|
|
 |
|
|
|
|
|
Red
|
Grey
|
|
|
|
|
|
|
Av. Weight
|
grams
|
300
|
530
|
|
Population density
|
per Ha
|
1.4
|
8.0
|
|
Total body weight
|
grams per Ha
|
420
|
4,240
|
|
Ratio (bodyweight)
|
|
1
|
10
|
|
Calorific requirement
|
each animal-kJ/year
|
147,000 (i)
|
191,000 (ii)
|
|
Calorific requirement
|
per Hectare
|
205,800
|
1,528,000
|
|
Ratio (calories)
|
|
1
|
7
|
|
Litters
|
p.a.
|
2
|
2
|
|
Litter size
|
young
|
3
|
3
|
|
UK population in 1998 estimated (iii)
|
|
140,000
|
2.5 million
|
|
|
|
|
|
|
Notes:
|
|
|
|
|
(i) Gurnell 1987
|
142,026
|
|
|
|
Gronwall 1982
|
152,716
|
|
|
|
|
|
|
|
|
(ii) Ludwick 1969
|
209,218
|
|
|
|
Montgomery 1975
|
173,309
|
|
|
|
|
|
|
|
|
(iii) During the six years since 1998, the grey figure will have grown and the red fallen.
|
|
|
