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YFF-Yngre, fremragende forskere

Processes in the life history and dynamics of managed ungulate populations

Awarded: NOK 8.5 mill.

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2004 - 2009

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Populations of large mammals are strongly structured according to age, sex, individual attributes, temporal factors (climate and density) and spatial factors. A detailed understanding of the interactions between these factors, i.e. the life history, has p roven necessary to successfully predict population dynamics. We have a good basic understanding of this in naturally regulated populations. However, constraints are different in heavily managed populations, typically due to strongly male-biased harvesting or poaching and subsequent skews in the sex ratio and age structure. The management paradigm for polygynous mammals are that males are not limiting, as a single male can inseminate large number of females. However, time is a severe constraint in strongly seasonal environments. Strongly skewed sex ratios delay breeding, or may even lead to a critically low proportion of females breeding when a lower critical threshold proportion of males are reached. At a mechanistic level, there is little information reg arding whether key life-history features such as timing and rate of calving are due to changes in ovulation, conception, fetal loss or gestation length, and very few studies have linked individual foraging processes to life history. Using a combination of approaches, I aim to determine: (1a) What is the cost of reovulation in terms of offspring weight and subsequent survival, by manipulating timing of conception in two reindeer herds by sterilizing males. (1b) What is the cost of previous reproduction to females in terms of delayed or lower rate of ovulation. (1c) What is the relationship between local climate, plant phenology (NDVI) and timing and rate of ovulation. (2a) To what extent does female fecundity and calving depend on the proportion (and age) of males present? (2b) Are younger males trying harder and are females more aggressive when sex ratio is female-biased? (2c) What is the role of duration of rutting for age-dependent rutting effort? (3a)


YFF-Yngre, fremragende forskere