20 MEMOIRS OF THE NL'TTALL ORNITHOLGICAL CLUB. 



are either afraid to venture on long, exposed journej-s by daylight, or unable 

 to continue these journeys day after day without losing much time in stopping 

 to search for food. By taking the nights for travelling the}' can devote 

 the days entirely to feeding and resting in their favorite haunts. Good ex- 

 amples are Thrushes (exceptthe Robin) Wrens, Warblers, and Vireos. 



Bold, restless, strong-winged birds migrate chiefly, or very freely, by day, 

 because, being accustomed to seek their food in open situations, they are 

 indifferent to concealment, and being further able to accomplish long dis- 

 tances rapidly and with slight fatigue, they can ordinarily spare sufficient 

 time by the way for brief stops in places where food is abundant and easily 

 obtained. Under certain conditions, however, as when crossing large bodies 

 of water or regions scantily supplied with food, they are sometimes obliged 

 to travel partly, or perhaps even exclusiveh't by night. Excellent examples 

 are the Robin {Merula) , Horned Lark {Otocoris), and most IcteridcB. 



Birds of easy, tireless wing, which habitually feed in the air or over very 

 extensive areas, migrate exclusively by day, because, being able either to 

 obtain their usual supph' of food as they fly, or to accomplish the longest 

 journe}' s so rapidly that they do not require to feed on the way, they are 

 under no necessity" of changing their usual habits. The best examples are 

 Swallows, Swifts, and Hawks. 



Nocturnal and crepuscular birds, at least migratory species, are all strong- 

 winged and accustomed to seek their food over wide areas. Hence, like 

 Swallows, Swifts, and Hawks, they migrate during the hours of their habit- 

 ual activit}'. 



The conclusions just reviewed will also applj- to the several families and 

 numerous genera of wading and swimming birds ; for their migrations, 

 making due allowance for the peculiar habits of certain species and groups, 

 are easily explainable by considerations either identical with, or similar to, 

 those above mentioned. 



The Bittern, Woodcock, Wilson's Snipe, Spotted Sandpiper, and the 

 Rails without exception, migrate exclusively* by night. They are all 

 sedentar}- birds addicted to feeding in particular and usually limited areas, 

 and all but one f seek safety, when alarmed, in concealment. Accordingly 

 it is essentially, if not strictly, in line with the previous reasoning that they 

 should migrate by night, and rest and feed by day. The case is not, how- 

 ever, exactly parallel with that of any of the land birds, for these waders 

 (except perhaps the Spotted Sandpiper) feed habitually more by night than 



* The Wilson's Snipe does occasionally migrate also by day, but only in very dark and 

 stormy weather. 



t Tyingoides which, however, is conspicuous among Scolopacidce for its comparatively feeble, 

 restricted powers of flight. 



