The Isles of Scilly are an archipelago off Land's End, Cornwall. Little of the fauna on, above or in the seas surrounding the isles was described prior to the 19th century, when birds and fish started to be described. Most records of other animals date from the 20th century onwards.
Historical overview
There are few pre-19th-century records for animals. William Borlase published The Natural History of Cornwall in 1758, commenting on the number of rabbits, and Jonathan Couch's A Cornish Fauna gave an account of some the animals known in Cornwall and the Isles of Scilly. In the 19th century, following the fashion of the time, birds were shot and stuffed, especially by Augustus Smith and his predecessors on Tresco. Egg collecting was allowed and in the Natural History Museum there are, in the collection, forty-five eggs taken between 1880 and 1936 from Annett, even though it was a bird sanctuary. Newspapers recorded some of the fish caught but there was little recording of other groups of animals.
It was in the 20th century when regular accounts can be found for other animal groups following visits from naturalists who often published their observations in the scientific literature. For example, William Bristow visited the islands on three occasions from 1927 to 1934, recording spiders including on some of the uninhabited islands. The Cornwall Bird Watching and Preservation Society published bird reports from the 1930s onwards and the Isles of Scilly Bird Group (founded 2000) took over publishing their own annual reports – Isles of Scilly Bird and Natural History Review – which included other groups of animals such as the diptera.
Planarian (flatworms) Fourteen species of terrestrial flatworms have been recorded in Britain and Ireland with five found on the Isles of Scilly. Only three or four of the fourteen species are native with two recorded on Tresco.
The Australian flatworm (Australoplana sanguinea) – a flatworm from Australia and New Zealand and first found on Tresco in 1960. Now found in many parts of Britain. Feeds on earthworms. Australopacifica coxii – a flatworm from Australia and found on Tresco in 1975. Feeds on earthworms. Kontikia andersoni – found on Tresco in 1984; it is native to Australia and/or New Zealand. Microplana terrestris – recorded on Tresco (1982). Native Microplana scharffi – recorded on Tresco (1984) and St Mary's (1985). Native
Opiliones (harvestmen) Dicranopalpus ramosus Leiobunum blackwalli – found on all the inhabited islands, Annet and Great Innisvouls. Leiobunum rotundum – recorded on Tean, Tresco and St Martin's. Nelima gothica – found on St Mary's and Tresco. Nelima silvatica Opilio saxatilis Phalangium opilio – found on St Martin's, St Mary's, Samson and Tresco.
Odonata
The Atlas of the Dragonflies of Britain and Ireland published in 1996 listed just three species; blue-tailed damselfly, common darter (both breeding residents) and the migrant hawker. The pools can be slightly brackish at times and only species that can tolerate these conditions can establish populations on the islands.
Steve Jones compiled a list which was published in the Cornwall Dragonfly Group Newsletter (numbers 6–8) and the list below is based on that information. In comparison, at that time, Cornwall had 23 breeding species and 28 species recorded. Common blue damselfly (Enallagma cyathigerum) – in 1994 an ovipositing female was at Lower Moors, St Mary's. Blue-tailed damselfly (Ischnura elegans) – can tolerate brackish conditions and breeds on St Agnes, St Mary's and Tresco. Migrant hawker (Aeshna mixta) – increased sightings since the mid-1990s on St Agnes, St Mary's and Tresco. Southern hawker (A. cyanea) – recorded on St Mary's in October 1992 and October 1996 and from Tresco also in October 1996. Common hawker (A. juncea) – Great Pool, Tresco in October 1992. Emperor dragonfly (Anax imperator) – individuals seen on St Mary's, September 1992 and August 1996. Green darner (A. junius) – At least two individuals (male and female) were found on St Agnes on 10 September 1998 (just one day after the first record for the Western Palaearctic in Cornwall, the previous day). There was a male on St Mary's during the following week and a female on Tresco on 30 September and the next day. Golden-ringed dragonfly (Cordulegaster boltonii) – October 1996 on Tresco. Red-veined darter (Sympetrum fonscolombii) – two males on Great Pool, Tresco, May 1992. Yellow-winged darter (S. flaveolum) – one seen on St Mary's during the ″Invasion Year″ of 1995. Common darter (S. striolatum) – breeding on St Agnes, St Mary's and Tresco.