Full text of DOI:10.1007/BF03193566

Acta Theriologica 47 (1): 55–62, 2002.
PL ISSN 0001–7051
Home ranges of European mink Mustela lutreola
in southwestern Europe
Inazio GARIN, Inigo ZUBEROGOITIA, Jabi ZABALA, Joxerra AIHARTZA,
Anthony P. CLEVENGER and Ana RALLO
Garin I., Zuberogoitia I., Zabala J., Aihartza J., Clevenger A. P. and Rallo A. 2002.
Home ranges of European mink Mustela lutreola in southwestern Europe. Acta
Theriologica 47: 55–62.
We radiotracked 7 European mink Mustela lutreola Linnaeus, 1761 (5 males and 2
females), to determine their distribution, size and temporal changes of their home
range in an area of southwestern Europe, where American mink M. vison was not
established. Size of home ranges varied from 11 to 17 km along watercourses in males
and were 0.6 and 3.6 km in females. Home ranges of males were larger than those
found in previous studies. Most females captured (either radiotracked or not) were
found within the home range of males. Males occupied adjoining river sections with
minimal range overlap, suggesting an intrasexually exclusive spacing pattern for males.
Each month males used new river stretches, mainly along tributaries; meanwhile they
showed a steady use of their stem river section. Resting sites were mainly beneath
dense brambles of Rubus patches located in the river bank.
Zoologia eta AZD Saila, UPV/EHU, 644 PK, E-48080 Bilbao, Basque Country, e-mail:
zopgaati@lg.ehu.es (IG, IZ, JZ, JA, AR); Faculty of Environmental Design, University
of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada (APC)
Key words: Mustela lutreola, home range, radiotracking, semi-aquatic carnivore, spatial
organisation
Introduction
The endemic European mink Mustela lutreola Linnaeus, 1761 is the smallest
species of the semi-aquatic carnivore guild in Europe. Its populations have
decreased for last centuries. Although no single factor could be identified as
responsible for the decline (Maran and Henttonen 1995, Sidorovich et al. 1995),
recent studies suggest that the introduced American mink Mustela vison may be
displacing the endemic species from some areas (Maran et al. 1998, Sidorovich et al.
1999). Currently, the European mink can be found in two major areas: one in the
east with the larger populations in Russia and another in the southwestern
European countries near the Bay of Biscay. Both populations are separated by more
than 2000 km (Youngman 1982).
It has been suggested that the size of home range in male solitary carnivores,
during the mating season, is mainly determined by the distribution of females;
[55]

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I. Garin et al.
whereas, size of home range of females is determined by the availability of food
(Erlinge and Sandell 1986, Genovesi et al. 1997, Schmidt et al. 1997). In addition,
males of these species exhibit larger home ranges than females; with male ranges
encompassing those of females (Lockie 1966, Dunstone 1993, Kruuk 1995, Ferreras
et al. 1997, Genovesi et al. 1997). Finally, Sandell (1989) suggested that if males are
territorial, their home range size does not change through seasons.
Surveys based on footprints and track data found that home ranges of European
mink were about 2.4 km in length (Danilov and Tumanov 1976 cit. in Youngman
1982, Sidorovich et al. 1995). Only one radiotracking study on home range size of
the species is published. Palazón and Ruíz-Olmo (1998) found that home range of
M. lutreola was slightly larger than 6 km. However, since they could only survey a
small number of individuals for more than a week, home ranges were probably
underestimated. The size of home range of other semi-aquatic carnivores of Europe
is 20–40 km in the Eurasian river otter Lutra lutra (Green et al. 1984, Kruuk 1995)
and 1–6 km in the American mink (Gerell 1970, Birks and Linn 1982).
Little is known of habitat requirements and spatial patterns of European mink.
This knowledge would permit determination of the carrying capacity of similar
areas for the species, and offer the framework for studies on its habitat use. In our
study, we describe the seasonal home range pattern of a population of European
mink inhabiting an area of southwestern Europe where American mink are not
established. Our aims were to determine the home range size of European mink, to
assess the changes of home range through seasons and to establish their spatial
arrangement.
Study area
This study was conducted in the Urdaibai Biosphere Reserve (UBR, 43°29’N, 2°40’W), Basque
Country, southwestern Europe (Fig. 1). It is a hilly 230-km2 area that encompasses the catchment of
the Oka River. Elevational range is 0–900 m, and climate is typically oceanic. Mean temperatures are 6
and 18°C (January and July, respectively) and average annual rainfall is 1400 mm. Major landscape
units are: forest (54%), mainly plantations of exotic species (Monterey pine Pinus radiata and
eucalyptus Eucalyptus globulus) and holm oak Quercus ilex, woodlands, meadows and cultivated fields
(29%), estuarine mudflats and saltmarshes (5%), and urban areas (5%) (Arrieta et al. 1993, Aldai and
Ormaetxea 1998). The human population of ca 44 000 is mainly clustered in the towns of Gernika and
Bermeo, both having a population of 18 000. The Oka River and tributaries show low pollution levels,
except near the main towns where levels of nutrients and heavy metals are high (Rodríguez and Cid
1995).
Material and methods
Animals were live-trapped in single entry cage traps (25 ´ 25 ´ 45 cm). Three trapping sessions
were conducted in streams: 877 trap-nights from February to March 1999, 621 trap-nights in
September 1999, and 111 trap-nights in January 2000. Mink were immobilised with 0.8 mg of Zooletil
(Virbac, Carros, France) per 100 g of animal weight, and collared with radiotransmitters (Biotrack,
Dorset, UK).

