The rabbit in continental Europe




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Table 3.7 Reproductive parts of plants found in faecal pellets of rabbits in Spain, illustrating their role in seed dispersal


Species Year Number Dry matter off take

Species Part of plant



(t. day- ')

Corema album

Cistus salvif olius

complete fruit capsules with seeds



Coypu 1977-78 50 0.017 Halimium halimif olium -ditto-

Grasshoppers

1977




0.020

L av andula stoechas

flowers and seed

Horses

1976

26

0.356

A rmeria gaditana

flowers and fruits




1977

35

0.466

A sphodelus aestiv us

-ditto-

Rabbits

1976

838

0.087

Juniperus phoenicea

buds, fruit and seed




1977

670

0.067

Rosmarinus officinalis

old flowers and seed

1983 3450 0.352 Olea europea

Pistacia lentiscus

Data from various sources in Duncan (1992). P. terebinthus

Retama sphaerocarpa

Juncus buf onius

Trif olium spp.

whole ripe fruit

ripe fruit

-ditto- seed

-ditto-

-ditto -


list the seeds of 16 species found in the faecal pellets A sparagus aphy llus fruit and seed

of rabbits in Spain. All were checked and found to

germinate normally.



Philly rea augustif olia -ditto -


Source: Soriguer (1981b).

3.5 Population ecology


The population ecology of the rabbit is not very well- known in many countries of Europe. We have used European data when they are available, but have otherwise largely relied on data from Spain and France. Those from Spain are from Andalucia, the main study areas being of evergreen-oak forest (highland) and olive forest and scrub (lowland). Much of the French data comes from three areas where many studies have been done: in the north, Ile-de-France, the area around Paris, the landscape is predominantly agricultural, but with extensive woodland, and the climate temperate; in the south the Vaucluse is an upland area with a Mediterranean climate; and southernmost is the Camargue, a flat, saline, deltaic area on the Mediterranean coast.

3.5.1 Reproduction
Just as there is a latitudinal gradient in rabbit weights, so there are clear trends in the length and ti ming of the reproductive season (Table 3.8). The

larger rabbits of northern France and Sweden start breeding later and continue longer (180 days or more) than the smaller rabbits of the south of France (96 days); in Mediterranean areas the season starts earlier still, but its end is very variable.

Seasonal patterns of reproduction in males are

clear throughout Europe, with latitudinal trends. Indices of testicular activity, for example size and position of testes, tend to start rising slightly earlier in the south of Spain (Fig. 3.11) than in the south of France (Fig. 3.12), with variations from year to year, but clearer is a tendency to later decline in testicular indices in the north of France than in the south (April-May) (Fig. 3.13).

Male rabbits can reach sexual maturity at 6

months of age in France, although 8-9 months is the average (Rogers 1979; Arthur 1980); in Sierra Morena (southern Spain), Soriguer (1981a) reports 4-5 months.

In the north, gravid females may be found from

early March to mid-August or even mid-September;




Table 3.8 Reproductive season of rabbits for various places in Europe
Locality First pregnancies Last pregnancies Length of

Spain SW

Month

Week

Month

Week


season (days)

November

1

May

3

210


S1

(dry)

January

1

March

1

90

S2

(irrigated)

October

2

June

2

210

Portugal S




September

3

April

4

240

Spain N




December

2

August

1

270

France S

(Camargue)

January

2

May

1

96

C

(Vaucluse)

January

2

June

1

142

N

(Paris)

February

1

July

3

192

Holland




March

2

July

3

150

Sweden




March

3

August

2

180

Source: Andersson et at. (1979); Arthur (1980); Arthur and Gaudin (unpublished); Lopez Ribeiro (1981); Soriguer (1981a); Vandewalle

(1989); Wallage-Drees (1983).


Fig. 3.11 Changes in testis weights of rabbits from 3 plots in southern Spain from 1980 to 1982 (Soriguer unpublished). (-

- - -) Plot 1, irrigated throughout all years. ( - -) Plot 2, seasonal rainfall only in 1980, irrigated throughout thereaf-

ter. ( ) Plot 3, no irrigation, seasonal rain only.



in the south of France, from early January to the end of May; and in southern Spain from December or earlier, to March assuming a dry spring, sometimes later, except on irrigated plots or in exceptional years. The proportion of females that are gravid tends to rise throughout the season, as do other indices of fertility in females (ovary weight, numbers of corpora lutea, in utero litter size); 95 per cent of

births in the Camargue were recorded between the

6th and 22nd week of the year (Table 3.9; Rogers

1979; Vandewalle in preparation).

