Z. Tierpsychol., 37, 75-98 (1975) @ 1975 Verlag Paul Parey, Berlin u n d Hamburg ISSN 0044-3573 / ASTM-Coden: ZETIAG
Department of Psychology, Corriell University Ithaca, N e w Y o r k , U.S.A.
Scent Marking by Male Golden Hamsters (Mesocricetus aurutus) I. Effects of odors and social encounters By ROBERTE. JOHNSTON With J figures Received: 2 4 . 7. 1973
Introduction The importance of olfaction in the life of mammals has been repeatedly emphasized (HEDIGER 1949; BARNETT 1963; WILSONand BOSSERT1963; BOURL I ~ R E1964; WHITTEN 1966; EWER1968), but until recently there has been little experimental work on mammalian pheromones or scent marking behaviors. Dramatic success in the analysis of chemical communication among insects (WILSON1965; BUTLER 1967, 1970), and the discovery of several primer pheromone effects in mice (WHITTEN 1966, 1969; BRONSON 1968) have further emphasized the importance and potential of this line of research. Most mammalian species have one o r more specialized exocrine glands, or regions of enlarged sebaceous and/or apocrine glands, which may emit pheromones (POCOCK 1910,1915 a,b, 1918; SCHAFFER 1940; QUAY 1968). Although perfume chemists have analyzed the contents of several mammalian scent glands (STEVENS and ERICKSON 1942; STEVENS 1943, 1945; HARDY 1947a,b, 1948; LEDERER 1950; KINGSTON 1965), the biological function of these secretions is unknown. Progress has been made toward the chemical identification of sexual attractandexcitant substances in the rhesus monkey (MICHAEL, KEVERNE and BONSALL1971) and of some components of a secretion important for social communication in mule deer (MULLER-SCHWARZE 1971). Stereotyped scent marking behaviors which serve to deposit secretions of scent glands, urine o r feces are characteristic of many mammalian species, and are often species-specific in form, suggesting that they may also have a visual communication function (KLEIMAN 1966; JOLLY 1966). In only a few species have experimental studies of scent marking and responses to the marks been reported: the marsupial sugar glider of N e w Guinea, Petaurus breviceps papua1965, 1969), the European rabbit, Oryctolagus cuninus (SCHULTZE-WESTRUM culus (MYKYTOWYCZ 1965, 1966a, b, c, 1968, 1970; MYKYTOWYCZ and DUDZINSKA 1966), the common marmoset, Callithrix jacchus (EPPLE1970), and
76
ROUERTE. JOHNSTON
Maxwell’s duiker, Cephalophus maxwelli (RALLS1971). Physiological factors influencing scent marking behavior of the gerbil, Meviones unguiculatus, have been investigated in detail by THIESSEN and co-workers (THIESSEN, FRIEND and LINDZEY 1968; THIESSEN and YAHR1970; THIESSEN, OWEN and LINDZEY 1971). I have studied scent marking and chemical communication in the domestic strain of the golden hamsters, Mesocvicetus nuratus (JOHNSTON 1970). Hamsters have clearly defined, oval regions of enlarged, pigmented sebaceous glands on the dorsal portion of each flank which are called flank glands (MONTAGNA and HAMILTON 1949; HAMILTON and MONTAGNA 1950). These glands are sexually dimorphic, measuring approximately 9 X 4 mm in 8 8 and 2.5 X 1.5 mm in 90, and this dimorphism is entirely testosterone dependent (KUPPERMAN 1944 a, b, 1946; HAMILTON and MONTAGNA 1950). DIETERLEN (1959) first described a stereotyped behavior pattern which apparently serves to deDosit the secretion of the flank gland, which I have called flank marking (Fig. i).Typically the marking animal arches its back and rubs one side against a vertical surface (particularly in corners); the ears are erect and the tail is horizontal or slightly raised. I n laboratory conditions hamsters mark their home area o r cage and other familiar areas, and have particular marking spots within any such area. DIETERLEN (1959) reported that flank marking was especially frequent after agonistic encounters, and suggested that it was an agonistic behavior concerned with defense of territory. LIPKOW (1954) on the other hand claimed that the gland was of sexual importance, particularly in sexual excitation of the 0. H e removed flank glands from several 8 8 and claimed 90 would not mate with them, or
Fig. la, b: Sequences of photographs of a male hamster flank marking. N o t e the characteristic arched back, erect ears a n d raiscd rump a n d tail. Exposures were taken 3 per scc, shutter speed 1/125 scc
78
ROBERT E. JOHNSTON
D a t a were recorded with pencil and paper. The 1 0 m i n test periods were timed with a stop watch. Tests were carried out at approximately the same time every day, 1-2 hr after the beginning of the dim part of the light cycle. The dim illumination (two 15 w x t incandescent bulbs) was sufficient for observation.
