THE WESTWARD FLIGHT OF THE SWALLOW, ETC. in 



further west than the preceding, a drifting maze of circling 

 birds apparently engaged in feeding as they travel. This 

 last flighting is seen only in calm weather ; at other seasons 

 the flocks linger in the lee of a wood or other sheltered 

 corner to feed. The House-martin has rarely accompanied 

 the Swallow on passage. Its individuals pass westward in 

 earnest flight, and flocks, scarcely coherent, snap and chatter 

 in company as they fly. 1917 marked an early appearance 

 of this passage as with the Swallow, the 12th August being 

 the date in question ; but the records of former years fall into 

 the period already detailed for the Swallow. The House- 

 martin has been seen on passage at all times of day as with 

 the Swallow, but whether it is as impervious to weather is 

 not evident from the records. Wind, however, does not 

 seem to deter it. The Sand-martin was evidently on passage 

 on 16th July 1916, a very early date, but unfortunately the 

 direction of its movement could not be discovered. On 7th 

 August the first flight to west was seen, fully a fortnight 

 earlier than usual, and in 191 7 the first westward passage 

 was noticed on 22nd July. The average date of the move- 

 ment, however, lies in the third week of August ; passage has 

 been seen in progress during forenoon and afternoon, but 

 evening passage has not been recorded with certainty. In 

 most cases the Sand-martin has travelled alone in parties 

 low down, often some distance from the shore line over the 

 estuary, but the drifting, wheeling flocks commonly consist of 

 all three species in company. 



This movement of the Hirundines, then, is one of some 

 magnitude, occupying a period of at least two months, and 

 in numbers far exceeding anything seen of passage to the 

 east; but its reason remains uncertain. In consequence of 

 the war, it has not been possible to determine the point 

 where the parties turn westward up the estuary. All that is 

 known is that many flocks pass Dundee on an east to west 

 flight, apparently using the north bank as a guide, in a most 

 definite manner. Rarely, parties have been detected passing 

 on a line from north-east to south-west behind the town. 

 Flight to west of the Swallow and the House-martin has 

 also been noticed on a very small scale along the south bank 



