Eden Valley Priority species -Northern brown argus

The Eden Valley region of Cumbria { NW England} is formed by the course of the river Eden, one of the major rivers in the north west of England, lying between the Cumbrian Mountains { Lake District} and the northern Pennine range, the vale lies entirely in the county of Cumbria. The vale may be accessed by leaving the M6 Motorway at junction 28 following the signs for Appleby and Kirby Stephen.

The river Eden begins its life in the dale of Mallerstang in the Yorkshire Dales { NE England} where it forms the boundary between the counties of Cumbria and North Yorkshire.. It follows its course, which becomes the Vale of Eden, flowing through Kirby Stephen and Appleby in Westmorland and receives the water from many streams flowing off the Pennines in the east and the longer rivers from the Lake District in the west.

As it continues north it passes through the sparcely populated Vale of Cumbria on its way to Carlisle  and finally concluding its journey  by entering the sea, via, the Solway Firth, which divides England from Scotland.


River Eden -Cumbria----Below  Gypsy horses in the River Eden at Applebey  Photograph by Dave Deben

Photograph by Cacolantern

Area of Outstanding Natural Beauty

The Eden Valley is an Area of Outstanding Natural Beauty but is just as famed by naturalists' as being of great importance to key habitat and priority species of fauna and flora under the UK Biodiversity Action Plan {BAP}. It is also a region that plays host to many Nationally Scarce and Nationally Rare species of fauna and flora.


In the UK there are three lists of conservation concern they are--

The Green list-- species on this list have populations that are stable or have increased over the last 40 years or so, and as such have no current conservation concerns.

The Amber list--Species on this list have seen declines in population numbers and/or distribution of between 25-50% over the last 40 years or so. They are thought to be in moderate decline and as such are closely monitored by the relevant conservation bodies.

The Red list-- if the population and/or distribution has declined by 50% or more over the last 40 years, the species is added to the red list. These species are classed as Priority species of conservation concern. As such these species will have been dedicated a Species Action Plan _{SAP} that has been formulated and currently being implemented on behalf of the species concerned, with a view to halting and eventually reversing these declines.

Under the UK BAP, habitats that are regarded as being important to species, or indeed, under threat in their own right are subject to a Habitat Action Plan {HAP}. In many cases SAPs and HAPs work in conjunction with each other.

In the Eden Valley there are many habitats that fit the Criteria, for instance, upland oak woodland, hay meadows and pastures and riparian habitat. On this page we have under review  one of the Priority species of conservation concern which occurs in the Eden Valley, and hence is subject to a SAP. it is the Northern Brown Argus, Aricia artaxerxes. 


Northern Brown Argus

The Northern Brown Argus raises but a single brood per season. The species only occurs in northern England and Scotland. { The species that occurs in Scotland is considered to be  a sub species Aricia artaxerxes artaxerxes which is characterised by a white spot on the forewing}

It seems the larval plant for the Northern Brown Argus is the common rock rose Helianthemum nummularium. It has not been recorded feeding on any other species of flora in the UK. 

Northern Brown Argus

photograph courtesy of Vetela Creative commons attribution

Common rock rose the larval food plant of the butterfly

Photograph courtesy of Jerzy Opiola creative commons attribution

Studies have revealed that the butterfly lays its eggs, singly, on the upperside of the rock rose foliage. The larvae  hibernate while they are quite small. The following spring they begin to feed again and commence new growth until they are about 1.5 cm long. Pupation takes place at ground level in late May. Butterflies emerge and are on the wing from mid June to mid July.

Description of the Northern Brown Argus.

To distinguish this species from the Brown Argus one needs to look at the orange spots on the upper wings. Those of the Northern Brown Argus are small and either absent or very faint on the fore wings. The wings have a dark brown ground colour with a sub marginal row of spots on the upper hind wings. The wingspan is 2.5cm.

They are associated with flower rich grassland especially on limestone up to 300 metres above sea level. 

Species Action Plan {SAP}

The UK Biodiversity Action Plan criteria for this species, includes a marked decline in the UK and other important factors.

The decline is estimated to be at 91% from 1984-2003. It is classed as being vulnerable. A species is vulnerable when it is not endangered  or critically endangered but is facing a high risk of extinction in the wild in the medium term future.

They appear on Schedule 5 Section 9.5a and 9.5b of the Wildlife and Countryside Act 1981 {as amended}. This Act is the backbone of protection for wildlife in the UK. Section 9.5a protects animals from being sold, offered for sale, or being transported for sale either dead or alive, whole or part. Section 9.5b -animals which are protected from being published or advertised as being for sale.

Included in the SAP are key actions---

To ensure known sites are managed appropriately { Principally base rich limestone grassland in England} 

To continue monitoring and surveys for the species.

Wider landscape action to improve delivery of agri-environmental schemes, targeting etc.

To encourage monitoring at key sites, coordinating data and produce trend for UK and national indicators.

Only time will tell if the SAP and the dedication of interested parties will halt the decline and hopefully reverse them, so that this unique creature may be commonly encountered again in the northern rich flower meadows. 

Flower rich meadows are important to the survival of the species.

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The name of the relevant author must be attributed along with any accompanying license.

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