November 24, 1898] 



NA TURE 



77 



In Greenland, also, the bees are Boiiibtis. Peary saw tme 

 quite at the northern end of that country. The one exception 

 in America to the rule that only Bombus occupies the far north, 

 so far as I remember, is the occurrence of Osmia huinphala at 

 Great Slave Lake. In Europe and Siberia the same rule seems 

 10 hold, but doubtless several genera go further north than in 

 America. Aitdnna lapponiia, for example, is a decidedly 

 northern type. The object of this note is to draw attention to 

 the interesting question of the northern distribution of bees 

 Those who have i>ccasion to visit northern regions should collect 

 what bees they can, noting the flowers they frequent, and in this 

 way much valuable information may be gained. Probably some 

 <tf your readers are already in a position to throw light upon the 

 subject. T. D. A. COCKEREI.L. 



Mesilla Park, New Mexico, U.S.A., Nov. 6. 



Why Birds are not Killed by Eating Poisonous Fruit. 



There is a great difference of opinion on this subject. While 

 some maintain that birds do not eat fruits of this kind, others 

 hold that they eat only the surrounding pulp, as of the berries of 

 Taxus, which is perfectly harmless, whereas the seed is very 

 poisonous ; others, again, have maintained that they do not 

 eat sufficient to be poisonous. The real fact is, I believe, that 

 none of these statements are true, but that actually the birds 

 eat largely of these berries, both pulp and seed, and that they 

 very shortly afterwards eject the seeds and skins by the mouth, 

 thus avoiding any poisonous action. 



The first experience I had of this habit was in finding in 

 September last an immense number of thrushes and missel- 

 thrushes feeding on the berries of Pyrus aucitparia in Sutton 

 Cold field Park. At least a square mile of ground had every 

 patch of grass covered with the ejected seeds and skins of these 

 berries, all the pulp having disappeared, while the colour of the 

 skins was as bright and fresh as when they were swallowed ; 

 showing that they could not have passed through the alimentary 

 canal. Each of the pellets was flat and round, and about the 

 size of a sixpence. The birds were incessantly flying to and fro 

 betwixt the trees in the adjoining woods and the park. The 

 excessive drought of last summer, by decreasing the supply of 

 their ordinary food, was evidently the cause of their attacking 

 the berries at this early period. 



The next evidence I had of this being the explanation of their 

 immunity from the effect of poisonous food was in October last, 

 when I found on Boxhill, in company with Prof. Conwentz, of 

 Dantzic, a number of similar pellets, but consisting entirely of 

 the seeds and skins of yew berries ; the former being as bright 

 green, and the latter as scarlet as they were on the tree. In 

 each of these pellets I counted twenty or more seeds. 



The real difficulty in accepting this explanation is that, so 

 <ar as I know, no one has actually seen the birds eject the seeds. 

 Two friends of mine saw, the other day, what was very nearly the 

 accomplishment of the process. A thrush was seated under a 

 well (ruited yew, and going through violent spasmodic con- ; 

 tortions, the wings drooping on the ground ; they thought it was i 

 ill, but it flew away strongly as if there was nothing- the matter. ^ 



The idea that these birds only suck off the pulp from the I 

 berries is, I think, fallacious. Prof. Conwentz and I found j 

 under a large tree on Boxhill a great number of small fruit- I 

 bearing shoots, which had clearly been bitten off by squirrels ; i 

 the ground was quite covered with seeds divested of their j 

 aril, and unbitten, though a few berries with the pulp bitten i 

 had been dropped by the squirrels. Mr. Morton Middleton ' 

 tells me that at Dicksgrove, Co. Kerry, the yew-berries I 

 are largely eaten by thrushes, missel - thrushes, blackbirds, j 

 greenfinches, linnets, &c. , and afterwards rejected, but he has I 

 not seen the birds in the act of doing this. He says, however, 

 that turkeys, not being able to eject the seeds, are killed by 

 them, although Rhind {" Vegetable Kingdom") says that these, 

 as well as peacocks and fowls, eat thtm with impunity. Mr. 

 Bennett (Nature, October 13, 1S9S) asks for information as to 

 the effect of birds and animals eating poisonous plants, and says 

 that blackbirds eat the berries of Atropa belladonna. IE does 

 not appear that this was more than a supposition, neither is 

 there any observation, so far as I am aware, as to what part of 

 the berry, seeds or pulp, is poisonous. He says that mice eat 

 the seeds of Datura stramonium. Here again we do not know 

 whether they eat more than the kernel, which they would readily 

 extract from the seed, as I have found them do in the case of 



NO. I 5 17, VOL. 59] 



Ranunculus repens, a small hole being bitten at the edge of the 

 seed, while every kernel was extracted from the double-handfuls 

 of seeds, which were collected in heaps. 



"J. C." (Nature, vol. Iviii. p. 597, October 20, 1898) saw 

 thrushes feeding freely on the berries of Daphne niezereon, an 

 undoubtedly poisonous plant. In this instance there can be 

 little question that they eject the seeds. He says they were 

 so stupefied that they might apparently have been taken with the 

 hand. 



Mr. E. Langley, in the same number of Nature, says that 

 he saw blackbirds also eat these berries, but they did not appear 

 the worse for a number of them. 



Gilbert White (" liistory of Selborne, 1789, 329) speaks of 

 milch-sows being killed by yew-berries, while " barrow-hogs and 

 young sows" did not suffer. He attributes this result to the 

 former being weak and hungry, and therefore eating a much 

 larger quantity. 



Prof. Tuson found {Field, 1877) that pheasants were killed by 

 the leaves of yew, and there are several similar instances 

 recorded since that date. 



A. von Kerner made a number of experiments to show that 

 seeds eaten by blackbirds, germinated in the following June ; 

 whilst those not so eaten, remained on the ground three or four 

 years. O. Kirchner says that a species of Motacilla eats the 

 berries ; but this I regard as a doubtful statement. I have 

 frequently seen them capture flies attracted by the fruit, but 

 have never seen them touch the fruit itself. Every one is, of 

 course, familar with the manner in which owls disgorge the fur 

 and bones of mice and skulls of small birds, a habit which Mr. 

 Ilarting tells me is shared by all the raptorial birds, as well as 

 by shrikes, flycatchers, and rooks ; and there are other facts 

 alluded to by Sir Herbert Maxwell in his "Memories of the 

 Months," and others of insects feeding on deadly poisons 

 without any injury. The habit of ejecting the indigestible 

 parts of their food by birds, seems to require further observation 

 and experiment. JOHN Lowe. 



Sun-spots and Air Temperature. 



The following comparison is, I think, instructive : — 

 Make out a table (from Greenwich data), in which each 

 month since the beginning of 1841 is simply characterised as + 

 or - , according as its mean temperature has been above the 

 average (warm), or below it (cold). 



Then, in each five-year group having a sun-spot maximum 

 year central, count the warm and the cold months ; and the 

 same with five-year groups having a minimum central. We get 

 these tables : — 



a b a -i 



Max. Warm Cold 



134 



166 



32 



Thus, in each of the maximum groups, there is an excess o. 

 warm months ; and taking the whole, an excess of 44 warm 

 months. In most of the minimum groups, on the other hand, 

 an excess of cold months ; total excess, 32 months. 



With regard to the exceptional case — 1865-69 — in the second 

 table, it may be worth remarking that 1S60-70 is one of 

 Brtickner's warm periods. It seems to ine that a consideration 

 of both those cycles — the sun-spot cycle of about 1 1 years, and 

 Brtickner's of aljout 35 years — furnishes the clue to a great deal 

 of our weather. A. B. M. 



