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Mating System of Free-Ranging Dogs (Canis familiaris)

Mating System of Free-Ranging Dogs (Canis familiaris) Hindawi Publishing Corporation International Journal of Zoology Volume 2011, Article ID 314216, 10 pages doi:10.1155/2011/314216 Research Article S. K. Pal Katwa Bharati Bhaban, Katwa, Burdwan 713 130, India Correspondence should be addressed to S. K. Pal, drskpal@rediffmail.com Received 22 December 2010; Revised 1 March 2011; Accepted 14 May 2011 Academic Editor: Marcel Eens Copyright © 2011 S. K. Pal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fourteen females belonging to five groups were selected for the study of mating system in free-ranging domestic dogs (Canis familiaris) All the matings occurred between August and December with a peak in late monsoon months (September to November). Both males and females differed in their degree of attractiveness to the opposite sex. The duration of courting association increased with the number of courting males in an association. The females exhibited selectivity by readily permitting some males to mate and avoiding, or even attacking others, if they attempted to mount. Frequency of mounting in courting association increased with the number of males present. There was a positive correlation between the duration of courting association and the frequency of mounting. The young adult males were more likely to copulate successfully than the old adult males. There was a negative correlation between the number of males present in an association and the number of successful copulations. In this study, six types of mating (monogamy, polygyny, promiscuity, polyandry, opportunity and rape) were recorded. Mean (±S.E.) duration of copulatory ties was 25.65 (±1.43) min. Several natural factors influencing the duration of copulatory ties were identified. 1. Introduction have shown that extra pair mating occurs among two canid species, the Ethiopian wolf (Canis simensis) and the Mating system is the basis of any mammalian social system; African wild dog (Lycaon pictus;[7, 8]. As predicted by [9], and it can be defined as the ways in which different kinds genetic investigations of canid mating have revealed, thus of animals are associated during copulation and the factors far, a flexible mating structure, similar to the findings of that contribute to identification of partners, interaction, and investigations into mating structure of socially monogamous eventually fertilization. Monogamy is the rarest form of birds [10]. mating system among mammals, estimated to occur in 3– Sexual behaviour of domestic dogs (Canis familiaris) 5% of all mammalian taxa [1, 2]. However, it is the most has attracted the attention of scientists for a long time. common breeding system for canids [3]. This is due in Several studies on the sexual behaviour have been made part to the high demands that pups place on their parents, in the domestic dog (e.g., [11, 12].)Mostofthe previous as for most species of canidae they are born altricial in studies dealt with attractions between the members of the large litters and require an extended period of training to opposite sex when the females were in oestrus. Heterosexual learn to hunt and survive on their own. Also, puppies in attraction as well as intrasexual behaviour in domestic dogs many canid species require protection, as they face danger of was first extensively studied by [13, 14], although, male- intraspecific infanticide from neighboring territorial canids. male mounting was not observed in these studies. Later, [15] Recent investigations of the mating behaviors of canidae gave a comparative account of the roles of attractiveness and raise doubts as to whether any canid species is genetically receptivity in the mating behaviour of different mammalian monogamous. For instance, the red fox (Vulpes vulpes), females. In the case of domestic dogs, most previous studies the swift fox (Vulpes velox), and the island fox (Urocyon on oestrous females and their attractiveness have been done littoralis), all of which were thought to have exclusive mated in enclosed areas except [12, 16, 17]. Although, till now, the pair systems, were shown through genetic analysis to be mating system of free-ranging domestic dogs is a mysterious polygamous [4–6]. Observational and genetic investigations subject, no extensive studies have been done. 2 International Journal of Zoology The purpose of this study was to investigate the degree sexes and mating behaviour. Female-male, male-male and of attractiveness to the opposite sex and mating systems female-female mounting behaviour was also observed. A of free-ranging domestic dogs. Both intra- and intersexual total of 2750 h was devoted collecting data on inter- and behaviour of free-ranging domestic dogs were also investi- intra-sexual behaviour of the free-ranging domestic dogs. gated in this study. Aggregation of one or more male dogs within 5 m of the female in oestrous for at least 1 min was defined as “courting association”, and the males present in the courting 2. Materials and Methods association were defined as “courting” males. The courting males who followed and stayed for 10 min within 5 m of the 2.1. Study Area. The study was carried out in the town of ◦  ◦  oestrous female and attempted to mount or copulate, were Katwa (lat 23 39 N, long 88 8 E) in the state of West Bengal, 2 defined as “willing” males and the males that did not show India. The study area (0.5 km ), inhabited by a population any interest to mount or copulate were defined as “unwilling” of approximately 4500 people, was on the outskirts of the males. The willing males who were allowed by the oestrous town and was linked with other parts of the town by a paved females to mount and copulate were defined by “preferred” road. It was surrounded to the North and North-West by males. wetland, and to the East, South, and South-West by paddy An oestrous female was identified on the basis of fields. The main bus stop of the town was situated in this area. behavioural cues described by [14]. The first day of oestrus Garbage was the food resource for the dogs and was scattered was determined when the courting male(s) attempted to throughout the study area. The restaurants near the bus stop mount and copulate. Observations continued until that were the main food resources for the subjects. female refused to allow the male(s) in her company to mount and copulate for two or more successive days. The first of 2.2. Subjects. From March 2008 to February 2010, a total of these days was considered to be the end of oestrus [23]. 33 residential individuals (17 males and 16 females) from 5 In this study mating system was divided into six cate- neighbouring dog groups (3 groups in 2008 and 2 groups in gories. 2009) that roamed freely throughout the day and night, and whose home range, prior reproductive history, and origin (1) Monogamy: when males and females form extensive were known, were selected for this study. From the previous pair bonds and have only one mate at least for the studies [18] it was confirmed that there were no natal duration of the reproductive season. relations between the mating partners of the dog groups. (2) Polygyny: when males have multiple mates, females Puppies and juveniles were excluded in this study (Table 1). typically mate with only one male. Moreover, throughout the study, a total of 46 “transient” (3) Promiscuity: when both males and females mate with individuals (34 males and 12 females) were noticed in this several individuals of the opposite sex. area. A “residential” dog was defined as any individual that was present in the study area for more than one season. (4) Polyandry: when females have multiple mates, males A “transient” dog was defined as any individual that used typically mate with only one female. the area for less than one season. The behaviour of both (5) Forceful mating or rape: when an extra-group non- residential, and transient dogs associated with those females preferred and physically powerful male mated force- during the oestrus period was observed. fully with the unwilling females. Dogs were classified as puppies (birth—4 months), (6) Opportunity: when a transient male was able to juveniles (4 months–12 months), young adults (1 year–7 copulate successfully after being present