Agonistic and sociable behaviors in the mound‐building mice,Mus spicilegus: A comparative study with Mus musculus domesticus

Present social organization and mating systems result from selective pressures and ecological conditions but also from proximate interactions between individuals. Many studies report on a polygynous mating system with a social group territoriality in commensal populations of Mus musculus domesticus. However, little is known about the social organization of other Mus species living in outdoor conditions, such as the mound‐building mouse Mus spicilegus. Comparative studies between M. m. domesticus and M. spicilegus have already shown behavioral differences in female sexual preferences and paternal care. To study agonistic and sociable interactions and gain insight into the social organization and the mating system of M. spicilegus, the present study compared intraspecific dyadic encounters between unfamiliar adults in these two species. Results demonstrated less tolerance between females and between the sexes in M. spicilegus than in M. m. domesticus unfamiliar mice. The consequences of those differences between M. spicilegus and M. m. domesticus on social organization and mating system are discussed. Aggr. Behav. 28:75–84, 2002. © 2002 Wiley‐Liss, Inc.     

Aggressive interactions among female,semi-captive pampas deer (Ozotoceros bezoarticus) increase within the hierarchy and after short-term removal of the male

Two trials were carried out to determine: (a) if there is a positive relation between the frequency of aggressive interactions among female pampas deer and their position within the hierarchy (HI), (b) if short-term removal of the male triggers an increase in the frequency of aggression, and (c) if the magnitude of this increase is related to the individual rank position of the female. Each of 19 breeding groups comprised one adult male and from four to six adult females. The HI was determined for each female and all aggressive interactions were recorded. These were recorded while the male was present (i.e., all of Trial 1 and the “with male” period in Trial 2) and after removal of the male (i.e., the “without male” period in Trial 2). The individual percentage change in the frequency of aggressive interactions after male removal was calculated. In Trial 1 the HI, the frequency of different types of aggressive interaction and the total of aggressive interactions were positively related (all: p < .001; General Linear Mixed Model [GLMM]). In Trial 2, the frequency of total aggressive interactions increased after male removal (F(1, 27) = 3.5; p < .001; GLMM). The individual percentage changes in aggressive interaction between periods were positively related to HI (F(6, 24) = 2.56; p = .05; GLMM). For female pampas deer maintained in breeding groups, we conclude that the frequency of aggressive interactions increases within the hierarchy. Aggression also increases after the short-term removal of the male, mainly among females of higher social status.     

Mate choice in the domestic cat (Felis silvestris catus L.)

The domestic cat (Felis silvestris catus L.) has colonized different types of environments that differ in their spatial distribution of resources. Urban environments are characterized by highly clumped distributions of food and shelter, allowing domestic cats to live in large multimale‐multifemale groups. In such a situation, questions arise about male and female mating strategies. In particular, do females exert active mate choice? We tested this question using behavioural records on acceptance and refusal of males by estrous females. Our results showed that most females copulated with several males during a single estrus period. The variability of female behaviour was high: six females copulated with all courting males whereas three others mated with most courting males; six others copulated with half or less of the courting males. Even if some females copulated with certain males more often than with others, the identity of the most successful males changed each time. These results show that most females did not choose mates among different males available. The results are discussed in terms of optimal reproductive strategies of males and females in an urban environment. Aggr. Behav. 26:455–465, 2000. © 2000 Wiley‐Liss, Inc.     

Genotype and environment in the social interactions of wild and domestic “Norway” rats

Wild rats, Rattus norvegicus, (a) trapped as adults or (b) of the second generation in captivity (lab-wild), and domestic rats of two strains, were studied for 28 days in artificial colonies in large cages with attached nest boxes. Controls were kept in mated pairs in small cages. Each colony consisted of six males and six females. The interactions of the males in six colonies of trapped rats were highly “stressful;” 61% died; and most of the survivors lost weight and had greatly enlarged adrenals. In each colony, however, there was a male (an alpha) that gained in weight and spent much time, during the dark hours, in the open on the floor of the cage; and in three colonies there were also other males (“betas”) that gained in weight. The adrenals of alphas and betas weighed about the same as those of the controls. In one of the 12 colonies of domestic rats one male behaved like a wild male; but in the other colonies the males gained in body weight and their adrenal weights resembled those of the controls. In three colonies of lab-wild rats 22% of the males died, but there was no evidence of males of different status. The findings confirm that the “agonistic” behavior of domestic rats is usually much attenuated in comparison with that of the wild type; a number of methodologic implications are discussed.     

