108 THE ZO0O0OLOGIST. 
tion of seeing them turn in the sunlight so as to show their 
white under sides, so dazzlingly white in the glare that the rest of 
the bird is unseen, and two hundred flakes of bright silver 
flash back the rays of the sun. There can be no doubt in your 
mind, as you watch them, that, whatever philosophers may say 
to the contrary, these birds are taking conscious pride and 
pleasure in the varied but accurate evolutions of their flight. 
These are travellers, for, although the bird nests in the neigh- 
bourhood, they are not resident in sufficient numbers to gather 
into such a large mob as this. It is, however, quite possible 
that this party may have now arrived at the end of their 
journey, and may be going to spend the winter months on the 
happy hunting-grounds of the mud-flats and saltings of the 
Thames and Medway. 
There is more than one route by which you may find your 
way down to the beach, which is your destination. You choose 
that which leads you along the edge of a shallow tidal creek, 
now empty of water. With the embankment as a shelter, you 
are able to watch a stately and sedate gathering of some ten or a 
dozen Herons (Ardea cinerea), rather an unusually large number 
of these birds to be assembled together feeding in one spot. 
They soon sight you, and flap away upon their broad, loosely 
feathered wings. But there still remain on the ooze and short 
turf of the bank some less conspicuous birds—a number of Cur- 
lews (Numenius arquata) and Redshanks (Totanus calidris), and 
a few Peewits (Vanellus vulgaris), who, although alert and ready 
for departure, do not move, and after a moment’s quiet return 
to their feeding. You notice among the Redshanks several 
waders which seem to differ from them. When you finally 
disturb the mob these birds separate from the others, and by 
their alarm-note, their dark upper plumage, and more especi- 
ally by the striking patch of white tail-coverts, you distinguish 
them as Green Sandpipers (Totanus ochropus), birds that are on 
their way—possibly from the Arctic Circle—to the warmer skies 
of Africa. 
Moving on to the river-wall, and viewing from its shelter the 
widening expanse of mud-flat laid bare by the falling tide, the 
whole of it, from the sandy beach to the distant breakers, is 
dotted with white flecks, which resolve themselves, through the 
