EUROPEAN BLACKBIRD 73 



lation, it is found that the expectation of life of a first-year bird on 

 August 1 is about 1.6 years. At the next August 1, it is about 1.9 

 years, and, in contrast to the situation in a modern human population, 

 it remains about the same in subsequent years up to the fifth, after 

 which the records are too few to be of value. The average life of 

 wild blackbirds is thus only about 8 percent of the potential age 

 of about 20 years indicated by records in captivity. This result may 

 be compared with the average span of 2)i years under favorable condi- 

 tions established by Airs. Nice for the song sparrow and serves to 

 emphasize how few wild birds — or at any rate small passerines — 

 survive to die of old age. 



Territory. — The activities of the blackbird in spring present a 

 number of features of particular interest, but in spite of some notable 

 recent observations it is still not possible to give a completely rounded 

 and satisfactory picture of the early stages of the breeding cycle of 

 this common bird. The species is certainly territorial, though perhaps 

 not equally strongly so under all conditions. Lack and Light (1941) 

 in a valuable, though incomplete, study, interrupted by war service, 

 found that in Devonshire territories varied from about 1% to 2% acres. 

 If an attempt was made to drive one out of its territory, it behaved 

 in the manner characteristic of strongly territorial species, flying 

 in front of the observer till it reached the boundary, then refusing 

 to go farther, and eventually flying back past the observer into the 

 center of the territory. 



In February and March, males regularly patrolled their territories, taking 

 short nights with intervals for feeding and perching quietly, and usually the 

 observer was not long in the territory before the male came by on his round, the 

 female often being in attendance. 



The owning male at once attacks any other male Blackbird trespassing in 

 the territory, and does not desist till the trespasser leaves. Probably the male 

 also drives out trespassing females, as some violent male-female chases were 

 seen * * *. But females were not attacked nearly so often as trespassing 

 males, and sometimes were apparently ignored. 



The authors found that "females certainly take much less part than males in 

 the defense of the spring territory," though chases, and even fights, between 

 females do occur and there are certainly temperamental differences between 

 individuals. 



As with other territorial species, most encounters between males are settled by 

 threat-display * * *. On seeing an intruding male, the owning male flies 

 towards it and, if the intruder flies off pursues it out of the territory. But if the 

 intruder stays put, the male docs not usually attack at once, but perches some 

 feet away and, with lowered and retracted head, approaches gradually and 

 indirectly in a series of hops, runs or very short flights. This occurs both on the 

 ground and in the trees * * *. By the time the attacker is within a few 

 inches, the intruder usually departs. On three occasions when the intruder did 

 not retreat, the attacking male repeatedly snapped its beak open and closed. 

 The bright orange-yellow of the beak and the inside of the mouth, and also of the 

 eyelid, are then in contrast with the black plumage, and can perhaps be regarded 

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