The population dynamics of Newfoundland caribou

• Main Author: Bergerud, Arthur Thompson
• Format: Thesis
• Language: English
• Published: University of British Columbia 1969
• Subjects: Caribou; Animal populations; caribou; Newfoundland; Rangifer tarandus; Lynx
• Online Access: http://hdl.handle.net/2429/35483

The population dynamics of caribou (Rangifer tarandus) on the Island of Newfoundland were studied 1957 to 1967. Four herds were recognized and censused: the Northern Peninsula — 450 animals in 1958 and 400 in 1966, the Avalon Peninsula — 125 in 1957 and 720 in 1967, the Humber River — 130 in 1956 and 115 in 1964, and the Interior -- 4600 in 1957 and 6200 animals in 1966. The Island population 1900-1910 was estimated at 40,000 animals. After 1915 these herds rapidly declined and reached a low of perhaps only 2000 animals by 1930. The annual rate of increase (r) of all the herds was low. The Humber and Northern Peninsula herds showed no increase while the Interior Herd grew at only 0.044. The Avalon Peninsula Herd showed the greatest rate-of-increase 1961 to 1967, r= 0.120. The potential r of Newfoundland caribou is probably greater than 0.30. A herd of caribou introduced to Brunette Island increased at r=0.352, from 17 to 100 animals in 5 years. In the Interior Herd, birth rates were high and constant and averaged 0.85 calf per doe 2-years-of-age and older and 0.94 calf per doe 3 years and older. Natural mortality rates were low beyond 6-months-of-age. They were 4 per cent for does, yearlings, and calves and 9 per cent for stags 2-years-of-age and older. The kill of stags by hunters was 11 per cent and reduced the proportion of stags in the population. The survival of calves to 6-months-of-age was strongly correlated with growth of populations and appeared the main influence on numbers (correlation coefficient r=0.922, P<0.01). The mortality of calves in the first summer was high; an average of 69 per cent died in the Interior Herd and in the Avalon Peninsula Herd 30 per cent of the calves died. The major cause of mortality of calves was apparently predation by lynx (Lynx canadensis). As early as 2 weeks after calving, 27 per cent of the calves were missing. They were apparently dragged into forest cover by lynx. Of 114 dead or morbid calves located 74 per cent were bitten by lynx, escaped and had developed cervical abscesses from infections of Pasteurella multocida. The two major factors limiting populations of caribou in Newfoundland 1900 to 1967 appeared to be lynx predation of calves and shooting mortality of adults. Poor recruitment and high loss to hunting probably caused the decline of the herds 1915 to 1930. The primary factor limiting numbers in the Interior and Avalon Herds, 1957 to 1967 was lynx predation of calves in their first summer. Illegal hunting was probably important in the Northern Peninsula and Humber River herds 1957 to 1967. Science, Faculty of Zoology, Department of Graduate