Table I : Male flank marking: sequence of experimental conditions Purpose of Testing
Condition #
Effects of odors
d ‘ s home cage
2
CLean cage
3
Effects of odors and social encounters
# of Days
Tested in
1
21
‘ s home cage
b
0 ‘ s home
5
d ‘ s home cage ,
6
6 ’ s home
7
3 ’ s home cage,
cage , after an encounter with that after an encounter with a
18
- 22 - 22
0
0 13
12
after an encounter with that
6
After an initial series of 10 min observations of the six test $ $ in their own homc cages the test $ $ were observed in a sequence of seven conditions (Table 1). First, each 8 was tested in the vacant home cage of another 8,then in cages scrubbed clean of hamster secretions and excretions, and third in the vacant home cage of a 9. These first three conditions explored the effects of the odors of another hamster in test areas. The remaining four conditions tested the effects of social encounters. In condition 4, each 8 encountered a in a neutral arena and then he was tested in her vacant home cage; there was a different stimulus Q for each $. Since in condition 3 each 8 had been tested in the same 9’s cage, and encountered this 9 before being tested in her cage, the encounter was in condition 4 the the only difference between conditions 3 and 4. I n condition 5 each 8 again encountered the same Q,but he was then tested in a 8 ’ s vacant home cage. Condition 5 thus presented 8$ with a different test situation after the encounter with a In condition 6 each $ was 8’s tested in the same stimulus 8’s cage but with no prior encounter; thus a comparison of behavior in conditions 5 and 6 demonstrate the effect of an encounter with a Q on a 8’s behavior in a cage smelling of another $. Finally, in condition 7 each encountered the same stimulus 8 for 5 min in a neutral arena just before being tested in this 8 ’ s cage for the third time (conditions 5, 6, 7). Thus differences between conditions 6 and 7 should indicate the effects of an encounter with a 8 before testing in a 8’s home cage. Durinq a n y one condition 8 8 were tested o n successive days and throughout a condition each $ was tested in the same cage. O n e exception resultcd from the death of a Q after condition 4 ; $B? was paired with a new Q in condition 5. During testing the stimulus hamster was allowed to enter a holding cage and its empty home cage was placed on the observaticn table. A cage containing an experimental $ was placed o n the table, the hinged door of his cage was opened and he was allowed to enter the test cage. The door of the test cage was shut and the 8 was observed for ten minutes. Then the $ was allowed t o return to his home cage. Test cages rescinbled those in which the experimental $ lived. Each experimental 8 entered the same test cage day after day, and each test cage was used for only one test $. I n addition to entering the same cage d a y after day, the test 8 $ left some of their own secretions behind, so the test cages no doubt became increasingly “familiar” to them. Also, the test cage was a relatively “safe” place since the test animal never met the resident hamster there. Thus the test c a p in this experiment are not directly analogous to another’s home area or burrow in the wild; rather, the test cage is a familiar area in which there are odors of another hamster. An attempt was made throughout to avoid stress in all manipulations. Experimental animals were always allowed to entcr test areas from their home cage and to return home afterward in order t o avoid handling. Social encounters were staged in a painted, wooden box (2’ X 2‘ X 1’) with a Plexiglas front and top; it was divided by a “T”-shaped partition 8” high and 4” wide which the hamsters could climb on. The test 6$ and their “stimulus” partners were familiarized with this arena before the staged encounters - each animal was allowed to explore the arena f o r 10-15 min on 4-6 consecutive days immediately preceding the first encounter days.
8
9.
8
8
Scent Marking by Male Golden Hamsters (Mesocricetus auratus). I.
8-9
79
8
For encounters (conditions 4, 5, 6) the was allowed into the arena approximately 1 min before the The encounter lasted 5 min, after which the 0 was allowed t o enter a holding cage and the 8 was allowed to enter a test cage for the usual 10 min test period. When a was receptive she was removed from the arena after the 8’sfirst intromission, which successfully avoided impregnation; 8 8 were allowed into the test cages 2 min later. For 8-8encounters (condition 7) the arena was initially divided in half by a piece of clear plcxiglas. Approximately 1 min later the plcxiglas was replaced by the “T” divider and the 8 8 were allowed contact. The encounter lasted 5 min, after which both 8 8 were allowed into each other’s cage and both were observed for 10 min.
