28 SHORE BIRDS. 
coast line, or they may divide as they d) in going north in 
spring, on a question of food, some taking the shore and 
tome the inland route. Still there is a serious obstacle in 
the way of their following the shore. The “trade winds,” 
which blow constantly fromS.E., would be likely to drift them 
inland, and this possibly may account for their appearance 
at Concepcion. The same influence would bear upon them 
on their return trip, though it would not be a head wind. But 
the birds do return the next autumn, say, March and April, 
and do arrive on the northern shore of the Continent. From 
this point one would naturally expect them to return by the 
same route, which undoubtedly they would do were there no 
disturbing causes, but in crossing the Caribbean Sea they 
meet the northern “trade wind?,” which blow at an average 
N.E. current of fifteen knots from the ninth to the thirtieth 
degrees of north latitude. Of course at cither extreme there 
is very little, if any, observable current, not enough to im¬ 
pede the progress of the birds whichever way they might 
wish to steer. We have seen, however, by the letters from 
the Barbadoes and Turks Island, that they do not come there 
in spring. They are forced by the trades down on to the 
c:ast of Central America and Mexico, from whence they 
beat their way up across the Gulf, some reaching Cape Cod 
via the Atlantic coast, and some turning up the valley of the 
Mississippi, soon reach Fort Dodge, where they will be 
heartily welcomed by our friend, the Doctor, having com¬ 
pleted their circuit as hereinbefore narrated. 
W. Hapgood. 
