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Early-life social isolation has profound effects on adult social competence. This is often expressed as increased aggression or inappropriate displays of courtship-related behaviors. The social incompetence exhibited by isolated animals could be in part due to an altered ability to participate in communicatory exchanges. House mice (Mus musculus) present an excellent model for exploring this idea, because social isolation has a well-established influence on their social behavior, and mice engage in communication via multiple sensory modalities. Here, we tested the prediction that social isolation during early life would influence ultrasonic vocalizations (USVs) emitted by adult male mice during same-sex social encounters. Starting at three weeks of age, male mice were housed individually or in social groups of four males for five weeks, after which they were placed in one of three types of paired social encounters. Pair types consisted of: two individually housed males, two socially housed males, or an individually housed and a socially housed male (\"mixed\" pairs). Vocal behavior (USVs) and non-vocal behaviors were recorded from these 15-minute social interactions. Pairs of mice consisting of at least one individually housed male emitted more and longer USVs, with a greater proportional use of USVs containing frequency jumps and 50-kHz components. Individually housed males in the mixed social pairs exhibited increased levels of mounting behavior towards the socially housed males. Mounting in these pairs was positively correlated with increased number and duration of USVs as well as increased proportional use of spectrally more complex USVs. These findings demonstrate that USVs are part of the suite of social behaviors influenced by early-life social isolation, and suggest that altered vocal communication following isolation reflects reduced social competence.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons regulate fertility and integrate hormonal status with environmental cues to ensure reproductive success. Here we show that GnRH neurons in the olfactory bulb (GnRH OB ) of adult mice can mediate social recognition. Specifically, we show that GnRH OB neurons extend neurites into the vomeronasal organ and olfactory epithelium and project to the median eminence. GnRH OB neurons in males express vomeronasal and olfactory receptors, are activated by female odors and mediate gonadotropin release in response to female urine. Male preference for female odors required the presence and activation of GnRH OB neurons, was impaired after genetic inhibition or ablation of these cells and relied on GnRH signaling in the posterodorsal medial amygdala. GnRH receptor expression in amygdala kisspeptin neurons appear to be required for GnRH OB neurons’ actions on male mounting behavior. Taken together, these results establish GnRH OB neurons as regulating fertility, sex recognition and mating in male mice. Studying GnRH neuroendocrine cells in the mouse olfactory bulb (GnRH OB neurons), Decoster et al. show that these cells respond to female odors and their activation regulates males’ female-odor preference and mating behavior.

Social hierarchies emerge when animals compete for access to resources such as food, mates or physical space. Wild and laboratory male mice have been shown to develop linear hierarchies, however, less is known regarding whether female mice have sufficient intrasexual competition to establish significant social dominance relationships. In this study, we examined whether groups of outbred CD-1 virgin female mice housed in a large vivaria formed social hierarchies. We show that females use fighting, chasing and mounting behaviors to rapidly establish highly directionally consistent social relationships. Notably, these female hierarchies are less linear, steep and despotic compared to male hierarchies. Female estrus state was not found to have a significant effect on aggressive behavior, though dominant females had elongated estrus cycles (due to increased time in estrus) compared to subordinate females. Plasma estradiol levels were equivalent between dominant and subordinate females. Subordinate females had significantly higher levels of basal corticosterone compared to dominant females. Analyses of gene expression in the ventromedial hypothalamus indicated that subordinate females have elevated ERα, ERβ and OTR mRNA compared to dominant females. This study provides a methodological framework for the study of the neuroendocrine basis of female social aggression and dominance in laboratory mice.

To improve the detection speed of cow mounting behavior and the lightness of the model in dense scenes, this study proposes a lightweight rapid detection system for cow mounting behavior. Using the concept of EfficientNetV2, a lightweight backbone network is designed using an attention mechanism, inverted residual structure, and depth-wise separable convolution. Next, a feature enhancement module is designed using residual structure, efficient attention mechanism, and Ghost convolution. Finally, YOLOv5s, the lightweight backbone network, and the feature enhancement module are combined to construct a lightweight rapid recognition model for cow mounting behavior. Multiple cameras were installed in a barn with 200 cows to obtain 3343 images that formed the cow mounting behavior dataset. Based on the experimental results, the inference speed of the model put forward in this study is as high as 333.3 fps, the inference time per image is 4.1 ms, and the model mAP value is 87.7%. The mAP value of the proposed model is shown to be 2.1% higher than that of YOLOv5s, the inference speed is 0.47 times greater than that of YOLOv5s, and the model weight is 2.34 times less than that of YOLOv5s. According to the obtained results, the model proposed in the current work shows high accuracy and inference speed and acquires the automatic detection of cow mounting behavior in dense scenes, which would be beneficial for the all-weather real-time monitoring of multi-channel cameras in large cattle farms.

