8 



KNOWLEDGE 



[January 1, 1901. 



available, and its capacity is very small, but Mr. Tripp 

 informs me that as soon as machinery now building is 

 completed it will be possible to supjaly viewing screens 

 of the American standaird lanternslide size (4 in. x 3J in ) 

 at §2 a dozen, or say, eightpence each ; and that in the 

 course of a couple of years it should be possible to 

 make them for one or two shillings a dozen. As for 

 the ruled paper, since prints made upon it, photo- 

 mechanically, can compete in price with prints by the 

 trichromatic pi'ocess, the ruling itself must be done very 

 cheaply, and thei'e is no apparent reason why paper 

 ruled from the reel, and printed with registering marks 

 to correspond with similar marks on the camera screen, 

 should not be supplied to the photographic paper-makers 

 at a price that will add but little to the price of their 

 product. 



As regards the transparencies and prints made by this 

 process, one must admit that their " truth to natui'e " is 

 dependent upon care in the photographing. Exposure, 

 development, and printing offer as great a field for the 

 personal influence in this, as in the ordinary monochrome 

 methods of photography. While one man. will represent 

 nature in the brilliant hues of a modern French water- 

 colour or chromo, another will give us the sajne scene 

 lost in the brown-vai'nish gloom of an oil-painting by 

 an old master. The scientific man who wants bold 

 accuracy can secure it ; while he who has the artist's 

 fancy and imagination can let them wander at will in 

 fields of colour, just as he now attemjDts to satisfy them 

 with variations of tone and texture. 



BIRD-LOVE IN WINTER. 



By Charles A. Witchell. 



Although the season of nidification is the time when 

 birds seem the most erotic, there is no little evidence 

 that a degree of mutual affection between birds of 

 opposite sex often exists at other periods of the year. 

 Much of this evidence is perhaps hardly within the scope 

 of scientific proof; but some of it, on the other hand, 

 is strongly suggestive of at least a kindly interest, though 

 this be indicated only by couples of birds sepai'ating 

 themselves from others in the same assemblage or com- 

 pany. Among the more solitary common species the 

 same nest-places, dormitories, and general habitats ai-e 

 usually tenanted by what seem to be the same respective 

 pairs of birds. The crow, magpie, and kestrel ai-e 

 familiar instances. It is clear that in these cases there 

 is at least no ill-will existent between the birds of a 

 pair; they seem not to- bicker and snap at each other; 

 nor to derive satisfaction from each other's misfortunes; 

 but to desire each the presence of the other, and to be 

 content in it. Selective conipanionshiis, therefore, is oiu' 

 first piece of evidence; and it is given, not only by the 

 solitary birds, but also by some of the gregarious kinds. 

 Why do the jackdaws and rooks in evening flight to the 

 great roost^place so often fly in couples, even as early as 

 September, unless it be that they have begun to select 

 their mates for the next year? They do not behave thus 

 on every evening, for when the wind is high, or they are 

 flying down-wind, the couples ai'e broken, if, indeed, 

 over formed. But on a still autumnal eveaing, when 

 the birds are not seeking food nor avoiding enemies, 

 but merely passing onwai'd to the accustomed resort, 

 four-fifths of them, at least, fly in couples. The jack- 

 daws are the more restless, some of the couples being 

 disturbed by one or more erratic and noisy members 

 of the troop ; but most of them, like the more staid 



rooks, seem to prefer to have one only near them. 

 Although at first sight the statement may seem hardly 

 credible, I have noticed similar behaviour in small 

 groups of starlings flying to roost. When living at 

 Eltham I had constant opportunities of observing this, 

 for at evening immense numbers of starlings assembled 

 in the near thickets, and I was often sui-prised to notice, 

 even in autiunn, how many birds in the small clusters 

 had distinctly tended to arz-ange themselves in couples, 

 though the preference only attained to the lessening of 

 the average distance in the flock, to the extent of a few 

 feet, between the jDarticular birds. In the case of the 

 rook and jackdaw the young birds of the yeai' seem to 

 demonstrate this selective association as freely as the 

 old birds, but the natiu'al tendencies of starlings in 

 this respect arc less discernible, for the latter birds 

 are much the more timid of aerial enemies — and justly 

 so The sight of a sparrow-hawk will break up their 

 formation in a moment, and send the scattered detach- 

 ments streaming wildly ai)out the sky, or scuri-ying low 

 among the ti'ee-tops. 



Friendly hawks not only tolerate each other's presence 

 in autumn and winter, but sometimes indulge in bye- 

 play suggestive of at least a kindly interest in each 

 other. In October last, one breezy day on the Cottes- 

 wolds, a male and female kestrel came into view flying 

 lazily. They soared and drifted somewhat, and then 

 swooped at each other more than once, obviously in 

 play ; an.d then drifted on as before. At the end of 

 November I was watching a jiretty male kestrel search- 

 ing a hillside. Presently across the valley came another 

 kestrel, a female bird, going directly towards him. 

 She passed in full view, and it was noticeable that she 

 was not flying cjuite in the usual way, but with vei^y 

 rapid and ceaseless beat of wing, and yet not travelling 

 at a great pace. She did not alter or stay her course; 

 but the other did not seem to fear her at all, and let her 

 stoop full at him, as though he knew she would not 

 hui-t. him. As a fact, she seemed to lessen her spaed 

 when approaching him; for she spread her wings, and 

 swung at him like that; and both birds soon afterwai-ds 

 settled in a tree. It seemed that by this mode of 

 approach she was showing a kindly interest in her 

 mate — six months before nesting-time. Her flight 

 reminded me of that of an amoi-ous lark or chaffinch. 



The call-notes and songs naturally afford much 

 stronger evidence than what is above written, of the 

 existence of winter-love in birds. So far back as Sep- 

 tember, the robin was in full song; and, although he 

 always sang before fighting another singer, still there 

 was often near him a robin which did not sing, and 

 which he did not attack, but to which, very possibly, 

 some of the songs may have been addressed, for, at that 

 season, the call-note of the singer was heai'd almost as 

 often as it is in early spring. Throughout the cold season 

 the presence of that silent robin is tolerated by the 

 singer, though the vocal rival is persistently attacked. 

 The starling has love-notes in his song all the winter. 



The wren, another autumn singer, makes great use of 

 its call-note at the time of the' falling leaf. In a garden 

 is a wren's nest, I know, which has been in existence 

 for two years. Eggs have never been laid in it, and 

 in summer the presence of spiders' webs across the 

 ojiening indicates that the tenement is then unoccupied ; 

 but in winter the webs are not there, and a wren may be 

 seen going in and out. In November, in a tree close 

 to the nest, were two wrens, about a foot apai't; the one, 

 with head raised, was obviously addressing the other 

 with continuous call-notes. One would have required 



