A look at some of the UK’s freshwater fish-eating birds; some common, some less so. Some loved, some less so. The majority of the fish-eating bird species foraging the UK’s freshwaters are generally not considered to adversely affect the functioning of natural wild fisheries. There are occasional localised impacts on fish rearing facilities but these are usually isolated occurrences. Fish-eating birds are opportunistic predators and can take advantage of artificially high prey densities such as fish farms. However, the impact of certain bird species on fish populations and angler catches is perceived as significant by the recreational angling community across many areas of the country.
The following summary looks at some of our feathered waterside companions, some common, some less so. Some loved, some less so.
Grey Heron (Ardea cinerea)
An unmistakable waterside companion seen by (or startled by) many an angler, the grey heron is a tall, distinctive species with its long yellow bill, pale neck, grey body and long black plumes from eyebrow to neck. It is frequently present along rivers, lake margins, wetlands or standing in flooded fields. They can often be seen purposefully stalking for fish, small mammals, small water birds and amphibians with their neck stretched out, staring with laser-focus.
In flight their large size, impressive wingspan, long legs, and retracted neck give them an easily recognisable silhouette. Usually silent away from their colonies, flight is sometimes accompanied by a harsh ‘kraaak’ call.
Some heron facts: –
• Roast herons were popular at medieval banquets: young birds, called branchers, were thought to be the best to eat.
• Herons are sociable birds when nesting, invariably in tree-top sites called heronries, some of which have been occupied for decades. The majority of nests are usually at least twenty-five metres above the ground.
• Heronries can reach a prodigious size with 100+ nests not unusual and single trees holding as many as ten nests.
• The annual count of heronries is the British Trust for Ornithology’s longest running survey. The first took place in 1928.
• Various egret species are now present in the UK and often join heronries at nesting times.
• Herons are among the earliest nesters. It has been known for some birds to lay their first eggs in early February, though the normal start is early March, peaking at the end of the month.
Kingfisher (Alcedo atthis)
Possibly the most loved of all our waterside companions, a kingfisher’s vividly coloured plumage gives it an exotic appearance and makes it one of the UK’s most recognisable birds. Those who are fortunate enough to witness its spectacular azure blues and bright oranges close up are unlikely to forget the experience. Some lucky anglers are even bestowed the honour of a kingfisher perching on their rod – a very special, intimate encounter.
Many will often hear its high-pitched call but will not see it as it darts past, low over the water. Widespread throughout the UK but absent from Northern Scotland, they tunnel into high sided banks making a small chamber for their eggs. They are indeed extremely adept at catching small fish and invertebrates, plunging into the water from their observation perch and more often than not, emerging with their prize firmly held in their beak as they return to their perch.
Some kingfisher facts: –
• There are eighty-seven different species of kingfisher in the world but only one, Alcedo atthis, breeds in Europe.
• In winter, a kingfisher needs to eat around fifteen small fish a day. Freezing winters can therefore have a major impact on populations.
• Though adults pair in the autumn, they retain separate territories until the spring, when they gradually merge together.
• Kingfishers are renowned for the insanitary conditions of their nests, which become littered with droppings, pellets and fish bones.
• Many young kingfishers die within days of fledging, their first dives leaving them waterlogged, ultimately drowning.
• Because of the high mortality of young, kingfishers usually have two or three broods a year, with as many as ten in a brood.
Osprey (Pandion haliaetus)
Ospreys are an ‘Amber List’ species due to their historical decline and low breeding numbers. This means their numbers are a concern but they are not critically endangered. There are currently around 300 breeding pairs of Osprey in the U.K.with Scotland remaining their stronghold. Ospreys became extinct in the UK in the 19th Century. Hunted for sport, used in fashion and taxidermy, their habitat and nest sites were also destroyed due to farming and building. In addition, their food sources were increasingly impacted by pollution from industry. These majestic raptors now have the highest legal protection under UK law and it is an offence to injure or disturb any bird, nest or egg.
Ospreys returned to the UK for the first time to breed in 1954 at Loch Garten near Aviemore. As a result of significant efforts to protect nesting sites over recent years, ospreys now nest in all countries of the UK. Generally, ospreys arrive in the UK in late March to early April. They tend to head south again around September with their journey taking four to six weeks.
Some osprey facts: –
• Ospreys will hold fish headfirst to limit air resistance and help in flight.
