:

intentionally kill or injure any of the species listed on Schedule 5;

intentionally or recklessly damage, destroy or obstruct the places these animals use for shelter and protection;

intentionally or recklessly disturb these animals when they are using such places.

Persons found guilty of any of these offences could be fined or even imprisoned. This means that surveying to ensure early detection of these species prior to development is essential to guarantee compliance with this Act.

A number of other UK invertebrates, which are not protected under the Wildlife and Countryside Act, are also of conservation concern. These species are listed in the UK Biodiversity Action Plan (UK BAP) and IUCN Red List, and are identified as priority species for conservation. Surveying for these species is essential to meet the Biodiversity Action Plan targets, in addition to ensuring any development is ecologically sensitive, with minimum impact on the surrounding environment.

When considering planning applications, the authorities are required by law to take account of protected species and the conservation of habitats. A detailed ecological survey is usually required before planning permission can be granted.


The best way to assess a habitat for invertebrates is to carry out an initial scoping visit. Experienced invertebrate specialists can often determine a site’s quality without necessarily undertaking a detailed survey. Such a visit focuses on examining habitat features and conditions, which help estimate the site’s potential for any protected invertebrates that may be present.

Invertebrate surveys can take a variety of different forms depending on the species or group of interest. Effective surveying often involves using a combination of different sampling methodologies. For terrestrial invertebrates, light traps, malaise traps, timed quadrat searches, suction sampling and pitfall trapping are all classic methods of sampling, whilst for aquatic invertebrates, kick sampling and sweep netting are the methods most often used.

Although surveys are often required by the planning regulations, you may consider commissioning one for other reasons, for example as part of biodiversity enhancement work. The results will frequently reveal how a habitat could be improved, not just for invertebrates, but in turn all the other animals and plants that rely upon them.


Any activity likely to contravene legislation in regard to protected invertebrate populations will require a licence if committing an offence is to be avoided. Applications for licences must be submitted to Natural England by a competent ecologist, i.e. a person able to demonstrate to the satisfaction of Natural England that they have the relevant skills and knowledge of the species concerned.