Friday, 30 April 2010

Little Grebes shy and retiring

Down the road at Livermere the Little Grebes are going about the business of breeding in their usual shy and retiring manner. Familiar to many readers as the dabchick, the Little Grebe is the smallest of our grebes and my own personal favourite waterbird. While the Little Grebe may lack the elaborate plumage ornamentation of the more familiar Great Crested Grebe, there is still something charming about its appearance. It might be the combination of small size and powder-puff rear end that promotes such an endearing character or it might be the sense of understatement, the ease with which the Little Grebe exploits its watery world without any fuss or drama.

Just as they lack the flamboyant headdress of their larger relative, so Little Grebes also refrain from the associated elaborate courtship displays so often shown on wildlife documentaries. Instead, Little Grebes use their trilling calls, with the individual birds duetting to one another at close range and in a highly ritualised fashion. Sometimes a bird will go a stage further and present some waterweed to a prospective mate, a token of affection or a demonstration of their ability to provide for the pair’s future needs? Of course, it is the latter, with the display often progressing to a more purposeful piling up of weeds, the very basics of nest building.

Like other grebes, the Little Grebe constructs a simple nest in shallow water out of fresh and decaying aquatic plants. This mound of vegetation clears the water’s surface and allows the grebe to shape a simple depression into which the eggs will be laid. Positioning the nest in the water like this reduces its accessibility to terrestrial predators but does not necessarily spare it from more versatile ones, like Grey Heron or Mink, and there is also the danger of a sudden rise in water level. The nest site is usually on some small waterbody or on the still reaches of a lowland river, the nest itself placed among emergent vegetation or, as is the case at Livermere, within the branches of a tree that has toppled into the water.

The adult birds are very careful when visiting the nest, approaching quietly so as to avoid attracting unwanted attention to their nesting attempt. The young leave the nest and accompany the adult from a very young age and may sometimes be carried on the parent’s back, although this behaviour is less common than is the case for the Great Crested Grebe. In some ways it is the challenge of picking out the Little Grebe’s nest that attracts me to this bird. You have to work at finding the nest to prove that they are breeding at the site.

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