Grey Heron (Corr réisc) Ardea cinerea
An unmistakable long-legged and long-necked waterbird, the Grey Heron is a familiar sight in marshes and estuaries and along lake edges and riverbanks all across Ireland. At around 1 metre in length, and with its long, broad wings and slow, flapping flight, it is unlikely to be mistaken for any other Irish species. It is known in some parts of the country, erroneously, as the "Crane"; in fact, this name really refers to an even larger species, once common in Ireland though extinct here for many years as a breeding species.
Grey Heron courtship usually starts around mid-February, when both sexes grow longer crest and chest feathers. At the start of the nesting season their normally yellow bills temporarily become flushed with red, which is due to increased blood flow and which indicates that they are now in prime breeding condition.
Nest-building begins at around this time also. The male collects and brings the material and the female does the actual construction. They normally begin to lay their eggs from roughly mid-March until the end of April; some pairs begin earlier than others in the same colony, though the reasons for this are not fully understood. If eggs are lost or destroyed, the female may re-lay eggs through to June.
Broods average from 3 to 5 chicks; Grey Herons usually only have 1 brood per year, but occasionally have a second one. Both parents take turns incubating the eggs, and incubation generally lasts between 25 and 28 days. The parents continue to brood the chicks for a further 18 days, then after that the young leave their nests and start to clamber around in the branches. They finally take flight when they are about 50 days old, but usually continue to return to their nests for the following 2 to 3 weeks.
Fish form the main part of a Grey Heron’s diet, a fact that does little to enamour the species to owners of goldfish-stocked garden ponds. Frogs are also a favourite food, as are small mammals such as mice and shrews; occasionally even other birds will be eaten. Despite their strong aquatic associations, however, most Grey Herons nest in trees, usually in colonial groups known as heronries. With its grey back, grey and black wings, black and white head and neck and long trailing black plumes on the rear of the crown, the Grey Heron cuts quite a handsome and stately figure. Young birds are greyer and darker overall, and lack the head plumes. In flight, with its long legs trailing behind and its head characteristically ‘tucked in’ against the body, with its long neck bent into a bulging ‘S’ shape, the Grey Heron takes on a rather more ungainly, even slightly reptilian, appearance; it is sometimes likened to a pterodactyl, of all things.
Grey Herons possess a number of interesting adaptations that help them to hunt more effectively. Their long, sharp dagger-like bills are perfectly designed for stabbing and impaling fish, and they can often be observed standing completely motionless in the water, long neck held poised, waiting for their unsuspecting target to swim close enough: a sudden sharp strike downwards indicates that their patience has paid off. Their long unfeathered legs are ideal for wading into deep water where other birds cannot go, and their forward facing eyes, unusual for a bird, afford them excellent binocular vision, making it simple for them to accurately judge the distance between bill tip and fish and to aim their strikes.
Most remarkable of all perhaps, they have special brittle-tipped feathers on their necks that enable them to catch and kill eels, a species that other predators have great difficulty dealing with. When caught, an eel will attempt to wrap itself around its attacker’s neck, covering it with a sticky slime that fouls up feathers or fur on contact. When it tries to do this to a heron, however, the feather tips act like talcum powder, breaking off as a fine dust and absorbing the slime. The eel can then be dispatched and swallowed without much inconvenience.
Grey Herons are very susceptible to water pollution, which robs them of their main food source, and their presence in an area often indicates that the local water quality is high. They will sometimes move away from water though, and occasionally can be seen pacing methodically through fields searching for mice and frogs. They are generally wary of people, though in areas where they are unmolested they can become quite tame and will sometimes venture close to anglers and other quiet, still humans. Happily, their numbers are fairly stable in Ireland and our population does not seem to be in any immediate threat of decline.
