26 Trans. Acad. Sci. of St. Louis 



make inteivstinju:, cliarinin^ P^'ts, for the Shrikes are 

 intolli<j:eiit l)ir<l.s with a coniparativcly hir^e brain. How- 

 ever, they are (luarrelsoine and <'nvious, and wlien two 

 are kejjt in one ca^e it will not he lon;^ before one of them 

 is killed by the other. Shrikes require nuich food, and 

 it is for this reason that they are not sociable, prefer a 

 solitary life and drive intruders from tln-ir chosen 

 domain. Although belonging: to the Oseinc l*asserine 

 birds, Shrikes are generally not classed among singing 

 birds, but they have a melodious song, though not loud 

 and only given wiien they l)elieve themselves not heard 

 by man. It was only when I was entirely out of his sight 

 tliat my pet indulged in his vocal ])raetices, soft and 

 really ])leasing i)erformances. Mueh ean be learned from 

 birtls kept in continement. 



One grand dominating impulse of migration in spring 

 is breeding, to insure the perpetuation of the si)ecies. 

 Migratory birds come north to breed, to rear their young 

 iu a climate where the temperature is best suited to their 

 recpiirements. Another i)hysiological process tells them 

 when to leave their summer homes. The failure of food 

 supply is undoubtedly the most imj)ortant impulse, but 

 this southern Hight has been performed so often and so 

 regularly that the imimlse has become hereditary as is 

 demonstrated by many facts. My pet Shrike was in a 

 dark room where no noise such as the calls of migrants 

 passing over could reach him, the room was wann and 

 the food plentiful, but when October came along every 

 evening about nine o'clock he began to tlutter in his cage 

 and thrust hims<df against the wires until (piite ex- 

 hausted. This migratory instinct forces most birds to 

 leave their breeding grounds long before real want of 

 food is felt, often at a time when nothing indicates the 

 approach of winter. Many insect-eating birds leave in 

 August and September when insects are most abundant; 

 seed and fruit eaters depart when there is still an 



