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IC.O. 885
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188
APPENDICES.
migrations were nearly all 30 to 35 or 40 ft. in length, and according to Lars Iversen's opinion they were sexually immature animals of from one to two years old.
In the cold current off Saldanha Bay one could meet single young males, probably yearlings, throughout the whole summer, but the majority moved southwards at this time.
At the breeding places opposite Portuguese West and East Africa the first humpbacks arrive at the beginning of June, but the majority come first about the middle of July.
The pregnant females have on arrival fœtuses of very different size, and the breeding period lasts, therefore, quite until October, by which time the majority again betake themselves southwards; at Port Alexandra southward migrating hump- backs may be seen as early as 23rd August.
The first southward migrating females with calves are seen at Port Alexandra at end of September; in October they become continually more numerous, and at the end of this month very few females not accompanied by young are seen.
A large female caught at Port Alexandra 20th August, 1911, had twin fœtuses 8 ft. and 12 ft. long respectively; she would scarcely have given birth to them simultaneously.
A female caught at same place on 23rd September, 1911, was accompanied by a yearling; yearlings are seldom observed so far northwards.
Unpaired single individuals flock together sometimes and wander around the breeding places. On 15th September, 1911, at Port Alexandra, a very old and excessively lousy female, 15 metres long, was killed, and she was followed by two very young, probably only yearling, males. Shortly before, two large females were killed at same spot; these were together, and possibly their spouses had been pre- viously destroyed.
After parturition the females appear to be greatly weakened. They remain for about four weeks quite quietly on the breeding place, and repose usually about one fathom below the surface of the sea, since they hold the young, which have not yet learned to dive, upon their backs (A. Ingebrigtsen). At this time they are very easy to kill.
Before the southward migration begins the humpbacks pair afresh, and in many of the females killed in the autumn at Saldanha Bay and Durban one has found newly established foetuses.
Two such fœtuses found at Sandanha Bay on 2nd and 3rd November, 1911, were respectively 30 mm. and 35 mm. long. In October, 1911, two females killed at same place had foetuses of about 70 mm. When these were drawn up on the slip milk flowed out of their mamma, proving that they had given birth in the same year.
It is probable that the humpback, as a rule, gives birth to a calf in each year, and that impregnation takes place about four weeks after parturition—that is, when the new-born calf is capable to some extent of taking care of itself. According to this, gestation should last for about eleven months, a period which has also been assumed in the case of the northern humpback.
The majority of the embryos found at Saldanha Bay in the first third of Novem- ber are less than 500 mm. long. The greater number of the humpbacks appear, therefore, to pair off Benguela in October. About the same time avails for the east
coast.
On the southern journey the humpback pairs are accompanied by their new-born calves, which have usually then a length of 15 ft. or more.
The male shows great solicitude for his family, and if the female be killed first it remains as a rule on the spot, so that both it and the calf can be taken afterwards. If the male be shot first the female flees with the young.
On the southward journey the humpback usually gives itself a good time, and hunts what it can find on the way. In a frolicsome way it often springs out of the water, and, like the northern humpback, it frequently rolls on the surface of the sea lashing the water with one of its flippers.
The sexes can usually be distinguished at sea by the fact that the dorsal fin of the female is more rounded and usually ends in a fine curved point, while that of the male is straighter and blunt at the point (A. Ingebrigtsen).
At Saldanha Bay the whalers distinguish between a little humpback, called the "bahiaknöl," and the large " kongeknöl." The first is said to be much overgrown with Coronule, and springs more frequently out of the water than the other hump- backs. Probably the bahiaknöl" is only the young animal.
Parasites: Cyamus, Coronula, and Nematodes (Ascaris).
At Port Alexandra the interesting observation has been made that, although the humpbacks which pass by in the winter (June and July) are thickly infested with
APPENDICES.
189
Coronula, when they turn back about spring (October) they are nearly clean or have only small Coronule. This is most readily explained by assuming that the Coronulo fall off in the relatively fresh water off the Congo. Sailors frequently take their ships, in order to cleanse them of Cirripedes, into the mouths of the rivers.
The humpback is a sagacious whale, and quickly realises that it is being hunted: it goes out to sea at once. When it is among "kril" it is less shy than usual. At the beginning of the chase at Durban it could be found close to the shore, but since whaling became so intense at this place it has to be sought much farther out. Some- times it teaches itself to escape the whale-boat by diving straight down and remain- ing motionless while the boat passes over it, whereupon it comes up behind the boat to blow. Such whales are impossible to kill.
three
In 1912 the humpbacks did not follow quite the same route as in the preceding years, and on the whole their behaviour was different. Thus, in Saldanha Bay very few were seen on the spring migration, and in Durban very few on the autumn migration. On the southward migration the humpbacks at both places were very unquiet and shy and did not move continuously southwards, but went for a long time up and down the coast. It is possible that this differing behaviour can in part be ascribed to the intense whaling, but since the sea is said to have been unusually cold and deficient in plankton during this year this local difference can be thought of as a contributing cause.
It has been definitely proved that individual humpbacks follow the whole coast. Thus in August, 1912, the 8.8. Jupiter" put a harpoon in a humpback at Durban: this whale was caught later at Linga Linga, Inhambane, 23° 30' S. lat. The floating- factory "Normanna," early in November, 1912, recovered at Durban a harpoon in a humpback which she had lost at Angoche, 16° 20′ S. lat., two or three months earlier. Already, one year after the beginning of whaling at Durban several humpbacks with wounds or healed scars of harpoons were found, and, since one did not expect to rediscover previously wounded whales on this spot so soon, it was thought that the whales must have come from South Georgia or the neighbouring region where whaling had begun earlier. This idea was the more ready since some of the whalers at the Cape of Good Hope had seen humpbacks on a westerly migration. Still, in the meantime, one has no certain ground for this assumption.
Fœtuses. Twins appear to occur more often in southern than in northern humpbacks, since, in all, three cases are known to me; I was informed of other cases but did not receive data concerning them.
The following is the list of foetuses of southern humpbacks recorded by Olsen and Kükenthal :--
1911, August 8, Port Alexandra 1912, October 5,
A.---AFRICA,
[18 ft. (N.) Olsen]
1911, 19
10, Saldanha Bay
1912, 1911,
16,
11
1
?
"
?
JI
1912, November 1,
11
2,
1971, 1912,
3.
D
5, 31
17
Twins.
1911, August 20, Port Alexandra
[Male 8 ft. (N.) Olsen] [Female 12ft.(N.)
*
19
>>
+
22,
November 7
21
(7 485 Olsen)
(7 450
B. SOUTH GEORGIA,
1908, September 2
2
"
*
October 23
26
1918, January?
נו
Direct Length.*
Length along Back.
mm
11.
3,300
Olsen.
49
92
Kükenthal.
58
1
105
69
114
70 circa
70? Olsen.
70
M
70?
145
210 Kükenthal.
(80 Olsen
28
58
"
"}
(85 ) 80
62
"
220
280
"
2,800
2,540
3,300 Olsen
5,000
980 890
480 Kükenthal.
600
11
89
47
*
51
126
"
59
114
17
64
151
68
148
1
* The "direct length" is that of a line passing from most forward point of head (parietal region in the small embryos) to the most backward point: owing to the foetal curvature this is much less than the length along back in the smaller embryou.
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