9.
9
a) Test Animals The six test 88 were selected from a group of ten on the basis of flank marking scores so that the group consisted of high, intermediate and low frequency markers. Selection was based on t w o tests: six 15 min sessicns in a large (2’ X 4’) vacant arena and four 10 minute Test 8 8 were 4-8 months of age when the experiment tests in the empty home cage of a began. 8 8 BZ and B:, had had sexual and nonsexual experience with as well as a 3 hr encounter with each other 5 months before tEe experiment began. The other four test 6 8 were sexually naive and had no contact with other 6 8 since being purchased from the dealer (88 10, 1 1 , 12) o r weaned in the laboratory (615) 2-3 months before. Home cages used as test cages were those of normal hamsters 5-10 months old. All stimulus had encountered 8 8 before these tests, but none had been mothers. O n e $2 (A17) died just after condition 4 ; she had been obviously ill for several weeks during conditions 3 and 4; another of the same age (A15) was substituted for her in condition 5. The 8 8 whose home cages served as test cages in conditions 5, 6, and 7, and who acted as stimulus 8 8 in condition 7, were 5-6 months of age with no social experience from time of receipt 3 X months before (68 2 1 , 2 2 , 2 3 , 2 4 , 2 5 , 2 6 ) o r from weaning 4 months before 17).
9.
$29
99
9
(8
b) Criteria used in Counting Flanks Marks Although flank marking is a relatively sterectyped behavior (Fig. l a , b), its vigor and temporal patterning vary considerably. Sometimes, an animal marks discretely just once. At other times, an animal marks vigorously many times in succession and a criterion of what constitutes “one mark” is necessary. Whenever an animal was observed t o rub its flank continuously along a substrate, this was scored as one mark. If a marking animal paused and then continued marking, two marks were scored. In corners animals would frequently mark, immediately turn and mark again, etc.: each change of direction was considered as the end of one mark. Marking along one side of a cage for more than one half of the length of that side and up t o a corner was scored as one mark; if this was followed by marking along a second side it was scored as t w o marks. Scmetimes an animal assumed the marking posture and went through the marking movement without actually rubbing against anything; when no contact was made with a substrate the behavior was classified as an “intention” mark. Intcntion marks were not included with the flank marks when tabulating data.
c ) Terminology The terms “dominant” and “subordinate” refer to animals who initially won or lost a fight and maintained an advantage in repeated agonistic encounters. Although these terms are more precisely used to describe competitive status in natural populations o r social groups, 8 8 who won or lost in repeated encounters displayed consistent differences in behavior for which the terms dominant and subordinate seemed the most appropriate. The behavior of dominant and subordinate 8 8 in these experiments was quite similar to that of 8 8 observed in a semi-natural environment where a 8 ’ s status was clearly related to differential access to food and space as well as to agonistic behavior (JOHNSTON 1970 and in press). For the sake of consistency “dominant” and “subordinate” have also been used in describing pairs although the relationship between a 8 and a is much less polarized than that between t w o 8 8.
9
8-9
d) Statistics The non-parametric Walsh test (SIEGEL 1956) was used for all comparisons between conditions.
ROBERTE. J O H N S T O N
80
TEST Own I 2 Home Another Clean cage 60,cage, d ' s cage ,
mim CONDITION 3
?ns
4 coge, encounter with ? before test
cage
?,s
0" 15
4
4
4
4
4
4
4
4
4
k
4
x
0" 12
40[
j
4
k
40
0
Doys
[ t = s t i m u l u s ?as
estrus]
Fig. 2a: Male marking in different test conditions
Results Flank marking scores for each 6 on every day in each test condition are shown in Figs. Z a and 2 b. Comparisons between conditions will be discussed with reference to this individual data as well as summary figures and tables.
&%za)
The Effects of Different Odorous Environments
All six 6 6 flank marked a t higher rates in the home cages of 99 or other 8 6 than in clean cages or in their own home cages (Fig. 2 a). Since the clean cages were otherwise identical to the soiled cages, the chemical substances left behind by the resident animal were most probably the stimuli responsible for stimulation of marking. Qualitative observations of the test 6 8 indicate that
81
Scent Marking by Male Golden Hamsters (Mesocricetus uurutu5). I.
CONDITION
TEST 4 as cage enCOUfllef with before test
?
