112 EDWARD A. WILSON. 
day, in varying numbers. It followed us close in shore to Table Bay, and appeared 
again at once as we put to sea. Throughout October it was more abundant than 
any other of the larger birds.) Some were pale grey all over the head and neck, 
others had merely a broad or narrow collar of grey, incomplete below; the size also 
varied considerably, but all had the bill of D. melanophrys, dusky yellow, and always 
with a darker tip. We considered these grey-headed and grey-necked individuals, 
if the bill was broad, yellowish and darker-tipped, to be the young of D. melanophrys. 
There was no difficulty in distinguishing the grey-headed D. melanophrys from the 
grey-headed Th. chlororhynchus and Th. culminatus, since the colour of the bill in 
the two latter is much more clean cut and distinctly black and yellow than the 
dusky brownish or yellowish bill of the immature D. melanophrys. 
Until October 19th we saw only immature birds, but on that day the 
white-headed adult, with lemon-yellow bill and orange tip, appeared. After this we 
saw each day for a while only adult birds, but on October 28th we had the following 
together: White-headed adults with lemon-yellow bill and bright-orange tip; 
white-headed birds with bright yellow bill and dusky tip, or with dull yellow bill 
and blackish tip ; and grey-headed birds with dusky brownish bill and darker tip. 
Throughout the first half of November, 1901, we saw one or other of these forms 
almost daily, and came to the conclusion that they were simply age changes, and 
that the grey-headed were the immature. We lost them all as we approached the ice, 
but had four with us of the yellow-billed phase the day after we left it. These 
birds had such deep yellow bills that the orange tip was hardly to be differentiated. 
They all had pure white heads. It will be convenient to arrange them thus :— 
Phase 
1 Orange-yellow bill, deep orange tip. 
2. 
. oR ! White head and neck. 
4 
5 
Lemon-yellow bill, deep orange tip. 
Lemon-yellow bill, dusky brownish tip. 
Dall yellow bill, blackish tip. 
Grey head and neck. Dusky brownish bill, darker tip.* 
On November 20th we saw phase 8. On November 21st, phase 1. On 
November 22nd we saw phases 2 and 3, eight or ten birds at once, sometimes. 
We were then in sight of the Macquarie Islands, and the birds were here exceptionally 
plentiful. They also accompanied us on our way to New Zealand. 
On leaving New Zealand for the south we found D. melanophrys exceedingly 
numerous on December 26th and 27th (8. lat. 53°). Most of them were of phase 1. 
One was small in size, though white-headed, and of phase 4, and a few were of 
phase 2. On December 28th they were more abundant than ever. Nearly all were 
of phase 2, and these, being the older and more plentiful, were the birds that we 
generally caught. A few were of phases 3 and 4. All had white heads (see fig. 44, 
p. 94). 
* It is, of course, quite possible that these were really of a distinct species, but we failed in all our efforts to 
procure one, and I can here only give impressions received at the time from watching birds at some little distance. 
