Fauna Series No. 5

Fauna of the National Parks — No. 5 The Wolves of Mount McKinley

CHAPTER FOUR:
CARIBOU (continued)

Some Predator-Caribou Relationships

LYNX, WOLVERINE, AND CARIBOU

No signs of lynx were noted; the wolverine was relatively scarce and so secretive that no observations on this animal in relation to the caribou were made. During calving time both of these species might prey on calves, but ordinarily the predation would be unimportant.

COYOTE AND CARIBOU

So few coyotes are present in the park that no data were secured on their relationship to the caribou. If numerous they might kill a few calves, but it seems probable that a cow could generally ward off a coyote attempting to get her offspring. A young bull kept in captivity by my brother and me in 1923 showed much dexterity in the use of its hoofs. When we tried to force him to one side of a corral with a rope he struck the rope on the ground fiercely and accurately with fore hoofs and then with hind hoofs. This bull was full of spirit and often chased us when we came near. Only the heavy toggle to which he was tied stopped his rushes. This exhibition in the use of the hoofs indicates that they could be used effectively on a coyote.

GRIZZLY AND CARIBOU

On May 28, 1941, a lone grizzly and a pair of grizzlies were seen between Teklanika and Savage Rivers where many caribou calves were being born. The lone grizzly was surprised feeding on the carcass of a very young calf, and a little later it was seen feeding on another calf carcass. The pair of grizzlies was also feeding on calf carcasses.

On May 29 a large herd of caribou was noticed moving away from two approaching grizzlies. The bears did not follow the herd, but the general movement of the caribou indicated that they considered the grizzly an enemy.

After the first few days the calves are probably fairly safe from grizzly attack unless taken by surprise. But before the calves gain strength and speed the bears evidently are able to get some of them. The total effect of grizzly predation is not large, however, for there seems to be no special movement of grizzlies to the calving grounds, and the few bears preying on calves would not take a heavy toll. Some of the calves eaten probably represent carrion, and there would be many afterbirths which might also attract bears. No information indicating bear predation on adults was secured. The best time for predation on weak adults would be in the winter, and at this period the bears are not active. Six adult caribou were found eaten by bears. Two of these carcasses were greatly decayed when eaten. Some of the caribou eaten were known to be carrion and the probability is that they were all dead when found by the bears.

GOLDEN EAGLE AND CARIBOU

Eagles are known to prey on caribou calves but the number they kill is insignificant. Not only is the number of eagles extremely small in proportion to the number of calves, but also, so far as I could determine, the eagles seldom prey on young caribou, which are vulnerable to eagle attack for only a short period.

A Mr. Brown, an Alaska Road Commission foreman, told me of an interesting incident which occurred about June 13, 1938. He saw a calf left behind by a startled cow. Soon an eagle appeared and commenced to swoop at the calf, which warded the eagle off by rearing up on its hind legs and striking at it with front hoofs. The calf finally took refuge in some willows. When it came forth, two eagles began swooping at it. Once it struck one of the eagles with its forelegs and caused it to cry out. For a few seconds there was a mingling of calf and eagle. The besieged calf again took refuge in the willows, where it lay down. When it emerged, two more eagles had arrived and four eagles were swooping at it. After fighting them off for a time, it again hid in the willows. The eagles were perched on the ground in the general vicinity of the calf when Mr. Brown left the scene. It was surprising that the calf was able to put up such a spirited defense. If the cow behaved normally, she would in time have returned to her offspring. Lone calves evidently sometimes fall prey to eagles but probably a calf with its mother is seldom attacked.

On June 14, 1939, I found the carcass of a recently killed calf east of Toklat River. While I was examining it, an eagle soared over head. It had been feeding on the dead animal, and wounds indicated that the bird had killed it. The talons had punctured the hide and penetrated the muscle on both sides of the neck. The skull was cracked from one eye to the antler but on the opposite side. At this point there were no punctures in the skin, so it appeared that the skull had been cracked by a blow from the eagle. The wounded areas were all bloodshot. Only the eagle had fed on the carcass.

Later in the day another eagle was seen perched on a dead willow 2 feet from the ground. Twenty-five yards from the perch was a freshly killed calf. Part of the brisket, lungs, and tongue had been eaten and a part of one jaw had been torn loose. There were talon marks surrounded by bloodshot areas on the left shoulder and just behind it. The rear part of the skull was cracked open, apparently by a blow, as the skin was not punctured. The evidence indicated that an eagle had killed this calf, too.

Both calves were probably less than 2 weeks old. They were found where large herds had recently passed, so it is possible that they had strayed and had been left behind. As mentioned elsewhere, calves are occasionally lost, especially when large herds are suddenly disturbed. The above observations are the only ones which showed calves being molested by eagles.

Relation of Reindeer to Caribou

The domestic reindeer is a smaller animal than the fine, large Alaska caribou. Unfortunately the two animals readily cross, so that when reindeer are brought into caribou country there is grave danger of the caribou herds deteriorating because of cross breeding. In view of this danger the reindeer herds should be kept away from the region inhabited by the caribou.

In 1922 a large herd of reindeer was brought through Mount McKinley National Park and for a few years was kept in the Broad Pass region. During the drive many reindeer strayed and joined the caribou. Since the caribou migrated to the Broad Pass region at the time the reindeer were kept there, some reindeer had opportunity to join the caribou herds. The reindeer at Broad Pass were permitted to stray and now are entirely gone. Many crossings no doubt were made with the caribou and, although they may have had some effect on the herd, it is not now noticeable. It is fortunate that the reindeer in that region were exterminated. Perhaps the wolves were an important factor in ridding the caribou country of these reindeer.

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Last Modified: Thurs, Dec 20 2001 10:00:00 pm PDT
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