only for a years), and old adults (>7 years). Age of the puppies was short time. determined by visual means. Age of the juveniles, adults, and old adults was determined by direct observations, interviews During coitus part of the dog’s penis (the bulbus glandis) with the area residents, and sometimes according to the enlarged and was held firmly by the contracted muscles of eruption and wear patterns of their dentition [19]. the vagina, thus preventing the penis from being withdrawn. All the animals being studied were identified by photo- This was the “tie” that was considered a desirable feature of a graphic mark-recapture method described by [20], and also successful mating. visually by coat colour and pattern. The sex of the dogs was The seasons were defined as summer (March–May), determined by observing the animals and their behaviour monsoon (June–August), late monsoon (September–No- especially their urination postures [21]. vember), and winter (December–February). All observations were videotaped following the dogs either on foot or by a 2.3. Experimental Procedure. The study began in March 2008 bicycle using Sony Handycam without any interruption of and continued until the end of February 2010. Throughout the normal activities of the subjects. Five local people assisted the study period, the dog groups were observed daily between to collect data. 06:00 and 08:00 h. During the oestrus period, the focal Data collected in this study were normally distributed. females were followed for the first 6 days of the oestrus (or A Pearson’s chi-square model was followed. Paired and until the end of oestrus); and they were followed between unpaired t-tests were used to examine the differences 06:00 and 22:00 h. A combination of ad libitum and focal between young adult males and old adult males in relation to animal sampling [22] yielded data on the preference of both courting, male-female preferences, and mounting. Pearson’s International Journal of Zoology 3 Table 1: Neighbouring dog groups with their mating history observed between 2008 and 2010. Dog code Group Sex Age Mating partners Type of mating Number of mating Opportunistic mating Forceful mating Total mating SM male OA SF ,SF ,SF SM 1 3 4 SM male YA SF ,SF ,SF SM 2 3 4 SM male YA HF SM 2 SM male J SM SM female OA SM polygyny 4 — — 4 SF 1 SM female YA SM polygyny 5 — — 5 SF 2 SM female YA SM ,SM promiscuity 5 — — 5 SF 1 2 SM female YA SM ,SM promiscuity 3 — 1 4 SF 1 2 HIG male YA HF HM 1 HIG male YA HF HM 2 HIG female YA HM monogamy 5 — — 5 HF 1 1 HIG female YA HM ,SM ,T-M polyandry 5 — — 5 HF 2 2 3 HIG female J HF MIG male YA MM MM 1 1 MIG male YA MF MM 2 2 MIG male J MM MIG female YA MM monogamy 3 — 1 4 MF 1 1 MIG female YA MM ,T-M polyandry 5 — — 5 MF 2 2 LIG male OA LF ,LF LM 1 1 2 LIG male YA LF ,LF LM 2 2 3 LM LIG male YA LF ,LF 3 2 3 LM LIG male J LF LIG female YA LM polygyny 4 1 — 5 1 1 LF LIG female YA LM ,LM ,LF promiscuity 4 1 — 5 2 1 2 3 LF LIG female YA LM ,LM promiscuity 5 — — 5 3 2 3 BM BS male OA BF ,BF ,BF 1 1 2 3 BM BS male YA BF ,BF 2 2 3 BM BS male YA BF ,BF 3 2 3 BM BS male J BF BS female YA BM polygyny 4 1 — 5 1 1 BF BS female YA BM ,BM ,BM promiscuity 5 — — 5 1 2 3 BF BS female YA BM ,BM ,BM promiscuity 3 — — 3 1 2 3 BF BS female J OA: Old Adult, YA: Young Adult, J: Juvenile, T-M : Transient Male. coefficient of correlation was used in this study to calculate the period of mating (χ = 18.50, df = 3, P< .0003, the correlation between the number of courting males Figure 1). Table 2 shows the data on the courting behaviour and the duration of association and also to calculate the of 14 focal females during a single oestrus. Throughout correlation between the number of courting males and the the study period, a total of 136 courting associations were number of successful copulations. An analysis of variance recorded, and a total of 467 males were observed in the 136 (ANOVA) was used to test the variations among the dogs of courting associations. It should be noted that a single male both sexes in relation to mounting, number of copulations, was present in different associations of a particular female mating types, and factors influencing the copulatory ties. during a single oestrus. Each oestrous female was courted Average values and Standard Error were expressed as mean by 11 to 60 males during a single oestrus, whereas, during ± S.E. a single courting association it varied from 1 to 10 males (3.40 ± 0.32) (Table 2). Of all courting males (N = 467), 356 (76%) were young adults and the rest were old adults 3. Results (Table 2). Therefore, the focal oestrous females were courted 3.1. Courtship. All14focal femaleswereobservedtocopulate by young adult males with a greater frequency than old adult between August and December showing late monsoon as males (t = 8.00, df = 13, P< .0001). Mean duration of 4 International Journal of Zoology Table 2: Number of courting association, mean (±S.E.) duration of each courting association, no. of courting males, no. of males willing to mount, number of preferred males, number of mounting attempts, and number of successful copulations by the preferred males. No. of Mean (±S.E.) no. of Female Males preferred by the No. of successful copulations by courting Total no. of courting males courting males in No. of willing males No. of mounts code oestrous females preferred males association each association YA OA YA OA YA OA YA OA YA OA SF 12 24 5 21 4 2.08 ± 0.38 11 1 127 26 31 SF 11 26 7 25 5 2.73 ± 0.52 10 1 123 41 50 SF 924 9 22 4 2.89 ± 0.54 9 1 110 46 50 SF 11 17 9 16 5 1.91 ± 0.25 10 1 73 30 30 HF 11 37 9 35 8 3.91 ± 0.86 11 0 130 0 50 HF 914 2 14 2 1.78 ± 0.32 14 2 69 21 50 MF 11 26 8 24 6 2.73 ± 0.63 10 1 108 16 30 MF 911 4 10 2 1.33 ± 0.33 10 2 43 35 41 LF 12 45 13 42 7 4.08 ± 0.83 11 1 155 34 40 LF 13 45 15 43 11 4.05 ± 0.93 13 3 78 91 31 LF 831 8 29 6 4.38 ± 0.60 9 2 64 28 50 BF 619 7 18 3 3.50 ± 0.96 6 0 63 0 40 BF 9 27 14 25 8 3.67 ± 0.62 12 1 125 25 50 BF 510 1 10 1 2.20 ± 0.20 5 0 53 0 30 Total 136 356 111 334 72 2.99 ± 0.19 141 16 1321 393 57 3 YA: Young Adult Male, OA: Old Adult Male. International Journal of Zoology 5 3.4. Mounting and Mating. All the preferred males (141 young adults and 16 old adults) were observed to mount and copulate with the 14 focal females. A total of 1714 mountings were recorded in the 136 courting associations (Table 2). Of all mountings (N = 1714), 77% were performed by young adult males and the rest were performed by old adult males. So, most of the mountings were performed by young adult 2 males (t = 6.03; df = 13; P< .0001). But it should be noted that the sample size for old adult males was very low, and they were present only in 16 courting associations out of 136 associations. The number of mounting initiated in each courting association was 12.60 ± 0.68 times (Table 3), Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb and it varied with the associations (F = 1.81; df = 12, 135; Months of the year P< .0523). Moreover, the number of mounting occurred in each association increased with the number of males present in the courting associations (r = 0.9865, P< .0001), and Figure 1: Mating frequency of the free-ranging domestic dogs in successive months as observed from March 2008 to February 2010. also with the duration of courting (r = 9230, P< .0001). Furthermore, the frequency of mounting per hour for an individual in each courting association was 8.48 ± 0.30 times in the case of young adult males, and it was 14.06 ± 2.09 times in the case of old adult males (Table 3). Therefore, the courting was 75.63 ± 2.67 min, and it varied from 45.69 ± rate of mounting was higher in the case of old adults than in 2.41 to 133.50 ± 4.50 min (Table 3). The duration of courting the case of young adults (t = 3.33, df = 9, P< .0088). varied in different associations (F = 3.71; df = 12, 135; Throughout the study, the 14 focal females copulated P< .0001). Moreover, the duration of courting increased successfully 65 times (copulation with tie), of which 60 with the number of willing males present in a courting copulations were performed by the preferred males and the association (r = 0.9426, P< .00002). other 5 copulations were performed by transient opportunist and dominant males (Table 1). The number of successful 3.2. Preference for Females. Of all courting males recorded copulation for each female