December, 1902.] 



KNOWLEDGE, 



2(59 



the discharge of the crater lakes as torrents of water or of 

 mud. In theni there is nothing unusual, but as soon as 

 the throat of the crater is thorou^'hly cleared, and the 

 climax of the eruption is reached, a mass of incandescent 

 lava rises and wells over the lij) of tlie crater in the form 

 of an avalanche of red-hot dust. It is a lava blown to 

 pieces bv the expansion of the gases it contains. It rushes 

 down the slopes of the liill, earrjingwith it a territic blast, 

 which mows down everything in its path. The mixture 

 of dust and gas liehaves in many ways like a fluid. The 

 exact chemical composition of these gases remains unsettled. 

 They apparently consist principally of steam and sulphurous 

 acid. There are many reasons which render it unlikely 

 that they contain much oxygen, and they do not support 

 respiration." ('. D. 

 « 



THE DOMESTIC ECONOMY OF THE THRUSH. 



As observed by A. H. Machell Cox, m.a. 

 From an aesthetic point of view never did summer-house 

 less justify its existence than the hideous reclungular 

 erection which disfigured one of the most perfect gardens 

 I have known. There was not the faintest pretence of 

 rusticity about it. Painted a vivid green outside and in, 

 it boasted a door at one end. and glass windows, incapable 

 of lieing opened on each remaining side. It was a matter for 

 congratulation that such an atx)minable structure should 

 be partially concealed behind a screen of laurel, box, and 

 holly, and especially so to my mind, because by this 

 means it became converted into a unique post of obser- 

 vation for the prowling naturalist. I soon learnt to 

 appreciate it as such, and one Easter, when I was more or 

 less incapacitated from strenuous exertion by the effects of 

 influenza, I availed myself to the full of the opportunities 

 it offered. 



A tour of inspection on April 11th had revealed the 

 nests of two thrushes in the laurels on different sides of 

 the summer-house. One of these was not conveniently 

 placed for close observation, and I will dismiss it with 

 only a word or two. It had been built in evident haste, and 

 the mner lining of mud and decayed wood was so incomplete 

 that the light showed through the whole of one side of the 

 nest. Nevertheless it contained one egg, on which, as is 

 frequently the case, the mother thrush was already sitting 

 for a great part of the day. A second egg and a third were 

 laid on succeeding days, and the clutch appeared to be 

 complete, for these were sat on closely for three full days 

 before a fourth egg made its appearance in the nest. 

 Three of these eggs were eventually hatched on April 28th, 

 and the last on April 29th. 



A peculiarity of the second nest was that it had been 

 built upon the remains of a bullfinch's nest of the previous 

 year. There were four eggs which were hatched on April 

 14th. From that date onwards I spent many an hour in 

 studying the principles of the domestic economy of these 

 birds. It might be supposed by anyone who had not made 

 the experiment that the familiar ^^^ng-thrush would be a 

 good subject for this purjiose, but, as a matter of fact, 

 it is most fidgetty and impatient under scrutiny. 



" Being observed," wrote Mrs. Browning, " when obser- 

 vation is not sympathy, is just being tortured"; if this i.s 

 true of miUikind, it may l)e accepted as an axiom where 

 birds are concerned, and for the most part even without the 

 qiKilifving clause, for, through no fault of their own, they 

 are slow to recognise sympathy. This, however, was an 

 excellent opportunity for seeing without being seen. The 

 nest was four feet from the ground, and about the same 

 distance from the window; so nothing more was needed 

 than to paste the latter u]> from inside, leaving a small 

 spvhole. A chair was placed in position, with a small 



table beside it, on which were my watch and paper .and 

 pencil ready for use. By ajiproaching cautiously from the 

 opposite side I generally managed to sliji in unobserved, 

 and, once there, I could sit taking copious rough notes with 

 the happy consciousness that, in spite of my startling 

 proximity to the nest, I could breathe freely and make 

 small movenients with no fear of betraying my presence. 

 1 even removed some of the laurel leaves outside, so that 

 nothing should imiiede my view. 



After a little while I found to my satisfaction that I was 

 able, as a rule, to distinguish the female from the male by 

 the slightly different markings of the throat. The male 

 seemed to do a good share of the work, and he found very 

 little time for singing. Food was brought on an average 

 once every five minutes throughout the day, and there 

 was no perceptible increase in the number of visits as the 

 young became bigger. 



By very close watching I satisfied myself as to the 

 impartial distribution of food, though at first sight it 

 seemed to be left entirely to chance. As often as not, at 

 a single insit one himgry mouth was fed, and one 

 only, and not unfrequently this privileged nestling 

 would receive the next supply too. But the pangs of 

 hunger soon restored the balance ; those in most immediate 

 need struggled hardest to assert themselves and to gain 

 the best position. All mouths would be opened to the 

 widest extent on the next visit, and the parent without 

 hesitation would deposit the food in that which was 

 readiest to receive it. Thi.s primitive arrangement em- 

 bodies a principle which alone makes it possible to provide 

 for a ravenous brood with the necessary impartiality. 

 Watch an old starling surrounded in the field by her 

 inexperienced family, who press eagerly round her as she 

 probes deep into the ground for a hidden grub ; this 

 obtained, she does not dispose of it at once, but dashes off 

 at top speed followed by her youngsters ; after running a 

 score of yards she stops abruptly and gives the prize with- 

 out more ado to the nearest pursuer. The hungriest will 

 have exerted himself the most. It is the same principle, 

 and a fair one on the whole, but what happens when one 

 is more weakly than his fellows from the first ? 



I must now allude to the sanitary arrangements for 

 keeping the nest clean and habitable. Here I confess my 

 preconceived ideas received a shock, and I made, what waa 

 to me, quite a new discovery. For instead of the droppings 

 being removed to a distance by the parents, the latter 

 invariably swallowed them. At first I thought I must be 

 mistaken, but I witnessed it again and again, and the mode 

 of procedure was always the same. A mouth was filled, 

 a parent remained waiting a moment or two on the edge 

 of the nest, and then, after a slight change of position of 

 the young bird, reached down to receive the excrement, 

 which was deliberately eaten. Any delay brought an 

 impatient peck as a reminder ; only once did this fail to 

 have the desired effect, and then the omission was 

 rectified on the next visit . These methods were scrupulously 

 adopted by both parents from the very first, and were only 

 discontinued when the young birds left the nest. I may 

 add that a year later I watched just the same proceeding 

 at a mistle-thrush's nest, and I can well believe that the 

 blackbird has a similar habit. Now, at the time I searched 

 all the books available, but failed to find any mention at 

 all of this remarkable fact. Quite recently, however, 

 when looking through some back numbers of Knowledoe, 

 I came across a most interesting paragraph on the subject 

 by Mr. H. F. Witherby.* His remarks were based on 

 observations of a mistle-thrush's nest. From this para- 

 graph T learnt that the habit of swallowing the droppings 



• See Knowledge, 1898, p. 66. 



