102 G. Steinbacher—•Breeding of the Hammerhead and Night Heron


which at that moment covered the young ones, adopted a characteristic

attitude of defence, spreading its wings and lowering its body. It

erected the elongated feathers of its occiput and snapped at the

intruder.


At five weeks old the young ones for the first time left the nest.

At first they climbed about on the branches near it, then they fluttered

from branch to branch and at last went on the soil of the cage. The

juvenile dress is similar to that of the two and three years old Boat¬

billed Night Herons. Back, wings, and tail are brown, the top of the

head black, while elongated feathers of the hind head, neck, and under¬

side are light brown. The bill of the young ones from the first day

is broadened in a way characteristic of this species.


Extremely remarkable with these birds is their being typical night

birds. Already their extraordinarily large eyes prove that. They

only become lively in the evening. Then they like to wade about in

the water seeking for their prey like Herons. Silent during the day,

they are very noisy in the evening, especially in the pairing season.

When they are displaying one of the birds runs towards the other

while holding its body in an horizontal attitude, stretching out its

neck and erecting the elongated feathers of its occiput, rattling with

its bill and cawing aloud. The other bird either takes up the same

position, then both run by the side of each other or around each other.

Or the other bird arises to its full height and caws. As there was no

certain way of discerning the sexes, I cannot tell which was the male

and which the female.


When the Boat-billed Night Herons came into the Berlin Zoo,

they lived almost entirely on horsemeat chopped into narrow strips.

Later on they got accustomed to eat fish, on which they now live

entirely.


The Hammerheads, too, have been in the Zoological Gardens of

Berlin since 1934. In 1936 they built two nests on an artificial base,

but which fell down. They were more successful in 1937. At first they

erected a nest, which they did not use for breeding, but pulled down

again. Then they built a nest of dry sticks on the branch of an artificial

tree directly near the trunk. It weighed 64 kilograms when finished.

In erecting it, they at first built a base of wet materials and on that a