Home range of European mink in southwestern Europe
57
Table 1. Survey data, home range size and number of resting sites of European mink.
Home range
Resting sites
(no./km)
Number
of days
tracked
(km)
Loca-
tions
Mink Sex
Survey period
Stem
river
Day
time
Total
Night
M1
M2
M3
M5
M6
F1
M
M
M
M
M
F
March–May 1999
19
20
56
32
48
21
19
30
39
87
52
71
27
24
11.1
11.8
11.2
16.8
12.7
3.6
2.5
6.5
3.7
11.2
6.5
0
1.2
1.3
0.3
0.3
1.4
0.5
1.0
0
February–April 1999
February–October 1999
March–August 1999
September 1999 – February 2000
March–May 1999
2.4
1.1
2.0
1.4
F3
F
January–March 2000
0.6
0.3
10.3
0
In February, we trapped 7 mink (5 adult males and 2 adult females). One of the females, noticeably
pregnant, was released without a transmitter. Two adult male mink were caught in September, one of
them previously captured and surveyed. In January 2000, we captured two adult females. European
mink were the only stream-dwelling mustelid captured. Tagged individuals and tracking periods are
summarised in Table 1. Two individuals were not considered for analysis: M4, which was found dead
during a blizzard 3 days after capture, and female F4, found dead at release site several days later.
A hand-held 3-element Yagi antenna and TRX-1000S radio-receiver (Wildlife Materials Inc.
Carbondale, Illinois, USA) were used to monitor movements. Radiotracking was carried out weekly.
Full night surveys were performed, lasting from 3–4 hours before dusk to 1–2 hours after dawn and
recording a minimum of one location every hour. Additionally, we gathered several daylight radio-
locations in a non-systematic basis. Telemetry fixes were achieved by homing-in and located in a map
to the nearest 100 m. Animals were classified as either active or inactive according to the level of
variations in strength of radio signals (Kenward 1987). Distance measurements were made after
transferring the locations into a Geographic Information System (Arcview 3.2. ESRI, California, USA).
As minks are usually associated with streams (Youngman 1982) two-dimensional home range
estimators represent an overestimate of movements (White and Garrott 1990). Hence, home range was
calculated as meters of waterway used by mink. This home range estimation procedure has no
statistical basis, and thus, over the sampling schedule used, the estimate is unlikely to be affected by
time-dependent data. However, to avoid inflation of sample size with locations that contributed little
or no additional information (White and Garrott 1990), we performed time-independence analysis for
consecutive nightime radio fixes using the Schoener’s index, as suggested by Swihart and Slade (1985,
1986). The minimum time interval between independent night fixes was 2 h. Therefore, only
consecutive fixes separated by more than 2 h were considered. Among successive inactive fixes only
one location was picked up for analysis.
Results
Males occupied adjoining home ranges which covered most of the length of the
main rivers in the Urdaibai Biosphere Reserve (Fig. 1). Male home ranges spanned
from 11.1 to 16.7 km (x = 12.7 km, n = 5). Mink occupied rivers measuring 5–10 m
wide to streams less than 1 m in width, and also nearby marshes. Length of stem
river, defined as the river of higher order that provides direct access to water-
courses of lower order, ranged from 2.5 to 11 km (x = 6.0 km, n = 5; Table 1).
Inter-individual variation in home range size was not significantly related to the

