农田周围生态保留带中普通田鼠的种群生态学：种群数量动态及结构

于2003年5月~2004年11月,采用标志重捕法对栖息在生态保留带的普通田鼠种群结构和数量动态进行了跟踪研究。结果表明,两年中种群密度夏季最大分别达到410个体/hm2和641个体/hm2,春季最少分别达到166个体/hm2和153个体/hm2,种群数量从7月份开始增长,8月份种群密度减少并于11月份开始重新增长。种群中雌性个体数量比较多,雌性在种群中的居留时间较长,同时存活率比雄性高,这导致种群数量的季节变化。种群周转率比较高,在两个捕鼠期间种群中的80%个体被更新,这表明普通田鼠在生态保留带中的活动非常频繁,不断与周围的其他种群进行交流,提高了种群对环境的适应能力。种群中雌雄个体的巢区之间没有年间变化,活动巢区比较小,巢区长度2003年平均为11 m,最长为37.5 m,2004年平均为13 m,最长为52 m。Pearson相关指数表明种群数量和生态保留带年龄、覆盖率和高度之间没有相关性。     

棕色田鼠洞群内社会组织

每月选取农田样方,用洞道内置夹及挖捕法对棕色田鼠洞群内的群体结构进行调查发现,棕色田鼠在不同的季节,洞群内个体组成不同。在4月和10月,同洞群内成年雄性和雌性的数量较多,往往有两个以上的雌性个体参与繁殖,而且亚成体和幼体的数量也较多;而6月至9月,棕色田鼠多呈雌雄一一配对,有些洞群内也有幼体和亚成体,雌雄共巢,而呈现单配制特征。所以其社会组织呈现群居家庭、双亲家庭和单亲家庭3种类型。4月和10月群居家庭最多（60%,61.53%）,6月和9月双亲家庭较多（80%,75%）,双亲家庭所占比例和密度呈负相关,而群居家庭所占比例和密度呈正相关。在不同的季节洞口系数不同,洞口系数和密度呈正相关。     

佛坪自然保护区羚牛的种群数量与结构特征

１９９６年对佛坪自然保护区内的羚牛种群进行了数量调查,结果表明,保护区内羚牛的数量为４３５～５２７只,种群密度达到１．２９～１．５６只／ｋｍ２。羚牛种群的成体雌雄个体之比约为１∶０．５,明显地偏向雌性。在羚牛种群中幼仔占１２．２４％,亚成体占３５．０３％,成年雄性个体占１７．３３％,成年雌性个体占３５．４０％。该羚牛种群在１９９１年至１９９６年间的年均增长率为１８．４８％,明显高于１９８４至１９９１年间羚牛种群的年均增长率。保护区周边地区的生境不断丧失,迫使羚牛向保护区境内迁移,是保护区内羚牛种群数量在短期内迅速升高的原因。     

千岛湖岛屿社鼠的扩散特征

2009年7月—11月,2010年3月—11月对千岛湖两个岛屿上的社鼠(Niviventer confucianus)种群进行标志重捕,通过分析扩散个体的性别、年龄及扩散距离等,探讨陆桥岛屿环境下社鼠的扩散特征。研究结果显示:岛屿环境下社鼠的扩散率为37.96%,不同季节社鼠的扩散率存在差异,社鼠倾向于在春季发生扩散,尤其是3月份,社鼠扩散个体数最多;对于整个捕获史而言,雌雄扩散个体数存在极显著的差异(x~2=12.542,df=1,P0.001),雄性个体更倾向于发生扩散;而在繁殖高峰期,当怀孕鼠存在时,雄性扩散数亦大于雌性,两者存在显著差异(x~2=4.504,df=1,P=0.034)。扩散个体体重的季节差异不显著;扩散与社鼠的年龄密切相关,社鼠更加倾向于在亚成年阶段发生扩散;另外,家群大小对社鼠扩散个体数量也有显著影响,家群越大,扩散个体越多;对扩散距离进行分析发现存在显著的性别差异(t=-9.229,df=50,P0.001),雌性个体的平均扩散距离为(282.97±16.14)m,显著大于雄性的(146.70±6.80)m,而扩散距离与年龄、体重、最大活动距离均无显著相关性。     

社鼠种群生态研究

1983—1987年在北京西山研究了社鼠的种群生态学,共捕获标本870只,用胴体重方法划分5个年龄组。种群年龄组成,随季节而有变化。年龄锥体有季节和年度差异。雌雄性比亦有年度变化。在多数年份中,幼体和亚成体的雌性比例高于雄性。社鼠一般在3—4月开始繁殖,9月基本结束,10月见到个别孕鼠。雄性个体性成熟时的睾丸重量在0.8克以上,雌性产仔数平均为5.20。多数雌体一年繁殖2次,个别可繁殖3次。生态寿命约一年半或更长一些。有些雌体参加两年的繁殖活动。社鼠的种群数量,有明显的季节和年度变化。     