In southern Spain most females become gravid at

3-4 months, whereas in the south of France, where

adult weights are 10-15 per cent more, the equival- ent age is up to 6 months. In all regions, rabbits are just capable of reproducing in the year of their birth,




Fig. 3.12 Indices of male fertility in rabbits at La Tour du Valat, southern France, 1975-77 (after Rogers 1979).


though they have more opportunity to do so in the south. However, the contribution made by first-year females to recruitment is questionable, given that they are less fecund than adults, and that they must give birth late in the season when the quality of food is poorer (Rogers 1979).

In general, litter sizes are smaller in the south of Europe than in the north; this may, in turn, be associated with the smaller body size of rabbits in the south (Soriguer 1981a, 1983b). Average litters are around 3 or 4 in the south of Spain. In the south of France, they average about 5 versus 4.5 in the north (Tables 3.10; 3.11), but the season is shorter and the average female produces only 10 to 13 young per year in the south of France versus about 17 in Ile-de- France.

Whilst the reproductive cycles of both males and females appear to be fundamentally linked to photo- period, geographical patterns of reproduction sug- gest that changes in temperature and rainfall can modify both the beginning and the end of the repro- ductive season. For example, at the beginning of the

reproductive season, low temperatures affect both male fertility (Figs. 3.11-3.13) and the weight of the uterus (Fig. 3.14). Conversely, ambient summer temperatures in the Mediterranean are close to the upper limits for spermatogenesis in other lago- morphs (Terroine and Trautmann 1937; Hart et al.

1965). In the Camargue, reproduction may start late if the previous winter was unusually wet and cold

(Vandewalle personal communication), and stop early in a dry summer. In Ile-de-France, drought reduces pregnancy and lactation rates, whereas in the south of France, early autumn rain stimulates new vegetative growth and a second reproductive season. The difference in reproductive seasons on irrigated and unirrigated plots near Cadiz (southern Spain), shown in Table 3.8, is consistent with the effect of rainfall elsewhere.

Soriguer and Myers (1986) planned a field ex- periment to test the effects of climate and food on reproduction in rabbits in southern Spain, their presumed ancestral home. They showed that both male and female reproductive cycles can be pre-




Fig. 3.13 Changes in rabbit testis weights (mean ± standard deviation) in (a) the Camargue and, (b) near Paris (after Arthur 1980 and Vandewalle 1989).


dicted from a combination of climate, food availabil- ity, and food quality, although the effect of each may vary between sexes (Table 3.12). Male reproduction is influenced mainly by climatic factors, particularly radiation and temperature, which accounted for 65 to 79 per cent of the variance. Mineral elements in food accounted for only some 5-10 per cent of the variation in males, and the organic components were not relevant. For females, climate was also import- ant, but less so than the quality (organic and inorganic fractions) of food.

In summary, therefore, the rabbit's reproductive

activity in Europe is governed by climate within a framework of photoperiod, particularly winter con- ditions in the north, and summer conditions in the south. Food quantity and quality, also influenced by climate, have a lesser role, albeit an important one, influencing mainly the length of the breeding season. The rabbit's reproductive cycle fits the broad seasonal pattern of the Mediterranean climate. But Mediterranean weather is unpredictable; our experi-

ence is that exceptional years seem to be normal! The rabbit is well placed to take advantage of them as they arise.



3.5.2 Survival and mortality
Survival and mortality again show distinct regional differences. The survival rate of the young rabbits in southern Spain is much lower than in France. Con- versely, amongst adults the average survival rates are much higher in Spain. At the three sites within France survival rates are similar (Table 3.13).

In Ile-de-France there are two important periods



of adult mortality, May-July (15-20 per cent per month) and September-October (20 per cent). From January to April, adult mortality is almost nil (Fig.