Effect of residence and size asymmetries upon the agonistic interactions between juvenile white‐seabream (Diplodus sargus cadenati de la Paz,Bauchot and Daget, 1974)

The behavioural patterns of juvenile white‐seabream suggest that asymmetry in residence is an important factor governing the outcome of contest between individuals of this species. Asymmetries due to resident status had strong effects on agonistic behaviour, with asymmetries in body sizes producing weaker effects. Resident fish won all the combats against intruders of lower or similar length. However, when the intruder was larger than the residents (higher than 5% in length and 20% in weight), the percentage of combats won by the residents decreased to 85.7%. There was a significant correlation between fight intensity and size asymmetry in favour of the resident fish. The resident fish was more aggressive and persistent in attacks, and contests were more intense when the size of the intruder was greater. During agonistic interactions, the frontal attacks and lateral displays were more frequent when the intruders were similar or larger than residents. Attacks to the flanks and chases were more frequent in pairs where the intruders were smaller. Aggr. Behav. 25:297–303, 1999. © 1999 Wiley‐Liss, Inc.     

The introduction of a group of alien mice (Mus musculus L.) into hierarchically organized groups of five male mice

Groups of 3 male or female Mus musculus were introduced into hierarchically organized colonies of 5 male mice for a period of 8 days. The colonies were of 2 kinds; high-level aggressive (HLA), which had been set up 3 days prior to the introduction of the aliens, and low-level aggressive (LLA), which had been established for 21 days before strangers were introduced. Both males and anestrous females were attacked, but males were attacked 5 times more frequently than females. In HLA colonies most of the attacks on the aliens were by the dominant; in LLA colonies there was no difference in the behavior of dominant and subordinate mice toward strangers. Both aggression toward aliens and intracolony aggression declined over the 8 day experimental period. In HLA colonies the dominant mouse mounted females 5 times more frequently than did either his subordinates or male mice in the LLA colonies. In HLA colonies aliens huddled with subordinates to form a single colony with 1 dominant and 7 subordinates. In LLA colonies alien males remained as a discrete group spatially separated in the cage. Female aliens were incorporated into the main colony. In all cases dominant male mice made more attacks on aliens as compared with familiar mice.     

Diversity in agonistic behavior of croaking gouramis (Trichopsis vittata,T. schalleri,and T. pumila; Anabantoidei) and the paradise fish (Macropodus opercularis; Anabantoidei)

Agonistic encounters of all three species of the vocalizing genus Trichopsis were observed in order to compare species-specific fighting strategies and the specific investment in acoustics. Additionally, these encounters were compared to agonistic encounters of Macropodus opercularis which was considered to be mute. The aim of this comparison was to investigate if mute fishes stress visual or tactile displays. Within the genus Trichopsis, significant differences among the three species were found in qualitative and quantitative analysis of displays. Frontal display occurred only in Trichopsis vittata, whereas a strong tail-beating while vocalizing was only observed in Trichopsis pumila. Fight duration and the number of sounds and circlings were highest in Trichopsis schalleri. The largest relative distances between circling opponents occurred in T. pumila, the smallest species. Also, the number of attacks was lowest in T. pumila. Fighting assessment seemed to be different in each species. For the first time, sound production has been reported for Macropodus opercularis (infrequently and with extreme low sound pressure levels), but much more investment in visual and tactile displays has been demonstrated. Lowering the branchiostegal membrane and spreading the opercula occurred only in M. opercularis and was never observed in any of the Trichopsis species. The number of attacks was higher in Macropodus than in any Trichopsis species. The relative distance between Macropodus opponents while circling was closest compared to the three Trichopsis species. Visual and contact displays are reduced in extensively vocalizing fish species, like Trichopsis sp., compared to mute or seldom vocalizing species, like Macropodus. © 1996 Wiley-Liss, Inc.     

Using positive peer reporting to improve the social interactions and acceptance of socially isolated adolescents in residential care: a systematic replication

We studied how rewarding youth in residential care for publicly reporting positive social behavior influenced the social interactions and acceptance of their most socially isolated peers. Results showed that the intervention resulted in substantial improvements in social interactions by the previously isolated peers. Peer acceptance ratings also improved for 2 of the target youths.