What Wildlife lives in UK Rivers?

In the UK our lowland rivers are the highway of wildlife and there's so many species that live there. In today's video I'm going to show you some of the common and some of the rarer species you might find along the UK's lowland rivers. And where better to start than with the humble minnow. Almost all lowland rivers in the UK are home to large shoals of these gregarious and curious fish which sometimes gather in their thousands. Minnows grow to an average of around six centimetres long with 10 centimetres being very large for them, which is quite surprising given they're actually members of the carp family and are related to some of the largest fish in the country. Their colour can change during the breeding season but they're usually a mottled brown along their backs, cream coloured underneath and they have a darker line running along their bodies. Being so small and so common minnows are one of the top prey for perhaps the most beautiful bird in Europe, the common kingfisher. The kingfisher family consists of 118 different species but the only one that is native to the UK is the common kingfisher. With their metallic blue and vibrant orange markings they are unmistakable. Males and females look quite similar to one another but the colouring along their bill is a good way to separate them. In females their lower bill is orange and in males it is black. Kingfishers can be found along a wide variety of waterways including lowland rivers but also around lakes, smaller streams, marshland areas and even along the coast, especially in the wintertime. Although they are very capable when it comes to catching small fish, they will also dive into the water for invertebrates, crustaceans and small amphibians. Kingfishers aren't the only species along waterways that will eat a wide range of prey, that is also true of the chub. This species usually grows to around 30 to 40 centimetres long but they have a big appetite and big mouths to match. It's thought that they are where the word chubby comes from and they eat everything they can fit into their mouths including smaller fish, insects and crustaceans but also aquatic plants and fruits and berries which fall into the water. There are lots of generally grey or silver coloured fish in the UK but I find an easy way of separating chub from most of the other species is the darker line along their tails which can often be seen from above the water's surface. Chub will sometimes move into shallow water and will often rise to the water's surface in search of prey which at some times of the year would definitely include mayflies. Despite their name, mayflies can actually be seen emerging from their aquatic larval stage and taking flight from April all the way into September. There are 51 species in the UK and their scientific name Ephemeroptera is indicative of their short adult lifespans. This translates to temporary winged and is suitable as most adult mayflies only survive for a day or two whilst they quickly rush to breed before dying. Whilst mayflies can cause quite a spectacle, the little grebe is a very timid and often overlooked river resident. These cousins of the better known great crested grebe spend their entire lives on the water and often dive beneath the surface to search for food or to get away from danger. They have lobed feet that are at the back of their bodies and although their dives will only last for 15 to 30 seconds, this is plenty of time to search for small fish, aquatic snails and insect larvae to feed upon. Little grebes are also known as dab chicks and they really are quite small, barely larger than a duckling. This makes them vulnerable to predators including one of the top freshwater predators in this country, the pike. With their rocket-shaped bodies, rear-facing teeth and paddle-like tails, pike will lunge towards and swallow whole many aquatic creatures. This includes fish, amphibians, small mammals and small waterfowl. Male pike are typically smaller than females, growing to an average of around 16 inches but females can get much larger than this, sometimes exceeding 30 inches in length. They're also quite long-lived with some fish surviving for as many as 25 years. Pike often hang around aquatic vegetation and in the shallows, waiting to ambush prey but they don't have it all their way. Even the largest pike is potentially dinner for the Eurasian otter. You may have heard people referring to coastal otters in the UK as sea otters but this is a mistake. There is only one species here and even they were almost extinct not too long ago. Thanks to some captive breeding and improved education and legal protection, otters have made a drastic comeback over the past 50 years. Now they are found all over the UK and are present in every county. Male otters are known as dogs and are around a third larger than females. They can measure up to 135 centimetres long and weigh more than eight kilos. At this size and with their powerful teeth and high intelligence, otters really are the top predator of freshwater rivers and will eat anything that they can catch and overpower, including fish, waterfowl, amphibians and even other aquatic mammals, including the water vole. Over the past 30 years, the water vole has been the UK's fastest declining native mammal, caused in part by habitat destruction and pollution but also by predation from a non-native invasive species, the American mink. Thankfully, their decline seems to have slowed in the last 10 years and their numbers might even be increasing in some parts of their range. Water voles are a similar size to a large hamster and are brilliant swimmers. They live in colonies inside tunnels that they have dug into waterside margins. These sometimes even have entrances beneath the waterline. Their diet is almost exclusively vegetation and they need to eat almost 80% of their body weight per day just to sustain themselves. In Britain, they have been recorded feeding on 227 different plant species. In this video, I've been trying to segue smoothly from one species to the next but I can't find the connection between water voles and perch, so let's talk about perch. With their striped markings and jagged fins, perch are one of the first species that most freshwater anglers encounter as they are found in most freshwater habitats. When perch are young, they feed mostly on small invertebrates and crustaceans and during this time, they also shoal with other similar sized fish, including other species. As they get bigger, their diet changes to include mostly other fish and they become more solitary. When perch are threatened or alert, they can hold the fin along their back, which is known as a dorsal fin, high above their bodies to show a dark eye spot. This might confuse some predators and they're not the only river species to use darker dots to their advantage. Banded demisels are one of our most beautiful and common species of damselfly and the males use darker spots on their wings to signal to members of the opposite sex. Female banded demisels have plainly coloured wings and are green over most of their bodies, whilst males are much more brightly coloured and each of their wings has a darker spot or band across it. Like all other damselflies and their close cousins the dragonflies, the larvae of banded demisels develop underwater. After a period of up to two years, they emerge and gather along waterside vegetation where the brightly coloured males compete for territories and subsequently for the opportunity to mate. Lowland rivers have remained as one of the UK's best habitats for wildlife and hopefully in the last few minutes you've learned about some of the species that call them home. And that's all for today, if you did enjoy this video then why not check out this one here with the wildlife that lives in our ponds. Thanks for watching and I'll see you next time.