are frequently entirely obscured by a coating of mud. The eggs look as if they had been purposely 
rolled about on the muddy ground so as to cover up their light colors and make them appear like 
chunks of earth or stones, a procedure which must be very effectually protective. 
In long-diameter the eggs measure from 1.25 to 1.35, and in short-diameter from .85 to .98; a com- 
mon size is about ;92 x 1.30 inches. 
DIFFERENTIAL POINTS : 
The size, shape, and colors of the eggs will easily distinguish them, excepting in extreme cases, from 
any other species. See “ Upland Plover.” 
REMARKS : 
The three eggs illustrated, Plate XLVII, Eig. 1, were selected from a number of sets in the pos- 
session of Mr. J. B. Porter, of Glendale, 0. They represent the different sizes, shapes, ground-colors, 
and markings commonly observed. Mr. Porter, to whom I am under obligations for the examination and 
use of his specimens, has several years found the Black Tern building in large numbers in the marshes 
in Ottawa county, and has collected a good many eggs and noted their breeding habits. Dr. E. W. 
Langdon, who has also observed the Black Tern in its summer home, wrote of it, in Volume III, No. 3, 
of “The Journal of the Cincinnati Society of Natural History,” as follows: “A very common summer 
resident in the marsh ; nesting, or rather laying its eggs on the little islands of decaying vegetation and 
mud formed by sunken muskrat houses. . . . The sun appears to be their chief incubator, although 
the decaying vegetation of which the abandoned muskrat houses consist, doubtless plays some part in 
the process. In no instance did we succeed in flushing a bird from the eggs, although they would appear 
in pairs to the number of twenty or thirty and hover about within a few feet of our heads making a 
great outcry when we approached their property, which was soon to be ours by right of discovery. At 
other time's the birds were not at all gregarious, being usually observed foraging singly or in pairs. 
Several young of the year were taken, thus confirming the statement of the resident who informed us 
that he had taken numbers of the eggs of the first brood in May. Of the dozen or more sets of eggs 
taken by us early in July, more than half were fresh or nearly so.” 
In the spring and fall I have frequently seen Black Tern singly or in small flocks fishing along the 
Scioto river. It seemed at these times to be fearless, often coming within a few feet of me, and then 
gracefully sailing off as if its curiosity had been satisfied. It often remains several days or even weeks 
in the same locality. Having selected a stretch of river, it flies up and down, back and forth, constantly 
watching for some small fry in the water beneath or catching small insects in the air. When a minnow 
is espied a rapid dive is made for it, the bird often going entirely below the surface and out of sight. 
Suddenly it reappears and, stretching its long wings with a laborious and uncertain movement, rises in 
the air again, to repeat, at the first opportunity, its difficult work for food. Its flight is graceful and 
even careless. It sails through the air with the ease consequent upon a large expanse of wing and a 
small light body. Now circling up, now dropping like a feather upon some log lodged in the current. 
Here it sits for a few moments, apparently contemplating suicide, then suddenly, as though some circum- 
stance over which it has no control had decided the matter, it starts off to repeat its search for food. 
160 
