LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 3 
season. It was almost impossible to count or even to estimate the 
number of western grebes in this colony, for the nests were scat- 
tered over a wide area among the reeds or bulrushes (Scirpus 
lacustris), and many of them were beyond our reach in water too 
deep to wade; there were certainly hundreds, and perhaps over a thou- 
sand of them. The nests were floating in water 2 feet deep or more 
and consisted of compact masses of rubbish, dead and rotten reeds, 
mixed with a few green flags, and plastered with soft slimy vege- 
table substances. They were generally anchored to growing bul- 
rushes in plain sight, but some were well concealed from view in 
thick clumps. They were built up from 3 to 5 inches above the 
water and measured from 18 to 25 inches in diameter, the inner 
cavity being from 7 to 9 inches in diameter. We were surprised to 
find the bodies of a large number of these grebes lying dead on or 
near their nests, during both seasons, and were unable to account 
for it; sometimes two bodies were found at one nest. Muskrats 
were quite common in this slough, and a pair of minks had a den 
on the island; perhaps the latter may have indulged in a midnight 
massacre. In another deep-water slough, near Crane Lake, we 
found a small colony of 12 or 15 pairs of western grebes nesting 
among the cat-tail flags (Z'ypha latifolia), where the nests were often 
well concealed in thick clumps. 
Although they were not so shy and retiring about their breeding’ 
grounds as the other grebes, I was never able to surprise a western 
grebe on its nest until one cold, rainy day when I waded into the 
slough and saw the birds sliding off their nests all around me, 
swimming away almost under my feet and bobbing up unexpectedly 
near me; the sun came out soon afterwards and I longed for my 
camera; I tried to repeat the experience later but never succeeded. 
Apparently they sit more closely in wet weather, but under favor- 
able circumstances do not find it necessary. Evidently both sexes 
assist in incubation. They seldom, if ever, cover the eggs with the 
nesting material as other grebes do. I once flushed a female ruddy 
duck from a clump of bulrushes, but a careful search revealed 
nothing but grebes’ nests and later I took from a grebe’s nest two 
eggs of the western grebe and an egg of the ruddy duck. The 
smaller grebes also occasionally lay an egg in a western grebe’s 
nest. 
In North Dakota the western grebes breed abundantly in some 
of the sweet-water lakes, generally in deep water and often among 
the tall canes and wild rice which grows 8 or 10 feet high. The 
extensive marshes of tall canes (Phragmites commumis) bordering 
the Waterhen River in Manitoba form a safe and almost inaccessi- 
ble breeding resort for this species where large numbers find a con- 
genial summer home. The water in these marshes is too deep to 
55916—19—Bull. 107—-—2 
