342 AUTUMN AND WINTER 



year, but especially at the two migration times, when they 

 sometimes appear in little flocks. Grey wagtails, with their 

 beautiful glint of sulphur yellow beneath the tail, are winter 

 birds in London and other parts of the south and east of 

 England, whither they almost all migrate in late summer 

 from the hill streams of the west and north, where they 

 breed. They may be seen along the Thames in London 

 from about the beginning of September to early March. 



GREY WAGTAILS 



Occasionally they are found resting in some City garden or 

 churchyard, or on some high ledge of a building in the middle 

 of the most densely overbuilt areas. Sometimes they appear 

 in pairs, even in the autumn and early winter months, when 

 birds' family ties appear loosest ; but usually we see single 

 birds scattered here and there along favourite reaches of the 

 river. One of their most frequented haunts is off the Chelsea 

 Embankment, where they can find rest on certain floating 

 timbers when the shore-line is submerged at high water. At 

 all states of the tide they can often be seen flirting their 

 yellow tails, or flitting with their sharp double call-note, 



