THE GROWTH OP CONFINED COLONIES OF THE WILD HOUSE-MOUSE (MUS MUSCULUS L.)

Authors

  • PETER CROWCROFT,

    1. Infestation Control Division, Ministry of Agriculture, Fisheries and Food, Hook Rise, Tolworth, Surbiton, Surrey
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    • *Zoology Department, British Museum (Natural History), London, S.W.7.

  • F. P. ROWE

    1. Infestation Control Division, Ministry of Agriculture, Fisheries and Food, Hook Rise, Tolworth, Surbiton, Surrey
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Summary.

  • 1The growth of four confined populations of wild house mice (Mus musculus L.) was studied for approximately eighteen months. Each colony was started with one male and two females and constantly provided with excess food and water. Censuses were carried out fortnightly at first, and later monthly.
  • 2The variation in the rate of increase was greatest in the early stages, but all four colonies contained comparable numbers after eighteen months.
  • 3The main factor limiting population growth was the low fecundity rate of the females. Reproduction ceased altogether after ten months in the colony which grew most rapidly and had the most stable social structure.
  • 4Most females with closed or partly closed vulvae were found at postmortem to have inactive ovaries, thread-like uteri and excessive fat deposits. Most adult males remained fecund at all stages of population growth.
  • 5The survival rates of infants, juveniles, and adults of both sexes, were not significantly affected by increased total numbers.

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