3.15). For all ages combined, monthly mortality in the 11e-de-France samples ranged from a high of 34 per cent from May to July, dropping to an average of



20 per cent until December, and then less than 10 per

cent from January to April (Arthur unpublished). In



44 P. M. Rogers, C. P. A rthur, and R. C. S origuer

Table 3.9 Proportion of female rabbits pregnant each month across Europe


Month

Spain









Portugal




France




Holland

Sweden




SW

S1


S2a

N

S




S

N

NW

S


January

0.36

0.60

0.29

0.20

0.11




'0.0



0.0


0.0


0.0

February

0.55

0.33

0.67

0.78

0.22




0.05

0.28

0.0

0.0

March

0.69

0.33

0.22

1.00

0.75




0.65

0.77

0.12

0.20

April

0.65

0.0

0.0

0.86

0.67




0.68

0.57

0.12

0.71

May

0.38

0.0

0.0

0.67

0.0




0.61

0.80

0.36

0.59

June

0.0

0.0

0.10

0.25

0.0




0.21

0.65

0.07

0.68

July

0.0

0.0

0.0

0.67

0.0




0.0

0.65

0.01

0.56

August

0.0

0.0

0.0

0.27

0.0




0.0

0.44

0.0

0.13

September

0.0

0.0

0.0

0.0

0.11




0.0

0.32

0.0

0.0

October

0.0

0.0

0.14

0.0

0.31




0.0

0.07

0.0

0.0

November

0.30

0.0

0.29

0.0

0.20




0.0

0.0

0.0

0.0

December

0.36

0.0

0.05

0.05

0.67




0.0

0.01

0.0

0.0

Mean

0.28

0.10

0.15

0.40

0.25




0.18

0.38

0.06

0.24

° Irrigated plot. Sources:

France S-Camargue: Rogers (1979). Vandewalle (in preparation). France N-Ile-de-France: Arthur (1980 and unpublished data). Holland: Wallage-Drees (1983). Data are frequency of births. Portugal: Lopez Ribeiro (1981).

Spain (north): Ceballos (unpublished).

(south): Soriguer (1981a, 19836); Soriguer and Myers (1986). Sweden: Andersson et al. (1979).

Table 3.10 Some mean annual reproductive parameters of wild rabbits in France and Spain




Camargue

Vaucluse

Paris region


Andalucia



% pregnant

Length of reproductive


64 ± 6

58 ± 18

64 ± 9





season (days)

Date of first conception

(week number) No. of pregnancies


94 ± 30

2

(1-7)



142 ± 31

2

(1-6)



174 ± 10

5

(1-8)



90-150

per female

No. of embryos



2.0

2.7

3.4




per female

No. of live births



4.9 ± 0.4

5.0

4.4-0.3

3.7

per female per year

9.8 ± 3.0

13.1 ± 4.2

17.4 ± 2.7





Sources: C. P. Arthur (Paris-unpublished); C. P. Arthur and Gaudin (Vaucluse-unpublished); P. M. Rogers

( Camargue litters-1979); R. C. Soriguer (Andalucia-unpublished); P. Vandewalle (Camargue other-unpublished).

Table 3.11 Litter sizes of rabbits in Europe and the Mediterranean

Location

Mean litter size

Source

Spain








NW Andalucia

3.21

Soriguer (1981a)

SW Andalucia

3.88

Delibes and Calderon (1979)

Navarra (N. Spain)

4.11

Ceballos (in prep.)

France







Camargue

5.20

Rogers (1979)




4.89

Vandewalle (in press)

Vaucluse

5.00

Arthur and Gaudin (unpublished)

Ile-de-France

4.40

Arthur (unpublished)

Holland

5.00

Wallage-Drees (1989)


Sweden (S)

4.70

Andersson et al. (1979)



Great Britain







Wales

4.36

Stephens (1952)

Caernarvonshire (1941)

4.89

Brambell (1944)

Caernarvonshire (1942)

5.64

Brambell (1944)

Morocco

3.7

Soriguer (unpublished)






Fig. 3.14 Relationship between uterus weight and ambient temperature in rabbits near Paris, 1977-79. Source: Arthur

(unpublished).




46 P. M. Rogers, C. P. A rthur, and R. C. S origuer

Table 3.12 Canonical correlation coefficient (CCR) and probability (in parentheses) for reproductive correlates of rabbits in southern Spain
Canonical variables CCR-males CCR-females

A

Climate + food availability

0.87

(<10- 4 )

0.84



(<10')

B

Organic fraction

0.65

(0.06)

0.75

(0.03)

C

Inorganic fraction

0.71

(0.002)

0.82

(0.001)




A+B+C

0.98

(0.003)

0.99

(<10')

Source: Soriguer and Myers (1986).



Table 3.13 Survival rates (%) of wild rabbits in France and Spain

Age (months)


Spain

France










South

Camargue

Vaucluse

Paris region


0-3 a


16


32


34


25

4 b -8

63

58

52

26/49'

adult

85

58

42

52/58'

3.7 months for the Spanish data.

3.8 months for the Spanish data.

26 and 52 in years with hunting, 49 and 58 in years without hunting.

