March, 1922.] 



The Canadian Field-Naturalist 



55 



TERRITORY IN BIRD LIFE. 



By H. Eliot Howard 



With illustrations by G. E. Lodge and H. Gronvold, 



London, John Murray, 1920, 8vo., pp. SOS, 



pi. 11, plans 2. 



A most interesting book and one that it will 

 repay any student of avian behavior to read. It 

 crystallizes thoughts that have been latent in 

 many of us. We have been so accustomed to the 

 idea that male birds fight each other for the favor 

 of the female that we have scarcely thought to 

 question it. When, however, Mr. Howard ad- 

 vances another explanation we realize that he is 

 but stating that of which we have long been 

 subconsciously aware. He advances that, when 

 birds fight in the spring time, it is not directly 

 for mates that they contend, but to possess or 

 defend territory in which to rear their families, 

 assume definite proprietory rights and tolerate 

 no competitors. This explains much that was 

 unsatisfactory under the older conventional 

 concept; for males fight females as well as males; 

 females engage others of their own sex and both 

 combine against rival pairs or either individual. 

 The fighting also rarely passes certain geographic 

 boundaries, beyond which differences seem to be 

 forgotten, and on neutral territory birds mix 

 indiscriminately without animosity. These well- 

 known facts do not harmonize with exhibitions of 

 sexual jealousy, but are perfectly reconcilable with 

 a competition for territory. An outline of the 

 theory is as follows: 



It is the general rule amongst most of our song 

 birds for the male in spring to return to the 

 nesting ground some little time ahead of the 

 female. His first business is to prospect for 

 and establish ownership in the territory he and 

 his mate are to occupy through the coming season. 

 This territory must contain satisfactory nesting 

 sites and promise of food supplies in sufficient 

 quantity so that the young need never be left 

 unprotected from the elements for longer than 

 their tender constitutions can endure under the 

 conditions normally prevailing during the season 

 of their helplessness. Once possession is estab- 

 lished he occupies a prominent observation point 

 within his territory and pours forth his song, by 

 which he warns off trespassers and advertises, to 

 such females as may hear, a vigorous male in 

 breeding condition with property qualifications 

 that will refuse no reasonable offer of matrimony. 

 The female therefore comes to the male's call 

 instead of being wooed through it. This is a re- 

 versal of our familiar concepts of the working 

 of sexual selection, but does not deny them in any 



essential. The most vigorous male, with the 

 clearest and most incessant song, will be most 

 likely to hold his territory against competitors, 

 or to attract a female. A premium is thus 

 placed on virility in the one case as in the other. 

 When he is joined by a mate, they unite in de- 

 fence of their territory. Intruders that may 

 seek to establish themselves in too close proximity 

 are immediately attacked and, if possible, driven 

 off. In this, no respect is shown to sex by either 

 bird. A female is as certain to be attacked by 

 either or both of the pair as is a male. Tres- 

 passers are, however, usually driven only to the 

 boundaries of the preserve and victories are 

 rarely followed up when this object is achieved. 

 However pugnacious birds may be in their own 

 bailiwick, those of either opposite or the same 

 sex will meet freely on common feeding grounds 

 without evidence of animosity. Non-competi- 

 tive neighbors are tolerated much closer than 

 are those of similar species. In these struggles 

 the established bird or birds have the advantage. 

 They are fighting with the vigor of determina- 

 tion for home and fireside, while intruders are 

 less determined and, unless desirable localities 

 are at a great premum, will retreat to seek quar- 

 ters than can be more cheaply acquired. We 

 often see one bird chase another ignominiously 

 away and into its own proper territory, when 

 the tables are reversed, the aggressor becomes 

 the defendant and retires with equal haste before 

 the assault of the late fugitive. 



Most of this reads very convincingly in connec- 

 tion with many of our small song birds and we 

 can see the details of it any day in spring or early 

 summer, but the experienced observer will 

 realize what the author does not suggest, that 

 there are species whose modes of life do not fit 

 into the scheme. Species that mate for life do 

 not have to advertise annually for a mate; those 

 that pair before arrival on the nesting ground 

 have other methods of attracting mates. Prae- 

 coces, whose young run at birth and can be taken 

 to the food supplies, are relatively independent 

 of the immediate surroundings of the nest, and 

 polygamist species are fundamentally different 

 from the monogamists in all their family relations. 

 The exceptions in these species, however, cannot 

 be regarded as objections to the application of 

 the rule to others. In fact, in studying the 

 reaction of such a law to varying conditions, a 

 more intelligent understanding of its workings can 

 be obtained. Such exceptions, by interpreting it, 

 may be said to prove the rule. 



In connection with this book, it is well to read 

 Mr. Mousley's Singing Tree* which confirms, in 



*Auk, XXXVI, 1919, 339-348. 