varied from 3 to 5; and there were in this study (N = 467), 406 (87%) males exhibited their no significant variations among the females in relation to willingness to mount and copulate the 14 focal oestrous successful copulation (F = 0.01; df = 13, 83; P> 1.0000). females and were identified as willing males (Table 2). Most Of all successful copulations (N = 65), 60 copulations of the courting males showed their preferences for the were performed by the 157 preferred males (Table 2), and oestrous females (t = 6.22, df = 13, P< .0001). After so, not all preferred males copulated (t = 15.88, df = anogenital investigations, few males left the area and were 156, P< .0001). Among the preferred males (N = 157), identified as unwilling males. Of all willing males (N = 406), 40% of the young adults and 19% of the old adults copulated 82% were young adults and the rest were old adults. So, successfully, (Table 2), and so, most of the copulations were young adult males showed their preferences to mount and performed by young adult males (t = 2.96; df = 13, P< copulate with greater frequency than the old adult males .01). Moreover, in the case of young adults 4.9% of mounting (t = 5.20, df = 13, P< .0001). were successful, whereas, in the case of old adults, it was 0.6%. So, mounting was more successful in the case of young 3.3. Preference for Males. In this study, during a single oestrus adults than in the case of old adults (t = 6.78, df = 13, P< period, the 14 focal females only allowed to be mounted .0001). Observations recorded from a variety of situations by 157 males out of 406 willing subjects (Table 2). So, revealed that successful copulation depended in part on the these females exhibited selectivity by readily permitting some number of males courting an oestrous female at a given time males to mate and avoiding, or even attacking others, if they (Table 3). The number of successful copulation decreased as the number of courting males in the mating association attempted to mount (t = 5.52, df = 13, P< .0001). Exceptionally, 2 focal females (HF and MF ) during a increased (r =−8813, P< .0003). 2 2 single oestrus allowed indiscriminately all the willing males (N = 28) to mount and copulate, although, only 10 males successfully copulated with them (Table 2). On average, the 3.5. Mating Systems. In thisstudy,6typesofmating focal females preferred 38% of the willing males; and it (monogamy, polygyny, promiscuity, polyandry, opportunity, ranged from 24% to 100%. So, the females were significantly and forceful mating or rape) were recorded (Table 1). different from each other in relation to their selectivity for the Of all matings (N = 65), 25 (38%) were recorded as males (χ = 173.33, df = 13, P< .0001). Of all willing males, promiscuous mating and 2 (3%) as forceful mating. So, 42% of the young adult males and 22% of the old adult males there were significant variations among the mating types were preferred by the focal females. So, the females preferred (F = 14.07; df = 5.18; P< .0001). However, there were the young adult males with a greater frequency than the old no significant variations among the females in relation to the adult males (t = 4.03, df = 13, P< .0014). type of mating system (F = 0.86; df = 13, 18; P> 1.0000). Number of females copulated successfully per month 6 International Journal of Zoology Table 3: Number of courting association, number of males present in each association, mean (±S.E.) duration of association, mean (±S.E.) number of mounting in each courting association, mean (±S.E.) number of mounting per hour, and number of successful copulations. Mean (±S.E.) no. of No. of males present in Totalno. of preferredmales Mean (±S.E.) duration No of successful No. of courting mounting in each Frequency of mounting per hour each courting present in the courting in each courting copulations in the associations courting association for an individual (min) association associations association (min) courting associations (min) YA OA YA OA 1 42 40 2 45.69 ± 2.41 10.10 ± 1.26 11.68 ± 0.22 27.70 ± 0.09 23 (39%) 2 31 31 1 59.68 ± 3.61 11.61 ± 1.58 10.64 ± 0.54 23.11 ± 0.00 14 (23%) 3 22 22 2 87.45 ± 1.16 12.91 ± 1.74 6.77 ± 0.41 21.99 ± 0.52 9 (15%) 4 14 15 2 102.00 ± 1.52 14.43 ± 2.04 5.80 ± 0.54 16.26 ± 0.37 6 (10%) 5 9 11 1 107.22 ± 1.98 14.11 ± 1.94 5.27 ± 0.65 13.27 ± 0.00 3 (5%) 6 6 7 1 115.33 ± 1.82 15.00 ± 1.91 5.22 ± 1.14 10.17 ± 0.00 2 (3%) 7 4 6 2 119.50 ± 2.02 17.75 ± 2.14 3.06 ± 0.53 9.52 ± 1.52 2 (3%) 8 3 3 3 123.67 ± 6.23 18.00 ± 1.53 3.82 ± 0.88 6.45 ± 1.14 1 (2%) 9 3 4 1 130.33 ± 3.76 20.00 ± 1.00 5.76 ± 1.20 4.62 ± 0.00 0 (0%) 10 2 2 1 133.50 ± 4.50 21.00 ± 1.00 7.70 ± 1.61 3.48 ± 0.00 0 (0%) Mean (±S.E.) 75.63 ± 2.67 12.60 ± 0.68 8.48 ± 0.3 14.06 ± 2.09 International Journal of Zoology 7 Table 4: Duration of copulatory ties in different situations. this situation the unwilling locked females were observed to escape by crying, biting, or lying on the ground. So, 2 forceful Mean (±S.E.) duration matings (rape) occurred among these females with a mean No. of Situations of copulatory ties cases 1.00 (± 0.00). (min) Uninterrupted condition 14 42.43 ± 1.73 3.6. Copulatory Ties. The duration of copulatory ties was Mounts and copulations by the recorded in different situations (Table 4). Of all copulations courting males to the locked 23 27.87 ± 0.96 (N = 65), 14 copulations occurred without any interruption female and the rest were influenced by different factors. Ten copu- Threatens given by the courting 16 20.00 ± 0.72 lations were affected by interference of vehicles and children. males to the locked male Since those were interrupted by nonnatural factors, they were Forcible mating by the dominant 2 13.50 ± 3.50 not included in the estimate of copulatory ties duration. and powerful males Mean duration of copulatory ties was 28.76 (±1.36) min, Total 55 28.76 ± 1.36 and it varied with the situations (F = 63.28; df = 3, 54; P< .0001). Several external natural factors influencing the duration of copulatory ties were identified. (1) In 23 In this study, only 2 females (HF and MF )out of 1 1 cases other courting male(s) attempted to mount the locked 14 focal females formed pair bonds with 2 males, HM female from side or rear. (2) Threatening and also physical and MM , respectively, during preoestrous period (Table 1). attack by the courting male(s) to the locked male was During the first 6 days of oestrus, these 2 females allowed the observed in 16 cases. (3) In 2 cases non-preferred dominant 2 preferred males to mount and copulate; whereas rejected and powerful male(s) intromitted forcibly. In all situations, all other courting males. A total of 8 successful copulations the locked female cried out, turned aggressively towards were performed by these 2 males with a mean 4.00 (±1.00). the locked male, and occasionally rolled on the ground Moreover, there was no significant difference between these 2 vigorously afterwards. Therefore, external factors had a more females in relation to monogamous mating (χ = 0.50, df = significant impact on the duration of copulation than the 1, P> .7401). uninterrupted conditions (χ = 31.38, df = 1, P< .0001). In 4 cases, males within the group mated with more than 1 female but the female mated with only 1 male (Table 1). A 3.7. Male-Male Mounting. Male-male mounting was a strik- total of 17 copulations were enjoyed by 4 females with a mean ing feature in this study. It was observed on 5 occasions and 4.50 (±0.25); and there was no significant difference between among 5 males (Table 5). On all occasions the alpha male the females in relation to the number of polygynous mating mounted the other from the rear with pelvic thrusts. The (χ = 0.16, df = 3, P> .9189). frequency of mating per hour was 9.20 ± 0.86. In 6 cases, both males and females were observed to mount and copulate with several individuals of the opposite 3.8. Female-Female Mounting. On 4 occasions, only 2 oe- sex within the group during a single oestrus (Table 1). A strous females (SF and BF ) were observed to mount other 2 1 total of 25 copulations were enjoyed by 6 females with females (SF and BF respectively) like sexually experienced 3 2 amean4.17(±0.31). Moreover, there was no significant male (Table 5). A total of 23 rear mounts without pelvic difference between the females in relation to the number of thrust were recorded in