554 MIGRATION 



throughout the year. It has long been known that Birds-of-Prey 

 customarily drive away their offspring from their own haunts so 

 soon as the young are able to shift for themselves. The reason 

 generally, and no doubt truly, given for this behaviour, which at 

 first sight appears so unnatural, is the impossibility of both parents 

 and progeny getting a livelihood in the same \acinity.^ The 

 practice, however, is not limited to the Birds-of-Prey alone, but is 

 much more universal. We find it to obtain with the Eedbreast, 

 and if we watch our feathered neighbours closely we shall perceive 

 that most of them indulge in it. The period of expulsion, it is 

 true, is in some Birds deferred from the end of summer or the 

 autumn, in which it is usually performed, until the following 

 spring, when indeed from the maturity of the young it must be 

 regarded as much in the light of a voluntary secession on theii' 

 part as in that of an act of parental compulsion, but the effect is 

 ultimately the same. These cases, however, which make certainly 

 the exception rather than the rule, we can account for in another 

 manner. It is to be observed that they are confined to species 

 having a peculiar mode of life, the individuals associating in family- 

 parties to form small bands. The members of the TiTMOUSE- 

 Family (Paridse) offer a good instance of this peculiarity, but it 

 requires no veiy abstruse reflection to perceive that the adoption 

 of this habit is one eminently conducive to the easy attainment of 

 their food, which is collected, as it were, into particular spots often 

 far apart, but where it does occur occurring plentifully. Thus a 

 single Titmouse searching alone might hunt for a whole day with- 

 out meeting with a sufficiency, while if a dozen are united by the 

 same motive it is hardly possible for the place in which the food is 

 lodged to escape their detection, and when discovered a few call- 

 notes from the lucky finder are enough to assemble the whole 

 company to share the feast. It is impossible to watch a band of 

 any species of Titmouse, even for a few minutes, without arriving 

 at this conclusion. One tree after another is visited by the active 

 little rovers, and its branches examined : if nothing be forthcoming 

 away goes the explorer to the next that presents itself, merely 

 giving utterance to the usual twitter that serves to keep the body 

 together. But if the object of search be found, another kind of 

 chirp is emitted, and the next moment the several members of the 

 band are flitting in succession to the tree and eagerly engaged Avith 

 the spoil. ^ 



^ It is a very ancient remark about young Ravens that " they wander for hick 

 of meat." 



- The case is altogether different with those species which in winter form 

 tliemselves into large flocks, as most of the Finches [Fringillidae,) and Buntings 

 [Bmberizidai). The discoverer of a favourite morsel perhaps by his actious 

 betrays what he has obtained, and accordingly his fellows mav repair to the 



