Art. XV.—Observations on Cook's Petrel (Grey), Procellaria cooki (Ti Ti), their Habits and Habitats.
[Read before the Auckland Institute, 24 August, 1885.]
This pretty little Petrel is not so common as the previous species, according to Dr. Buller, F.R.S., etc.; there have been only a few specimens obtained, and very little is known of their habits, but I have succeeded in observing them carefully. The first time I met with this bird was in December, 1880, on my second research at the Chickens or Morotiri Islands, on the western slope of the larger island, along with the Tuatara (Sphenodon punctatum), in one burrow. Professor von Haast, F.R.S., etc., read a paper of mine before the Philosophical Society, Christchurch, on the latter (see “Transactions, N.Z. Institute,” vol. xiv). On the north-eastern portion, near the centre of the Little Barrier or Hauturu Island, in October, 1882, my dog set a burrow; and on digging into it, I was surprised at finding a pair of these Petrels also on this island; they came ashore to clean out their burrows, which process is accomplished with their bill and feet, as I have already described in a previous paper. I measured several of their burrows, and found the average width at the entrance from 4 inches to 6 inches in diameter, and from 4 to 8, and even 12, feet from the entrance to the chamber, of which I always found two in each burrow, and which were from 1 foot to 1 ½ feet long, 1 foot deep, and from 6 inches to 1 foot high; in each chamber is a hollow filled with leaves, moss, or fine grass. I found these burrows even in the stiffest clay, winding about roots and stones. I often worked half a day, and then had to give it up without success. Male and female mutually assist at cleaning out or making fresh burrows. After sunset they begin to call like “ti, ti, ti,” repeated rapidly, which is the signal to assemble for their departure to their ocean haunts, from which they do not return till before sunrise; this process goes on nightly till their burrows are cleaned out and the nest made. I built a hut in the centre of the Little Barrier, near one of these burrows, on purpose to make a closer observation of these rare birds. The 1st November, when they returned as usual, early in the morning, I noticed that they made a peculiar noise in their burrows; in about half-an-hour one came out and stopped for a moment, then flew away, and did not return till after sunset, when he flew several times round above the burrow, and then went off again, not returning till next night, when he went into the burrow and made the same gurgling noise as before; after a while a bird came out and flew away, which returned before
sunrise and went into the burrow. After some time one came out, and again flew away. I then examined the burrow, and found a bird sitting on an egg; on dissecting the bird I found it was a female. I never found more than one egg, and always the female sitting on it; the male I have found not far off in a burrow by himself. When the young are hatched, male and female rear them together, and defend them pluckily; the young are full-grown in March, when the Natives collect them for food; the flesh of this species of petrel being the most esteemed by them.
When on shore, the habits of these birds are nocturnal; their breeding places are in the mountains in the interior, they do not breed in colonies as the previous species. When swooping through the air, they make a noise with their wings like the hiss of a bullet speeding through the air. On dissecting the crops of these Petrels I noticed a peculiarity: the absence of oily matter or remains of fish, which is common in most of the Procellaria family. I found animalculæ, minute seeds, and seaweed. In my opinion this Petrel is not destructive to fisheries.
The young of all the species of Procellaria could be made use of for food, if properly prepared. In former times the Natives had, to a great extent, to depend on these birds, and made long expeditions to collect them; the manner of which I have already described in a former paper read before this Institute. I am sorry to say I have found them every year decreasing. When I went on my seasonal researches on my last trip, 1885, on the Little Barrier, I could not see a single specimen of this Petrel; and of the other four species I found numerous on my first visit I found only a few, but plenty of remains such as wings, feathers, etc., destroyed by wild cats, Native dogs, and wild pigs. In former times the Natives protected their breeding places carefully; but now, as they have plenty of other food which is easier to be got, they are left to destruction in all the inhabited places. I procured a few specimens, as you see here: male, female, and egg.