In the present study, we aimed at investigating adult silver and blue fox vixens’ preference for differently placed nest boxes with respect to height. Moreover, we
attempted to evaluate the animals’ preferences for box types with a varying number of rooms, with entrance rooms or platforms and, finally, preferences between dark nest
boxes and light nest boxes with a transparent roof. Individual foxes with no previous permanent box experience were given free choice between two boxes that only differed
by a single parameter.
2. Animals, materials and methods
2.1. Subjects and housing Ž
. Studies were carried out during autumnrwinter using adult silver fox N s 50 and
Ž .
blue fox N s 50 vixens in their first year of life. The animals were randomly chosen from the unrelated offspring of 200 vixens of each species. Litters were raised under
Ž .
conventional farm conditions in 75 = 100 = 120 cm H, W, D wire cages. Experimen- tal animals were transferred to individual housing in two-row fox sheds with equally
distributed roof windows and with five cages in each row. The cages measured Ž
. 75 = 200 = 200 cm
H, W, D and were divided by a central partition with a small opening allowing the animals to move freely between the left and right compartments.
Solid plates between the experimental cages obstructed the animals’ view to neighbours
Fig. 1. Types of nest boxes.
and the cages were either left bare or supplied with a nest box in each of the compartments. There were three types of nest boxes all made on the basis of a closed
Ž .
plywood box measuring 40 = 40 = 120 cm H = W = D and supplied with two internal Ž
. partitions dividing the box into three equally sized rooms 40 = 40 = 40 cm . Admission
to the box was possible through 20-cm circular holes in the front and in the two internal partitions. Closing the holes in one or two of the internal partitions reduced the number
of accessible rooms in the box. Removing the roof, front, and the cage-directed wall of the first room and closing the hole in the innermost partition left a platform in front of a
one-room box with free view to the cage. Replacing the roof with transparent material
Ž .
increased the light conditions in a three-room box see Fig. 1 . 2.2. Design
Ž .
Each species group was randomly divided into five experimental groups N s 10 , which were subjected to the following choice conditions and periods in separate fox
Ž . Ž
houses: 1 the left or right compartment in an empty experimental cage for 2 silver .
Ž . Ž .
foxes or 4 weeks blue foxes ; 2 the left or right compartment supplied with a high or Ž
. Ž
. low difference in height 35 cm placed three-room nest box for 8 silver foxes or 16
Ž . Ž .
Ž .
weeks blue foxes ; 3 a three-room or one-room box for 2 silver foxes or 8 weeks
Table 1 Silver fox vixens choice experiments
Experimental condition, experimental week, calendar month, and percent distribution of the elements position Ž
. Ž
. Ž
. Ž
. Pos. , actiÕe Act. passiÕe Pas. , and in nest box Box in the left- and right-hand compartments.
Ž .
Exp. condition Exp. weekr
Mean percent recordings N s10 calendar month
Left Right
Left Right
Pos. Act.
Pas. Box
Pos. Act.
Pas. Box
No box no box
1rNov 52
17 35
– 48
19 29
– No box
no box 2rNov
55 19
37 –
45 20
24 –
UU UU
Box high box low
1rDec 56
15 25
16 44
20 20
4
UUU
Box high box low
2rJan 60
17 20
23 40
20 17
3
UU UU
U
Box high box low
3rJan 60
14 28
18 40
12 17
1
UU UUU
UU
Box high box low
4rJan 64
15 30
19 36
15 19
2 Box low
box high 5rFeb
45 20
15 10
55 21
27 7
Box low box high
6rFeb 45
10 25
10 55
16 31
8
U UU
U
Box low box high
7rFeb 40
13 19
8 60
17 31
12
U UUU
U
Box low box high
8rFeb 36
14 20
2 64
18 30
16
UU UUU
UUU
1 Room 3 room
1rOct 29
15 13
1 71
22 27
22
U UU
UUU
1 Room 3 room
2rOct 32
15 14
4 68
22 28
18
UUU UUU
Platf. entrance room
1rDec 66
18 16
32 34
17 12
5
UUU UUU
Platf. entrance room
2rDec 67
21 15
30 33
17 12
4 Light
dark 1rJan
43 10
9 24
57 14
12 31
Light dark
2rJan 39
9 5
23 61
15 7
40
U
p- 0.05.
