NOTICEABLE INCIDENTS 79 



I 3. Birds which are habitually laborious, watch- 

 ful, stealthy, or accustomed to gorge themselves 

 with food, are habitually silent. Several birds 

 exhibit all these characteristics. Among watchful 

 birds may be mentioned the kestrel, butcher-bird, and 

 others of similar habits, which watch for prey ; also 

 rasorial birds, most of which live or feed on open 

 land, and for this reason are compelled to watch for 

 the arrival of their enemies, many of which, 

 approaching in flight, may be seen at a great 

 distance. Birds stealthy in movement are generally 

 those which attempt to take their prey unaware — 

 such as the hawks — or which seek to escape un- 

 observed from their enemies ; of the latter the 

 pheasant is a notable example. Birds preying on 

 animals of comparatively large size generally gorge 

 themselves at every meal ; and in this condition they 

 become inert, and apparently are equally passive in 

 mind, uttering hardly a sound while digesting their 

 heavy burden. Of this kind are the divers generally, 

 and also the larger predacious birds. Many of these 

 last are alternately watchful, stealthy, and lethargic, 

 as they seek, attack, or digest their prey. Song is 

 foreign to their natures, but their usually loud shouts, 

 screams, or calls, are employed as signals when 

 they have wandered far apart in the search for food. 



