86 BRITAIN S BIRDS AND THEIR NESTS. 



or less from above, these parts are thrown into shadow, and 

 therefore appear no lighter than the surrounding ground. 

 An interesting experiment illustrating this point may be 

 performed with dummy pigeons, artificial decoy-ducks, or 

 home-made models. Given a surrounding of slate-gray, say, 

 and a top light, a model bird painted slate-gray all over 

 will always show up with perfect distinctness. One painted 

 slate-gray above and white below will, on the contrary, be 

 veiy indistinct, and may even be invisible at certain angles. 



Then as to the conspicuous pattern of the head and breast 

 regions. Does it diminish the protective effect ? Against a 

 surface of perfectly uniform shade it might, but such back- 

 grounds are unusual. Against an ordinary variegated 

 surface — sand or mud, with stones, shells, &c. — such 

 markings may stand out by themselves, but their shape 

 suggests nothing to the eye, and they distract attention from 

 the general outline of the bird, just as we have seen in the 

 case of the Golden Plover. 



On the other hand, a bird of uniform hue — or uniform 

 when we take into account the shadow effects on the under- 

 parts — will stand out as a whole if it differ in shade ever so 

 slightly from its background. From this we can more easily 

 understand how even some birds of bright but variegated 

 plumage are really protectively coloured. 



THE KENTISH PLOVER 



(/Egialitis cantiana). 



The Kentish Plover, a closely related bird of very similar 

 habits and appearance, has already been referred to. It is 

 one of the rarest and most local of our native birds, being 

 found in small numbers on the shingle beaches of Kent and 

 Sussex, from April or May till September, and otherwise 