5
'0
encounter with before test
60
;
40 2
i
7 0 " ' s coge,
6
d ' s coge,
?
encounter with & before test
0 " ' s coge
dl5
I
w
i
A
l
Department of Psychology, Corriell University Ithaca, N e w Y o r k , U.S.A.
Scent Marking by Male Golden Hamsters (Mesocricetus aurutus) I. Effects of odors and social encounters By ROBERTE. JOHNSTON With J figures Received: 2 4 . 7. 1973
Introduction The importance of olfaction in the life of mammals has been repeatedly emphasized (HEDIGER 1949; BARNETT 1963; WILSONand BOSSERT1963; BOURL I ~ R E1964; WHITTEN 1966; EWER1968), but until recently there has been little experimental work on mammalian pheromones or scent marking behaviors. Dramatic success in the analysis of chemical communication among insects (WILSON1965; BUTLER 1967, 1970), and the discovery of several primer pheromone effects in mice (WHITTEN 1966, 1969; BRONSON 1968) have further emphasized the importance and potential of this line of research. Most mammalian species have one o r more specialized exocrine glands, or regions of enlarged sebaceous and/or apocrine glands, which may emit pheromones (POCOCK 1910,1915 a,b, 1918; SCHAFFER 1940; QUAY 1968). Although perfume chemists have analyzed the contents of several mammalian scent glands (STEVENS and ERICKSON 1942; STEVENS 1943, 1945; HARDY 1947a,b, 1948; LEDERER 1950; KINGSTON 1965), the biological function of these secretions is unknown. Progress has been made toward the chemical identification of sexual attractandexcitant substances in the rhesus monkey (MICHAEL, KEVERNE and BONSALL1971) and of some components of a secretion important for social communication in mule deer (MULLER-SCHWARZE 1971). Stereotyped scent marking behaviors which serve to deposit secretions of scent glands, urine o r feces are characteristic of many mammalian species, and are often species-specific in form, suggesting that they may also have a visual communication function (KLEIMAN 1966; JOLLY 1966). In only a few species have experimental studies of scent marking and responses to the marks been reported: the marsupial sugar glider of N e w Guinea, Petaurus breviceps papua1965, 1969), the European rabbit, Oryctolagus cuninus (SCHULTZE-WESTRUM culus (MYKYTOWYCZ 1965, 1966a, b, c, 1968, 1970; MYKYTOWYCZ and DUDZINSKA 1966), the common marmoset, Callithrix jacchus (EPPLE1970), and
76
ROUERTE. JOHNSTON
Maxwell’s duiker, Cephalophus maxwelli (RALLS1971). Physiological factors influencing scent marking behavior of the gerbil, Meviones unguiculatus, have been investigated in detail by THIESSEN and co-workers (THIESSEN, FRIEND and LINDZEY 1968; THIESSEN and YAHR1970; THIESSEN, OWEN and LINDZEY 1971). I have studied scent marking and chemical communication in the domestic strain of the golden hamsters, Mesocvicetus nuratus (JOHNSTON 1970). Hamsters have clearly defined, oval regions of enlarged, pigmented sebaceous glands on the dorsal portion of each flank which are called flank glands (MONTAGNA and HAMILTON 1949; HAMILTON and MONTAGNA 1950). These glands are sexually dimorphic, measuring approximately 9 X 4 mm in 8 8 and 2.5 X 1.5 mm in 90, and this dimorphism is entirely testosterone dependent (KUPPERMAN 1944 a, b, 1946; HAMILTON and MONTAGNA 1950). DIETERLEN (1959) first described a stereotyped behavior pattern which apparently serves to deDosit the secretion of the flank gland, which I have called flank marking (Fig. i).Typically the marking animal arches its back and rubs one side against a vertical surface (particularly in corners); the ears are erect and the tail is horizontal or slightly raised. I n laboratory conditions hamsters mark their home area o r cage and other familiar areas, and have particular marking spots within any such area. DIETERLEN (1959) reported that flank marking was especially frequent after agonistic encounters, and suggested that it was an agonistic behavior concerned with defense of territory. LIPKOW (1954) on the other hand claimed that the gland was of sexual importance, particularly in sexual excitation of the 0. H e removed flank glands from several 8 8 and claimed 90 would not mate with them, or
Fig. la, b: Sequences of photographs of a male hamster flank marking. N o t e the characteristic arched back, erect ears a n d raiscd rump a n d tail. Exposures were taken 3 per scc, shutter speed 1/125 scc
78
ROBERT E. JOHNSTON
D a t a were recorded with pencil and paper. The 1 0 m i n test periods were timed with a stop watch. Tests were carried out at approximately the same time every day, 1-2 hr after the beginning of the dim part of the light cycle. The dim illumination (two 15 w x t incandescent bulbs) was sufficient for observation.
