Distribution of Black Shags.
It is evident from general summaries, such as that of Stead (1932), that the Black Shag is much less abundant in New Zealand than formerly. It is difficult to get comprehensive information on the number of breeding colonies but this could probably be done in the near future owing to the Dominion wide coverage of the recently
formed Ornithological Society of New Zealand. From the publications of the first three years of activity of this Society, 1941–44, the following information has been derived.
From North Auckland there are no records of large numbers, and only some colonies of less than a dozen nests are recorded by observers in this area. In the Lower Waikato the nesting headquarters appear to be Lake Waikare, where the number of nests, perhaps 200 in 1934, appears not to have increased in the last 10 years. From Taranaki and Northern Hawke's Bay no recent records are available, but for Southern Hawke's Bay Mr C. A. Fleming has contributed the following (Ann. Rept. O.S.N.Z., 1941):
“In six months in S. Hawke's Bay every Black Shag seen was noted. Though anglers report this species as abundant in the Manawatu and other trout streams, there were only 42 birds recorded in-this area, and less than 100 in the whole district. Odd birds were seen at Kumeroa, Mangatiwainui, Mangatainoka, Dannevirke, Mangapuaka, Waustead, Purimu Lake, Blackhead (coast) and lakes behind Blackhead. Flocks (over 12) at Manawatu near Tamaki Junction and north of Kumeroa, where there are regular roosting-places, and at Poanui, N. of Pourerere, where, on 23/5/41, numbers of birds had fine white flank patches and were making regular trips with nesting-material from Poanui to a point at least two miles north, where undoubtedly there is a nesting-colony. A further colony is reported at Hatuma Lake, south of Waipukurau.”
From Wairarapa and Palliser districts small colonies of up to 30 nests that have not increased over a number of years are reported, but at Gollans Valley, near Wellington, a colony observed at intervals by one of us (R. A. F.) since 1930, when there were 40 occupied nests, had dwindled to 20 nests in 1932, 12 in 1934, and finally had been found abandoned in 1942. It is not known if any survivors moved elsewhere, but the indications are that this colony has been exterminated.
The numbers recorded in Nelson and Marlborough are somewhat larger than from other districts, and flights of up to 300 birds have been recorded moving from the Waimea Plains towards the coastal region of the Sounds. The resident population of Marlborough would also number several hundreds. In Canterbury the coastal cliffs east of Lake Ellesmere and Forsyth still afford a nesting sanctuary for a scattered colony of several hundred birds. In the back country, nesting colonies are widely separated and of comparatively small size, such as those of the Wilberforce River and at Waimate, from which samples have been examined in the preparation of this paper. No full records are available from Westland, Otago, and Southland, but the species is fairly common in all three districts.