94 STUDIES IN BIRD-MIGRATION 



which is below 500 feet in elevation. Towards the end 

 of August, and during the first half of September, the 

 return takes place, and the migrants on reaching the 

 Humber move eastwards along the shores of the estuary 

 to reach the coast of the North Sea, whence they take 

 their departure for their winter quarters. These retiring 

 movements are sometimes performed simultaneously from 

 considerable areas, and may then be said to take the form 

 of a "rush." Thus, on the 23rd of August 1885, I saw 

 literally thousands on the north shore of the estuary and 

 its immediate vicinity, all working their way towards 

 Spurn Head. Most of these, perhaps all, took their 

 departure the same night, for on the following day 

 comparatively few were seen, and these may have been 

 fresh arrivals. These emigratory movements, as a rule, 

 extend over many days, and are most interesting to 

 witness. 



The southern shore of the Humber is also traversed 

 by large numbers of these Wagtails, many of them 

 proceeding to and from the Trent valley, where they are 

 also very abundant during the nesting season. Similar 

 movements also proceeding to and from the Yorkshire 

 dales by way of the Humber are observed on the part of 

 such species as the Wheatear, Redstart, Whitethroat, 

 Ring-Ouzel, Pied Flycatcher, Sandpiper, etc. 



In the autumn considerable numbers of Starlings, 

 Skylarks, and Lapwings, from the south-east enter the 

 Humber at its mouth, and pass along its southern 

 shores, proceeding westwards. These immigrants appear 

 with great regularity, and have come much under the 

 notice of Mr Caton Haigh. 



The Trent Valley, already alluded to, is a much- 

 used highway, according to Mr Whitlock {^Zoologist, 