this study. The frequency of mating promiscuous mating (χ = 0.67, df = 5, P> .9846). per hour was 5.75 ± 0.86. It was noticed when the preferred Two focal females (HF and MF ) out of 14, allowed 2 2 male was in unwilling mood. indiscriminately all the courting males (N = 28) to mount and copulate during a single oestrus (Table 3). Both intra- group and transient males were observed in the mating 4. Discussion places. A total of 10 matings were recorded for these 2 females (Table 1) with a mean 5.00 (±0.00). The timing of reproduction is an important aspect of the Interestingly on some occasions (N = 3), mounting biology of free-ranging domestic dogs with respect to the attempts were made by 3 opportunist transient males number of breeding periods and the time of year breeding (Table 1). When the courting males were engaged in occurs. Reference [24] reported that domestic dogs breed aggressive encounters, an opportunist transient male after twice a year, and this was confirmed by a number of authors being present only a short time mounted the oestrous female (e.g., [25, 26]). In contrast, the results of this and other and tied. In this situation the alpha male, while showing studies suggest that the free-ranging domestic dogs of West no aggression towards the opportunist male, then attempted Bengal breed once a year [17, 27–29]. Single mating season to mount to the locked female. A total of 3 opportunistic was also reported by [30–34]incaseofcoyotes (Canis matings were recorded among the 3 focal females with a latrans). Domestic dogs (Canis familiaris) are considered mean 1.00 (±0.00). nonseasonal breeders with the exception of the Basenji which In 5 courting associations out of 136, 5 transient powerful shows an annual seasonal period of estrus during the fall and aggressive males attempted to mount and copulate [35]. But all the matings recorded in this study took place forcibly with 5 focal females (Table 1). Only in 2 cases out between August and December with a peak in late monsoon of 5 cases, successful copulation ending in “ties” occurred. In months (September to November) showing a prolonged 8 International Journal of Zoology Table 5: Male-male and female-female mounting. Male-male mounting Female-female mounting Average no. of Duration of Average no. Average no. of Duration of Average no. of No. of case males present in each occasion of mounting No. of cases females present each occasion mounting per each case (min) per hour in each case (min) hour 52.40 ± 0.25 60 9.20 ± 0.86 4 1.00 ± 0.00 60 5.75 ± 0.86. mating period [12, 28, 29, 36]. In the tropics, more females species. Polyandrous mating in domestic dogs was also were seen in estrus during late autumn and winter by [37]. previously reported by [12, 17]. Why do some females Among the free-ranging domestic dogs in this study, prefer mating with more than one male? Although multiple both males and females were highly attracted to each other mating entails risks [49], including decreased control over when the females were in oestrus. Males were more attracted paternity, this strategy may benefit females by: (1) confusing to the females than vice versa; however, all of the males paternity and discouraging infanticide [50, 51]; (2) providing present in the mating places were not equally attracted to high-quality genes through enhanced male-male and sperm a particular female [12]. Some research has suggested that competition [52, 53], and (3) ensuring fertilization [54, 55]. age of males is an important factor that may influence female Predation of puppies by dogs of another group was noticed preference; and older males may be preferred since prolonged by [56]. So, it may be presumed that multiple mating may survival attests to physical and/or social quality and confirms also reduce male aggression toward females [57] and increase viability in the current environment [38, 39]. Contrarily, social support or protection from predators [58–60]. the females in this study preferred the young adults with a It is interesting to note that when the courting males greater frequency, and it was also previously reported by [12]. were engaged in aggressive encounters, opportunist transient Perhaps older males may be less preferred since sperm may be males were able to copulate after being present only a short less viable or sperm counts may be low [40, 41]. The duration time; and it may be described as “opportune” mating. This of courting association increased with the number of males behaviour was previously reported in dogs by [12] being also gathered in an association as previously reported by [12, 17]. described in feral cats as “short-time courting strategies” by Although, most of the mountings among the old adult [42, 61]. males were unsuccessful (without ending in tie), the fre- Females prefer to mate with some males and resist others quency of mounting per hour was higher among the old [23]. Some authors suggest that females prefer dominant adult males as previously reported by [12]. Perhaps due males [38, 62–66]. In contrast, in this study oestrous females to failure in successful copulations, the old adult males generally disliked the aggressive and physically powerful mounted frequently. However, the number of courting old males. This agrees with the findings of [12, 17]. Moreover, adult males was very low in this study, and further data are some authors [67–69] found no direct relationship between needed to distinguish the mating behavior between young dominance ranks and mating success. On some occasions, adults and old adults. Successful copulation was prevented the aggressive and physically powerful males were observed when more than 2 or 3 males were present in the mating to copulate the unwilling females forcibly which may be association [12, 17]. This was also noticed by [42]inferal described as “rape” in free-ranging domestic dogs [12, 17]. cats. The duration of copulatory ties varied with several exter- Mating system was the most striking feature of this nal factors. In this study mounting by the courting males(s) study. In this study, two females and two males within to the locked male, forcibly mating by the dominant and the social group formed pair bonds and mated successfully large male(s), children interference, and running vehicles during a single oestrus showing the evidence of monogamy were identified as copulation-interrupting factors [12, 17, in dogs [43]. The prevailing mating system in canids is 70]. Significant human interference on the reproduction was monogamy [1, 3, 44]; however, on some occasions, males also reported by [71] in the case of village dogs. within the group mated with more than one female but the Male-male mounting was an interesting finding of this female mated with only one male showing the evidence of study since it was previously reported by [12]but not polygyny. In most cases, both males and females within the observed in the study of [14]. Although, female-female social group mated with several individuals of the opposite mounting was rare in this study, occasionally the oestrous sex showing evidence of promiscuity. Two females in this female mounted the waiting female from the side or study, mated indiscriminately with all the courting males rear without pelvic thrusts. Male-male and female-female during a single oestrus period which may be described as mountings were observed in this study, but the purpose of “polyandry” in the domestic dog. Although evidence is scant, this behaviour is not understood. the observations of this study may suggest that monogamy, polygyny, promiscuity, and polyandry occur in free-ranging Individual differences in relation to sexual behaviour domestic dogs. Interspecific variations in mating systems were observed both in males and females, and the present among canids, and both polygamy and monogamy have authors presume that both inter- and intrasexual behaviour also been reported by [45–48]. Moreover, [46]suggested of free-ranging domestic dogs are partly dependent on that both polygyny and monogamy occur within the same individual psychology and situations. International Journal of Zoology 9 Acknowledgments [17] B. Ghosh, D. K. Choudhuri, and B. Pal, “Some aspects of the sexual behaviour of stray dogs, canis familiaris,” Applied The author thank Professor M. Bekoff, Professor E. Font, Animal Behaviour Science, vol. 13, no. 1-2, pp. 113–127, 1984. and Professor L. Boitani who read the drafts of this paper [18] S. K. Pal, “Play behaviour during early ontogeny in free- and improved the quality. 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Mating System of Free-Ranging Dogs (Canis familiaris)

