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Fisher's Estuarine Moth
Colchester Zoo is launching a breeding programme for a rare moth found only in very small pockets of the North-East Essex coast. The Fisher’s Estuarine moth is a rare and highly threatened species and, therefore, is of a high conservation priority. If action is not taken soon, this beautiful moth may soon become extinct in the wild. It is thought that the moth has lived on British shores since around 1923 but it has only been studied since the late 1960’s. The Fisher's Estuarine Moth is found solely in an area between Walton on the Naze, Kirby- Le Soken, and Harwich; the salt marsh area known as Hamford Waters, and even here it is restricted to localised sub-populations.
The Fisher's Estuarine Moth occurs in one National Nature Reserve; an island called Skippers Island, which is classified as being an SSSI (Site of Special Scientific Interest) which are deemed to be the country's very best wildlife and geological sites and are considered to be internationally important for their wildlife. The Fisher’s Estuarine Moth therefore receives a degree of protection at that site, and is also fully protected under Schedule 5 of the Wildlife and Countryside Act of 1981; it is illegal to intentionally kill, injure, take or sell this moth, or to damage or destroy its habitat under this act. The species is also included in English Nature's Species Recovery Programme, and has an Essex Biodiversity Action Plan (BAP), and is listed as a British Red Data species.
However, despite all of this the Fisher’s Estuarine Moth is still 25% below the favorable reference population and over the past ten years this figure has been rising. It is threatened by rising sea levels, climate change and increased intensification of walking the footpaths around the sea wall. Interference in the sites over the past ten years has also lead to a decline in the amount of Hog’s Fennel that populates the area. It was believed that by leaving the site alone the Hog’s Fennel and the Fisher’s Estuarine moth would be given the best opportunity to thrive, but it has since been discovered that by cutting the fennel annually it actually grows much better. It seems that the grass was growing too densely and smothering the re-growth of next years Hog’s Fennel, therefore leading to a temporary decline in this crucial habitat for the moth.
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Colchester Zoo is, therefore, developing a captive breeding programme for the Fisher’s Estuarine Moth which will then enable the species to be established at the newly created sites, without necessitating the translocation from naturally occurring sites where populations are relatively small and vulnerable and should not be disturbed. It is hoped that the breeding programme will provide a readily available supply of Fisher’s Estuarine Moths that will ensure the sustainability of the High Level Stewardship for the species in the long term! Colchester Zoo is setting up a captive breeding programme of Fisher’s Estuarine Moth at the zoo that will run for at least three years from April of 2008. We will form part of a working group that will be responsible for establishing Fisher’s Estuarine Moth at newly created sites when conditions are suitable.
Colchester Zoo is aiming to provide opportunities for education about the important roles zoos have in native species conservation, and to publicise the project to a broad range of different audiences. We will carry out the proposed breeding programme within outside breeding cages that are purpose built and away from other species. Ultimately it is hoped that there will be 40 cages at the zoo. Hog’s Fennel and a coarse grass plant will be placed in the cages which will be watered twice a week in the summer. Keepers will ensure that the nets remain free from predators and that the caterpillars are dispersed amongst the plants. They will also ensure that a male and female moth are put in the same net on emergence from the pupae.
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It is very much hoped that this will become a very successful breeding programme that goes along way towards protecting the future of this rare native species. Colchester Zoo, Natural England and the Essex Biodiversity Project coupled with local conservation workers, will all be involved to ensure that the breeding programme and the establishment of these special created sites are as successful as possible and continue to thrive in years to come.
The Fisher’s Estuarine moth is completely reliant upon Hog’s fennel (Peucedanum Officinale) as its sole larval food plant. It also relies on long coarse grass species to fulfil its egg laying requirements and getting the balance of this correct is another reason why it is so difficult to get exactly the right environment for this rare moth to grow. The Sea Hogs Fennel is a large attractive perennial plant that can grow up to 5ft tall. It has feathery leaves and yellow flowers, and can technically tolerate a range of soil conditions. However, ironically though the species is found in coastal areas, it is not a salt-water tolerant plant and with raising sea levels it needs to grow further inland to survive and offer food for the Fisher's Estuarine Moth. Therefore, despite it’s seemingly high tolerance; this species is also listed as a British Red Data species. |
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The moth currently can be found in six localities around the North East Essex coast. Disappointingly, none of these are secure sites and are indeed extremely popular areas for ramblers and general members of the public to walk. This, coupled with the fact that this is an area of low-lying ground with a fast rising sea level, makes the future of the Fisher’s Esturaine Moth even more precarious.
It was therefore decided that habitat creation was a viable option to try and improve the outlook for the Fisher’s Esturaine Moth. Following extensive research into the history and habitat of the Fisher’s Esturaine moth and habitat creation trials, a two year project commenced in April 2006 to set up a sustainable landscape-scale network of sites to protect the moth. It was decided that suitable sites needed to be secure from flooding and cliff collapse, within five kilometres of the North Essex Coast, either behind a substantial coastal defence or above five metres in contour and between 0.0 and 1 hectare in size! The majority of this land, that is deemed suitable for habitat creation and is within the moth’s natural range, is agricultural. Therefore a programme has been developed to enable farmers and landowners to receive support for creating and managing sites for the moth through the Higher Level Stewardship (HLS) agri-environment scheme. Through this scheme, payments are made to farmers to establish Hog’s Fennel and grasses at such suitable sites and enhance them as much as possible. So far 15 of these sites have been successfully established through agreements under this scheme.
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The ultimate aim is that within ten years, a network of interconnected sites for the moth will have been created at sites away from the dangers of flooding, and human interference, thereby securing the long term future of the Fisher’s Esturaine moth in England. In order to be able to facilitate the sustainability of this programme, an agreement has been made with British Flora to grow and provide Hog’s fennel seed and seedlings to farmers for this habitat creation. Once the Hog’s Fennel is suitably established and is in at the very least it’s third season of growth, arrangements will be made for the Fisher’s Esturaine moth to be introduced to the newly created site, when conditions are suitable and where it is unlikely that the species will colonise naturally. Trials carried out so far have found that the moth responds well to being introduced in the egg stage of the life cycle to the suitable site.
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17th April, 2008 saw the first Fisher's Estuarine Moth hatch at Colchester Zoo! At just 1.5mm long they are not even easy to see with the naked eye, however this new caterpillar is the start of Colchester Zoo's breeding programme for one of the UK's rarest moth species!
Since then we have managed to fill all 40 of our breeding nets with between 4 and 8 caterpillars in each. The caterpillars feed off of Hog’s Fennel plants which have been put inside the nets. They are in fact also cannibalistic, so the larger of the caterpillars will end up killing its rivals to ensure that it gets access to the best food stock, so only one caterpillar in each net will survive.
The rest of the unhatched eggs were released back into a protected site in the wild on the 2nd of May where the emerging caterpillars will have to fend for themselves and find their own way from their grass stem to the Hog’s fennel plants.
We are now faced with a long wait for our moths to emerge. The caterpillars will remain feeding in the root stocks of the Hog’s Fennel plants for a number of weeks before they start to pupate in the summer. In the autumn, our reptile keepers must play cupid and match up male and female moths so that they can breed and begin our cycle all over again!
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