UU
p- 0.01.
UUU
p- 0.001.
Table 2 Blue fox vixens choice experiments
Experimental condition, experimental week, calendar month, and percent distribution of the elements position Ž
. Ž
. Ž
. Ž
. Pos. , actiÕe Act. passiÕe Pas. , and in nest box Box in the left- and right-hand compartments.
Ž .
Exp. condition Exp. weekr
Mean percent recordings N s10 calendar month
Left Right
Left Right
Pos. Act.
Pas. Box
Pos. Act.
Pas. Box
No box no box
1rNov 47
18 29
– 53
20 33
– No box
no box 2rNov
50 17
33 –
50 15
35 –
U
Box high box low
1rDec 56
8 30
21 41
7 19
15
U U
Box high box low
4rDec 62
9 28
25 38
6 21
11
UUU UUU
Box high box low
8rJan 70
7 29
34 30
5 21
4
UU UU
Box high box low
12rFeb 61
7 26
28 39
7 25
7 Box low
box high 13rFeb
55 12
29 14
45 13
21 11
Box low box high
14rMar 61
15 31
15 39
12 16
11
U UU
Box low box high
15rMar 41
10 19
12 59
9 32
18
UU UU
U
Box low box high
16rMar 37
14 8
15 63
11 29
23
U
1 Room 3 room
1rNov 43
8 24
11 57
10 25
22
U
1 Room 3 room
2rNov 41
7 24
10 59
10 26
23
UUU UU
UU
1 Room 3 room
7rDec 22
5 9
6 78
10 23
45
UU UUU
UUU
1 Room 3 room
8rDec 23
7 9
7 77
8 27
42
UU U
Platf. entrance room
1rJan 33
7 21
6 66
10 15
41
UU U
Platf. entrance room
2rFeb 37
9 22
6 63
9 17
37 Light
dark 1rFeb
52 10
21 21
48 8
19 21
Light dark
2rMar 41
9 29
20 59
13 22
24
U
p- 0.05.
UU
p- 0.01.
UUU
p- 0.001.
Ž . Ž .
blue foxes ; 4 a one-room nest box with an entrance room or a one-room box with a Ž .
platform for 2 weeks in both species; and 5 a dark or light three-room nest box for 2 weeks in both species. Height of boxes under condition 2 was switched between the left
Ž .
Ž .
and right compartments after 4 silver foxes or 12 weeks blue foxes . Likewise, under condition 2, access to the area above and below the boxes was prevented by vertical
wire mesh. Under conditions 3–5, all boxes were placed high in the cages due to the results obtained under condition 2.
Prior to experiments, all animals were allowed a 2-week adaptation period to the experimental conditions. The duration of choice conditions depended upon practical
constraints, but was fixed to a minimum of 2 weeks since reliable results were obtained under the first highrlow condition within that period.
The time course of experiments is shown in Tables 1 and 2. 2.3. ObserÕations
After the 2-week adaptation period, foxes were individually video-recorded during weekly sets of five consecutive 24-h periods. Tapes were analysed by scanning
observations every 15 min, giving a total of approximately 480 observationsrindivid- ualrweek. The following elements were recorded:
Position in left and right compartments ActiÕe in left and right compartments
PassiÕe in left and right compartments In left or right nest box
2.4. Statistical analysis Ž
. Wilcoxon tests Siegel and Castellan, 1988 were applied to individual scanning
observations within each experimental group. Levels of significance as indicated in the tables imply that 0, 0–1, or 1–2 individuals chose differently at p - 0.05, p - 0.01, and
p - 0.001, respectively.
3. Results
