_Eggs._--The knot lays four eggs, perhaps sometimes only three. The eggs are ovate pyriform in shape, with a slight gloss. In the set of three eggs, taken by the Crockerland expedition and now in Col. John E. Thayer's collection, the ground colors vary from "pale olive buff" to "olive buff"; they are spotted all over, but more thickly at the larger end, with small spots or scrawls of "sepia," "Saccardo's umber," and "Vandyke brown," with underlying spots of "pallid" and "pale brownish drab."
The other set of four eggs, from the same source and now in the American Museum of Natural History, is thus described for me by Ludlow Griscom:
Ground color varying from white with the faintest tinge of light olive (1 egg) to "olive buff" (2 eggs) and deep "olive buff" (1 egg); clouded and spotted, especially at the larger end, with shades of color varying from "dark olive buff" to "olive brownish," the intensity varying in direct proportion to the intensity of the ground color; where the spots coalesce into blotches at the larger end of the darkest egg, the color is blackish brown; the spotting is scant at the smaller end.
Referring in his notes to the same two sets of eggs, Doctor Ekblaw describes the ground colors as varying from very light pea-green, almost gray, to dark pea-green, "with brown, umber, and almost black dots and blotches of varying size and shape over the green, and faint subcrustal lavender blotches showing through." Other eggs which I have seen figured or described would fit these descriptions fairly well. The measurements of 42 eggs average 43.1 by 29.6 millimeters; the eggs showing the four extremes measure =49.8= by =33.8=, =39.9= by 29.7 and 41.5 by =27.7= millimeters.
_Young._--The period of incubation is said to be between 20 and 25 days. Both sexes have been taken with incubation patches, so this duty is doubtless shared by both. I quote from Doctor Ekblaw's notes again:
Though we found but two clutches of eggs, we discovered many families of young birds. They are able to leave the nest as soon as hatched, little gray downy chicks with faint blotches of brown, so like the dried tufts of _dryas_ as to be quite undiscoverable when hidden among them. Three or four, or rarely five, chicks constitute the group. Their faint plaintive "cheeps" are so ventriloquistic and illusory that it is impossible to distinguish the direction from which they come. When an intruder approaches the little fellows squat at the signal from the parent bird wherever they happen to be at the time, and remain immovable as the pebbles and tufts of _dryas_ until the danger is over, even though it be hours before the safety seems assured. Even the tiniest of these downy fledglings seem able to look after themselves. They run eagerly and constantly about independently pursuing the moths, crane flies, and flies upon which they feed, often 40 or 50 feet from their mother. The first signal from the mother, a mellow, solicitous _coo-ee_ transforms them into immovable pebbles or tufts of _dryas_. When they are discovered and realize that their concealment is no longer effective, they scatter panic stricken like a flock of little chickens, chirping appealingly to their "mother" who dashes valiantly to their defense, quite beside "herself" with concern, fear, and anger.