Red -breasted Merganser 1 1 1 
As the young grow up and are still unable to fly they will " run " over the surface of the 
water at great speed when alarmed — so fast, in fact, that it is impossible to overtake them 
either in a boat or canoe. 
I have not noticed any particular flocking on the part of the males once they have left 
the females and assumed the full eclipse dress. I have seen parties of adult males in July 
in Orkney, but much more often single birds, which are always very shy. 
The adult males do not seem to join the females again until October, and then only 
attach themselves to flocks of adults that are resident. 
Occasionally an old male may be seen with the packs that are about to migrate, but 
this is unusual, and they would doubtless leave them at the time of departure. The 
flocking of young birds and females prior to migration has already been described. 
Mergansers are very rarely assailed by large birds of prey, owing to the fact that they 
always fly over the water where Peregrines and Iceland Falcons will only " stoop " for 
practice. Predatory Crows and Skuas, however, take their eggs and kill and eat the 
young. The same parasitic insects that affect the Goosander are also found on this species. 
There is no doubt that, both on account of its habits and its numbers, the Red- 
breasted Merganser is one of the most destructive birds to fresh-water fish there is. The 
quantities of small trout and salmon consumed by them must be enormous. Yet it is 
somewhat of a fortunate circumstance that, in spite of the fact that they are seldom killed, 
they do not seem to increase in numbers in any one locality — in the case of our islands at 
least — and this may be accounted for by the fact that they do not frequent either rivers or 
lakes unless they are so full of trout and salmon that the waters can stand a certain 
amount of depredation. Moreover, it seems to be an accepted law amongst many species of 
birds that certain areas can only supply a certain quantity of food, and the old birds them- 
selves regulate the numbers that are allowed within its confines. Twenty swans are seen on 
a lake before the spring fights settle who is to remain there, and one pair or perhaps two are 
left to partake of the food, &c., that is only sufficient for perhaps two families. A pair 
of Golden Eagles drive off their young year after year, as they know there is not sufficient 
hunting grounds for another pair in the same valley and its adjacent corries. So, too, 
nearly all the young Mergansers leave in autumn, only a very small percentage returning 
in spring to supply the losses, whilst the rest move about in packs until they are adult 
and eventually find fresh lakes and rivers which are not overcrowded. Thus the summer 
habitats of this and other species are frequented by the same number of birds year after 
year, and if the neighbouring waters are also well stocked with fish the range is extended 
without any very serious depletion of the fish-supply in any one locality. 
On the open coasts Red-breasted Mergansers are very shy and wary, and in conse- 
quence difficult to stalk and shoot, nor do they often come within gun-shot of a sailing 
boat or punt. I have found that this species and the Goosander recognise the danger of 
a punt quicker than any of the true sea-ducks except the Golden-Eye, and they will seldom 
sit on the water and await its approach. They may, however, be surprised occasionally in 
shallow bays and killed as they fly past the boat to the open sea. Mergansers are, however, 
easy to shoot on tidal rivers and estuaries where there are narrow channels at low water, 
owing to their habits of flying directly up and down-stream at no great height above the 
water. On rivers they are easily " driven " to a concealed gun. They are tough birds to 
-J 
