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SHORT COMMUNICATION
Do faecal odours enable domestic cats (Felis catus) to distinguish
familiarity of the donors?
Miyabi Nakabayashi •Ryohei Yamaoka •
Yoshihiro Nakashima
Received: 3 April 2011 / Accepted: 28 November 2011 / Published online: 3 January 2012
ÓJapan Ethological Society and Springer 2011
Abstract We studied the ability of domestic cats to dis-
tinguish familiarity based on faecal odours. This was
evaluated by comparing the sniffing duration of cats’ own,
familiar, and unfamiliar faeces. We found that (1) sniffing
durations differed between unfamiliar faeces and the other
types of faeces, (2) sniffing durations of faeces of the same
unfamiliar individuals decreased over time, and (3) sniffing
durations toward unfamiliar faeces increased after change
of donors. These results indicate that domestic cats can
distinguish the faecal odours based on familiarity. This
ability could be adaptive for domestic cats to maintain their
social relationships.
Keywords Felis catus Faecal odours Familiarity
Sniffing durations Olfactory communication
Introduction
Olfaction plays key roles in communication in various
mammalian species. Many species of Carnivora use olfac-
tion for intra-specific communication and inter-specific
communication among individuals and groups (reviewed by
Dielenberg and McGregor 2001; Gorman and Trowbridge
1989; Macdonald 1980). They rely on various odour sour-
ces such as urine for their scent marking (Gorman and
Trowbridge 1989; Macdonald 1980). Faeces are one such
odour source and provide information about the sex, rela-
tive health conditions, and reproductive status of individu-
als (Gorman and Trowbridge 1989). Faeces also provide
spatial and temporal records of an individual’s and group’s
movements and behaviours, even in the absence of the
producer (reviewed by Brown and Macdonald 1985).
For domestic cats, familiarity may be important for the
relationship with the other individuals. The domestic cat is
known to form groups when the food resources are suffi-
cient (Kerby and Macdonald 1988; Liberg and Sandell
1988). Among group members, they exhibit amicable
relationships (Izawa et al. 1982; Macdonald et al. 1987). In
contrast, unfamiliar cats are prone to antagonistic behav-
iours from the other cats (Crowell-Davis et al. 2004)
because an unfamiliar individual would cause a greater
threat than well-known individuals (Temeles 1994).
Some scents may be important tools for adjusting the
social interactions of domestic cats (Natoli 1985, Natoli
et al. 2001). They occasionally leave some faeces exposed
when they are out hunting or on the periphery of their
territories, but they usually bury them after defecation near
their nesting sites or within their home range for hygienic
reasons or avoidance of informing others about their
physical conditions (Bradshaw and Cameron-Beaumont
2000; Case 2003; Liberg 1980). Thus, faeces are likely to
play a role in olfactory communication in domestic cats.
While urinary odours are often presumed to be olfactory
communication tools, faecal odours have rarely been
studied despite their potential importance.
If faecal odours play an important role in their society,
cats might have the ability to distinguish other cats by their
M. Nakabayashi (&)
Wildlife Research Center of Kyoto University,
2-24 Tanaka-Sekiden-cho, Sakyo, Kyoto 606-8203, Japan
e-mail: bqdbd255@yahoo.co.jp
R. Yamaoka
Kyoto Institute of Technology, Matsugasaki,
Sakyo, Kyoto 606-8585, Japan
Y. Nakashima
Graduate School of Science, Kyoto University, Oiwake-cho,
Kitashirakawa, Sakyo, Kyoto 606-8502, Japan
123
J Ethol (2012) 30:325–329
DOI 10.1007/s10164-011-0321-x
faecal odours. This ability might be very important for
perception of the existence of unfamiliar individuals, pos-
sible competitors for limited resources. In this study, the
possibility of domestic cats’ distinguishing familiarity based
on the faecal odours was studied by comparing the sniffing
durations of their own, familiar, and unfamiliar faeces.