International Journal of Zoology , Volume 2011 – Jul 3, 2011

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Hindawi Publishing Corporation
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Copyright © 2011 S. K. Pal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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1687-8477
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10.1155/2011/314216
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Abstract

Hindawi Publishing Corporation International Journal of Zoology Volume 2011, Article ID 314216, 10 pages doi:10.1155/2011/314216 Research Article S. K. Pal Katwa Bharati Bhaban, Katwa, Burdwan 713 130, India Correspondence should be addressed to S. K. Pal, drskpal@rediffmail.com Received 22 December 2010; Revised 1 March 2011; Accepted 14 May 2011 Academic Editor: Marcel Eens Copyright © 2011 S. K. Pal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fourteen females belonging to five groups were selected for the study of mating system in free-ranging domestic dogs (Canis familiaris) All the matings occurred between August and December with a peak in late monsoon months (September to November). Both males and females differed in their degree of attractiveness to the opposite sex. The duration of courting association increased with the number of courting males in an association. The females exhibited selectivity by readily permitting some males to mate and avoiding, or even attacking others, if they attempted to mount. Frequency of mounting in courting association increased with the number of males present. There was a positive correlation between the duration of courting association and the frequency of mounting. The young adult males were more likely to copulate successfully than the old adult males. There was a negative correlation between the number of males present in an association and the number of successful copulations. In this study, six types of mating (monogamy, polygyny, promiscuity, polyandry, opportunity and rape) were recorded. Mean (±S.E.) duration of copulatory ties was 25.65 (±1.43) min. Several natural factors influencing the duration of copulatory ties were identified. 1. Introduction have shown that extra pair mating occurs among two canid species, the Ethiopian wolf (Canis simensis) and the Mating system is the basis of any mammalian social system; African wild dog (Lycaon pictus;[7, 8]. As predicted by [9], and it can be defined as the ways in which different kinds genetic investigations of canid mating have revealed, thus of animals are associated during copulation and the factors far, a flexible mating structure, similar to the findings of that contribute to identification of partners, interaction, and investigations into mating structure of socially monogamous eventually fertilization. Monogamy is the rarest form of birds [10]. mating system among mammals, estimated to occur in 3– Sexual behaviour of domestic dogs (Canis familiaris) 5% of all mammalian taxa [1, 2]. However, it is the most has attracted the attention of scientists for a long time. common breeding system for canids [3]. This is due in Several studies on the sexual behaviour have been made part to the high demands that pups place on their parents, in the domestic dog (e.g., [11, 12].)Mostofthe previous as for most species of canidae they are born altricial in studies dealt with attractions between the members of the large litters and require an extended period of training to opposite sex when the females were in oestrus. Heterosexual learn to hunt and survive on their own. Also, puppies in attraction as well as intrasexual behaviour in domestic dogs many canid species require protection, as they face danger of was first extensively studied by [13, 14], although, male- intraspecific infanticide from neighboring territorial canids. male mounting was not observed in these studies. Later, [15] Recent investigations of the mating behaviors of canidae gave a comparative account of the roles of attractiveness and raise doubts as to whether any canid species is genetically receptivity in the mating behaviour of different mammalian monogamous. For instance, the red fox (Vulpes vulpes), females. In the case of domestic dogs, most previous studies the swift fox (Vulpes velox), and the island fox (Urocyon on oestrous females and their attractiveness have been done littoralis), all of which were thought to have exclusive mated in enclosed areas except [12, 16, 17]. Although, till now, the pair systems, were shown through genetic analysis to be mating system of free-ranging domestic dogs is a mysterious polygamous [4–6]. Observational and genetic investigations subject, no extensive studies have been done. 2 International Journal of Zoology The purpose of this study was to investigate the degree sexes and mating behaviour. Female-male, male-male and of attractiveness to the opposite sex and mating systems female-female mounting behaviour was also observed. A of free-ranging domestic dogs. Both intra- and intersexual total of 2750 h was devoted collecting data on inter- and behaviour of free-ranging domestic dogs were also investi- intra-sexual behaviour of the free-ranging domestic dogs. gated in this study. Aggregation of one or more male dogs within 5 m of the female in oestrous for at least 1 min was defined as “courting association”, and the males present in the courting 2. Materials and Methods association were defined as “courting” males. The courting males who followed and stayed for 10 min within 5 m of the 2.1. Study Area. The study was carried out in the town of ◦  ◦  oestrous female and attempted to mount or copulate, were Katwa (lat 23 39 N, long 88 8 E) in the state of West Bengal, 2 defined as “willing” males and the males that did not show India. The study area (0.5 km ), inhabited by a population any interest to mount or copulate were defined as “unwilling” of approximately 4500 people, was on the outskirts of the males. The willing males who were allowed by the oestrous town and was linked with other parts of the town by a paved females to mount and copulate were defined by “preferred” road. It was surrounded to the North and North-West by males. wetland, and to the East, South, and South-West by paddy An oestrous female was identified on the basis of fields. The main bus stop of the town was situated in this area. behavioural cues described by [14]. The first day of oestrus Garbage was the food resource for the dogs and was scattered was determined when the courting male(s) attempted to throughout the study area. The restaurants near the bus stop mount and copulate. Observations continued until that were the main food resources for the subjects. female refused to allow the male(s) in her company to mount and copulate for two or more successive days. The first of 2.2. Subjects. From March 2008 to February 2010, a total of these days was considered to be the end of oestrus [23]. 33 residential individuals (17 males and 16 females) from 5 In this study mating system was divided into six cate- neighbouring dog groups (3 groups in 2008 and 2 groups in gories. 