Habitat Survey

Otter, Water voles and Mink share similar habitat, being aquatic mammals adapted to life in and around fresh water and even estuaries and sea coasts. 

Otters and water voles are native to the British Isles and are a part of the natural riparian ecosystem. Mink, on the other hand, are an introduced North American species causing great damage to our native aquatic fauna – in particular to the once-common Water vole, which through mink predation and loss of habitat, has suffered a catastrophic decline in populations.

Otters and Water voles are now protected species and are listed on the national BAP (biodiversity action plan) designed to conserve existing populations and help their return to wetlands where they have previously disappeared. Central to these plans is getting the conditions right, with action on continuity of long stretches of good quality habitat (or “corridor”), safe migration routes, improved water quality and supply, availability of food and undisturbed breeding territory, free of predators such as Mink. In getting habitat right for Otters and Water vole, this naturally promotes a broader diversity of animals and plants sharing the ecosystem.

Our Otter habitat surveys began with work for the Environment Agency and the Hampshire and Dorset Wildlife trusts to pre-empt the spread of otters from their stronghold in Cornwall and the west of England into central southern England, assessing and mapping the quality of habitat and making recommendations for consolidation and improvement of habitat and corridor in the coastal strip between the River Stour in Dorset and the River Test Hampshire. We also looked at potential hazards such as road and rail crossing points for migrating otters, in case work could be done to allow otters to pass safely beneath or round without risking getting run over. 

Work also included surveying for quality of habitat for water vole, recording water voles where found, and also looking out for signs of Mink so that a trapping programme could be targeted at areas where Mink were present. A further aspect of these surveys was to record the presence of invasive alien plant species such as Japanese knotweed and Himalayan balsam, which can cause great damage to natural vegetation (and thus habitat quality) in wetlands.

We then went on to investigate and report in detail on entire river catchments including tributaries, associated ponds, wetland, wet woodlands etc on the Rivers Avon, Rother, Hamble, Meon, Wallington and parts of the Itchen and Test in Dorset, Hampshire and West Sussex. Since moving to Cornwall we have been involved in the Otter DNA study of the river Camel and its tributaries with good results identifying fourteen individuals from the DNA collected from their spraint.

Robin Roper has recently completed his section of the Fifth National Otter Survey