Materials and methods
Collection of samples
The faeces of domestic cats were obtained from five dif-
ferent groups: Hyogo group, Kyoto 1 group, Kyoto 2 group,
Osaka 1 group, and Osaka 2 group. The Kyoto 1 group
consisted of four individuals that were kept in a cat cafe
´,a
theme cafe
´where customers can watch and play with cats.
In contrast, all the other cats were kept by private citizens;
the Hyogo group consisted of three individuals, the Kyoto 2
and Osaka 1 group consisted of two individuals, and the
Osaka 2 group consisted of only one individual.
We chose sexually mature individuals as sample donors
and recipients. For all these individuals, we checked sex,
age, breed, and the history of castration. All the cats were
fed the same food (Adult Fit 32; Royal Canin Japon, Tokyo,
Japan) from 3 days before sample collection until the end of
the experiment. Faeces were collected in resealable plastic
bags and stored in styrol boxes with cooling elements until
experiments, for a maximum of 3 days.
Behavioural experiment
To test the ability of domestic cats to distinguish between
faeces, we observed behavioural responses when presenting
the following three types of faeces simultaneously; (1) own
faeces, (2) familiar faeces, which were excreted by cats
belonging to the same group as the recipient cat, and (3)
unfamiliar faeces, which were excreted by cats belonging to
a different group than the recipient cat’s group.
All the observations were carried out in the rooms of the
cat owners, which typically measured about 10 m
2
, in the
Hyogo, Osaka, and Kyoto areas. In the centre of the rooms,
3 plastic plates (15 cm 915 cm) were placed on the
ground in a straight line at 15-cm intervals, and three types
of fresh faeces (collected within 3 days) were randomly
placed on the plates (Fig. 1). The order of the plates was
changed randomly before each experiment in order to
prevent the cats from remembering the order of the faecal
samples. The plastic plates were not reused after each
experiment in order to avoid cats sniffing the odours left on
the plates from previous trials.
We determined a point on the circumference of the
circle of 100-cm radius around the central plate where we
placed the recipient cat at the start of each experiment. The
circles were not written in the experimental fields. That
point was located at 100 cm from the central plate, and the
same distance from the other plates. Sniffing durations of
recipient cats for each faecal sample were recorded for ten
minutes after the cats entered the area within a 100-cm
radius around the central plate. This experiment was
repeated three times, hereafter referred to as 3-day suc-
cessive bouts. In all experiments, sniffing duration was
recorded with a precision of 0.01 s as the time during
which a cat’s nose came to within about 5 cm of the faeces.
Observations were made from a point situated at least 3 m
from the plates.
In this study, habituation to sniffing of cat faeces was
said to occur when sniffing duration decreased across
experiments, indicating that the recipient cats perceived the
stimulus as the same, as described in Halpin (1974) and
Johnston et al. (1993). To assess this paradigm, we used a
new batch of faeces for all three types of faeces at every
new bout. At the same time, the donors of unfamiliar faeces
were changed. If there were more than two familiar cats,
the donors of familiar faeces were also changed. When
they failed to discriminate a novel faecal odours under this
procedure, it may be caused either by a lack of interest in
the faecal odours or by an inability to distinguish between
faecal odours. The experiments were performed only once
a day per recipient cat.
In each place, we conducted a different experiment,
hereafter referred to as test 1, test 2, and test 3, respec-
tively. In test 1, experiments were conducted in Hyogo.
The bout of experiments was measured four times each on
three recipient cats (#1 and 3, $2, all in the Hyogo group)
for 12 consecutive days. In test 2, experiments were
Fig. 1 Schematic illustration of the experimental room and apparatus
used. The dashed circle was not drawn in the room itself
326 J Ethol (2012) 30:325–329
123
conducted in Osaka. The bout of experiments was mea-
sured twice on a recipient cat (#10 in the Osaka 1 group)
for 6 consecutive days. In test 3, experiments were con-
tinued for 3 consecutive days in Kyoto using different
faeces of the same individuals on 2 recipient cats ($8 and
#9 in the Kyoto 2 group). After each observation, the
faeces were collected and stored to avoid faecal desiccation
and loss of odours.
