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July, 1910 SOME COLORADO NIGHT HERON NOTF. S 121 hundreds of eggs examined. The nests were without exception entirely devoid of lining, the eggs being laid on the closely woven network'of small sticks which was generously littered with excrement and filth. All of the bilding material was carried by the birds in the bill. Of all the birds observed not one was seen carrying anything (including food) in the claws. The birds' only call given when on the wing, was a low, coarse, guttural sound resembling the word "whork" or "whark" when spoken in a very low pitch; and they decoyed with surprising stupidity to even the poorest imitation of the sound. Mr. J. Alden Loring who was my companion on several of these trips, and who is an adept at bird and animal mimicry, repeatedly brought the birds almost to us by his excellent imitation of the Night Heron call. The young when on the defen- sive open their great mouths to an amazing extent, and give vent to a very loud, Fig. 39. NESTS hoarse, rasping squawk OF BLACK-CROWNED NIGHT HERON IN WILLOW SAPLINGS which is quite terrifying. After leaving the nests, the' young and adult birds congregate in flocks of varying sizes, and during the day frequent the cottonwood trees around the small lakes and ponds, where the mottled brownish plumage of the young blends won- derfully with the lights and shades of the foliage, affording them perfect concealment. Most of the feeding is probably done in the late evening and during the night, as the croak of the Night Herons could be heard about the Barr lakes at all hours of the night. Taken in all, this quaint, queer, awkward, and erratic bird is one of the most intensely interesting species with which my tramps afield have brought me into close acquaintance, and I hope that future field work will enable us to solve some of the many problems which up to this time we have been unable to answer.