i6 THE SCOTTISH NATURALIST 



What strikes one chiefly about the Gadwall's breeding 

 records is their scattered geographical distribution and their 

 sporadic nature; in so many instances the birds seem to 

 nest for one or two years and then forsake the locaHty, and 

 there would appear, as yet, to be no centre of dispersal 

 in Scotland itself We should expect to see within the next 

 few decades, that the lochs where they settle permanently 

 become centres of distribution and colonise the surrounding 

 districts ; this will be an interesting line of study for 

 ornithologists in future years. 



In dealing with the arrival and spread of breeding Duck 

 in this country the first and most important point to be 

 considered is their foreign distribution, as on this largely 

 depend their lines of arrival and subsequent dispersal. 

 We shall therefore detail, rather fully, the foreign distribu- 

 tion of each of the Duck with which we deal and endeavour 

 to trace the connection between their distribution in other 

 countries and their line of advance in this. The foreign 

 breeding range of the Gadwall and the Pochard does not 

 extend as far north as that of the other Duck with which 

 we purpose dealing, and there appears to be a marked 

 analogy between the arrival and spread of these two species 

 in Scotland. Their advance seems to be from east to west, 

 in contradistinction to that of certain Duck which breed 

 further north, as for instance the Wigeon, which, as we shall 

 see in our next paper, shows a very marked line of advance 

 from north to south. 



The Gadwall breeds in the temperate regions of the 

 Northern Hemisphere ; in England it breeds in considerable 

 numbers in Norfolk and Suffolk where it was originally 

 introduced, and has bred in one or two other localities, while 

 to Ireland it is a scarce and uncertain winter visitor. In 

 Europe its principal nesting grounds appear to be in 

 Southern Sweden, Germany (most plentifully in East Silesia), 

 Southern and South-eastern Russia, and Central Eastern 

 Europe generally. It also breeds more sparingly in Holland, 

 Denmark, Iceland, Poland, and apparently locally in Spain ; 

 also across temperate Asia and America. It winters as far 

 south as the basin of the Mediterranean, the inland waters 