Table I : Male flank marking: sequence of experimental conditions Purpose of Testing
Condition #
Effects of odors
d ‘ s home cage
2
CLean cage
3
Effects of odors and social encounters
# of Days
Tested in
1
21
‘ s home cage
b
0 ‘ s home
5
d ‘ s home cage ,
6
6 ’ s home
7
3 ’ s home cage,
cage , after an encounter with that after an encounter with a
18
- 22 - 22
0
0 13
12
after an encounter with that
6
After an initial series of 10 min observations of the six test $ $ in their own homc cages the test $ $ were observed in a sequence of seven conditions (Table 1). First, each 8 was tested in the vacant home cage of another 8,then in cages scrubbed clean of hamster secretions and excretions, and third in the vacant home cage of a 9. These first three conditions explored the effects of the odors of another hamster in test areas. The remaining four conditions tested the effects of social encounters. In condition 4, each 8 encountered a in a neutral arena and then he was tested in her vacant home cage; there was a different stimulus Q for each $. Since in condition 3 each 8 had been tested in the same 9’s cage, and encountered this 9 before being tested in her cage, the encounter was in condition 4 the the only difference between conditions 3 and 4. I n condition 5 each 8 again encountered the same Q,but he was then tested in a 8 ’ s vacant home cage. Condition 5 thus presented 8$ with a different test situation after the encounter with a In condition 6 each $ was 8’s tested in the same stimulus 8’s cage but with no prior encounter; thus a comparison of behavior in conditions 5 and 6 demonstrate the effect of an encounter with a Q on a 8’s behavior in a cage smelling of another $. Finally, in condition 7 each encountered the same stimulus 8 for 5 min in a neutral arena just before being tested in this 8 ’ s cage for the third time (conditions 5, 6, 7). Thus differences between conditions 6 and 7 should indicate the effects of an encounter with a 8 before testing in a 8’s home cage. Durinq a n y one condition 8 8 were tested o n successive days and throughout a condition each $ was tested in the same cage. O n e exception resultcd from the death of a Q after condition 4 ; $B? was paired with a new Q in condition 5. During testing the stimulus hamster was allowed to enter a holding cage and its empty home cage was placed on the observaticn table. A cage containing an experimental $ was placed o n the table, the hinged door of his cage was opened and he was allowed to enter the test cage. The door of the test cage was shut and the 8 was observed for ten minutes. Then the $ was allowed t o return to his home cage. Test cages rescinbled those in which the experimental $ lived. Each experimental 8 entered the same test cage day after day, and each test cage was used for only one test $. I n addition to entering the same cage d a y after day, the test 8 $ left some of their own secretions behind, so the test cages no doubt became increasingly “familiar” to them. Also, the test cage was a relatively “safe” place since the test animal never met the resident hamster there. Thus the test c a p in this experiment are not directly analogous to another’s home area or burrow in the wild; rather, the test cage is a familiar area in which there are odors of another hamster. An attempt was made throughout to avoid stress in all manipulations. Experimental animals were always allowed to entcr test areas from their home cage and to return home afterward in order t o avoid handling. Social encounters were staged in a painted, wooden box (2’ X 2‘ X 1’) with a Plexiglas front and top; it was divided by a “T”-shaped partition 8” high and 4” wide which the hamsters could climb on. The test 6$ and their “stimulus” partners were familiarized with this arena before the staged encounters - each animal was allowed to explore the arena f o r 10-15 min on 4-6 consecutive days immediately preceding the first encounter days.
8
9.
8
8
Scent Marking by Male Golden Hamsters (Mesocricetus auratus). I.
8-9
79
8
For encounters (conditions 4, 5, 6) the was allowed into the arena approximately 1 min before the The encounter lasted 5 min, after which the 0 was allowed t o enter a holding cage and the 8 was allowed to enter a test cage for the usual 10 min test period. When a was receptive she was removed from the arena after the 8’sfirst intromission, which successfully avoided impregnation; 8 8 were allowed into the test cages 2 min later. For 8-8encounters (condition 7) the arena was initially divided in half by a piece of clear plcxiglas. Approximately 1 min later the plcxiglas was replaced by the “T” divider and the 8 8 were allowed contact. The encounter lasted 5 min, after which both 8 8 were allowed into each other’s cage and both were observed for 10 min.
