Casual Observations on a Colony of Black-crowned Night Herons.
BY D. A. COHEN, ALAMEDA, CAL.
[Read before the Northern Division of the Cooper Orn. Club, Jan. 6, 1900.]
DOUBTLESS ornithologists were surprised to see a nesting colony of Black-crowned Night Herons spring up in the city of Alameda, and have not ceased to expect strange things--the time when women no more adorn their headgear with any bird but English Sparrows--when all oologists blow fresh eggs with small holes and Duck Hawks learn to change their roost after having been robbed five or six times a season. I often wondered why the numerous Black-crowned Night Herons that roosted in the tall trees in town used them for a diurnal skulking place only and never nested within my recollection, although in 1883 I found two or three large, flat nests composed of sticks, in an oak grove frequented by these herons. It was not until 1898 that a nest was discovered in any of the roosting places and it is reasonable to conclude that eggs would have created young herons whose clamorous noises would have indicated their presence to anyone living within five hundred yards.
The 10th of May is the date I had fixed in previous years to obtain complete sets from the colonies I knew of m the county, and having climbed to the top of a tall cypress on our premises and found young almost able to fly on June 23 , would indicate the parents began nesting at the common period. I was attracted to the tree by hearing the noises of the young the night before and was at the time over three hundred yards distant in an air line. The dense tree also held at the same date two nests of two eggs each, a nest of three young, unfledged, that snapped viciously at my fingers and coughed up the contents of their stomachs that had a "kill-me-quick," muscular odor. This vomiting seems to be a common trait of self-defense with this bird as noticed in other colonies. Also the young climb away along the branches at the intruder's approach, with the agility of a tight-rope performer, and a very severe shaking of the branches is necessary to loosen their hold.
The next tree, close by, held a nest containing one egg and was found empty two days later. In the third tree several sticks were placed cross-wise in a likely position for a nest, but no more were ever added. All the nests were at least sixty feet from the ground close to the tree tops and high- est of all was a nest full of English Sparrows. They were easy to reach, being placed on small branches near the main limb and were flat affairs, averaging one foot in diameter and com- posed of dead twigs of cypress and locust apparently detached from the trees by the birds. No more eggs were added by June 30. The shells once encircling the young lay directly below on the ground and spatters of dried egg with fragments of shell on the trunk and limbs just below the nests gave a clew to a previous possible combat. The larger brood of young were now flying and the younger brood kept up their noise for several weeks, and as no sounds of young birds or egg shells were heard and seen from any other of the numerous trees except from one group of cypress, where shells and noises indicated three or four nests, I am conscious of having ascertained the total juvenile census for that year. The colony roosted by day in the thick evergreen, departing at dusk in Indian file with many a "squawk" to the salt marsh half a mile distant, as has been their wont for years.
In 1899, on May 23, I climbed a "new" tree and found six nests, invisible from the ground, as in all cases, on account of the height and density of the trees. One nest was easily reached and the second was rather risky to get at, both near the main limb. The eggs of two more far out on the branches were taken in with the aid of a small tin can on the end of a pole, and the other two were too far out to reach, but eggs were seen in them. The pole was maneuvered with tediousness and difficulty among the many branches. Of the first three trees mentioned for 1898, the first one contained two sets of eggs
