acta ethologica最新文献

The addax antelope (Addax nasomaculatus) is a species under serious threat of extinction, as it is more abundant in captivity than in the wild. However, little is known about its basic biology. The aims of this study were to determine how locomotor, feeding, aggressive, marking, and sexual behavior of male addax allocated in all-male groups vary with season and with female contact (i.e., biostimulation). The study was conducted in captive conditions, in two groups of adult males: one with no-physical contact with females, aside from visual and olfactory interactions (CF group, n = 4), and another group completely isolated from females (IF group, n = 4). The frequency of behaviors was recorded during the daytime, 4 days per season (total time of observation = 256 h). Lying, standing, walking, aggressive, marking, grazing, and ruminating behaviors as well as water and supplement consumptions varied with season (all p < 0.05). The lying, walking, marking, grazing, and ruminating behaviors were more frequently observed for CF than IF males (all p < 0.05). Also, all behaviors, except for marking, varied with the interaction between the group and seasons (all p < 0.05). Sexual behavior was extremely scarce, so it was not possible to analyze how it varied with seasons and the group. The present study suggests that management program and housing conditions, especially in ex situ breeding plans, should consider the influence of the season and the sociosexual context on the behavior of addax males.

The Japanese serow (Capricornis crispus) exhibits spatial behavior adapted to forest habitats with relatively stable food supply and climatic conditions, such as sedentary habits, small home ranges, and little seasonal variation in habitat selection. However, investigations have not previously been conducted in open mountainous habitats with high seasonal variability. Therefore, I examined spatial behavior of the Japanese serow in an open mountainous region of Mt. Fuji, central Japan, based on GPS location data. These mountain-dwelling serows had much larger annual home ranges (female: 316.5 ha, male: 373.1 ha) compared with forest-dwelling populations. Spring and summer home range sizes were the largest, and winter home range size was the smallest, ranging from 20.3%–56.1% of maximum. Limited forage and harsh climatic conditions in winter seemed to drive such energy-minimizing behavioral strategies. Selection of vegetation types and elevation varied seasonally, likely because of changes in forage availability and climate conditions. These spatial behaviors in mountain-dwelling serows resemble those of several related mountain ungulates, implying that these behaviors are adaptations to highly seasonal open mountainous habitats. My findings suggest that the main factors affecting spatial behavior are habitat characteristics, such as climate, forage abundance, and seasonality. These findings provide support for an ecological pattern in ungulate spatial behavior whereby closed habitats promote small and stable home ranges, whereas open habitats promote large and seasonally fluctuating home ranges.

The fight or flight decision (i.e., engage in or evade from an interaction) is one of the most important for animals, occurring in many different ecological contexts and dictating the occurrence of agonistic encounters that could lead to injuries or even death. The southern lapwing Vanellus chilensis is one of the most conspicuous bird species from South America, living in the natural grasslands but frequently found in rural and urban area. The species is known by its typical vocalization and its patterns of aggression and territoriality, considered exaggerated, creating a cultural prejudice towards the species. To better understand the agonistic interaction process in the species, we used general linear models to verify the influence of individual characteristics, environmental characteristics, and opponent features on five different response variables related to the interactions: the time of alert behavior display, probability to attack and evade, total duration of the interaction, and the Behavioral Diversity Index (BDI) of each interaction. Despite the models showing that for each response variables the predictors had different importance and weights, it was possible to note that individual features like age, breeding status, and month impact directly the probability to evade or attack, while the opponent species and distance better explained the other variables related to the interaction. The results also showed that the southern lapwings increase the intensity of responses and sensibility to intruder during the breeding season, displaying a trade-off between self-preservation and the protection of the offspring that is present in other bird species.

