Field signs
On soft sediments, tracks of otter are distinctive, showing five toes arching around the front of a central pad. Webbing between the toes shows rather rarely, but may be present along with claw marks on very soft, muddy areas. Regular paths, especially around holt sites, and otter slides have been found in Kent. Generally surveys seek to find otter faeces (spraints) which are deposited on prominent places such as fallen tree trunks, under bridges and on rocks. These droppings have a rather pleasant smell, often described as cut grass mixed with fish oil, and can vary in size from very small dabs to over 100 x 150 mm. Spraints generally contain numerous fish bones and are often dark green to black in colour when fresh, but dry to resemble cigar ash.
Habits
Adult otters without young live a solitary life in linear freshwater habitats, though group territories have been reported in large lakes and some marine environments in the UK. Home ranges can be large and individual otters have been recorded as utilising up to 50 km of riverine habitats in several areas. Males tend to have home ranges that cover one or more females. Otters tend to be more active foraging for fish, amphibians and other prey at night, especially in England. During the day they may rest above ground in couches, or in underground holts that are often sited around root systems of riparian trees.
Reproduction and life cycle
Otters show aseasonal breeding in England, with perhaps some tendency for more summer births in Scotland. There is one breeding cycle per year, with no delayed implantation, and litters tend to be two to three cubs born after a gestation period of two months. Cubs are independent after a year though some may accompany their mother for longer periods. Otters typically live for three to four years but individuals as old as 16 years have been recorded in the wild.
Distribution, status and conservation
Due to the scarcity of this species within Kent and a resulting need for protection, the distribution map shows a central occurrence dot within a hectad for all records.
Prior to 1956, otters were distributed on all river catchments in Kent, though generally at rather low numbers. At that time, good populations were recorded in the Medway catchment, above Maidstone, and in the Stour Valley below Ashford.
After 1956 otter numbers in Kent significantly declined due to pesticide and other water pollution, loss of bankside habitat (especially riparian trees and holt areas) and the electrification of railway lines. For example the electrification of the line between Ramsgate and Deal is thought to have eliminated the otter population on the Worth Marshes.
A South East Otters and Rivers Project, based at Hampshire Wildlife Trust but covering Kent, was started in 1989 and ran for some 20 years. During that time a number of riparian habitat enhancement projects were carried out and surveys undertaken. This, in conjunction with the National Otter surveys carried out each decade since 1977, showed that otter numbers have increased nationally and also in some parts of the southeast, especially in Hampshire. However, otters in Kent have not shown a significant increase, which may reflect high levels of habitat fragmentation, unfavourable management of riparian habitat and the county’s rather isolated geographical position.
Current Kent records indicate that otters are limited to the Medway catchment. Given the increase seen elsewhere, it was thought that otters will recolonise many of their historic habitats in Kent. However, recent survey data show recolonisation is still slow and patchy with progress but slower than predicted, not yet widespread, with some catchments still lacking otter presence.
Significant work is still required to reduce threats and barriers. Increasing connectivity and allowing suitable holt sites to develop, and encouraging future sympathetic riparian habitat management are likely to be key.
