16 A NATURAL HISTORY OF THE DUCKS 



as far as Florida or even Cuba. The winter dispersal of diving ducks, Scaup, Canvas- 

 back, and Red-head, is markedly irregular, and apparently delicately adjusted to 

 crops of various water-plants, which vary greatly in luxuriance from year to year. 



In any famous ducking locality the proportion of the different species varies, sug- 

 gesting factors of which we are in complete ignorance. Shooting-records will show 

 great Teal, Mallard, or Widgeon years; still, as a rule, very big years show an abun- 

 dance of several species. 



In my own region, which is just east of the usual range of western -bred migrants, 

 there occasionally comes a season when Mallards, Red-heads, or Ruddies are much 

 more numerous than usual. This points to the fact that routes are not absolutely 

 fixed. Stray birds taken at points distant from the usual range are nearly always the 

 young of the year. 



The height at which the duck tribe travels and the speed of migration are subjects 

 often discussed, but it is impossible to lay down any hard-and-fast laws. It seems to 

 be generally agreed that older observers exaggerated the height at which birds usually 

 migrate. Meinertzhagen concludes that migrants are seldom found at over five 

 thousand feet altitude, and that the bulk of bird movement is conducted below three 

 thousand feet. Almost any sportsman knows that geese and ducks make their di- 

 urnal as well as their migratory flights much higher in fine than in foul weather. 

 Wild-fowl are seen migrating at their greatest height on clear frosty mornings with 

 light north or northwest winds. At these times such large birds as Canada Geese 

 may travel so far above the earth as to be difficult to see, probably over four thou- 

 sand feet, and it is possible that many ducks pass across the zenith at such a height 

 as to be invisible, say above thirty-five hundred feet. But any sort of bad weather 

 changes all this, and low clouds, heavy head winds, sleet, or snow will bring the 

 migration close to the earth. Under really adverse conditions geese and ducks may 

 be seen struggling along at scarce a gunshot above the ground. 



The time of the day probably makes little difference to most ducks, and in this 

 they differ widely from our passerine birds. Active migration takes place on favor- 

 able nights as well as by day, but I have often thought that the first part of the night 

 was a period of more activity than the last part, to be followed by renewed movement 

 just before morning and during the first hour after dawn. 



It is very remarkable that enormous numbers of one species often arrive at a favor- 

 ite stopping-place almost at the same time. Mr. Frank Benson tells me that on the 

 25th of October, 1920, he witnessed in broad daylight between the hours of eight and 

 ten in the morning the arrival of thousands upon thousands of Red-heads and Can- 

 vas-backs which before that day were entirely absent. This was at Long Point, Lake 

 Erie. They first appeared in long wavering lines, flock after flock in rapid succession 

 at a height of perhaps twenty-five hundred to three thousand feet. When directly 

 over the marsh, they "let go" and came down at terrific speed, so that in a very 