Statistical analyses
To test whether cats distinguish between different types of
faecal odours, differences in the sniffing durations of each
type of faeces were compared using repeated one-way
analysis of variance (ANOVA). The Bonferroni post hoc
procedure (with an adjusted alpha of 0.017) was applied to
assess differences in the sniffing durations of each type of
faeces within each experimental day, although these post-
priori tests may be statistically risky.
Habituation to repeated exposures to faecal odours from
the same donors was tested by comparing time spent
sniffing each type of faeces on the first and third experi-
mental day with paired ttests.
To test whether cats distinguish between novel faecal
odours and that of less novel which they have experienced
in sniffing during this experiment, differences in the
sniffing durations of faeces just before and after presenta-
tions of a new batch of faeces for all 3 types of faeces were
compared using paired ttests.
All analyses were conducted using the statistical pro-
gramme R 2.10.1 (R Development Core Team 2009) with
the critical value set to 0.05 unless otherwise indicated.
Results
Collection of samples
In total, 46 faecal samples were collected from seven
domestic cats during May to December 2009 and May
2011. Totals of 24 samples were collected from the Hyogo
group, 14 from the Kyoto 1 group, 4 from the Kyoto 2
group, 2 from the Osaka 1 group, and 2 from the Osaka 2
group. The profiles of the tested cats are shown in Table 1
and the donor sources of the faeces used are shown in
Table 2.
Behavioural experiment
With respect to time spent sniffing three types of faecal
odours, the ANOVA reveals that there was significant
difference among types (F
2,141
=28.2, P\0.001). On all
experimental days, the sniffing duration of unfamiliar
faeces was significantly longer than that of their own faeces
(first day: t=4.26, P\0.001; second day: t=3.70,
P\0.001; third day: t=3.43, P\0.001) and that of the
familiar faeces (first day: t=3.92, P\0.001; second day:
t=3.82, P\0.001; third day: t=4.50, P\0.001).
However, the sniffing durations showed no significant
differences between the familiar faeces and their own
faeces on all experimental days (first day: t=0.34,
P[0.1; second day: t=0.12, P=0.90; third day:
t=1.07, P=0.29).
The sniffing durations of unfamiliar faeces on the first
experimental day were significantly longer than those on
the third day (t=5.37, P\0.001). However, the sniffing
durations of familiar and own faeces showed no significant
differences between the first and third experimental days
(familiar faeces: t=1.31, P=0.21; own faeces: t=0.79,
P=0.44) (Fig. 2).
Table 1 Profiles of all the tested domestic cats
ID Sex Age Breed Castration
a
Group
b
1#15 Mix Y Hyogo
2$7 Mix Y Hyogo
3#5 Mix Y Hyogo
4#2 Mix Y Kyoto 1
5$2 Mix Y Kyoto 1
6#2 Mix Kyoto 1
7$2 Mix Y Kyoto 1
8$0.75 Mix Kyoto 2
9#0.75 Mix Kyoto 2
10 #1 Mix Y Osaka 1
11 $Unknown Mix Y Osaka 1
12 $2 Mix Y Osaka 2
The number after the name of the area indicates the place within that
area
a
Yindicates the cat was castrated
b
Group shows the names of the area where the cats lived
Table 2 The donor sources of the faeces presented to the recipient
cats
ID of recipient
cats
ID of familiar
donor
ID of unfamiliar
donor
1 2(1,3), 3(2,4) 4(4), 5(1), 6(3), 7(2)
2 1(1,3), 3(2,4) 4(2), 5(4), 6(1), 7(3)
3 1(1,3), 2(2,4) 4(1), 5(3), 6(2), 7(4)
8912
9812
10 11 1(1), 3(2)
ID numbers are equivalent to those in Table 1
Numbers in parentheses indicate the number of the 3-day successive
trial bouts, while their absence means the same donors were used in
all the experiments
J Ethol (2012) 30:325–329 327
123
In test 1 and test 2, when the faeces were replaced with a
new batch of faeces (on the fourth, seventh, and tenth
experimental day in test 1, and on the fourth experimental
day in test 2), the sniffing durations of the novel batch of
unfamiliar faeces were significantly longer (t=2.39,
P=0.04) than those that the recipient cats had experi-
enced sniffing on the previous day (Fig. 3). Meanwhile,
sniffing durations of the familiar (t=0.24, P=0.82) and
their own (t=1.92, P=0.09) faeces showed no signifi-
cant differences (Table 2).
