34 
BULLETIN OF THE NUTT ALL 
NOTES ON THE BREEDING OE THE BLACK TERN ( HYDRO - 
CHELIDON LARIFORMIS) IN MINNESOTA. 
BY T. S. ROBERTS. 
The Black Tern is the most abundant representative of its family 
in this State, making its appearance in the vicinity of Minneapolis 
about the middle of May. Stragglers remain until the first week 
in September, but the majority leave during the latter part of 
August. For a short time after their arrival they are to be seen 
flying leisurely around the larger lakes ; but as the nesting-season 
approaches they select some prairie slough or marshy lake, and 
there spend the greater part of their time until the young are able 
to fly. Late in May or early in J une the nest is built and the eggs 
are laid, or the eggs are deposited without any nest, as the case 
may be. Dr. Coues mentions (Birds of the Northwest, 1874) meet¬ 
ing with a colony breeding along the Red River, and states that 
there were no nests whatever, the eggs being placed on beds of 
decaying reeds. Such is their habit under some circumstances, but 
only two instances of the kind have come under my notice as yet. 
Once, I found three eggs laid directly on the mud on an abandoned, 
broken-down muskrat house in the midst of a large slough. The 
same day I found another set of two eggs on a bed formed by the 
bending over of the tops of some tall dead grass. They were thus 
raised more than a foot above the water, which w'as of considerable 
depth. There was no indication of a nest, the eggs being held in 
place by resting among the coarse grass. A very interesting and 
valuable note on this subject occurs in a short article by Dr. P. L. 
Hatch, published in the Bulletin of the Minnesota Academy of 
Natural Sciences for 1876. It is an extract from a letter written 
by Mr. E. W. Nelson of Chicago, and although the observations 
were not made in this State, I will introduce them here : “ I have 
seen the eggs of Sterna plumbea deposited on masses of floating 
weeds in several instances, but only for the third brood, the bird 
having previously built two nests and deposited the eggs in both, 
which had been removed by myself to ascertain how many they 
would lay. The result was almost invariably as follows : first nest, 
three eggs; second nest, two eggs; and the third, one egg. In 
ORNITHOLOGICAL CLUB. 
35 
several instances I found the nests floating in two and a half to 
three feet of water without the least sign of floating rushes in the 
vicinity ; in fact, there were no rushes or anything else except fine 
swamp grass growing anywhere near, and of this the nests were 
built.” 
As already stated, they build in this section (vicinity of Minne¬ 
apolis) in the latter part of May or early in June, usually placing 
the nest in a prairie slough or marsh bordering an open pond. The 
material used in the construction is short bits of grass and reeds 
disposed in such a manner that a neat, but loose structure is 
formed. Occasionally greater skill is displayed, longer material 
being used, which is slightly interwoven, so that the nest may even 
be removed alone without injuring it. These frail structures are 
sometimes found upon floating masses of decayed debris, and when 
so situated it is necessary, with but few exceptions, to detach a por¬ 
tion of this underlying bed in order to remove the nest intact. But 
they are oftener placed upon the tops of small mounds of partially 
decayed vegetable matter. These mounds, undoubtedly made by 
the Terns as foundations for their nests, are seven or eight inches 
in diameter, and rise one or two inches above the surface of the 
water. They are placed over beds of live moss, and are partly sup¬ 
ported by the water and partly by the moss below. It takes but a 
slight motion of the water to rock them, and they would undoubt¬ 
edly often go adrift were they not generally protected by the grass 
growing around them. To obtain the nest in good condition the 
hand may be inserted beneath the pile and the whole lifted up. 
The average external diameter of the nest of this Tern is aboul 
five inches ; internal diameter, three inches ; while the depth varies 
from a slight depression to three fourths of an inch or more. The 
eggs are either two or three in number, perhaps oftener three than 
two. Their ground-color varies from deep brown to greenish white. 
The markings consist of blotches, dots, etc., of various shades of 
brown. On some specimens there are a few, and on others numer¬ 
ous, obscure pale spots in the shell. Frequently the markings are 
nearly equally distributed over the entire surface of the egg, but 
usually are aggregated to form a wreath around the larger end. So 
far as my observations have extended, all the eggs taken from one 
nest ..have about the same ground-color and character of marking. 
The average measurement of fifteen eggs before me is 1.35 inches 
in length by .98 inches in width. 
Birc/s of Fort Klamath, Oregon. J.C 
Merrill. Remarks by Wm.Brewster 
Hydrochelidon nigra surinamensis. Common summer visitor, breeding 
in small colonies of six or eight pairs, generally near the edges of the 
marsh, but apparently placing their nests among tules and broken rushes 
surrounded by water too deep to permit approach by wading. The only 
nest I found was on a floating but almost submerged cow ‘chip,’ a rather 
unusual place for a bird’s nest; it was at the edge of a grassy pond in the 
middle of which several Terns were nesting, and it had probably drifted to 
where I found it. On the top of the ‘chip,’ a large one, were a few water- 
soaked grass and tule stalks, and the lower half of the egg was wet, though 
the bird was on it when found.* 
* A small white Tern, probably .S'. antillarum , was occasionally seen among the 
Black Terns, but none were secured for positive identification. 
Auk, V. April 188ts. p.140 - / “t. 
