JOURNEYINGS AND DISPERSAL OF ANIMALS. 579 



said to " abound most where monkeys do not occur, and in South 

 America the same birds are comparatively scarce, in the forest-plains, 

 where monkeys are very abundant, while they are plentiful on the 

 open plains and carnpos, and on the mountain plateaux, where these 

 nest-hunting quadrupeds are rarely found." When we consider that 

 the pigeon is the most careless and awkward of birds in the construc- 

 tion of its nest, it is not difficult to understand how formidable an 

 enemy it must have in the artful and wary monkey. 



The term migration is strictly applied to the annual movements 

 of birds and fishes, which take place in large bodies, and are imme- 

 diately connected with the process of reproduction. In all temperate 

 regions a large number of birds reside temporarily. Some arrive in 

 spring, and leave in autumn ; others arrive in autumn, remain during 

 the winter, but depart in spring ; and yet others, birds of passage, pass 

 through the country twice a year, without long delay. The species 

 which winter here are those which build their nests and rear their 

 young farther north, and in returning, on the appearance of spring, 

 they simply act as do those whose homes are nearer the equator. The 

 birds of passage, like our winter-birds, have their breeding-quarters 

 nearer the poles, but, like our summer-birds, seek a warmer climate 

 for the winter. The arrival of migratory birds from warmer regions 

 seldom varies more than a week or two, though their departure is 

 more dependent on the weather, and consequently less constant. 



The migratory birds of Europe seem to have a definite route : 

 they " go southward to the Mediterranean, move along its coasts east 

 or west, and cross over in three places only either from the south of 

 Spain, in the neighborhood of Gibraltar, from Sicily, over Malta, or 

 to the east by Greece and Cyprus." The passage is mostly accom- 

 plished by night, and is undertaken only when there is a steady wind 

 from the east or west, and when there is moonlight. It is an interest- 

 ing fact that the males often leave before the females, and both parents 

 before their offspring; the latter, however, rarely go so far as do the 

 old ones. On returning they vary their course, some following the 

 old, others adopting a new line of travel. In connection with the 

 routes taken by European birds, it is suggestive and interesting to 

 note that fossil remains of huge animals, and the shallow waters in 

 this part of the Mediterranean, indicate that Gibraltar, Sicily, and 

 Malta, must have been at no very distant date united with Africa ; the 

 submersion of this land involved considerable time, and the change 

 could hardly have been perceptible from one year to another. It is 

 natural to conclude. that the migration, which w r as at first a land- 

 passage, would be kept up over marshes, then over a channel, and 

 finally over the sea. The sea-passage is a dangerous one for birds, 

 and, from the immense flocks of quails which annually undertake it, 

 large numbers are drowned when the weather proves unfavorable for 

 the passage. 



