Where have you bean goose?

TWO hundred years ago the bean goose was one of the commonest winter migrant wild geese in Ireland.

But around the 1880s a rapid decline occurred in Ireland and Britain, though the species still over-wintered in large numbers in continental Europe, particularly in the Netherlands. Throughout the 20th century bean geese remained rare vagrants in Ireland and in many years none were reported at all.

But in the last few years the number of Irish reports has increased and the bean goose is showing signs of including us in its winter range again. In fact there may be more of them here than we realise because it isn’t the easiest bird to recognise and, at long range, can easily be confused with the much more familiar greylag or white-fronted goose.

If you’re a bird-watcher it could be a good idea to familiarise yourself with the key identification marks. Wild geese sometimes form flocks of more than one species so each individual in a flock may have to be scrutinised through a telescope and identified separately.

To make things even trickier there is quite a bit of variation in the size, shape and colour of bean geese. Two distinct types are recognised. Birds that breed in the tundra of northern Siberia are smaller with shorter necks and darker beaks. Those that breed a bit further south, in the wetlands of the taiga, are larger and more elegant with much more orange-coloured beaks.

Nobody has a definitive explanation for why these historical variations in range take place. They don’t seem to fit very conveniently into models of climate change. If winters were getting colder in the Netherlands it would make sense for the birds to fly a bit further to reach the milder Atlantic coasts —- but we’re told that winters in continental Europe are actually getting warmer.

The decline of the bird in Ireland and Scotland used to be attributed to the draining of bogs and other wetlands and the replacement of marsh plants by agricultural grasses. This suits the greylag goose much more than the bean goose and, to some extent at least, the greylags did take up the vacated niches. But this doesn’t explain why the bean geese now appear to be making a comeback.

There are many mysteries like this in the world of birds. The colonisation of this country by little egrets at the end of the last century could be due to climate change — the Irish south coast had become a pleasant place for a Mediterranean species. But at almost the same time the whooper swan, an Icelandic breeding species, started nesting in Donegal.

Maybe birds sometimes just decide they’d like a change of scenery.

Nature table

COMMON FROG (Rana temporaria)

The frog mating season is now well underway in all but the coldest parts of the country and soon lumps of frog spawn will start appearing in ponds, ditches and canals.

Frogs are amphibians, the most endangered group of animals on the planet. The common frog, the only species found in Ireland, is classified as ‘vulnerable’ in the rest of Europe but, according to recent research, is doing quite well in this country.

This may be because some of the diseases that attack them haven’t reached Ireland but it also seems our frogs are leaving the open countryside where the habitat is becoming less suitable and taking up residence in gardens — particularly ones with ponds and rough grass.

They normally hibernate and feed on land and only spend a week or two in the water at this time of year. They can change their skin colour, like a chameleon.