LAKES AND TARNS 149 



throws itself on its back, as some birds of prey do, 

 grips its assailant with its uplifted toes and makes 

 savage dagger thrusts with its sharp and powerful 

 beak. A peculiarity which the Heron shares with 

 Parrots and a few other birds is the possession of 

 " powder-down " feathers. These occur in thick 

 patches, chiefly on the breast, under the ordinary 

 feathers; they are strange, quickly growing down- 

 feathers, that break into white greasy powder at the 

 tips. This powder is distributed through the French- 

 grey plumage, and it is believed to keep the.ordinary 

 feathers clean and in good condition. A widespread 

 story that the powder-down patch is luminescent is 

 without basis. 



There is another bird of great interest that we have 

 seen at the tarn, the Dabchick (Podicipes fluviatilis), 

 otherwise known as the Little Grebe. It has a peculiar 

 right to a place in this study, for it sometimes breeds 

 on little lochs high up on the Scottish hills, and, 

 besides, it is a very attractive bird. It is about nine 

 and a half inches long and of a predominantly brown 

 and grey colour. The food consists of small fishes, 

 aquatic insects, and Tadpoles, eked out with water 

 plants. When the loch or lochan freezes in winter, 

 the Dabchick shifts its quarters to the low ground or 

 even to the shore. Like other Grebes it swallows 

 feathers along with its food, just as Hens swallow 

 gravel. The Dabchick flies and runs very effectively, 

 but its swimming and especially its diving cannot be 

 overpraised. 



The nest is large for the size of the bird, and 

 consists, as in other Grebes, of a mass of water weeds, 

 usually floating and moored to growing plants. As 



