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May, 1918 THE WHITE-THROATED SWIFT IN COLORADO 109 had succeeded in getting an extension ladder to this nest, and, without disturb- ing it, discovered that it contained two eggs. On July 15, this nest was visited for the fourth time, the parent bird being present on each occasion, and as it still contained but two eggs, it was taken, together with the bird. One egg proved to be almost fresh, while the other was about one-third advanced in incubation; examination of the female proved that she would have laid no more. The nature of the cavity in which the nest was placed made it impossible to determine whether or not other eggs had been displaced from the nest and lost in the crevice. MEASUREMENTS OF NESTS, IN INCHES Outside Inside Set No. Depth Length and breadth Depth Length and breadth 1 1.50 4.25x3.75 1.00 4.00x3.50 2 .40 3.50x3.00 .30 3.40x3.00 3 1.75 4.50x3.40 1.10 3.70x3.00 Nest no. 1.--Base or bottom, of feathers with slight intermixture of fine grass blades. The balance of the nest contains no visible vegetable matter whatever, but the whole structure is so thoroughly glued together that no feather or grass blade can be re- moved without tearing it loose. The mass is not stiff, but extremely soft and flexible. (See fig. 18.) Nest no. 2.--This is a much more flimsy affair, as though finished in haste or the remains of an old nest, one side and the bottom being so thin as to be seen through. Probably 25 per cent grass and the balance feathers; the total bulk not one-third of that of no. 1or 3. Nest no. 3.--Is practically the same as number 1, except that an occasional spear of grass is visible. The whole nest, however, is probably 95 to 98 per cent feathers. MEASUREMENTS OF EGGS, IN INCHES Set. no. I Set no. 2 Set no. 3 .86x.59 . .88x.52 .91x.59 .89x.58 .92x.53 '.90x.58 ..87x.61 .85x.54 .89x.60 .85x.56 Measurements by F. C. Lincoln, Curator of Ornithology, Colorado Museum of Nat- ural History. Nests nos. 1 and 2 when taken were teeming with vermin from the size of a bed-bug down, and upon arrival in Denver were placed in a tight box with carbon bisulphide for their destruction. To the bottom of each nest was at- tached considerable quantities of light downy fluffy material, seemingly the remains of feathers eaten by moths or other insects. The eggs were all more or less spotted with insect excrement, but by my failure to give explicit instruc- tions to the contrary, this was washed off in blowing the eggs with water, but it still shows to some extent on set no. 3. It is interesting to study the varying amount of ingenuity and apparent reasoning with which nature has endowed the different species to enable them to protect their nests and young during the breeding season. As examples: Protective coloration of eggs and young without nest, shelter, or cover, as in the Mountain Plover; the selection of an isolated, barren island, as in gulls; the retreat beneath the surface of the ground, a hole in a tree, the suspension from the end of a limb that will support neither mammal nor hawk; the secrecy and camouflage of the nest of the hummer, kinglet, etc.; the hasty covering of the eggs and the noiseless submersion of the grebe; the broken wing stunt of the Mourning Dove and many others; the trickery and subterfuge of the ptarmi-