92 RUDOLF SÖDERBERG, STUDIES OF THE BIRDS IN NORTH WEST AUSTRALIA. 
Fam. Timeliidee. 
Pomatorhinus temporalis nigrescens MATH. 
Math. handl. n:r 532. 3 JJ ad., 2 29 ad. Nooncanbah, Fitzroy r. ”/12, ”/i2 1910, a. /i 1911 
all moult. 
Moulting. — These specimens shot in Dec. and Jan. moult in wings, tail 
and body (back and breast) at the same time. 
Ecological. — This babbler was common both at Mowla Downs, Derby, Meda, 
Beagle bay (Dampier land) etc., but was absent at Sunday Island. The birds always 
lived in small colonies. The nests were built out in the leafage either alone or 
several in the same tree, chiefly in smaller trees. 
On the llth of July I observed a rather peculiar habit in the bird, which ought 
to be mentioned here: 
Five birds were busy building the same nest. At first I only saw two at the 
nest, but a minute after a third one arrived, carrying a lot of grass-stalks in its bill. 
Both the other birds flew down to the ground, where they collected an equal amount 
of material. They returned to the nest, and now I saw all three jumping in and out 
of it, adding to it. Two more birds came and acted much in the same way. One 
of the birds was specially occupied in building on the outside of the nest. So they 
went on for about a quarter of an hour, after which they suddenly came together 
and then dispersed in different directions. For about ten minutes I could neither 
see them nor hear a sound of the various cries they had uttered before. They 
remained silent and concealed in the leafage of the trees after having hopped about 
before without the very least fear. The motive for their procedure I could not find 
out. When they appeared again at the nest, they stopped building and, gathering 
in a body, they marched away into the bush a minute after. This joint action is 
evidently an expression of a rather intimate social union. On another occasion I 
shot one of the company, upon which the others flew down to the ground and jumped 
round their comrade, crying loudly. In the middle of Dec. there were 2 eggs in the 
nests at Mowla Downs. 
Cinclorhamphus mathewsi (subalisteri MATH.). 
Math. handl. n:r 539. JF ad. Mowla Downs 39/;: 1910. 
Variant. — This specimen has the under surface (the belly) reddish brown 
(fulvescent), the ashy whitish tint present only on the sides of the breast and the 
sides of the body. The under tail-coverts pale buff rather than pale rufescent. 
The bird was a male, and it was singing in a lively manner. 
Ecological. — This lark was not uncommon round Mowla Downs. Its loud 
but not melodious singing was, as in the case of our Anthus trivialis (L.), for the 
