Tuesday, June 29, 2010

Troglodytes

The breeding seabirds that we have been looking at in recent posts share one thing in common: they all breed on rocky cliffs and islands from which they foray out to sea to catch their prey. The Guillemot is a perfect example: they nest in tight colonies in very confined space, situations that territorial birds would not tolerate. But food is dispersed at sea so the advantage in nesting all packed lies in protection from predators and is an inevitability anyway as safe nesting sites are discretely spaced out. So the Guillemots in the Farnes fly out to sea where they hunt in packs.




the prize is brought back home

the nest is barely a smattering of vegetation so the egg is in real danger of being knocked over the narrow ledge, especially in such packed colonies. So the Guillemot's egg is conical which ensures that the egg spins on its apex and stays in the nest. The risk of loss is minimised.


with luck, the chicks hatch and a new generation comes to the world



...but the troglodyte experience is not limited to seabirds. Next we will look at a different kind of colonial rock dweller - some vultures and other birds of prey nest on inland cliffs and rock islands, and they too breed in close proximity and venture far and wide away from the colony in flocks in search of dispersed food. When we see patterns emerging among distantly related species and with apparently different behaviours we discover the inner beauty of Nature.




2 comments: