反捕食不能充分解释獐的集群行为(英文)

我在江西鄱阳湖国家自然保护区研究了獐 (Hydropotesinermis)的集群行为并检验了集群是动物反捕食对策的假说。如果这个假说成立 ,我们则可以做三个预测 :(1)集群大小应与植物覆盖度成负相关 ;(2 )集群动物比单独活动的动物有更多的时间取食 ;(3)集群动物与单独活动的动物相比 ,用于警戒的时间较少。结果表明 ,獐的集群在交配季节最大而在产仔季节最小 ,獐在短草期比在高草期倾向于形成较大集群。因此 ,本研究支持了第一个预测。但是 ,集群的獐和单独活动的獐在取食和警戒时间分配上并无差异。因此 ,本研究不支持第二和第三个预测。时间收支 (timebudget)分析显示 ,在非交配季节 ,带幼仔的雌性用于取食的时间较少但走动频繁。在交配季节 ,与单独活动的雌性相比 ,与雄性在一起的雌性用于取食的时间较少 ,而单独活动的雄性却比与雌性在一起的雄性花较多的时间用于观望寻找雌性。鉴于獐集群行为的复杂性 ,本研究认为 ,獐并不只因反捕食而集群 ,其它社会和生态因子在决定獐的集群行为中也很重要。     

王朗国家级自然保护区岩羊集群结构及季节变化

岩羊(Pseudois nayaur)是青藏高原常见的食草动物,但对边缘分布区的种群了解较少.2018年6月到2019年8月,我们利用红外相机在四川王朗国家级自然保护区对岩羊的集群结构、特征及其季节变化进行了描述与分析.结果显示:调查共记录到岩羊1 921群次,共计6 623只次.按照性别和年龄组,可将岩羊集群划分为混...     

Social modulation of testosterone levels in male black howlers (Alouatta pigra)

The influence of social factors on the modulation of male testosterone levels has been demonstrated among several vertebrate species. In addition to sexual activity, parental care and reproductive competition affect testosterone secretion. We examined variations in testosterone levels among male black howlers (Alouatta pigra) in various social contexts. Fecal samples were collected from nine males living in five different groups in the Mexican state of Campeche. The potential for intragroup and extragroup competition varied among the groups. The number of resident males living in the groups was the only variable that significantly explained variations in testosterone levels. Males living in unimale groups had higher testosterone levels; the highest testosterone levels were recorded for males that had experienced a shift from multimale to unimale group compositions. In this species, the probability of being challenged by extragroup males and evicted from the group during immigration events increases when males live in unimale groups. Therefore, our results suggest that male black howlers respond to competition for group membership by increasing their testosterone levels. In this context, testosterone secretion represents an anticipatory response to reproductive conflicts. Therefore, although males living in unimale groups have exclusive access to females, they face higher physiological costs associated with sustaining high testosterone levels for extended time periods.     

Resurrecting the differential mortality model of sexual size dimorphism

In some animal groups males may be several times smaller than females. One of the hypotheses proposed to explain the evolution of this extreme sexual size dimorphism (SSD) is the differential mortality model (DMM), which is based on the assumption that when males are the searching sex, higher male mortality relaxes male–male contest competition, leading to the adaptive evolution of early‐maturing, small males that are favoured by viability selection. Evidence for the main prediction of this model, i.e. that there is a negative relationship between differential mortality and SSD, has remained elusive. Using sex differences in pitfall trap catches – a proxy of sex differences in mobility and mortality – across 40 spider species, and using the evolutionary comparative method, we found significant negative relationships between differential mortality and SSD for three size traits. Thus, the DMM can still explain part of the observed variance in SSD.     

A unimodal curve for primate group size along a gradient of population density

When plotted along a gradient of population density, the mean group size in populations of several primate species has a unimodal distribution, i.e., mean group size is greater at intermediate population densities than at higher or lower population densities. In this study I present a mathematical model to clarify the cause of this relationship. Population density is assumed to affect group size by enhancing between- or within-group competition and by changing the number of neighboring groups around each group. The mean group size is predicted to decline as population density increases above a critical value, owing to the increasing number of neighboring groups.     

Consequences of lethal intragroup aggression and alpha male replacement on intergroup relations and home range use in tufted capuchin monkeys (Cebus apella nigritus)

In conflicts between primate groups, the resource-holding potential (RHP) of competitors is frequently related to group size or male group size, which can remain relatively constant for long periods of time, promoting stable intergroup dominance relationships. Demographic changes in neighboring groups, however, could introduce uncertainty into existing relationships. Among tufted capuchin monkeys (Cebus apella nigritus), dominant male replacement is a relatively infrequent demographic event that can have a profound effect on both the composition and size of the social group. Here, we report such a case and the consequences for home range use and intergroup aggression. Between June 2008 and August 2010, we periodically followed two neighboring groups (Macuco and Rita) in Iguazú National Park, recording daily paths (N = 143) and encounters between the groups (N = 28). We describe the events leading to a change in the male dominance hierarchy in the larger group (Macuco), which resulted in the death or dispersal of all adult males, followed by the succession of a young adult male to the dominant position. This takeover event reduced the numerical advantage in number of males between the two groups, although the ratio of total group sizes remained nearly constant. Following this shift in numerical asymmetry, the degree of escalation of intergroup aggression increased, and we observed reversals in the former intergroup dominance relationship. These changes in behavior during intergroup encounters were associated with changes in the use of overlapping areas. In the 6 months following the takeover, the area of home range overlap doubled, and the formerly dominant group's area of exclusive access was reduced by half. These results suggest that RHPin tufted capuchin monkeys is related to male group size. Furthermore, they highlight the importance of considering rare demographic events in attempts to understand the dynamics of aggression between primate groups.     

Intergroup relations and home range use in Verreaux's sifaka (Propithecus verreauxi)

Relationships between neighboring groups feature prominently in socioecological theory, but few empirical studies have focused on the effects of neighbors on the behavior of primates. Interactions between neighboring groups are most conspicuous during intergroup encounters, but the likelihood of encounters with neighbors can also affect ranging and activity patterns indirectly, and, as a result, behavioral patterns in areas of exclusive use may differ from those in overlap areas of adjacent home ranges. The aim of this study was to examine intergroup relations and spatial variation in home range use in Verreaux's sifaka (Propithecus verreauxi) during the annual mating season. Based on 230 hr of focal animal data collected from ten members of five adjacent groups, we found that behavioral patterns and patterns of resource utilization were not markedly different between areas of exclusive use and overlap areas of adjacent home ranges. Group cohesion tended to be higher in overlap than in core areas, but the proportion of time spent resting and foraging did not differ between these two areas. However, dominant males exhibited a higher scent-marking rate in overlap areas. Observations during intergroup encounters revealed that chases between males occurred frequently, whereas fights involving physical contact were not observed. We also found that the intergroup dominance hierarchy depended on the relative group size or the number of males in each group, with groups of lower dominance rank exhibiting a tendency to sleep proportionally more often in their core areas. The results of this study suggest that in primate species with a moderate level of intergroup aggression, such as Verreaux's sifaka, the possibility of encountering neighbors in areas of home range overlap does not exert strong influence on their behavior and resource utilization.     

Cooperative vigilance: the guanaco's (Lama guanicoe) key antipredator mechanism

The concept of sociality has been associated with the effectiveness of antipredator mechanisms, like cooperative vigilance and the dilution effect. Lama guanicoe (guanaco) is a social native herbivore in South America and a social species. The objectives of this study were to evaluate the antipredator responses of different-sized groups of guanacos in areas with varying predation risks and to determine antipredator mechanisms in guanacos. For this, we measured different antipredator responses to a potential predator (human subjects). Detection of predator and flight distances from predator both increased with a greater number of guanacos per group and with greater distances among guanacos within the social group. Both buffer distance and flight time decreased with a greater number of guanacos per group, but increased with greater distances among guanacos inside the social group. Solitary adult males moved shorter distance and mixed groups moved greater distances. Flight distances were greater in areas with tall and dense vegetation than in areas with low vegetation. Buffer distance and flight time were shorter in undulating land than on flat lands, and groups were usually observed on hill slopes. Our results suggest that the benefit of social grouping in guanacos is the increased probability of avoiding predator with cooperative vigilance and not with the dilution effect. This means that a predator could be detected earlier when approaching a guanaco group than when approaching a solitary individuals and could thus be avoided.     

秦岭雄性羚牛的发情行为与其社会状态的关系

2004年5月31日至8月31日在陕西省佛坪县国家级自然保护区,对羚牛秦岭亚种（Budorcas taxicolor bedfordi）的繁殖行为及雄牛的社会状态进行了研究。研究期间每天在比较容易见到羚牛的区域内沿固定路线寻找羚牛,在不惊扰羚牛正常活动的情况下,记录牛群大小、群内个体的性别、年龄、雄性的社会状态,即是单独活动还是在繁殖群中;社会状态的变动,即每只是进入还是离开繁殖群;羚牛群中个体之间的相互关系,包括入群的独牛与群内其它雄牛之间的行为、与群内雌牛之间的行为。同时用摄像机辅助记录羚牛在群内的行为,并根据图像资料对记录的数据进行校正。研究期间累计对277 头次雄性羚牛的繁殖行为进行了观察,记录到241次繁殖行为。虽然6月初至8月下旬都可以见到羚牛的繁殖活动,但80% 以上的繁殖行为发生在6月20日至7月10日期间,其中以6月21 ～ 30日间的繁殖活动最多（105 次）。繁殖季节中雄性羚牛有两种社会状态,即在繁殖群中和单独活动（即独牛）。研究期间累计的独牛比例占成年雄性的30. 32%,其中72. 62%的独牛出现在6月10 日至7 月10 日。6 月21 ～ 30 日间独牛比例最高,占成年雄性个体的50. 67%。雄牛进出繁殖群的现象比较常见,独牛的比例与繁殖行为正相关。繁殖高峰期后,单独活动的雄牛数量迅速减少。雄牛的社会状态会随着繁殖期的不同阶段发生改变,独牛在不同繁殖群之间移动寻求更多的交配机会。我们的研究结果不支持以往认为独牛是繁殖争斗失败者的观点。     

Grooming Between Male Chimpanzees at Ngogo,Kibale National Park. II. Influence of Male Rank and Possible Competition for Partners

Allogrooming contributes to the development and maintenance of social relationships, including those that involve alliances, in many primate species. Variation in relatedness, dominance rank, and other factors can produce variation in the value of others as grooming partners. Several models have been developed to account for variation in the distribution of grooming in relation to dominance ranks. These start from the premise that individuals are attracted to high-ranking partners, but time limits, direct competition, and prior grooming engagement between high-ranking individuals can constrain access to them. Sambrook et al. (1995) formalized some of these models and showed the importance of taking group size variation into account when assessing them. Chimpanzees form multimale communities in which males are the philopatric sex. Males commonly associate and groom with each other; they also form dominance hierarchies and form alliances that influence dominance ranks and mating success. Both male rank and the rank distance between partners are significantly correlated with the distribution of grooming between males in an extremely large chimpanzee community at Ngogo, Kibale National Park, Uganda, that has more males than any other known community. High-ranking males had more grooming partners than mid- or low-ranking males. Grooming predominantly went up the dominance hierarchy, but was also concentrated among males that were close in rank. Rank and rank distance apparently both affected grooming independently of reciprocity in grooming and independently of the frequency with which males associated in temporary parties. However, the data do not clearly indicate how constraints on access to partners might have operated. Published data from a smaller chimpanzee community at Mahale show no rank or rank distance effect on male grooming. These results and earlier, conflicting findings on the association between dominance rank and grooming in male chimpanzees indicate that variation in group size, i.e., the number of males per community, probably influences the strength of any such effects, as happens for grooming between females in several cercopithecine species. Data on coalitions at Ngogo support the argument that high-ranking males are valuable social partners, and similarity in strategies of alliance formation may influence the distribution of grooming.     

Patterns of male residency and intergroup transfer in gray-cheeked mangabeys (Lophocebus albigena)

We describe the movements and fates of 36 collared gray-cheeked male mangabeys (Lophocebus albigena) that resided in seven social groups in Kibale National Park, Uganda. The male mangabeys were captured, radiotagged, and then contacted regularly over a period of up to 8 years. Individuals varied considerably in how tightly they were associated with their groups. "Central" males were usually found in close spatial association with their own groups, but they sometimes visited others. "Peripheral" males were often found several hundred meters away from their own groups. Most adult males were characterized by repeated intergroup transfers, manifested as "visits" and "dispersals." Visits were transfers that did not result in mating. The visits were brief, and ranged from a few minutes to a few days before the male returned to his previous group, moved on to another group, or returned to solitary life. The term "dispersal" refers to a transfer that results in mating, after which the male remains in the new group. Young males began to drift away from their natal groups in early subadulthood, but the timing of first associations with estrous females in other groups was highly variable. Natal dispersers were generally solitary for a month or more, and at least half moved into nonadjacent groups. Secondary dispersal was common. After they immigrated, adult males remained in a group for a median of 19 months before they emigrated again, with the probability of departure being approximately constant in time. Secondary dispersal was usually made into an adjacent group and lasted less than 7 days. Emigration and immigration were not seasonal, and males emigrated singly and apparently independently; however, immigrations were clumped in time, and male dispersal contributed to considerable heterogeneity of group composition. L. albigena dispersal patterns are intermediate between those described for Papio baboons and forest Cercopithecus, and models that predict demographic consequences of dispersal for baboons can be refined to apply to mangabeys.     

新疆天山中部北山羊社群结构

2013年10月至2014年9月,于天山中部天格尔山脉乌鲁木齐河源区研究了北山羊的社群结构。将其集群类型划分为雄性群、雌幼群、混合群和独羊4类。共统计北山羊497群,总计6 427只。北山羊最大集群为100只,最小群为1只,全年平均群大小为（12.93±0.65）只。其中春季（14.83±1.35）只,夏季（14.16±1.65）只,秋季（15.17±1.69）只,冬季（9.32±0.74）只。冬季北山羊平均集群大小显著低于其他三个季节。混合群的平均群大小最大,其余依次为雌幼群和雄性群。Kruskal-Wallis H检验结果表明各社群类型群大小差异极显著。北山羊多以2-7只的小群活动,占到总遇见频次比例的41.05%,8-20只群占32.80%,20只以上大群出现最少,占17.71%。在4种集群类型中,雌幼群出现频率最高,占51.91%,其次依次为混合群、雄性群和独羊。卡方检验结果表明4个季节间4种社群类型的出现频次差异显著。研究结果显示,北山羊在发情期混群,非繁殖期同性集群。受环境因素和自身生理周期的影响,其集群大小、集群类型均随季节变化而变化。     

印度喜马拉雅山区西藏盘羊的警戒行为

在几个动物类群中开展的许多行为研究中发现,个体的警觉水平与群体大小存在着负相关关系。一般认为,这种关系是由于个体在一个较大的群体中被捕杀的概率小。在本研究中,我研究了濒危的印度喜马拉雅地区西藏盘羊(Ovis ammon hodgsoni)的警戒行为与群体大小和逃逸地形的关系。我假设小群体中的、位于悬崖旁的盘羊比那些大群体中的、开阔地带(逃逸地形)中的盘羊的警戒水平高。结果发现随着群体增大,盘羊的警戒水平下降,但是,逃逸地形与盘羊的警戒水平没有关系。盘羊的不同性别、年龄组之间的时间预算存在显著差异。与雄性和亚成年个体比较,雌性用于警觉的时间多,它们比雄性采食时间长,移动少。因此,警戒行为是是盘羊的一种重要反捕食行为     

Number of males in primate groups: Comparative tests of competing hypotheses

Primate social groups frequently contain multiple males. Male group size has been hypothesized to result from male mating competition, but the selective factors responsible for the evolution of multimale groups are unclear. Short breeding seasons create situations that are not conducive for single males to monopolize mating access to females, and may therefore favor the formation of large male groups. Alternatively, since the costs of mate defense increase with the spatial clumping of females, female group size may be a primary determinant of the number of males in a primate group. We used comparative methods designed to control for the potentially confounding effects of hidden third variables associated with phylogeny to test the breeding season and female group size hypotheses for the evolution of multimale groups. Our results revealed no association between breeding season duration and the number of males in groups. In contrast, we provide support for the female group size hypothesis by demonstrating a strong pattern of correlated evolution between female and male group size. © 1996 Wiley-Liss, Inc.     

Vigilance behavior of Pyrenean chamois Rupicapra pyrenaica pyrenaica: Effect of sex and position in the herd

The Pyrenean chamois Rupicapra pyrenaica pyrenaica is a mountain-dwelling ungulate with an extensive presence in open areas. Optimal group size results from the trade off between advantages (a reduction in the risk of predation) and disadvantages (competition between members of the herd) of group living. In addition, advantages and disadvantages of group living may vary depending on the position of each individual within the herd. Our objective was to study the effect of central vs. Peripheral position in the herd on feeding and vigilance behavior in male and female Pyrenean chamois and to ascertain if a group size effect existed. We used focal animal sampling and recorded social interactions when a focal animal was involved. With males, vigilance rate was higher in the central part of the group than at the periphery, probably due to a higher density of animals in the central part of the herd and a higher probability of being disturbed by conspecifics. With females, vigilance rate did not differ according to position in the herd. Females spent more time feeding than males, and males showed a higher frequency of the vigilance behavior than females. We did not observe a clear relationship between group size and vigilance behavior. The differences in vigilance behavior might be due to social interactions.     

扁颅蝠与褐扁颅蝠的集群结构

2001—2002年在广西宁明县和龙州县利用直接观察、捕捉测量(共捕到197群蝙蝠,全捕180群)和标记重捕法(标记了31群的101只扁颅蝠,重捕到36只)比较研究了扁颅蝠(tylonycteris pachypusa)与褐扁颅蝠(T．robustula)的集群结构。结果发现：扁颅蝠与褐扁颅蝠主要栖宿在刺竹(Bambusa stenostachya)的竹筒内,通过竹筒上的裂缝进出。扁颅蝠栖宿的竹筒长平均为27．7cm,外围直径平均为23．6cm;褐扁颅蝠的分别为28．3cm和23．8cm。扁颅蝠栖宿群大小为1—24只,褐扁颅蝠栖宿群大小为1—13只;2种蝙蝠的栖宿群中皆为独居所占比例最大(扁颅蝠为22．30％,褐扁颅蝠为40．63％),2只所占比例次之(分别为14．87％和18．75％),其它大小类型呈不规则变化。扁颅蝠栖宿群的性别组成,以雌雄混居最常见(占54．72％),其次为独居雄性(占20．95％),而褐扁颅蝠栖宿群雌雄混居群与独居雄性所占比例相当(均为40．63％)。2种蝙蝠的雄性趋向于独居,而雌性趋向于群居。扁颅蝠与褐扁颅蝠可以栖宿在同一片竹林内,并且可以在不同时间轮流使用同一个栖宿竹筒,但2种蝙蝠从未共栖于同一个竹筒内。另外,标记重捕扁颅蝠发现：扁颅蝠经常变换栖宿竹筒(栖宿竹筒不固定);同时栖宿群之间经常发生个体交换[动物学报50(3)：326—333．2004]。     

Sex Differences in the Song of <Emphasis Type="Italic">Indri indri</Emphasis>

In some primate species, males and females within a social group emit loud calls in a coordinated manner or chorus. Indri indri emits a very conspicuous loud call that elicits the loud calls of neighboring groups. Previous investigations have hypothesized that the main functions of the indri chorus are related to territorial announcement, intergroup avoidance, and group cohesion. We investigated sex differences in indri song. We recorded and analysed songs given by 10 different groups over 160 d. Overall singing duration did not vary between the sexes. However, males emitted significantly fewer but longer notes. Adult males and females of each group participated in the song with sex-specific repertoires. Females had a song repertoire of 8 note types; males shared all of their 6 notes with females. Apart from the initial roars, in all note types shared by both sexes, male notes were significantly longer than female ones, whereas variations in frequency parameters differed according to the note type. These findings suggest that indri song may provide cues to conspecifics, such as group size and sex composition, which could influence interactions between groups.     

Long-term Site Fidelity and Individual Home Range Shifts in <Emphasis Type="Italic">Lophocebus albigena</Emphasis>

We investigated long-term site fidelity of gray-cheeked mangabey (Lophocebus albigena) groups in Kibale National Park, Uganda. Concurrently, we monitored shifts in home range by individual females and subadult and adult males. We documented home range stability by calculating the area of overlap in successive years, and by recording the drift of each group’s monthly centroid from its initial location. Home ranges remained stable for 3 of our 4 groups (overlap over 10 yr >60%). Core areas were more labile, but group centroids drifted an average of only 530 m over the entire decade. Deviations from site fidelity were associated with dispersal or group fission. During natal dispersal, subadult males expanded their home ranges over many months, settling ≤4 home ranges away. Adult males, in contrast, typically dispersed within a few days to an adjacent group in an area of home range overlap. Adult males made solitary forays, but nearly always into areas used by their current group or by a group to which they had previously belonged. After secondary dispersal, they expanded their ranging in the company of their new group, apparently without prior solitary exploration of the new area. Some females also participated in home range shifts. Females shifted home ranges only within social groups, in association with temporary or permanent group splits. Our observations raise the possibility that male mangabeys use a finder-joiner mechanism when moving into new home ranges during secondary dispersal. Similarly, females might learn new resource locations from male immigrants before or during group fission.     

江西鄱阳湖流域中华秋沙鸭越冬期间的集群特征

2010年11月—2011年3月,采用样线法对江西鄱阳湖流域8个河段的中华秋沙鸭Mergus squamatus的集群特征进行了研究。中华秋沙鸭的集群类型包括雄性群、雌性群、混合群、雌性孤鸭和雄性孤鸭5种类型。越冬期间共记录到89群次,432只次中华秋沙鸭。其中,混合群是最多的一种集群方式,孤鸭也是越冬期间出现频次较高的一种特殊的集群方式。集群类型存在时间变化(P<0.01)。混合群中,大多数群体中雌性个体数多于雄性个体或者是一雌一雄。89群次中,孤鸭和2—8只群占总群数的87.64%,提示中华秋沙鸭主要以集小群分散活动。中华秋沙鸭越冬期间的群体大小是(4.85±4.97)只/群。不同集群类型的群体大小差异较大。集群大小可能与采砂、捕鱼、食物的丰富度等环境因子有关。调查结果显示,中华秋沙鸭越冬期间的性比是1∶0.74(n=432)。中华秋沙鸭群体大小与性比有一定的关系。     

秦岭羚牛的集群类型

1995 年7～11月,1996 年3～8月在陕西佛坪国家级自然保护区用野外直接观察和无线电跟踪器追踪的方法, 对秦岭羚牛( Budorcas taxicolor bedfordi) 的集群类型进行了观察。工作期间共记录到羚牛146 群次, 按群体大小和结构可将羚牛群分为家群、混合群、社群、聚集群和独牛5 种类型。在野外记录到的家群共32群次, 混合群15次, 社群47次, 聚集群2次, 独牛50 次。家群的成员是具有亲缘关系的个体, 在羚牛各类型的集群中占据核心的地位,是构成其它类型的羚牛群的基本单位。混合群的成员或是以家群为核心混杂以多只亚成体组成、或全部由亚成体和性成熟不久的年轻成体组成, 是介于家群和社群之间的一种集群方式; 其形成与羚牛幼仔在成长过程中社会习性的形成和完善有关。社群是由多个家群构成的相对比较稳定的一种群体, 在各季节中出现的比例均很稳定, 是羚牛群栖的主要形式。聚集群仅见于夏季, 是临时聚集的一种不稳定的集群类型, 其形成与采食和繁殖活动有关。独牛是羚牛集群的一种特殊形式, 繁殖季节出现的频率高于非繁殖季节。