• Though their diet is predominantly fish, ospreys have been recorded catching a wide variety of other prey, including birds, reptiles and crustaceans.
• Some osprey populations, such as those on the Mediterranean islands of Menorca and Corsica, feed almost exclusively on sea fish.
• All British-bred ospreys move south to Africa after the breeding season, with most wintering in Senegal and the Gambia.
• Young ospreys remain in West Africa until they are three years old, when they fly north for the first time.
• Ospreys are early migrants. Returning birds are regularly seen in late March, with the males arriving a week or two before the females.
Great Crested Grebe (Podiceps cristatus)
The graceful great crested grebe is a familiar sight on lakes and reservoirs and is well-known for its elaborate courtship dance, during which it rises vertically out of the water and shakes its head. Grebes not only dive to feed on small fish and aquatic invertebrates but they rarely take to the air and prefer to dive in order to escape danger.
Some great crested grebe facts: –
• Young grebes have conspicuous striped markings and often ride on their parents back to avoid predators and shelter from wind.
• The great crested grebe has legs placed far back on its body, making it slow and clumsy on land.
• Historically persecuted for its beautiful feathers, the Great Crested Grebe population was once reduced to as few as thirty-two known pairs in England but increased from the mid-19th century. Numbers are not currently viewed as a concern.
Cormorant (Phalacrocorax carbo)
If the kingfisher is the most loved of our avian anglers, then the cormorant has undoubtedly become the villain of any waterside pantomime. They were once entirely coastal in habit but since the 1950s the abundance and range of cormorants have both increased dramatically to often unsustainable levels in many areas. An influx of the migrant, continental sub-species from mainland Europe, (Phalacrocorax carbo sinensis) is seen as largely responsible for the colonisation of many inland waterways. This significant expansion inland has brought the cormorant into conflict with many fisheries and anglers – the large numbers of birds and the sheer volume of fish they catch making them extremely unwelcome.
Some cormorant facts: –
• With a reptilian neck, it has an almost prehistoric appearance. It is often seen standing with its wings held out to dry.
• Cormorants are viewed as posing a direct threat to some designated endangered fish species protected under European legislation, including European eel, Atlantic salmon, lamprey and bullhead.
• Over-wintering cormorants in England are now estimated at over 30,000. Each individual requires approximately 500g (over a pound) of fish every day. As a result, the Angling Trust believes that cormorants should be included on the revised General Licences, under section 16(1) of the Wildlife and Countryside Act 1981 in order to enable fishery managers to adequately protect their fish stocks and their livelihoods.
Goosander (Mergus merganser)
Like cormorants, goosanders are generalist, opportunistic predators that will often flock in large numbers to take advantage of high prey densities. A report by The Wild Trout Trust in 2020 identified goosanders and cormorants as key threats to U.K. game fish. At the time, goosanders were centred on Scotland, with analysis showing that juvenile trout and salmon (smaller than twenty-five cm) were a key part of their diet. Smolt runs for example, were shown to be targeted by goosanders. On certain rivers such as the Tweed, goosander predation on the smolt run was cited as a key factor affecting the economic value of the salmon rod fishery. An expansion in their population over recent years has seen their distribution extend from Scotland to Northern England and Wales and as a result, they are seen as an increasing concern.
Protecting Fish from Avian Predation
For fish residing in rivers, freezing winters can have aparticularly adverse effect, diverting fish-eating birds from their usual still-water haunts to running water. Organisations like the Wild Trout Trust and Angling Trust offer advice regarding measures that can be taken in an attempt to protect river fish.
For example:
• Achieving a complex habitat is helpful (e.g. tree branches and roots trailing into the water, dense marginal vegetation); this is meant to provide cover for fish, reducing the hunting efficiency of fish-eating birds. Avian predators find it very difficult to follow fish into a complex web of trailing branches and tree roots.
• Consider the use of large woody debris to create localised areas of scour. These deeper parts of the channel will provide cover for fish from predators.
• Maintain a good mix of shrub-cover on river margins right through the year, particularly over shallow water in channel margins where juvenile fish often live.
• Ideally, try to remove bottlenecks that concentrate fish in vulnerable areas. For example, weirs can delay downstream fish migration and increase rates of bird predation. Equally, fish congregating below barriers during upstream spawning migrations are an easy target.
Sources:
Writing & Illustrations – Carl Hier, Winter 2025
You must be logged in to post a comment.