Discussion
In this study, we obtained three important findings. First,
the domestic cats spent a significantly longer time sniffing
the faeces of unfamiliar conspecifics than sniffing those of
familiar conspecifics and themselves. Second, sniffing
duration of faeces of the same unfamiliar individuals
decreased over time. Third, the time spent sniffing unfa-
miliar faeces was longer when they had not experienced it
before compared to when they had experienced it before.
These points suggest that domestic cats have the ability to
distinguish the familiarity based on faecal odours. Natoli
(1985) reported that domestic cats sniffed sprayed urine of
unfamiliar males longer than that of familiar males. We
obtained quite similar results here using faeces. In addition,
our results also found that cats habituate to the faecal
odours of unfamiliar individuals.
The ability to distinguish familiarity based on faecal
odours using their olfactory memories could be adaptive in
the social system of domestic cats. For example, during the
oestrous season, male cats extend the moving range,
thereby increasing the probability of encountering several
male cats within their ranges (Izawa et al. 1982; Liberg and
Sandell 1988). These abilities allow roaming cats to per-
ceive the presences of unfamiliar males in the area they
range and to evade unnecessary costs of fighting. The
faeces deposited within their territory could also be used as
territorial markers. Investigating familiarity by the faecal
odours would be efficient, because they can detect
unknown individuals without actual encounter.
Our results do not suggest that domestic cats distinguish
their own faeces from that of familiar individuals. With
regard to adaptation, it seems preferable to have ability to
distinguish their own faecal odours from familiar faecal
odours, because they exhibit antagonistic behaviour among
group members in the oestrous season since they become
competitors for mates as unfamiliar individuals especially
within males (Natoli and De Vito 1991; Yamane et al.
1996). However, our results do not always suggest that they
have no ability to distinguish chemical substances on their
faeces. Except in the oestrous season, they probably do not
have to be cautious about the presence of the other indi-
viduals under variable conditions of nutrition and season.
Further studies of their behavioural changes in sniffing
conspecific faeces along with seasonal change are never-
theless needed.
Acknowledgments We are deeply grateful to the cat keepers for
their warm assistance in sample collection and conducting behavioral
experiments. Their understandings and enthusiasms made this work
possible. We sincerely thank Assoc. Prof. Dr. T. Akino in Kyoto
Institute of Technology for his valuable supports and guidance. We
are also grateful to Dr. H. Samejima and Dr. R. Ito for their kind
advices and comments on earlier drafts of this paper. We thank two
Fig. 2 Sniffing duration of unfamiliar (n=6), own (n=6), and
familiar (n=6) faeces. Values are given as the mean ?SE. Asterisks
indicate significant differences of the sniffing duration between and
within types of faeces (P\0.001)
Fig. 3 Sniffing duration of unfamiliar, own, and familiar faeces on
the days previous and subsequent to the exchange the faeces for a new
batch of faeces. Values are given as the mean ?SE. Asterisk
indicates a significant difference between the duration of sniffing
unfamiliar faeces on the previous days and that on the subsequent
days after exchange of faeces (P\0.001)
328 J Ethol (2012) 30:325–329
123
anonymous reviewers for critical readings and helpful comments that
greatly improved previous versions of the manuscript.
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