Dairy cows have a partial preference to access an outdoor deep-bedded pack, but the effects of continuous access to an outdoor area on estrous behaviors has not been studied. Our objective was to investigate if access to an outdoor open deep-bedded pack improves the expression of estrus behaviors. We enrolled 60 lactating Holstein cows directly after calving and followed them each for 12 weeks. Cows were housed in a single freestall pen holding 36 cows at a time, with a dynamic group composition. Half of the cows were randomly assigned to the OUTDOOR treatment; these cows had access to an outdoor open pack via an automated selection gate. INDOOR cows were housed together with OUTDOOR cows but were not allowed outdoor access. All cows were fitted with an automated activity monitor (AAM) 21 ± 3 d before expected calving date. Estrous behaviors (i.e., standing to be mounted and mounting behaviors) were continuously monitored using video, and the intensity of mounting (i.e., the number of standing to be mounted and other mounting behaviors per hour) was calculated per estrus event per cow. Temperature and humidity were monitored by data loggers indoors, and these data were used to calculate the Temperature Humidity Index (THI). Following an alert from the AAM, cows were checked to detect the presence of a dominant preovulatory follicle and an absence of a mature corpus luteum (CL) by rectal ultrasonography following milking, as well as 7 d thereafter to confirm ovulation by the presence of a new CL. A total of 94 estrus events were used in the final analysis. INDOOR cows tended to have a lower mounting intensity with increasing indoor THI, but no such effect was noted for OUTDOOR cows. The total number of cows in estrus positively influenced mounting intensity. OUTDOOR cows had a longer duration of estrus, as measured by the automated monitors, compared with INDOOR cows (12.4 ± 0.7 h versus 9.9 ± 0.8 h). Estrus event number and the total number of cows in estrus were both positively associated with estrus duration. These results indicate that access to an outdoor pack tended to increase mounting behavior for freestall housed dairy cows, especially during periods of elevated THI. We conclude that providing dairy cows access to an outdoor area can help with estrus detection and may thus help improve the reproductive programs on dairy farms.

The laboratory mouse is an emerging model for context-dependent vocal signaling and reception. Mouse ultrasonic vocalizations are robustly produced in social contexts. In adults, male vocalization during courtship has become a model of interest for signal-receiver interactions. These vocalizations can be grouped into syllable types that are consistently produced by different subspecies and strains of mice. Vocalizations are unique to individuals, vary across development, and depend on social housing conditions. The behavioral significance of different syllable types, including the contexts in which different vocalizations are made and the responses listeners have to different types of vocalizations, is not well understood. We examined the effect of female presence and estrous state on male vocalizations by exploring the use of syllable types and the parameters of syllables during courtship. We also explored correlations between vocalizations and other behaviors. These experimental manipulations produced four main findings: 1) vocalizations varied among males, 2) the production of USVs and an increase in the use of a specific syllable type were temporally related to mounting behavior, 3) the frequency (kHz), bandwidth, and duration of syllables produced by males were influenced by the estrous phase of female partners, and 4) syllable types changed when females were removed. These findings show that mouse ultrasonic courtship vocalizations are sensitive to changes in female phase and presence, further demonstrating the context-sensitivity of these calls.

The Trichechus manatus latirostris (Florida manatee) is known to seasonally range into the northern Gulf of Mexico, but evidence of mating behavior in Mississippi has not previously been documented. On 24 September 2024, the first known instance of active manatee mating behavior in Mississippi waters was observed using an uncrewed aerial system (UAS) at the Grand Bay National Estuarine Research Reserve. Behavioral analyses, including all‐occurrence and continuous sampling methods, revealed mounting interactions characteristic of manatee reproductive behavior. The focal group consisted of three individuals, with one identified female (manatee B) and presumed male (manatee A) engaging repeatedly in mounting behaviors. Manatee C, sex unknown, did not participate in mating behaviors during the observation period. These findings suggest that Mississippi coastal habitats may support not only seasonal foraging but also reproductive activity, indicating a potential range expansion and reproductive plasticity of the species. This observation underscores the need for enhanced monitoring and conservation efforts in northern Gulf habitats to account for emerging manatee behaviors and potential establishment of reproductive areas beyond Florida. This study documents the first recorded instance of mating behavior by Florida manatees (Trichechus manatus latirostris) in Mississippi estuarine waters, observed opportunistically via a drone during a routine survey at the Grand Bay National Estuarine Research Reserve. The behaviors, including repeated mounting interactions, suggest that Mississippi coastal habitats may support not only foraging but also reproductive activity, with important implications for regional conservation and management strategies.