9.
9
a) Test Animals The six test 88 were selected from a group of ten on the basis of flank marking scores so that the group consisted of high, intermediate and low frequency markers. Selection was based on t w o tests: six 15 min sessicns in a large (2’ X 4’) vacant arena and four 10 minute Test 8 8 were 4-8 months of age when the experiment tests in the empty home cage of a began. 8 8 BZ and B:, had had sexual and nonsexual experience with as well as a 3 hr encounter with each other 5 months before tEe experiment began. The other four test 6 8 were sexually naive and had no contact with other 6 8 since being purchased from the dealer (88 10, 1 1 , 12) o r weaned in the laboratory (615) 2-3 months before. Home cages used as test cages were those of normal hamsters 5-10 months old. All stimulus had encountered 8 8 before these tests, but none had been mothers. O n e $2 (A17) died just after condition 4 ; she had been obviously ill for several weeks during conditions 3 and 4; another of the same age (A15) was substituted for her in condition 5. The 8 8 whose home cages served as test cages in conditions 5, 6, and 7, and who acted as stimulus 8 8 in condition 7, were 5-6 months of age with no social experience from time of receipt 3 X months before (68 2 1 , 2 2 , 2 3 , 2 4 , 2 5 , 2 6 ) o r from weaning 4 months before 17).
9.
$29
99
9
(8
b) Criteria used in Counting Flanks Marks Although flank marking is a relatively sterectyped behavior (Fig. l a , b), its vigor and temporal patterning vary considerably. Sometimes, an animal marks discretely just once. At other times, an animal marks vigorously many times in succession and a criterion of what constitutes “one mark” is necessary. Whenever an animal was observed t o rub its flank continuously along a substrate, this was scored as one mark. If a marking animal paused and then continued marking, two marks were scored. In corners animals would frequently mark, immediately turn and mark again, etc.: each change of direction was considered as the end of one mark. Marking along one side of a cage for more than one half of the length of that side and up t o a corner was scored as one mark; if this was followed by marking along a second side it was scored as t w o marks. Scmetimes an animal assumed the marking posture and went through the marking movement without actually rubbing against anything; when no contact was made with a substrate the behavior was classified as an “intention” mark. Intcntion marks were not included with the flank marks when tabulating data.
c ) Terminology The terms “dominant” and “subordinate” refer to animals who initially won or lost a fight and maintained an advantage in repeated agonistic encounters. Although these terms are more precisely used to describe competitive status in natural populations o r social groups, 8 8 who won or lost in repeated encounters displayed consistent differences in behavior for which the terms dominant and subordinate seemed the most appropriate. The behavior of dominant and subordinate 8 8 in these experiments was quite similar to that of 8 8 observed in a semi-natural environment where a 8 ’ s status was clearly related to differential access to food and space as well as to agonistic behavior (JOHNSTON 1970 and in press). For the sake of consistency “dominant” and “subordinate” have also been used in describing pairs although the relationship between a 8 and a is much less polarized than that between t w o 8 8.
9
8-9
d) Statistics The non-parametric Walsh test (SIEGEL 1956) was used for all comparisons between conditions.
ROBERTE. J O H N S T O N
80
TEST Own I 2 Home Another Clean cage 60,cage, d ' s cage ,
mim CONDITION 3
?ns
4 coge, encounter with ? before test
cage
?,s
0" 15
4
4
4
4
4
4
4
4
4
k
4
x
0" 12
40[
j
4
k
40
0
Doys
[ t = s t i m u l u s ?as
estrus]
Fig. 2a: Male marking in different test conditions
Results Flank marking scores for each 6 on every day in each test condition are shown in Figs. Z a and 2 b. Comparisons between conditions will be discussed with reference to this individual data as well as summary figures and tables.
&%za)
The Effects of Different Odorous Environments
All six 6 6 flank marked a t higher rates in the home cages of 99 or other 8 6 than in clean cages or in their own home cages (Fig. 2 a). Since the clean cages were otherwise identical to the soiled cages, the chemical substances left behind by the resident animal were most probably the stimuli responsible for stimulation of marking. Qualitative observations of the test 6 8 indicate that
81
Scent Marking by Male Golden Hamsters (Mesocricetus uurutu5). I.
CONDITION
TEST 4 as cage enCOUfllef with before test
?
5
'0
encounter with before test
60
;
40 2
i
7 0 " ' s coge,
6
d ' s coge,
?
encounter with & before test
0 " ' s coge
dl5
I
w
i
A
l
