MISCELLANKA, igi? — 1921 327 



MISCELLANEA, igiy ^/g2i. 



High Mortality aiiiong Frogs. 



The extreme fluctuations of temperature in the early months 

 of 191 7 seem to have been the cause of the death of an 

 abnormal number of frogs, Rana iemporaria, in a local pond. 

 This tiny lakelet on the outskirts of Gateshead is of cement, 

 only two yards by three, about one and a half feet deep, and 

 supplied with town's water controlled by a tap. It contains 

 several plants in baskets or pots, and has mud at the bottom. 

 The ordinary number of frogs to be seen in the pond during 

 summer has been 15 to 20. Two gold-fish that have been in 

 the pond about three years survived the winter safely. 



When tlie severe frost gave towards the end of February, 

 and the ice melted, several dead frogs were seen, and at 

 intervals 54 dead were taken out of the pond. In ordinary 

 years not more than three or four perish. Many of the dead 

 frogs had each a living male on its back tightly clasping it in 

 the usual conjugal embrace. 



The best opinion that can be arrived at is, that the mild 

 spell in January caused many of the frogs to become active 

 and to leave their safe hibernating quarters in the mud at the 

 bottom. They were observed to be on the move, elsewhere, 

 in that month. Then came the severe frost and they fell 

 victims to the treachery of the spring. After the thaw at the 

 end of February, the sexual activities of the living males were 

 stirred, and as they crawled along in search of females they 

 found the dead ones, and these sufficed. 



Among the dead were three tiny ones, about one to one-and- 

 a-half inches long, probably cases of arrested development, the 

 cause of which is obscure. Such cases are better known in 

 newts and in natterjack toads. 



Considering that frogs of this species are found as far north 

 as 70^ latitude, and at as high an elevation as 8,000-ft. in 

 the Alps, in both of which positions the winter temperature 

 must be extremely low, it is thought worth now putting on 



