Migration in War-time 
PIPER was met with over Arras, towards the 
end of March 1917, at an elevation of 12,000 
feet, and other Limicoline birds at 9,500 and 
10,000 feet ; WHIMBREL were observed at 4,000 
feet, and HERONS at between 2,500 and 3,000 
feet (Ibis, 1919, pp. 321-5). War-time does 
not offer the most favourable conditions for 
the solution of the question at what height 
birds fly when migrating, but the following 
advertisement was published in February 
I9g1g: ‘‘ Any notes on the flight of migra- 
tory birds made in the air would be highly 
appreciated. Where possible the species, 
height, and velocity of flight, time of day, 
and year would add greatly to value. Single 
or even negative notes would be most accept- 
able’? (Tames, 11.11.19). With the return of 
peace and a more general use of the aeroplane 
we may expect many interesting facts and 
discoveries concerning the question of bird 
migration, which is, at present, quite un- 
solved. 
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