Plate X.1.Horned Grebe within Arm’s Length of the Camera.2.2. Female, Hissing and Ready to Strike in Defense of Nest.
Plate X.1.Horned Grebe within Arm’s Length of the Camera.
Plate X.
1.
Horned Grebe within Arm’s Length of the Camera.
2.2. Female, Hissing and Ready to Strike in Defense of Nest.
2.
2. Female, Hissing and Ready to Strike in Defense of Nest.
The change of color which these eggs undergo, is also worthy of note. I do not refer to the nest-stains caused by contact with the fermenting vegetation of the nest lining, but to a uniform color change of the surface layer of the shell, which is brought about presumably by exposure to light and atmosphere. Referring to the eggs of the second nest by numbers it will be noted that egg number two, when first observed at 7:30 A. M., had apparently just been deposited. As previously stated, its color was a very delicate bluish-green. Egg number one had already attained its final color; a sort of drab-tinted buff, which rendered it less conspicuous in the nest. Twenty-four hours later, egg number two had changed to the same color as egg number one. No data were recorded for egg number three in this respect. Egg number four, after thirty-six hours, was “nearly but not quite the same color as the others.” After it had been in the nest forty-eight hours it was noted as, “same color as other eggs.” But egg number five could scarcely be recorded as fully changed after eighty-four hours had elapsed. These notes would seem to indicate that the first-laid eggs change color more rapidly than the later ones. It may be noted in this connection that the first eggs are slightly richer in the light green pigment; possibly, also, they receive less shelter from the parent bird than the later eggs.
The usual vocal performance of these Grebes, so far as I was able to determine, is a sort of “ko-wee, ko-wee,” repeated at regular intervals. It might be compared to the squeak of a dry wheelbarrow producing one double squeak at each revolution of the wheel. It is however of a clearer quality than this comparison might indicate. Each “ko-wee” has rising inflection and its two syllables are run closely together, with the accent on the last syllable.
The remarkable change of manner which came over these birds as the moult began will be appreciated by reference to the tabulated schedule of visits. The pugnacious bravery of the female at her first nest is amply attested by the photographs, while the records of the second nest show that the birds rarely permitted themselves to be observed, even at a distance, although they had eggs as before.
These Horned Grebes were absolutely isolated so far as concerns other individuals of the species.[2]There were certainly no other Grebes in the slough. Their nesting associates were as follows: Red-winged Blackbird (Agelaius phœniceus fortis), about three pairs nesting; Sora Rail (Porzana carolina), three or four pairs nesting; Wilson’s Phalarope (Steganopus tricolor), several pairs; Killdeer (Oxyechus vociferus), one pair in evidence; Savannah Sparrows (Passerculus sandwichensis alaudinus) were present at the slough all summer; and a pair of Pintails (Dafila acuta) were believed to have a nest in an adjoining field. The adjoining prairie was monopolized, as usual, by the Horned Larks (Otocoris alpestris leucolæma) and Longspurs (Calcarius ornatusandRhynchophanes mccowni).
At the present writing this slough is dry; the road which passes through it is traveled every day by automobiles; and the spot where the Grebes established their home a year ago has now been plowed and planted.