Predation risk can affect offspring phenotype and fitness via maternal effects. However, most studies have mainly focused on the effect of maternal exposure to predation risk on offspring anti-predator traits, and evidence of its impact on social behavior is still weak. We explored this using social Brandt’s voles (Lasiopodomys brandtii). To this end, we exposed pregnant female voles to one of three treatments: distilled water (DW), rabbit odor (RO, non-predator odor), or cat odor (CO, predator odor) for 60 min daily from gestation day 1–18 and compared the range of social behaviors of their offspring. The levels of anxiety-like behaviors and serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were also measured. Our data showed that maternal CO exposure had no effect on sibling play behavior, but female adolescent offspring displayed increased contact with their siblings. During the social interaction test, adult male offspring of CO mothers engaged in less aggression toward unfamiliar same-sex individuals. Additionally, they exhibited slightly shorter latency and longer duration of mounting behavior with a novel opposite-sex individual than the offspring of DW mothers. Following 72 h of cohabitation, both male and female CO offspring exhibited selective aggression toward strangers related to their partners. In addition, the offspring of the CO mothers spent less time in the central area of the open-field and entered the light box less often. Finally, we observed higher serum ACTH and CORT levels in offspring. These findings suggest that maternal exposure to predator risk during pregnancy can influence the social behavior of Brandt’s voles in a sex- and behavior-specific manner. Anxiety and HPA axis activity may play modulatory roles in the expression of these social behaviors. Further studies should examine this transgenerational effect in the natural environment.SignificancePredation risk is an important environmental factor for animal populations and can trigger transgenerational responses, ultimately influencing the phenotype and fitness prospects of prey offspring. However, in social animals, the extent to which this non-genetic maternal effect influences the offspring’s social behavior is unclear. Brandt’s voles are typical social and grassland rodents. Owing to their complex social behavior, Brandt’s voles may respond to predation risk in a variety of ways. We found increased contact behavior in adolescent females, decreased aggression and increased sexual motivation in adult males, and stable pair bonds in paired voles in a behavior-specific manner. As social behavior is important for survival, reproduction, and population fluctuations, we believe that our study makes a significant contribution to the literature and provides a reference for monitoring the population dynamics of social rodents, especially Brandt’s voles.

Research is needed to validate lesions recorded at meat inspection as indicators of pig welfare on farm. The aims were to determine the influence of mixing pigs on carcass lesions and to establish whether such lesions correlate with pig behaviour and lesions scored on farm. Aggressive and mounting behaviour of pigs in three single sex pens was recorded on Day -5, -2, and -1 relative to slaughter (Day 0). On Day 0 pigs were randomly allocated to 3 treatments (n = 20/group) over 5 replicates: males mixed with females (MF), males mixed with males (MM), and males unmixed (MUM). Aggressive and mounting behaviours were recorded on Day 0 at holding on farm and lairage. Skin/tail lesions were scored according to severity at the farm (Day -1), lairage, and on the carcass (Day 0). Effect of treatment and time on behaviour and lesions were analysed by mixed models. Spearman rank correlations between behaviour and lesion scores and between scores recorded at different stages were determined. In general, MM performed more aggressive behaviour (50.4 ± 10.72) than MUM (20.3 ± 9.55, P < 0.05) and more mounting (30.9 ± 9.99) than MF (11.4 ± 3.76) and MUM (9.8 ± 3.74, P < 0.05). Skin lesion scores increased between farm (Day -1) and lairage (P < 0.001), but this tended to be significant only for MF and MM (P = 0.08). There was no effect of treatment on carcass lesions and no associations were found with fighting/mounting. Mixing entire males prior to slaughter stimulated mounting and aggressive behaviour but did not influence carcass lesion scores. Carcass skin/tail lesions scores were correlated with scores recorded on farm (rskin = 0.21 and rtail = 0.18, P < 0.01) suggesting that information recorded at meat inspection could be used as indicators of pig welfare on farm.

Interspecies interactions present diverse forms and functions, contributing significantly to ecological and social dynamics. This study focuses on the mounting behaviours of Japanese macaques ( Macaca fuscata ) towards Sika deer ( Cervus nippon ), a rare and still unexplained phenomenon, with minimal emphasis on the behaviour of the deer. Using video data from two distinct sites, Yakushima and Minoh, Japan, we documented 45 sequences of macaque–deer interactions and analysed macaques’ behaviours and deer behaviours using focal and behavioural sampling techniques. We identified four primary activities performed by macaques during mountings—sexual, play, grooming, and resting—with resting being predominant. The study evaluates six hypotheses regarding the functions of these mounting behaviours: (1) interactions are sex-specific, (2) macaques use deer for transportation, (3) mutual warming through physical contact occurs, (4) deer provide support for resting, (5) macaques engage in grooming to consume parasites or play to strengthen interspecies bonds, and (6) aggressive signals relate to resource disputes or rejection of mounting behaviour. Statistical analyses using the Kruskal–Wallis test and Dunn’s post-hoc test revealed significant differences between resting and other active behaviours, but no significant differences in behaviour duration between lying and sitting positions. Adults engaged in mounting for longer periods than juveniles, suggesting potential age-related differences in social and reproductive roles. These findings enhance our understanding of interspecies interactions by focusing on macaque behaviours and emphasise the need for longitudinal studies to clarify the ecological and social implications of these interactions.