Abstract

Gibbons exhibit territorial behavior, and mated pairs defend exclusive territories. However, reports on contacts with neighbors near or outside the respective range boundaries are scarce because observing unhabituated neighboring groups is difficult. Studies of encounters have yielded a wide range of observations (aggressive, neutral, communicative, or affiliative) across gibbon species and geographic regions. As it is important to understand behavioral ecology and social relationships among gibbon groups, we studied three Northern Gray gibbon groups (Hylobates funereus) in the Danum Valley Conservation Area (DVCA), Malaysia and observed their interactions with neighboring groups. From 2001 to 2020, three groups were followed for 162 days (2236.4 h), and we observed 30 instances of encounters at the range boundary or intrusions between a study group and a respective neighboring group. Neutral or communicative encounters were observed in most cases, with the exception of one instance of aggressive encounter (chasing). Gibbons interacted through particular vocalizations (termed songs) in many cases. We report details of some characteristic interactions among gibbon groups during encounters at the range boundary or intrusions. Regarding intrusions, we observed an unusual instance where a neighboring group intruded deep into the study group’s territory, and the neighboring group did not respond to the songs of the resident group. Considering that no physical fighting occurred during encounters or intrusions, gibbon groups in the DVCA seem to be non-aggressive toward each other. We briefly discuss possible explanations for such non-aggressive relationships among gibbon groups.

Animal personality is defined as behavior that is consistent across time and context. Ecological and evolutionary pressures might exert sexually dimorphic effects on personality traits. In this study, variations in docility and exploratory behaviors of male and female plateau zokor (Eospalax baileyi) in two populations from different geographical sites were quantified during their breeding season, using bag and open field test. We observed significant repeatability of behaviors in the bag and open field test, except for sniffing behavior in zokors from TZ site. We found that sex influences the personality traits of plateau zokors more than geographical variation in both the bag and open field test. Females had a higher docility than males in the bag test. The findings of this study emphasize the importance of considering plateau zokors’ sex and personality traits when assessing their fitness, behavior, or suitability for behavioral future research work.

The impact of re-introduction of a temporally separated individual to a group on social integration and hormone levels is an important topic in terms of the management and welfare of captive animals. Using two cases in which a temporally separated male re-joined an all-male group of captive chimpanzees, Pan troglodytes, we investigated how social reunion affected social interactions and salivary steroid hormone levels (C, cortisol; T, testosterone). In both cases, social reunion was conducted over three stages, separation, acclimation, and reunion. In both cases, behavioral observations revealed increased agonism and tension reduction after the reunion, suggesting that the reunion induced reformation of social relationships. In both cases, the separated male showed an increased C level at the acclimation stage, in which the separated male was moved to its original indoor room and released solely into an outdoor compound. The T level did not vary among males or stages, but increased for the re-joined male after reunion in one of the two cases. This study suggests that the relationships between hormones and behavior during a reunion could be affected by multiple factors and that special attention should be paid to the acclimation rather than characteristics of social reunion, to ensure the success of member reunion.

Abstract

Species are facing environmental challenges caused by rapidly changing environments. Globally, extreme weather events, like droughts or extreme rainfall, are increasing in frequency. Natural selection usually acts slowly, while adaptations through phenotypic plasticity are limited. Therefore, organisms may utilise other mechanisms to cope with such rapid change. Cooperative breeding is hypothesised to be one such mechanism, as helpers could increase survival probabilities of offspring, especially in harsh years. Rainfall is a cue for onset of breeding in many tropical species, to ensure young are born when food abundance is highest. Using 21 years of data, we investigate the effect of rainfall on social behaviour and life history in the insectivorous Seychelles warbler (Acrocephalus sechellensis), a facultative cooperative breeder. We found that low rainfall is associated with reduced reproductive output and possibly with decreased survival. However, there were no statistical differences in response between groups with helpers, groups with only non-helping subordinates, and breeding pairs without subordinates. With low rainfall, more sons (the sex less likely to help) were produced, and those subordinate males already present were less likely to help. Thus, in contrast to expectations, cooperative breeding does not seem to buffer against harsh environments in Seychelles warblers, indicating that group living may be costly and thus not a mechanism for coping with changing environments. Our study showed that the interaction between the environment and life histories, including social behaviour, is complex, but that this interaction is important to consider when studying the impact of changing environments on species survival.