EEED WARBLER 



its young to remain in its territory. The instinct is better 

 known, perhaps, in connection with the birds of prey and the 

 Eaven; and in some cases it seems to be deferred until the 

 following spring ; young Partridges, for example, remain with 

 their parents throughout the winter. Hitherto, I have not 

 been able to trace it amongst the Warblers. Whether it is 

 more prevalent amongst those species that rear two broods, or 

 whether it is limited to those that remain more or less in one 

 particular territory throughout the year, we do not know. A 

 Warbler deserts its territory as soon as the young are reared, 

 but the Moorhen as a rule continues in the same place during 

 the winter months. A migratory species would have nothing 

 to gain by driving away its young, for although it is likely 

 that both old and young return to the same district the follow- 

 ing spring, yet it is not probable that the young would lay 

 claim, even if the parents did so, to the identical territory in 

 which they were reared. But the case is different with the 

 Moorhens ; they remain in or near their territory throughout 

 the year, and if they allowed the young to remain with them 

 it is unquestionable that, as the sexual instinct arose the 

 following spring, they would have serious rivals in their 

 offspring, by that time fully developed, and in strength equal 

 to themselves. There is much evidence to show that in many 

 cases parental affection is limited to the period in which the 

 young are helpless, and so the natural result of the law 

 of territory would be the banishment of the young ; and if in 

 addition the habit was of indirect benefit to a species by pre- 

 venting interbreeding, or by securing an ample supply of 

 food, then it would be fostered by selection and developed in 

 so far as it was beneficial. 



What, then, is the meaning of this law of territory ? 

 Why should one male struggle so fiercely with another for 

 a small plot of ground? It is claimed only at the breeding 

 season ; it is adhered to in many cases only so long as there 

 is a nest and eggs or young within its limits; it is of such 

 importance to the individual male that it may even lead to 



21 