Source: Arthur (1980), Soriguer (1981, 1983a) and unpublished data from C. P. Arthur, J. C. Gaudin, and P. Vandewalle.


the Camargue, monthly mortality (all ages) also peaks in April and July. During periods of reproduc- tion it reaches 20-30 per cent; in autumn and winter it falls to 5-10 per cent (Rogers 1979). We have few data available on causes of mortality in Europe. Pos- sibilities include hunting, predation, myxomatosis, other diseases, flooding, and injuries, for example from farm machinery.

Survival rates of rabbits over 4-months-old in the three French populations were fairly similar (averag- ing 42-58 per cent) when they were not hunted- that is, in the Camargue and the Vaucluse all the time, and in the Ile-de-France in some years. But in the years with hunting in Ile-de-France, the mortal- ity of 4-8-month-old rabbits was markedly higher, although the adults were little affected.

Arthur collected dead rabbits whenever he found them throughout a four-year study in Ile-de-France.

Excluding over 1000 rabbits that were shot, for the other 419 rabbits collected, the most frequent causes of death were predators or myxomatosis (Table

3.14), followed by injuries and various diseases (pasteurella, staphylococcus, coccidia, pseudotuber- culosis). Agricultural operations (especially mowing and harvesting) were an important hazard for younger rabbits. The importance of predation and myxomatosis was confirmed by radio-tagging rab- bits from the same population in non-hunting years (Table 3.15).

In the north, the most important predators of young rabbits are mustelids, and of older rabbits, foxes. However, foxes take many young as well: they may be responsible for 30-50 per cent of nestling mortality in spring (Arthur 1980; Mulder and Wal- lage-Drees 1979), when young rabbits may comprise

70-80 per cent of the diet of foxes (Fig. 3.16; Julliot




Fig. 3.15 Monthly mortality rates near Paris (a) of rabbits (>4 months) with radio tags, using Trent and Rongstat's (1974) method, 1984-86 years pooled (Arthur unpublished), (b) of marked adult (>9 months) rabbits, 1980-81 (Arthur

unpublished), (c) of rabbits known to be alive (all ages >1 month), 1979-80 (Arthur unpublished).




1987). Mortality from myxomatosis may be 10-50 per cent, according to year and season, and evidently influences more immediate causes of death.

In the Camargue, most mortality is due to a com- bination of predation and myxomatosis (Rogers



1979). Myxomatosis facilitates predation, since the proportion of rabbits in the diet of foxes rises to 70 per cent during myxomatosis epizootics, or during

flooding (Reynolds 1979). As rabbits can recover from severe myxomatosis that must affect their susceptibility to predation, the two must to some degree be additive. Over three years myxomatosis was responsible for 13-25 per cent of total mortality


annually (Vandewalle 1986; Arthur 1988), while in the Vaucluse it varied from 10 to 50 per cent over three years (Arthur and Gaudin in press).

In the west Mediterranean in general, and in southern Spain in particular, the number of species of predator is exceptionally high (Table 3.16). Fur- thermore rabbits are an important item of most predators' diet, especially in southern Spain, where, with the exception of wolf, all predators of medium and large size (3 kg for mammals, 1.5 kg for birds) rely to a large extent on rabbits for food (Delibes and Hiraldo 1981; Jaksic and Soriguer 1981; Soriguer

1981a, 1981b, 1983b; Soriguer and Rogers 1981).


Table 3.14 Causes of death of rabbits found dead in Ile-de-France, in four body-weight classes


<300 g 300-1000 g Immature/

Adult


sub-adult (>9 months)



n

%

n

%

n




%

n




%


Predation


33

34.3

19

22.1




31



29.8





55


41.7

Myxomatosis

0

-

26

30.2




48

46.2




38

28.8

Road kill

19

19.8

11

12.8




7

6.7




7

5.3

Injuries/disease

Agricultural



0

-

15

17.4




11

10.6




20

15.1

machinery 8 8.33 7 8.1 5 4.8 2 1.5

Unknown

27

28

8

9.3

2

1.9

10

7.6

Total

87




86




104




132



Source: Arthur (1950).



Table 3.15 Causes of death of radio-tagged rabbits in the Paris region during a three-year study


Myxomatosis Other

Predation Road kill Miscellaneous Number




disease










tagged

Juveniles (<1000 g) Adults and sub-adults

(>1000 g)



5
12


5
5


6
9

4
2




3
4


45
92

Source: C. P. Arthur-unpublished data.



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