loo British Diving Ducks 
adults, old males being rare on the English and German coasts in winter. In our northern 
islands, such as the Orkneys, the Shetlands, and the Hebrides, the old birds for the most 
part do not migrate at all, but stay all the winter there ; and I have only on rare occasions 
seen immatures in winter or spring about these islands. The same applies to the east and 
west coast of Scotland, where as a rule only adults are found on the sea and brackish waters 
in winter. In England the majority are immatures at this season. Whilst in Ireland both 
adults and large mixed flocks are found throughout the late autumn and winter. 
It is unusual to see very large flocks of these birds in our islands, though I have 
observed parties of fifty to a hundred birds in October on Loch Stenness. These were the 
united families of all the locally bred young birds, which had come together and were about 
to leave for the south; and I have more than once observed the gradual " packing " of 
immatures led by one or more adult females prior to migration. 
Enormous flights of Mergansers move south in early November in Canada, and 
sometimes flocks numbering several hundreds are seen on the coasts of Norway. It is 
interesting to note that large flocks also assemble in Ireland, concerning which the late 
Major H. Trevelyan contributed two interesting notes to the /^/^/^ (September 3, 1910, and 
October 21, 191 1). He says : 
" On a large inland lake in Ireland I saw on August 22 a pack of about fifty young Red-breasted 
Mergansers; they were unable to fly, but were wild, not allowing me to get within 100 yards of 
them ; they flapped off at a great pace, and appeared to break up into parties. The day was a quiet one, 
but not sufficiently so to enable me to ascertain whether there was more than one adult bird with them. 
Returning, however, over the same water within the hour, I saw two small parties of young birds, neither 
of which was accompanied by an old bird. About a mile more or less from where these fifty flappers 
were I saw another pack of them, in number about a hundred. They also were wild, and gave me little 
opportunity for observation. My man, who has been with me on the lough for the last seventeen seasons, 
has frequently told me of this packing in August, and that one adult female takes charge, but that it is 
not till September that it becomes general, i.e. till some time in that month single broods may be seen. 
He believes he has seen 200 young ones in a pack with one adult female as leader. Another 
local man tells me that in September some years ago, when Mergansers nested far more numerously on 
the lough than they do at the present time, he believes he has seen as many as 500 to 1000 young ones 
in a pack, and, as far as he could make out, there was never more than one old bird with them. He saw 
a good deal of them, as someone interested in fishing employed him with others to drive as many as 
possible of a pack towards a net stretched across an opening between the mainland and an island, when 
they would be successful in catching some and shooting others ; but the majority, of course, escaped. . . . 
I saw on August 15, 191 1, on the same lake in Fermanagh, a small flock of young Mergansers, about 
twenty-two in number. The day was very hot and still, and as at one time they were not more than 100 
yards from me, there was no difficulty in ascertaining that there was only one old bird with them. When 
scuttling off they maintained, as is their habit, a more upright position on the water than do the young of 
the Tufted Duck under similar circumstances. About forty minutes later and two miles away, I saw 
another pack of not less than forty in number. Again there was with them only one old bird. I watched 
them from my boat with my Zeiss binoculars for perhaps a quarter of an hour, at distances varying from 
200 to 400 yards. The one old duck was evidently in charge, for the young ones conformed to her 
movements. I saw no more packs up to my departure from the lake on September i. My boatman has 
written me that up to September 26 he had seen packs of about one hundred, sixty, fifty, and twenty-five, 
and he was able to ascertain that with the two smaller flocks there was only one old bird with each. 
Writing on October 2, he had seen on the previous day a pack of about 300 ; but as they were able to 
fly and apparently equal in size, he was unable to say whether they were young or old birds ; and on 
October 11 he wrote that the few Mergansers he had seen were then able to fly well, and that in his 
opinion the majority of them had left the lake." 
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