MIGRATIONS OF BIRDS AT TUSKAR ROCK. 191 



of the lantern are rendered feeble, I have beheld only single 

 birds and small parties flitting across the rays in somewhat 

 regular succession, and passing on without showing any signs of 

 being enchanted by the light. This feature may be noted for 

 many hours at a stretch, and as evidence that the birds were not 

 being held up, I observed that there was no augmentation in 

 numbers, or confusion, or even hesitation in the flight. At 

 first, when my main interests were centred in studying the 

 phenomenon of " striking," the behaviour of migrants on such 

 clear nights greatly disappointed me ; but when I became 

 thoroughly familiar with the processional migrations performed 

 by daylight, this analogous feature, detected at night, became 

 highly interesting. There is another noteworthy feature in 

 connection with the natural night-flights, namely, that the birds 

 show a decided preference for travelling with members of their 

 own kind. Of course, closely connected species and birds about 

 the one size probably fraternize more readily than when such 

 relations are wider apart.* By day one sees analogous frater- 

 nities. Pipits and Wagtails, birds of close affinities and 

 endowed with much the same velocity and power of flight, 

 appeared about the same time after dawn and travelled in 

 company, probably to the end of their journey. Swallows 

 (sociable and peacefully disposed to other small birds, though 

 brave and aggressive in their pursuit of the Hawk or other 

 piratical member of the bird-tribe), with affinities remote from 

 those of Wagtails and Pipits, and with power and velocity of 

 wing differing in a marked degree, appeared later in the morning, 

 but, soon overtaking their companions, accompanied them for 

 only part of the journey. 



In regard to larger communities of diurnal migrants than 

 usual, one main factor seems to be responsible for their forma- 

 tion, namely, any obstacle which can hold up the advancing body 

 of birds adequately and for a sufficient time to allow the rear- 

 guard (here represented by a procession of an indefinite length, 



* I could not imagine Goldcrests and Corn-Crakes, or Manx Shearwaters 

 and Sedge-Warblers, choosing each other's company when travelling, and 

 yet I have seen such, and other equally peculiar couplet combinations at the 

 lantern on hazy nights, when every sort of migrant runs the gauntlet of 

 being "held up." 



