336 AlsTNUAL REPORT SMITHSONIAN INSTITUTION, 1960 



but the songs, given high in the air, are obvious trade-marks for the 

 two species. 



In the Iceland birchwood where we found snipe, there were also 

 meadow pipits. We would never have dreamt of finding meadow 

 pipits in such a place in England, and their presence was clearly due 

 to the absence of their close relative and competitor, the tree pipit. 

 What is more, the song of one of them had a distinct tree pipit flavor, 

 and it was begun from a tree perch. 



Finnur Gudmunsson told us that in western Iceland he had once 

 spent a couple of hours stalking the singer of a song which was wholly 

 unknown to him : he eventually shot it for identification purposes — 

 only to discover that it was an ordinary meadow pipit ! This, too, 

 was in a birch area, though the birches here were only scrub. Thus 

 the relaxation of the need for distinctiveness seems to have permitted 

 the song to change. 



The meadow pipits of open country in Iceland have so far not been 

 heard to give any intermediate or markedly abnormal song (though 

 one we heard in the Westmann Islands was exceptional for its bril- 

 liance) . Possibly the woodland and scrubland birds are evolving into 

 a distinct ecological race. 



There remains to mention one amusing incident. In this same wood, 

 we found a redwing's nest quite high in a birch tree. Now in Iceland 

 the redwing, that attractive little thrush, is normally a confirmed 

 ground nester, though in Norway it frequently builds in trees, and 

 Dr. Gudmunsson was quite impressed by this unusual event. Then 

 on Myvatn we saw another tree nest, some 8 feet up in a willow; 

 and Dr. Gudmunsson grew reall}'^ excited — until Sigfinnson, the 

 farmer-naturalist, reminded him that this had been the latest season 

 in living memory, and that the ground had been deep in snow when 

 the breeding urge took the redwings. Seeing that they thus so readily 

 revert to ancestral habit under the stress of necessity, it is rather curi- 

 ous that they do not normally do so as a matter of convenience where- 

 ever trees or bushes abound. 



Finally, I come to what to me is the most interesting point of all — 

 the bearing of field natural history in Iceland upon the fascinating 

 and basic question of a world-wide change in climate. 



Professor Ahlmann, the well-known Swedish geographer, in a 

 recent issue of the Geographical Journal, has summarized all the evi- 

 dence on this subject. He concludes that in the Northern Hemi- 

 sphere a widespread amelioration of climate is in progress, most 

 marked in higher latitudes. It began about a hundred years ago, but 

 has been especially marked in the last two decades. The most likely 

 explanation (which would be assured if we get evidence of a similar 

 amelioration in the Antarctic, as it is hoped to do from the joint 

 Norwegian-British-Swedish expedition now operating there) is that 



