Januasy 1, 1897.] 



KNOWLEDGE, 



17 



mountains of Snowdon, Cader Idris, the Arenigs, and 

 others, and in the Scotch districts of Skye, Aran, the 

 Pentlands, the Ochils, the Sidlawg, and many other hills, 

 including the well-known Arthur's Seat. The age of such 

 mountains and elevated lands must be fixed obviously by 

 the geological considerations applicable when we approach 

 the determination of the age of ordinary or non-volcanic 

 moimtains. 



There is, however, one very striking example in our own 

 country of a lofty mountain mass being formed of volcanic 

 rocks that have never been interbedded. This grandly 

 towers above Borrowdale and the beautiful Derwent Water 

 of the Enghsh Lake District, and is of the Lower Silurian 

 age. One of the vents of this old volcanic area, now 

 filled with hard volcanic rock, was probably what is at 

 present known as Castle Head, near Keswick. Still older 

 volcanic rock forms a part of the Wreckin, in Shropshire, 

 which has been ascribed to pre-Cambrian or Archcean 

 times. 



BIRD-SONGS IN WINTER. 



By Ch.\rles a. Witchell. 



THE astronomical date of the commencement of 

 winter being so much later than that popularly 

 assumed for this event, it may be well to state 

 that for the present purpose the former interpreta- 

 tion has been adopted. The songs of birds will, 

 therefore, be discussed as they may be observed during 

 practically the three first months of the year ; for the con- 

 cluding days of December do not induce any vocal variation 

 from what was audible immediately prior to the shortest 

 day, unless, indeed, the weather be remarkably nuld. It is 

 quite possible that birds perceive the lengthening of the 

 last days of the year ; but I have never detected anything 

 in their behaviour indicating an appreciation of this 

 circumstance as foretelling the spring. A few warm days, 

 even in the darkest period of the year, wiU have more 

 eflect in calling forth their songs than several additional 

 hours of sunshine on a very cold March day. On the 

 other hand, a few nipping frosts will silence the robin, 

 thrush, wren, and hedge sparrow, although the starling 

 will often sing on through the cold, especially if sure of 

 obtaming food. If the weather at the beginning of 

 January be fairly even, however, and not too cold, the 

 lark will indicate the change of season by attempting a 

 song. Year after year I have noticed that under these 

 climatic conditions the bird renews its vocal efforts within 

 a few days after New Year's Day. Some of the larks — 

 probably old birds which were singing in October and 

 November — now give songs which are coherent and varied, 

 though not nearly so continuous and diversified as the 

 notes heard in ^larch and April. For this reason the 

 songs of the lark in January are a very interesting study, 

 since their gradual elaboration from simple to complex 

 modulations may be easily observed. The song is uttered 

 more particularly during the first hour or two of morning 

 sunshine ; and this habit is continued throughout the season 

 of song. The bird does not now often sing while rising 

 from the ground, as is customary in JIarch and later. One 

 will fly hoveringly, and with a kind of lilt, in an aimless 

 manner, at a slight elevation, and will then repeat its 

 ordinary call-note, which sounds like u-orrij you pronounced 

 very quickly. It may then utter another call — the cry of 

 the young, which may be suggested by tieuu, and then 

 change the other cry to iiorry u-orrij tvomjijuu, uttered very 

 rapidly, and so on. That is how the bird begins to sing. 



The distinguishable mode of flight employed during song 

 (except in a strong breeze) is now always exhibited before 



the song is commenced. In autumn the lark often 

 employs the ordinary call-note singly while flying, and at 

 such times the note is uttered at the moment corresponding 

 to that in which the wings are flapped. It is possible that 

 this may account for the hovering kind of flight being now 

 emplo\-ed when the call-note is frequently repeated. 



The lark appears to be the first bird which begins to 

 sing in the new year. Others may have been vocal during 

 warm weather in December, such as the robin, thrush, 

 starling, bro\\Ti wren, hedge sparrow, and, occasionally, 

 the blackbird ; but the lark is less likely than any of these 

 to sing at Christmastide. At the time when it is beginning 

 to sing, or a week or two before, some of the hedge 

 sparrows, probably birds of the last season, utter the 

 simple call-squeak of their species twice or more times 

 together, and thus make a little song. But this seems to 

 be only a transitory accomplishment, and is soon varied 

 by the introduction of other notes, the whole being very 

 rapidly uttered. 



On a warm day in December or January the nuthatch 

 repeats his short, low-pitched, and full-toned cry, tuuttutt, 

 several times very rapidly in succession, and thus pro- 

 duces a song which may be represented by ticuttuttuttutt. 

 Although these repetitions do not, in December and early 

 in January, generally exceed from three to six in number, 

 uttered at the rate of about four per second, in February 

 and later the repetition is often prolonged and executed 

 with much greater rapidity, so that ten or twelve notes 

 per second are produced, the general character of the whole 

 reminding one of the whistling of a railway guard. In 

 this development the nuthatch exceeds the degree of 

 repetition observable in the lark and hedge sparrow. 

 Early m January, however, he may also be detected in 

 developing another cry from the ordinary call-note. Instead 

 of the dissyllabic cry above described, a single full note 

 ! (ticutt) is given, and is prolonged, sounding like a very 

 [ short full whistle. As days pass the bird wiU prolong 

 i this more and more, untO we hear long slurred whistles of 

 much the same character as those we produce with the 

 mouth when whistling to a dog. 



At the same period the tree-creeper may be heard 

 repeating his somewhat plaintive call-squeak several times 

 together, and he does this in any weather ; but the single 

 note, though often prolonged, never attains so great a 

 development as the whistle of the nuthatch. About March, 

 however, the bird will repeat his squeaks so rapidly as to 

 make a little song, which increases in quickness of utterance 

 towards the termination, and may well be quoted as 

 proving how pleasant a result can be attained by the 

 simple reiteration of one cry. 



The above birds are mentioned as to some extent com- 

 mencing their songs in January ; but, as already stated, 

 there are others which, like the lark, have been singing in 

 the autumn, but have not also ceased in December. If 

 winter arrives with a spell of severe frost, however, these 

 birds are silenced, and afterwards, when the thaw arrives, 

 they begin to "record" or slowly recover their songs. 

 The wren is rather exceptional, for it sings much the same 

 song at any favourable time of the year, although in the 

 season of nesting it will greatly prolong its little melody 

 by repeating the same strain several times in one song. 



Early in January the thrush sings only brief songs — 

 totee totec tceuu treuu, and other simple cries, which may 

 be considered as the most widely prevalent in the species, 

 and as probably representing the ancestral song. The 

 rapid musical strains, some of tbem beautiful roulades, 

 which the bird gives later in the season, are never heard 

 now, nor are many cries uttered which resemble those of 

 other species ; but in regard to the latter point it should 