2009) that roamed freely throughout the day and night, and whose home range, prior reproductive history, and origin (1) Monogamy: when males and females form extensive were known, were selected for this study. From the previous pair bonds and have only one mate at least for the studies [18] it was confirmed that there were no natal duration of the reproductive season. relations between the mating partners of the dog groups. (2) Polygyny: when males have multiple mates, females Puppies and juveniles were excluded in this study (Table 1). typically mate with only one male. Moreover, throughout the study, a total of 46 “transient” (3) Promiscuity: when both males and females mate with individuals (34 males and 12 females) were noticed in this several individuals of the opposite sex. area. A “residential” dog was defined as any individual that was present in the study area for more than one season. (4) Polyandry: when females have multiple mates, males A “transient” dog was defined as any individual that used typically mate with only one female. the area for less than one season. The behaviour of both (5) Forceful mating or rape: when an extra-group non- residential, and transient dogs associated with those females preferred and physically powerful male mated force- during the oestrus period was observed. fully with the unwilling females. Dogs were classified as puppies (birth—4 months), (6) Opportunity: when a transient male was able to juveniles (4 months–12 months), young adults (1 year–7 copulate successfully after being present only for a years), and old adults (>7 years). Age of the puppies was short time. determined by visual means. Age of the juveniles, adults, and old adults was determined by direct observations, interviews During coitus part of the dog’s penis (the bulbus glandis) with the area residents, and sometimes according to the enlarged and was held firmly by the contracted muscles of eruption and wear patterns of their dentition [19]. the vagina, thus preventing the penis from being withdrawn. All the animals being studied were identified by photo- This was the “tie” that was considered a desirable feature of a graphic mark-recapture method described by [20], and also successful mating. visually by coat colour and pattern. The sex of the dogs was The seasons were defined as summer (March–May), determined by observing the animals and their behaviour monsoon (June–August), late monsoon (September–No- especially their urination postures [21]. vember), and winter (December–February). All observations were videotaped following the dogs either on foot or by a 2.3. Experimental Procedure. The study began in March 2008 bicycle using Sony Handycam without any interruption of and continued until the end of February 2010. Throughout the normal activities of the subjects. Five local people assisted the study period, the dog groups were observed daily between to collect data. 06:00 and 08:00 h. During the oestrus period, the focal Data collected in this study were normally distributed. females were followed for the first 6 days of the oestrus (or A Pearson’s chi-square model was followed. Paired and until the end of oestrus); and they were followed between unpaired t-tests were used to examine the differences 06:00 and 22:00 h. A combination of ad libitum and focal between young adult males and old adult males in relation to animal sampling [22] yielded data on the preference of both courting, male-female preferences, and mounting. Pearson’s International Journal of Zoology 3 Table 1: Neighbouring dog groups with their mating history observed between 2008 and 2010. Dog code Group Sex Age Mating partners Type of mating Number of mating Opportunistic mating Forceful mating Total mating SM male OA SF ,SF ,SF SM 1 3 4 SM male YA SF ,SF ,SF SM 2 3 4 SM male YA HF SM 2 SM male J SM SM female OA SM polygyny 4 — — 4 SF 1 SM female YA SM polygyny 5 — — 5 SF 2 SM female YA SM ,SM promiscuity 5 — — 5 SF 1 2 SM female YA SM ,SM promiscuity 3 — 1 4 SF 1 2 HIG male YA HF HM 1 HIG male YA HF HM 2 HIG female YA HM monogamy 5 — — 5 HF 1 1 HIG female YA HM ,SM ,T-M polyandry 5 — — 5 HF 2 2 3 HIG female J HF MIG male YA MM MM 1 1 MIG male YA MF MM 2 2 MIG male J MM MIG female YA MM monogamy 3 — 1 4 MF 1 1 MIG female YA MM ,T-M polyandry 5 — — 5 MF 2 2 LIG male OA LF ,LF LM 1 1 2 LIG male YA LF ,LF LM 2 2 3 LM LIG male YA LF ,LF 3 2 3 LM LIG male J LF LIG female YA LM polygyny 4 1 — 5 1 1 LF LIG female YA LM ,LM ,LF promiscuity 4 1 — 5 2 1 2 3 LF LIG female YA LM ,LM promiscuity 5 — — 5 3 2 3 BM BS male OA BF ,BF ,BF 1 1 2 3 BM BS male YA BF ,BF 2 2 3 BM BS male YA BF ,BF 3 2 3 BM BS male J BF BS female YA BM polygyny 4 1 — 5 1 1 BF BS female YA BM ,BM ,BM promiscuity 5 — — 5 1 2 3 BF BS female YA BM ,BM ,BM promiscuity 3 — — 3 1 2 3 BF BS female J OA: Old Adult, YA: Young Adult, J: Juvenile, T-M : Transient Male. coefficient of correlation was used in this study to calculate the period of mating (χ = 18.50, df = 3, P< .0003, the correlation between the number of courting males Figure 1). Table 2 shows the data on the courting behaviour and the duration of association and also to calculate the of 14 focal females during a single oestrus. Throughout correlation between the number of courting males and the the study period, a total of 136 courting associations were number of successful copulations. An analysis of variance recorded, and a total of 467 males were observed in the 136 (ANOVA) was used to test the variations among the dogs of courting associations. It should be noted that a single male both sexes in relation to mounting, number of copulations, was present in different associations of a particular female mating types, and factors influencing the copulatory ties. during a single oestrus. Each oestrous female was courted Average values and Standard Error were expressed as mean by 11 to 60 males during a single oestrus, whereas, during ± S.E. a single courting association it varied from 1 to 10 males (3.40 ± 0.32) (Table 2). Of all courting males (N = 467), 356 (76%) were young adults and the rest were old adults 3. Results (Table 2). Therefore, the focal oestrous females were courted 3.1. Courtship. All14focal femaleswereobservedtocopulate by young adult males with a greater frequency than old adult between August and December showing late monsoon as males (t = 8.00, df = 13, P< .0001). Mean duration of 4 International Journal of Zoology Table 2: Number of courting association, mean (±S.E.) duration of each courting association, no. of courting males, no. of males willing to mount, number of preferred males, number of mounting attempts, and number of successful copulations by the preferred males. No. of Mean (±S.E.) no. of Female Males preferred by the No. of successful copulations by courting Total no. of courting males courting males in No. of willing males No. of mounts code oestrous females preferred males association each association YA OA YA OA YA OA YA OA YA OA SF 12 24 5 21 4 2.08 ± 0.38 11 1 127 26 31 SF 11 26 7 25 5 2.73 ± 0.52 10 1 123 41 50 SF 924 9 22 4 2.89 ± 0.54 9 1 110 46 50 SF 11 17 9 16 5 1.91 ± 0.25 10 1 73 30 30 HF 11 37 9 35 8 3.91 ± 0.86 11 0 130 0 50 HF 914 2 14 2 1.78 ± 0.32 14 2 69 21 50 MF 11 26 8 24 6 2.73 ± 0.63 10 1 108 16 30 MF 911 4 10 2 1.33 ± 0.33 10 2 43 35 41 LF 12 45 13 42 7 4.08 ± 0.83 11 1 155 34 40 LF 13 45 15 43 11 4.05 ± 0.93 13 3 78 91 31 LF 831 8 29 6 4.38 ± 0.60 9 2 64 28 50 BF 619 7 18 3 3.50 ± 0.96 6 0 63 0 40 BF 9 27 14 25 8 3.67 ± 0.62 12 1 125 25 50 BF 510 1 10 1 2.20 ± 0.20 5 0 53 0 30 Total 136 356 111 334 72 2.99 ± 0.19 141 16 1321 393 57 3 YA: Young Adult Male, OA: Old Adult Male. International Journal of Zoology 5 3.4. Mounting and Mating. All the preferred males (141 young adults and 16 old adults) were observed to mount and copulate with the 14 focal females. A total of 1714 mountings were recorded in the 136 courting associations (Table 2). Of all mountings (N = 1714), 77% were performed by young adult males and the rest were performed by old adult males. So, most of the mountings were performed by young adult 2 males (t = 6.03; df = 13; P< .0001). But it should be noted that the sample size for old adult males was very low, and they were present only in 16 courting associations out of 136 associations. The number of mounting initiated in each courting association was 12.60 ± 0.68 times (Table 3), Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb and it varied with the associations (F = 1.81; df = 12, 135; Months of the year P< .0523). Moreover, the number of mounting occurred in each association increased with the number of males present in the courting associations (r = 0.9865, P< .0001), and Figure 1: Mating frequency of the free-ranging domestic dogs in successive months as observed from March 2008 to February 2010. also with the duration of courting (r = 9230, P< .0001). Furthermore, the frequency of mounting per hour for an individual in each courting association was 8.48 ± 0.30 times in the case of young adult males, and it was 14.06 ± 2.09 times in the case of old adult males (Table 3). Therefore, the courting was 75.63 ± 2.67 min, and it varied from 45.69 ± rate of mounting was higher in the case of old adults than in 2.41 to 133.50 ± 4.50 min (Table 3). The duration of courting the case of young adults (t = 3.33, df = 9, P< .0088). varied in different associations (F = 3.71; df = 12, 135; Throughout the study, the 14 focal females copulated P< .0001). Moreover, the duration of courting increased successfully 65 times (copulation with tie), of which 60 with the number of willing males present in a courting copulations were performed by the preferred males and the association (r = 0.9426, P< .00002). other 5 copulations were performed by transient opportunist and dominant males (Table 1). The number of successful 3.2. Preference for Females. Of all courting males recorded copulation for each female varied from 3 to 5; and there were in this study (N = 467), 406 (87%) males exhibited their no significant variations among the females in relation to willingness to mount and copulate the 14 focal oestrous successful copulation (F = 0.01; df = 13, 83; P> 1.0000). females and were identified as willing males (Table 2). Most Of all successful copulations (N = 65), 60 copulations of the courting males showed their preferences for the were performed by the 157 preferred males (Table 2), and oestrous females (t = 6.22, df = 13, P< .0001). After so, not all preferred males copulated (t = 15.88, df = anogenital investigations, few males left the area and were 156, P< .0001). Among the preferred males (N = 157), identified as unwilling males. Of all willing males (N = 406), 40% of the young adults and 19% of the old adults copulated 82% were young adults and the rest were old adults. So, successfully, (Table 2), and so, most of the copulations were young adult males showed their preferences to mount and performed by young adult males (t = 2.96; df = 13, P< copulate with greater frequency than the old adult males .01). Moreover, in the case of young adults 4.9% of mounting (t = 5.20, df = 13, P< .0001). were successful, whereas, in the case of old adults, it was 0.6%. So, mounting was more successful in the case of young 3.3. Preference for Males. In this study, during a single oestrus adults than in the case of old adults (t = 6.78, df = 13, P< period, the 14 focal females only allowed to be mounted .0001). Observations recorded from a variety of situations by 157 males out of 406 willing subjects (Table 2). So, revealed that successful copulation depended in part on the these females exhibited selectivity by readily permitting some number of males courting an oestrous female at a given time males to mate and avoiding, or even attacking others, if they (Table 3). The number of successful copulation decreased as the number of courting males in the mating association attempted to mount (t = 5.52, df = 13, P< .0001). Exceptionally, 2 focal females (HF and MF ) during a increased (r =−8813, P< .0003). 2 2 single oestrus allowed indiscriminately all the willing males (N = 28) to mount and copulate, although, only 10 males successfully copulated with them (Table 2). On average, the 3.5. Mating Systems. In thisstudy,6typesofmating focal females preferred 38% of the willing males; and it (monogamy, polygyny, promiscuity, polyandry, opportunity, ranged from 24% to 100%. So, the females were significantly and forceful mating or rape) were recorded (Table 1). different from each other in relation to their selectivity for the Of all matings (N = 65), 25 (38%) were recorded as males (χ = 173.33, df = 13, P< .0001). Of all willing males, promiscuous mating and 2 (3%) as forceful mating. So, 42% of the young adult males and 22% of the old adult males there were significant variations among the mating types were preferred by the focal females. So, the females preferred (F = 14.07; df = 5.18; P< .0001). However, there were the young adult males with a greater frequency than the old no significant variations among the females in relation to the adult males (t = 4.03, df = 13, P< .0014). type of mating system (F = 0.86; df = 13, 18; P> 1.0000). Number of females copulated successfully per month 6 International Journal of Zoology Table 3: Number of courting association, number of males present in each association, mean (±S.E.) duration of association, mean (±S.E.) number of mounting in each courting association, mean (±S.E.) number of mounting per hour, and number of successful copulations. Mean (±S.E.) no. of No. of males present in Totalno. of preferredmales Mean (±S.E.) duration No of successful No. of courting mounting in each Frequency of mounting per hour each courting present in the courting in each courting copulations in the associations courting association for an individual (min) association associations association (min) courting associations (min) YA OA YA OA 1 42 40 2 45.69 ± 2.41 10.10 ± 1.26 11.68 ± 0.22 27.70 ± 0.09 23 (39%) 2 31 31 1 59.68 ± 3.61 11.61 ± 1.58 10.64 ± 0.54 23.11 ± 0.00 14 (23%) 3 22 22 2 87.45 ± 1.16 12.91 ± 1.74 6.77 ± 0.41 21.99 ± 0.52 9 (15%) 4 14 15 2 102.00 ± 1.52 14.43 ± 2.04 5.80 ± 0.54 16.26 ± 0.37 6 (10%) 5 9 11 1 107.22 ± 1.98 14.11 ± 1.94 5.27 ± 0.65 13.27 ± 0.00 3 (5%) 6 6 7 1 115.33 ± 1.82 15.00 ± 1.91 5.22 ± 1.14 10.17 ± 0.00 2 (3%) 7 4 6 2 119.50 ± 2.02 17.75 ± 2.14 3.06 ± 0.53 9.52 ± 1.52 2 (3%) 8 3 3 3 123.67 ± 6.23 18.00 ± 1.53 3.82 ± 0.88 6.45 ± 1.14 1 (2%) 9 3 4 1 130.33 ± 3.76 20.00 ± 1.00 5.76 ± 1.20 4.62 ± 0.00 0 (0%) 10 2 2 1 133.50 ± 4.50 21.00 ± 1.00 7.70 ± 1.61 3.48 ± 0.00 0 (0%) Mean (±S.E.) 75.63 ± 2.67 12.60 ± 0.68 8.48 ± 0.3 14.06 ± 2.09 International Journal of Zoology 7 Table 4: Duration of copulatory ties in different situations. this situation the unwilling locked females were observed to escape by crying, biting, or lying on the ground. So, 2 forceful Mean (±S.E.) duration matings (rape) occurred among these females with a mean No. of Situations of copulatory ties cases 1.00 (± 0.00). (min) Uninterrupted condition 14 42.43 ± 1.73 3.6. Copulatory Ties. The duration of copulatory ties was Mounts and copulations by the recorded in different situations (Table 4). Of all copulations courting males to the locked 23 27.87 ± 0.96 (N = 65), 14 copulations occurred without any interruption female and the rest were influenced by different factors. Ten copu- Threatens given by the courting 16 20.00 ± 0.72 lations were affected by interference of vehicles and children. males to the locked male Since those were interrupted by nonnatural factors, they were Forcible mating by the dominant 2 13.50 ± 3.50 not included in the estimate of copulatory ties duration. and powerful males Mean duration of copulatory ties was 28.76 (±1.36) min, Total 55 28.76 ± 1.36 and it varied with the situations (F = 63.28; df = 3, 54; P< .0001). Several external natural factors influencing the duration of copulatory ties were identified. (1) In 23 In this study, only 2 females (HF and MF )out of 1 1 cases other courting male(s) attempted to mount the locked 14 focal females formed pair bonds with 2 males, HM female from side or rear. (2) Threatening and also physical and MM , respectively, during preoestrous period (Table 1). attack by the courting male(s) to the locked male was During the first 6 days of oestrus, these 2 females allowed the observed in 16 cases. (3) In 2 cases non-preferred dominant 2 preferred males to mount and copulate; whereas rejected and powerful male(s) intromitted forcibly. In all situations, all other courting males. A total of 8 successful copulations the locked female cried out, turned aggressively towards were performed by these 2 males with a mean 4.00 (±1.00). the locked male, and occasionally rolled on the ground Moreover, there was no significant difference between these 2 vigorously afterwards. Therefore, external factors had a more females in relation to monogamous mating (χ = 0.50, df = significant impact on the duration of copulation than the 1, P> .7401). uninterrupted conditions (χ = 31.38, df = 1, P< .0001). In 4 cases, males within the group mated with more than 1 female but the female mated with only 1 male (Table 1). A 3.7. Male-Male Mounting. Male-male mounting was a strik- total of 17 copulations were enjoyed by 4 females with a mean ing feature in this study. It was observed on 5 occasions and 4.50 (±0.25); and there was no significant difference between among 5 males (Table 5). On all occasions the alpha male the females in relation to the number of polygynous mating mounted the other from the rear with pelvic thrusts. The (χ = 0.16, df = 3, P> .9189). frequency of mating per hour was 