58
I. Garin et al.
number of locations or to the num-
ber of survey days (Spearman Rank
test: rS = 0.6, p = 0.23 for both).
Mean monthly home range size
was 6.0 km (SD = 2.3 km, n = 24)
and it was significantly different be-
tween individuals (Kruskall-Wallis
test: H = 9.5, df = 4, p< 0.05; Fig. 2).
No significant correlation was found
between the monthly home range
size and the number of locations or
the number of survey days per month
(rS < 0.36, p > 0.07 for both).
No encounters were recorded be-
tween radiocollared individuals. In
2 out of 20 direct sightings, radio-
tracked males were accompanied by
an untagged mink, although we could
not determine its sex or status. Co-
etaneous males with adjoining home
ranges overlapped in 2 cases out of
5, the extent of overlap being 3–10%
of their home ranges (Fig. 1).
N
0
5 km
Fig. 1. Spatial distribution of home ranges of Euro-
pean mink in Urdaibai Biosphere Reserve. Streams
inhabited by the surveyed minks are encircled and
stars show location of non-surveyed minks. Over-
lapping areas between home ranges of adjoining
males are shown by hatching. M2 and M6 occupied
the same home range in different periods.
From September 1999 to January
2000, M6 occupied almost the same
length of river as did M2 during
February–April 1999. In fact, their
overall home ranges overlapped for
as much as 84 and 85%, exploiting almost the same main length of stream (Table 1).
On the other hand, despite the intensive trapping effort made in September 1999
within the former home range of M2 (near 500 trap-nights), only mink number M6
was captured there (captured 3 times at different sites).
We periodically recorded on the extreme ends of the stem river section.
Meanwhile, almost every month males entered river stretches that were not
previously used (Fig. 2). From the 3rd month of survey, 93% (range 70–100%, n =
5) of the length of these new stretches were along tributaries of the stem river.
Overall, the tributaries encompassed 38
24.0% (n = 27) of the monthly home
ranges and use of some tributaries changed seasonally.
All captured females except F1 were caught within the home range of tracked
males (Fig. 1). F1 ranged along 3.6 km of a small stream and nearby marshes, and
F2 used only 0.6 km along a stem river.
We found 144 dens, most beneath dense brambles of Rubus shrub patches
located in river banks (n = 129), and reeds (Phragmites australis and Arundo

Home range of European mink in southwestern Europe
59
M5
12
5/3
13/9
10
M1
5/4
8
6
4
2
0
8
6
4
2
0
10/6
7/5
9/6
11/7
8/5
13/6
Mar Apr May
Mar Apr May Jun Jul
Aug
M2
M6
10
8
14/12
11/9
15/12
16/12
19/9
8
6
4
2
0
11/6
6
8/7
8/6
8/5
4
2
0
Feb
Mar
Apr
Sep Oct Nov Dec Jan Feb
M3
17/12
8
6
4
2
0
12/6
13/9
7/3
13/6
12/9
5/4
6/5
2/2
Feb Mar Apr May Jun Jul
Aug Sep Oct
Month
Fig. 2. Monthly size of home range (in kilometers along watercourses) of five male European mink. The
dark sections represent the length of the stretches used by first time and the light sections represent
the length of the stretches that were reused. Numbers above bars are number of radiolocations and
number of days surveyed.
donax) in the marsh (n = 13). In most cases we could not determine if they were in
burrows or on simple couches, but the signal strength suggested that animals were
always on the soil surface. However, female F1 often used a burrow in a reed patch
during the breeding season. Male M6 was twice found during the daytime beside an
underground waste collector tube opening into the bank and 5–6 m from it, resided
under the pavement of an occupied dwelling. All night resting sites were used once,
and daytime den use averaged 1.3 (SD = 1.0, n = 99) for males.

