Sunday, August 22, 2010

Mystery of strange orange-headed birds in Ireland solved

For weeks birdwatchers across Ireland have reported seeing unusual birds with bright orange heads, not found in any known field guides from anywhere in the world, hanging out in flocks with starlings and house sparrows. In some areas, the enigmatic avians even appear to outnumber the native birds.

Now the mystery of the strange orange-headed birds has finally been solved, thanks to investigators at BirdWatch Ireland. According to their report, the odd birds are nothing more than starlings and sparrows which have developed a new diet.

That new diet consists of a foreign plant called the New Zealand flax, which has recently become a popular introduced variety in gardens across Ireland (and has unfortunately escaped into the wild and become an invasive species as well). Unlike many other plants, the New Zealand flax does not rely on insects or the wind for pollination. Rather, it relies on birds.

In order to attract its pollinators, the plant produces a sweet, highly nutritious nectar that birds find irresistible. But as the birds bury their beaks in the flower, a tiny brush-like appendage loaded with brightly coloured pollen dusts itself off on the top of the bird's head. The pollen is sticky enough to keep the drab birds looking pretty until they get hungry for another flax flower, thus spreading the pollen and helping the plant to reproduce.

In its native home of New Zealand, the flax plant is mainly pollinated by a native bird called a Tui, which has evolved a beak shaped perfectly to fit with the curvature of the flax flower. Irish birds are only just beginning to learn about the new source of food, and obviously Irish birdwatchers aren't yet accustomed to seeing starlings and house sparrows sporting such bright colours.

The BirdWatch Ireland report noted that it's likely the birds aren't aware of their altered appearance after feeding on a flax flower, even though their new look obviously makes quite the fashion statement to human eyes. Since the New Zealand flax is an invasive species in Ireland, there is some concern that the new feeding behavior from the birds, though charming, may serve to spread the unwanted plant. BirdWatch Ireland is urging anyone who spots an orange-crowned bird to report their sighting.

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