74 HABITS OF BIRDS. 



caught, yet we are not aware of any recorded instance 

 of one eagle making prey of another, as spiders are 

 known to do, and as is common among fish. On 

 the contrary, the males and females of birds of prey 

 appear to be more closely attached than those of 

 most other species. They continue together riot only 

 during the breeding season, but throughout the year, 

 and even for a long succession of years, at least if we 

 may trust to the circumstantial evidence of a pair of 

 eagles frequenting the same locality, and building 

 on the same spot. 



The evidence indeed for the birds being always 

 the same is incomplete ; yet on the supposition that 

 it is not the same but successive pairs which are ob- 

 served in the same place, we are led to the curious 

 inquiry how the death or disappearance of one pair is 

 supplied by another. We have in more than ope 

 instance observed a pair of magpies nestle on the 

 same tree for a series of years, where they reared a 

 brood of four or five young ones every season. All 

 of these disappeared from the neighbourhood, at 

 least we observed no increase in the number of 

 nests. In one instance we observed a magpie's 

 nest thus successively occupied for ten years.* The 

 number of young, therefore, annually reared in such 

 an hereditary nest, as it may well be called, must 

 be nearly proportional to the supply of the mor- 

 tality among these birds either from accident or 

 disease. Should the female, for instance, which has 

 just reared a brood, be accidentally killed, the male 

 must either seek for another partner or abandon the 

 nest to some of his descendants. That the former 

 is the usual manner of proceeding, will appear from 

 facts which we shall immediately state ; but that 

 the latter may also occur may be inferred from the 

 young birds, upon leaving their parents, establishing 

 *J. R, 



