Impossible to mistake for anything else, grey herons are one of our most familiar birds. Tall, statuesque and found from busy urban parks to remote sea lochs, they are a common sight pretty much wherever there is water. Despite this, though, there are some surprising aspects to the life of the grey heron and, in my case at least, familiarity certainly doesn’t breed contempt. By April, their busy heronries will be all bustle with breeding well underway for the year. This gives me the perfect excuse to make them my April bird of the month.
The Grumpy Old Man
Grey herons are one of our tallest birds and as such, unmistakeable. Although they are about the same height as the great white egret, the latter species is a recent colonist and not seen in the UK with any regularity until the last decade or so. The egret is also completely white whereas grey herons are, as their name suggest, largely grey in colour. Adult grey herons have grey mantles and wings, a white neck and head and a distinctive black eye stripe that extends back into a long plume. They also have black wingtips and streaking on the long neck. Juveniles have a more washed-out appearance, being pale grey and white, with a grey eye stripe.
Despite their long legs, grey herons can sometimes appear much shorter than their full height. When not actively hunting, they will often sit hunched up on the water’s edge or in a wet field looking for all the world like a grumpy old man. If you come across a number of birds together in this pose, they look quite comical. They also often roost in trees, which seems quite incongruous for a tall, wading bird. The first time I saw a tree full of herons, I was completely taken aback as it was so unexpected. In flight, herons pull their long necks in to their bodies, making them easy to distinguish from the taller common crane which keeps its neck extended. There is something quite prehistoric and pterodactyl-like about a grey heron in flight. They perform long, slow wingbeats and can also glide or soar. Never particularly vocal outside of the breeding season, when they do call it is a harsh, croaking sound.
Of Fish, Fowl and Frogs
Most encounters with grey herons are with birds standing stock-still in or on the edge of water as they hunt. They can stand so still, they may be mistaken for ornaments, or even overlooked entirely. When prey comes into reach, a sudden, downward stab with that long beak aims to take the target by surprise. Herons are unfussy when it comes to diet. The majority of prey will be various fish species, but herons are fairly opportunist and will also eat frogs and toads, crustaceans, invertebrates, young waterbirds such as moorhens and ducklings, and also small mammals. Size of prey doesn’t often put a grey heron off either, and birds will attempt to swallow quite large fish.
As well as being unfussy eaters, grey herons are also not too fussy when it comes to habitat, as long as there is some form of water nearby. They are just as likely to be seen in a busy town park as a remote lake. Riverbanks, lochs, marshes and garden ponds are just some of the freshwater water bodies they visit. Herons are just as happy to hunt in saltwater as well, and can often be seen on estuaries and shorelines, especially in winter when inland water bodies are frozen. They will even hunt in fields, especially flooded pasture, from time to time. Grey herons can also swim surprisingly well, although they prefer to wade in shallow water. The UK’s resident birds are joined by birds escaping the cold in northern Europe over the winter.
Grey herons are one of our earliest breeders, with the first eggs usually laid in March. Some, however, lay as early as February. They are communal nesters, forming treetop colonies called heronries which have usually been in the same location for generations. Some colonies now have little egrets nesting in them as well, producing the sort of mixed heronries we used to have to visit mainland Europe to see. Remarkably, the British Trust for Ornithology has been carrying out annual censuses of our heronries since 1928. This makes it the longest running census for any single bird species in the world. Females usually lay between two and five eggs. Both male and female look after the scruffy youngsters once hatched, bringing a variety of food to the nest in their stomachs. Approximately 60% of young herons don’t survive their first year, either due to predation or starvation.
Despite the high mortality rate of birds in their first year, grey herons are doing fairly well in the UK. Harsh winters take their toll, and they are also at risk from discarded fishing lines and occasional persecution when taking fish from fish farms or ponds. But their ability to live in a variety of habitats, plus their generalist diets, means that they have coped well with the huge loss of wetlands that led in part to the bittern’s, albeit temporary, extinction in the UK at the end of the 19th century. Grey herons are also much less shy than bitterns and have proved willing to live reasonably well alongside humans. In the past, they faced much higher levels of persecution. Roast heron was a high-status food item in Medieval times, with 400 apparently served alongside hundreds of other items at the appointment meal of the new Archbishop of York in 1465. Birds were also hunted for their feathers, and falconers liked their birds to chase them because of the sport their flight style provided.
Grey herons may be one of our most familiar large birds, but they are certainly never boring. And their lack of secrecy means we often get to see their fascinating lives up close. Whether they are patiently waiting by the water’s edge for a fish to get just close enough to strike at, hunched up like a grumpy old man in the reeds or perched incongruously in a tree, they are always a treat to watch.