Norfolk Hawker

Anaciaeschna isoceles

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Description

Length: 67mm

Flight period: June to July (occasional individuals in May and very early August)

The Norfolk Hawker is one of two brown hawker dragonflies found in Britain. It has clear untinted wings, green eyes and a yellow triangular mark on the second abdominal segment.

Problems with the scientific name: This species has had a variety of names and its 'well formed name' in 2016 is Anaciaeschna isoceles. The spelling of genus Anaciaeschna (with 'sch') is correct even though it is inconsistent with the spelling of genus Aeshna (with 'sh') to which this species was formerly assigned. The spelling of specific epithet isoceles is correct even though the yellow triangular mark for which it is named is mathematically an isosceles triangle. Unfortunately, some of our materials here may not yet have been updated to match the latest taxonomic changes and still show a previous or incorrect name.

Management Fact File

Habitat

The optimum conditions for breeding appear to be unspoilt grazing marsh dyke systems with clean, non-saline water, rushy margins, preferably with an abundance of water soldier as well as other aquatic plants.

Status & Distribution

The Norfolk Hawker is currently restricted to the fens and grazing marshes that are relatively isolated from polluted water in the Broadlands of Norfolk and Northeast Suffolk. A Local Biodiversity Action Plan (LBAP) for the Norfolk Hawker has been drafted for Norfolk. This is a red data book species protected under the Wildlife and Countryside Act.

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Similar species

Similar in colour to Brown Hawker but the clear wings, green eyes and very restricted habitat help identification.

Threats

The main threats to this species come from the conversion of grazing marsh to arable farming, inappropriate ditch management, nutrient enrichment, pollution, the impact of global climate change and fluctuations in water levels.

Management

General management principles include maintaining grazing marshes, controlling saline intrusion, controlling nutrient enrichment. There are also best practice guidelines for managing inhabited sites, particularly the dyke vegetation and the surrounding terrestrial habitats.

Case Study

Work is underway to restore habitats for this species in Norfolk.