9.20 ± 0.86. In 6 cases, both males and females were observed to mount and copulate with several individuals of the opposite 3.8. Female-Female Mounting. On 4 occasions, only 2 oe- sex within the group during a single oestrus (Table 1). A strous females (SF and BF ) were observed to mount other 2 1 total of 25 copulations were enjoyed by 6 females with females (SF and BF respectively) like sexually experienced 3 2 amean4.17(±0.31). Moreover, there was no significant male (Table 5). A total of 23 rear mounts without pelvic difference between the females in relation to the number of thrust were recorded in this study. The frequency of mating promiscuous mating (χ = 0.67, df = 5, P> .9846). per hour was 5.75 ± 0.86. It was noticed when the preferred Two focal females (HF and MF ) out of 14, allowed 2 2 male was in unwilling mood. indiscriminately all the courting males (N = 28) to mount and copulate during a single oestrus (Table 3). Both intra- group and transient males were observed in the mating 4. Discussion places. A total of 10 matings were recorded for these 2 females (Table 1) with a mean 5.00 (±0.00). The timing of reproduction is an important aspect of the Interestingly on some occasions (N = 3), mounting biology of free-ranging domestic dogs with respect to the attempts were made by 3 opportunist transient males number of breeding periods and the time of year breeding (Table 1). When the courting males were engaged in occurs. Reference [24] reported that domestic dogs breed aggressive encounters, an opportunist transient male after twice a year, and this was confirmed by a number of authors being present only a short time mounted the oestrous female (e.g., [25, 26]). In contrast, the results of this and other and tied. In this situation the alpha male, while showing studies suggest that the free-ranging domestic dogs of West no aggression towards the opportunist male, then attempted Bengal breed once a year [17, 27–29]. Single mating season to mount to the locked female. A total of 3 opportunistic was also reported by [30–34]incaseofcoyotes (Canis matings were recorded among the 3 focal females with a latrans). Domestic dogs (Canis familiaris) are considered mean 1.00 (±0.00). nonseasonal breeders with the exception of the Basenji which In 5 courting associations out of 136, 5 transient powerful shows an annual seasonal period of estrus during the fall and aggressive males attempted to mount and copulate [35]. But all the matings recorded in this study took place forcibly with 5 focal females (Table 1). Only in 2 cases out between August and December with a peak in late monsoon of 5 cases, successful copulation ending in “ties” occurred. In months (September to November) showing a prolonged 8 International Journal of Zoology Table 5: Male-male and female-female mounting. Male-male mounting Female-female mounting Average no. of Duration of Average no. Average no. of Duration of Average no. of No. of case males present in each occasion of mounting No. of cases females present each occasion mounting per each case (min) per hour in each case (min) hour 52.40 ± 0.25 60 9.20 ± 0.86 4 1.00 ± 0.00 60 5.75 ± 0.86. mating period [12, 28, 29, 36]. In the tropics, more females species. Polyandrous mating in domestic dogs was also were seen in estrus during late autumn and winter by [37]. previously reported by [12, 17]. Why do some females Among the free-ranging domestic dogs in this study, prefer mating with more than one male? Although multiple both males and females were highly attracted to each other mating entails risks [49], including decreased control over when the females were in oestrus. Males were more attracted paternity, this strategy may benefit females by: (1) confusing to the females than vice versa; however, all of the males paternity and discouraging infanticide [50, 51]; (2) providing present in the mating places were not equally attracted to high-quality genes through enhanced male-male and sperm a particular female [12]. Some research has suggested that competition [52, 53], and (3) ensuring fertilization [54, 55]. age of males is an important factor that may influence female Predation of puppies by dogs of another group was noticed preference; and older males may be preferred since prolonged by [56]. So, it may be presumed that multiple mating may survival attests to physical and/or social quality and confirms also reduce male aggression toward females [57] and increase viability in the current environment [38, 39]. Contrarily, social support or protection from predators [58–60]. the females in this study preferred the young adults with a It is interesting to note that when the courting males greater frequency, and it was also previously reported by [12]. were engaged in aggressive encounters, opportunist transient Perhaps older males may be less preferred since sperm may be males were able to copulate after being present only a short less viable or sperm counts may be low [40, 41]. The duration time; and it may be described as “opportune” mating. This of courting association increased with the number of males behaviour was previously reported in dogs by [12] being also gathered in an association as previously reported by [12, 17]. described in feral cats as “short-time courting strategies” by Although, most of the mountings among the old adult [42, 61]. males were unsuccessful (without ending in tie), the fre- Females prefer to mate with some males and resist others quency of mounting per hour was higher among the old [23]. Some authors suggest that females prefer dominant adult males as previously reported by [12]. Perhaps due males [38, 62–66]. In contrast, in this study oestrous females to failure in successful copulations, the old adult males generally disliked the aggressive and physically powerful mounted frequently. However, the number of courting old males. This agrees with the findings of [12, 17]. Moreover, adult males was very low in this study, and further data are some authors [67–69] found no direct relationship between needed to distinguish the mating behavior between young dominance ranks and mating success. On some occasions, adults and old adults. Successful copulation was prevented the aggressive and physically powerful males were observed when more than 2 or 3 males were present in the mating to copulate the unwilling females forcibly which may be association [12, 17]. This was also noticed by [42]inferal described as “rape” in free-ranging domestic dogs [12, 17]. cats. The duration of copulatory ties varied with several exter- Mating system was the most striking feature of this nal factors. In this study mounting by the courting males(s) study. In this study, two females and two males within to the locked male, forcibly mating by the dominant and the social group formed pair bonds and mated successfully large male(s), children interference, and running vehicles during a single oestrus showing the evidence of monogamy were identified as copulation-interrupting factors [12, 17, in dogs [43]. The prevailing mating system in canids is 70]. Significant human interference on the reproduction was monogamy [1, 3, 44]; however, on some occasions, males also reported by [71] in the case of village dogs. within the group mated with more than one female but the Male-male mounting was an interesting finding of this female mated with only one male showing the evidence of study since it was previously reported by [12]but not polygyny. In most cases, both males and females within the observed in the study of [14]. Although, female-female social group mated with several individuals of the opposite mounting was rare in this study, occasionally the oestrous sex showing evidence of promiscuity. Two females in this female mounted the waiting female from the side or study, mated indiscriminately with all the courting males rear without pelvic thrusts. Male-male and female-female during a single oestrus period which may be described as mountings were observed in this study, but the purpose of “polyandry” in the domestic dog. Although evidence is scant, this behaviour is not understood. the observations of this study may suggest that monogamy, polygyny, promiscuity, and polyandry occur in free-ranging Individual differences in relation to sexual behaviour domestic dogs. 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