The water of winterbourne streams is filtered through chalk before it bubbles up as springs into the stream. This makes the water very clean at the source and has a fairly constant temperature - great for wildlife. However, the very changeable conditions of the winterbourne throughout the year mean that it takes very special plants and animals to cope with the extremes of differing water flows - some of them real winterbourne specialists and very rare.


Adult mayfly Paraleptophlebia wernerii - credit Mike Hammet

There are several species of mayfly, but all have 3 tails like this one. They live as larvae in streams and hatch as flying adults (with a very short lifespan) to mate in the spring. Some are winterbourne specialists, but it takes an expert eye to distinguish the rare Paraleptophlebia wernerii (a specialist of winterbournes) from the more common Ephemera danica. Mayflies need clean water and lots of emergent and marginal plants: plants which grow with their feet in the water or on the very edge of the stream.


Photograph of a kingfisher - credit Environment AgencyAn unmistakeable bird, the kingfisher often passes in a flash of colour. As the name suggests, they live mainly on fish which they catch by diving into the water. Read more detail here on the RSPB website.


Photograph of a great crested newt - credit Environment AgencyYou're more likely to see these amphibians in off-stream water bodies (such as garden ponds) than in the main river. This is mainly because their eggs and young (called efts) are quickly eaten by fish. They enter the water in the spring to breed, and spend the winter hibernating on land - usually under a pile of logs or similar. There are 3 species of newt that you can find in Dorset: the smooth newt (Triturus vulgaris), the palmate newt (T. helveticus) and the great crested newt (T. cristatus). Click on their names to see more details from the BBC website.

Brown Trout

Photograph of brown trout - credit Environment AgencyThese fish are native to UK waters and are restricted to parts of the streams that are always flowing - unlike newts, thay cannot tolerate drying out! Like mayflies, they are an indicator of good water quality because they mainly feed on pollution-sensitive invertebrates.

Water crowfoot

Photograph of water crowfoot - credit Environment AgencyThis is quite a big plant family related to the buttercup (Ranunculus spp). They are an important part of the winterbourne's habitat, being home to lots of water snails and other bugs that form the base of the food chain. A few species are winterbourne specialists, adapted to the summer drying of the streams.

Little egret

Photograph of a little egret - credit Kevin CookThis is a small white heron that's a relatively recent arrival to these shores (they first bred in the UK in Poole Harbour in 1996). From there, they have been making their way up Dorset's waterways and can be seen in the winterbourne valleys. Read more detail here on the RSPB website.


Photograph of an otter - credit Ian CrossOtters are being seen more and more frequently along our streams and rivers, as their populations grow. They tend to live in quiet, undisturbed areas, building their holt or burrow next to a watercourse. At first glance they can be confused with mink, but are larger (growing up to 1.2m) and have a broader, more blunt face. Click here to read more detail from the Mammal Society's website.

Water vole

Photograph of a water vole - credit Graham CaseThe water vole is currently the UK's fastest declining mammal, thanks partly to the mink's appetite. However, we have reasonably good populations on the winterbournes, but they are very isolated. They need lots of vegetation on the bank and in the river to feed on, and soft banks to burrow in. Don't confuse them with brown rats, which also swim: voles are much rounder, with small ears and a furry tail. Rats have a bald tail, a pointed face and pointy ears.


Photograph of a mink - credit Environment AgencyOriginally escapees from fur farms, mink first bred in the wild in the UK in the 1950s. A close relative of ferrets and stoats, the mink is a voracious predator and is partly responsible for the decline of the water vole, among others. It has a more pointed, ferret-like face than an otter, and is significantly smaller (growing up to 65cm).

Himalayan balsam

Photograph of Himalayan balsam - credit Dorset AONBImpatiens glandulifera is a sweet-smelling annual with an amazing growth rate and seedpods that 'pop' when ripe. It was introduced to the UK in 1839 and has made its home on riverbanks and damp, ungrazed places. Its rapid growth and wide seed dispersal mean it can take over, smothering native flora, only to die away in the winter leaving riverbanks bare and susceptible to erosion. Thankfully, it's shallow-rooting and can be pulled out with ease.

You can help in the fight against its spread by pulling out the plants on your land - once pulled, it composts easily.




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