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POPULATION REGULATION, FLUCTUATION, AND COMPETITION WITHIN SPECIES 119

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0.6

Winter mortality 0.2

2.0 3.0 3.4 3.8

Log of juveniles in winter Log of hatching population

Chick mortality

Fig. 8.9Examples of (a) Great tit (b) Partridge
density-dependent mortality
in birds. (a) Great tit (Parus
major) overwinter mortality
(log of [juveniles in
winter/first year breeding
population]) plotted against
log juvenile density in
winter. (After McCleery and
Perrins 1985.) (b) Chick
mortality of European
partridge (Perdix perdix)
(measured as log hatching
population/ log population
at 6 weeks) plotted against
log hatching population, in
Hampshire, England. (After
Blank et al. 1967.)

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60

40

20

0

80

70

60

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40

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20

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100

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(a)

Male

Female

60 100 140 180

Female population size (numbers)

(b)

0246810121416182022242628

Reindeer density in winter

(numbers / winter habitat area)

(c)

200 250 300 350 400 450 500 550

Study population size (number of sheep)

Lambing at 12 months (%)

Calves / 100 females

≥ 1 year old

Juvenile mortality (%)

Fig. 8.10Density dependence in large mammals. (a) Juvenile mortality of male and female red deer on the island of Rhum,
Scotland. (After Clutton-Brock et al. 1985.) (b) Juvenile recruitment per 100 female reindeer older than 1 year in Norway.
(After Skogland 1985.) (c) The fertility rate of 1-year-old Soay sheep on St Kilda island. (After Clutton-Brock et al. 1991.)