Monday, June 16, 2008
Richard Collins on the arrival of the cattle egret on our shores.
IT’S 11 years since the little egret first bred in Ireland. Twelve pairs of these gleaming white birds, which had arrived from mainland Europe, began nesting in a heronry near Youghal. There were doubts at the time as to whether the colony would become permanent; little egrets don’t like the cold and a severe Irish winter could put a stop to their gallop. Soon, however, other colonies were established and these exotic birds are now a familiar sight on most Irish estuaries. They nest in every county along the coast from Louth to Kerry.
Egrets are members of the heron family. ‘Heron’, from the old German ‘Haigron’, may be an imitation of the bird’s harsh cry. Adding ‘ette’, as in ‘cockette’, gives ‘haigronette’, which shortens to ‘egret’.
Now it seems that another kind of egret is about to make its Irish debut. This time it’s the turn of the cattle egret. This was once a very rare visitor; cattle egrets were recorded here on only five occasions between 1966 and 1986. Recently, however, numbers have risen dramatically and, this year, cattle egrets have arrived in force. Pairs are frequenting a heronry near Clonakilty in west Cork and, although there has been no official announcement from BirdWatch Ireland, it looks like this will be the year of our first cattle egret nests. It’s also expected to breed in Britain.
It’s easy to tell the two egrets apart. The cattle egret, which is actually smaller than the little egret, has a yellow bill and mature birds have yellowish crowns and backs. The legs are flesh-coloured rather than black and cattle egrets don’t have their cousins’ gaudy yellow feet. Not the tidiest of birds, they often look scruffy with feathers sticking out of the neck and chin. Little egrets pay more attention to their appearance; slim and elegant, they are always well turned out.
As the name implies, the cattle egret associates with livestock; perching and even riding, on animals’ backs. In Africa, the mount of choice is the buffalo but rhinos and elephants are also favoured. The bird will pluck ticks and other skin parasites from the fur of its host but this behaviour is actually rather rare. What benefit, therefore, large animals get from allowing egrets to perch on them is unclear. But, for the birds, a cow’s back is an excellent vantage point from which to spot something moving in the grass; grasshoppers are a favourite food. Hoofed creatures disturb the soil as they move, exposing insects and other creepy-crawlies, choice items for egrets. The cattle egret will visit wetlands, the habitat of choice of its little egret cousin, but it prefers drier areas and pasture.
As cattle egret populations expand, there may be competition for resources. Though not a great migrant, the bird has an adventurous disposition. It can roost up to 60km from where it feeds, commuting each morning and evening. Younger birds disperse widely and can travel long distances if the need arises. Two pairs nested, unsuccessfully, in the Camargue, France, in 1968. Others joined them the following year and, by 1974, there were 98 nests. Visit the Camargue today and you will see cattle egrets perched on the backs of the famous white horses.
In the 1930s, the bird performed a most extraordinary feat; cattle egrets crossed the Atlantic from Africa to South America and established colonies there. They have since spread into Central and North America. Similar expansions took place in South East Asia and cattle egrets are now found in Australia.
The nests are built in bushes, low trees and reed-beds. Colonies can be huge; sometimes thousands strong.
Impatient to get on with breeding, the first eggs are usually laid when the nest is only about one-third its final size. The adults keep adding new material after the young have hatched. Parents share tasks equally. Both birds build the nest, incubate the eggs and feed the young.
If they start breeding in Ireland, ours will probably be the most northerly cattle egrets in the world.
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