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I. Garin et al.
Discussion
The home range size of male and female European mink differed greatly in the
Urdaibai Biosphere Reserve: males used home ranges from 11 to 17 km, whereas
values for females were between 0.6 and 3.6 km. In their study of home range of
European mink in the southwestern area, Palazón and Ruíz-Olmo (1998) measured
movements of 6–8 km for males and 4.5 km for females. However, their tracking
periods did not last beyond 2 months for any individual and the values for males are
well within the range of sizes we calculated for a single month. This suggests that
the size of their long-term male home ranges would be similar to ours. The two
females surveyed in our study and the one tracked in the work of Palazón and
Ruíz-Olmo (1998) does not allow further comparison.
Although home ranges of some males overlapped, the length of overlap was
small and in general, males used separate river sections. This result agrees with
Sidorovich’s (2000) in the eastern range, since he did not observe simultaneous
presence of individuals of the same sex in the same place. Sandell (1989) considered
less than 10% overlap as a strong indicator of exclusivity of home ranges. Only 2
males were tracked within the same range (M2 and M6). But in that case, they were
surveyed at different periods and despite the large trapping effort they were not
captured at the same time. Thus, we believe M6 replaced M2 after the latter
disappeared. The distribution of sexes at the UBR suggests that the range of
females are encompassed by that of males, although our data do not allow to
determine the number of females included within the male range. The maintenance
of exclusive male home ranges may be the best spatial tactic when numbers of
females are high and evenly distributed, so that males can monopolise some females
and mate (Sandell 1989). Males at the UBR stayed rather steadily along their
stretch of stem river also during the nonbreeding season. Steadiness in exclusive
ranges all the year long has been also observed in stone marten Martes foina
(Genovesi et al. 1997).
The 38% of the monthly home range of males corresponded to tributaries and
some of them showed a seasonal use pattern. This space use pattern suggests a
seasonal exploitation of the smaller streams accessible from a single main river
section. Intensive use of areas that changed temporally has also been observed in
Mustela putorius (Weber 1989a, Lodé 1993). Lodé (1996) argued that this space-use
pattern was related to the changing distribution of preferred food resources, both in
time and space. On the other hand, the extent and timing of these excursions are
rather different to the large and seasonal ones showed by transient, dispersing or
juvenile individuals of other carnivore species (Woollard and Harris 1990, Lodé
1993, Kruuk 1995). Our data suggest that male European mink have exclusive
home ranges, exploiting the same stretch of main stream throughout the year and
periodically entering different streams accessible from there.

Home range of European mink in southwestern Europe
61
In contrast to other semi-aquatic carnivores, the European mink rarely used
burrows or tree root cavities in the UBR (Birks and Linn 1982, Melquist and
Hornocker 1983, Stevens et al. 1997, Palazón and Ruíz-Olmo 1998). Although
carnivores commonly used bramble patches as shelter, the almost exclusive use of it
by European mink is striking. Mild temperatures occurred at the study area
throughout the year. This may promote the use of these patches as insulation due
to their relatively low thermoregulation costs (Weber 1989b). In addition,
burrowing may be energetically more demanding than simple couches, especially if
many burrows have to be created in the home range. The use of brambles by this
species at the UBR probably reflects a compromise between safety and extensive
exploitation of home ranges.
Acknowledgements: This study was funded by both the Research and Environment Departments of the
Basque Government through the project PU-1998-8. We thank I. Gonzalo, A. Esparza, S. Lekerika,
E. Decharette and U. Goiti for field assistance. We are very grateful to A. Elosegi, T. Lodé and two
anonymous referees for their helpful criticisms on the manuscript. Regional Council of Biscay provided
authorization for animal handling and tagging.
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Received 22 August 2000, accepted 5 April 2001.