山地麻蜥生态的初步研究

山地麻蜥主要栖息在市郊海拔大于100m的山丘上部及山顶。研究结果表明,山地麻蜥正常密度大约为1只／100m^2,其数量与山丘土石状况、植被盖度及海拔高度有一定关系,与植被类型关系不大。山地麻蜥似乎有一定的“护洞”行为。主食昆虫和蜘蛛,春季食物生态位宽度大于秋季,食物生态位重叠度为0．61。性比变化较大,出蛰仞期和冬眠前期雄多雌少;而5～10月份期间,性比接近1。幼体至成体发育期间,雄性生长快于雌性;但成年期后,雌性头体部分的生长快于雄性,可能与怀卵有关。山地麻蜥种群可分为4个年龄组,个体数量比约为幼年：亚成年：成年A：成年B≈1．8：1．9：3．1：1,但成体与非成体的数量比约为1．2：1,应属于稳定型种群。个体自然寿命约为5.5～6周年。人类干扰是山地麻蜥种群下降的原因之一。     

洞庭湖区自然野化麋鹿种群的偏性扩散行为

大多数鹿科动物表现出偏向雄性的扩散行为。麋鹿(Elaphurus davidianus)于20世纪初在中国灭绝,1985年被重引入中国。1998年长江流域特大洪水导致部分麋鹿个体从湖北石首麋鹿国家级自然保护区围栏内外逸,最终在洞庭湖区形成自然野化种群。野化麋鹿是否也存在偏性扩散行为?1995—2012年,采用样带调查法、分区直数法、特殊个体识别法和访问调查法,按性别组成将扩散群分为雄性群、混合群和雌性群,对洞庭湖区自然野化麋鹿种群的扩散行为进行了研究,共记录到118次扩散。其中,有65次扩散可确认扩散群的类型;60次可确认扩散群准确的个体数。结果显示:(1)雄性麋鹿较雌性更倾向于扩散。雄性群的扩散频次高于雌性群和混合群;50%的雄性扩散群仅由单一成年雄体组成。(2)雄性麋鹿的扩散能力最强,雄性群、混合群和雌性群的平均扩散距离分别为(13.73±8.74)km、(11.05±4.16)km和(8.95±2.16)km,但三者之间的差异不显著(χ2=1.896,df=2,P=0.387)。雌性群和混合群的扩散距离均短于25km,而5.88%的雄性群扩散距离长于25 km。(3)雄性群的平均个体数与混合群的差异显著(F=5.324,df=24,P=0.000.05),与雌性群的差异不显著(F=9.830,df=35,P=0.813),而混合群与雌性群之间的差异显著(F=48.085,df=55,P=0.000.05)。(4)50.00%的雄性群和53.57%的混合群选择芦苇草地作为扩散目的地的生境。洞庭湖区自然野化麋鹿种群与其他野生鹿科动物一样,也存在"雄鹿较雌鹿更倾向于扩散"的现象,雄性的扩散能力比雌性强,雌性的扩散可能依赖于雄性。以上结果对麋鹿的野外放归和自然野化种群的管理与保护具有重要的意义。     

蓝尾石龙子的头部两性异形和食性

通过测量头、体大小和胃检研究浙江泰顺产蓝尾石龙子 (Eumeceselegans)个体发育过程中两性异形和食性的变化。蓝尾石龙子成体个体大小和头部大小的两性差异显著 ,雄性大于雌性。不同发育阶段雌性头长与SVL的线性回归斜率无显著差异 ,头宽与SVL线性回归斜率的差异显著 ,成体和SVL <5 0mm幼体头宽随SVL的增长速率显著小于SVL为 5 0 - 6 9mm的幼体。雄性头部相对于SVL呈加速式异速生长。两性比较发现 :雌雄幼体头长和头宽随SVL的增长速率无显著差异 ,SVL <5 0mm幼体特定SVL的头长和头宽无显著的两性差异 ,但SVL为 5 0 - 6 9mm的雄性幼体头长和头宽大于SVL相同的雌性幼体 ;雄性成体头长和头宽随SVL的增长速率显著大于雌性。SVL <5 0mm的雌性幼体头部相对小于SVL为 5 0 - 6 9mm的同性幼体 ,性成熟雌体头部相对小于SVL为 5 0 - 6 9mm的同性幼体。雌性幼体、雄性幼体、雌性成体和雄性成体食物生态位宽度分别为 12 3、 12 5、 4 8和 14 4。雌雄幼体食物生态位重叠度最高 ,雌雄成体食物生态位重叠度次之 ,成体与幼体食物生态位重叠度较小。成体摄入食饵的大小 (用胃内完整食物长度的平均值表示 )和变化范围大于幼体。两性成、幼体摄入的食饵大小差异显著。两性个体摄入的食饵大小均与其SVL呈正相关 ,表明较大     

鄱阳湖区黄毛鼠(Rattus losea)繁殖生态

2015—2016年对鄱阳湖区的滨湖农田和湖滩草洲的黄毛鼠种群繁殖进行了研究。研究结果表明,其种群雌雄比为81.36%,在不同的季节、生境和年龄组之间都有一定的差别,雌雄比在夏季较低,春、秋、冬季的雌雄比都超过了50.00%,其中冬季的达到了133.33%。农田和湖滩草洲上的雌雄比也都超过了50.00%,且农田的高于湖滩草洲的。在不同的年龄组之间,雌雄比最高的为幼体组140.00%,其次为成体90.20%。所有雌鼠全年的怀孕率为45.26%,平均胎仔数为6.74只,繁殖指数为1.36。夏和秋季的怀孕率都较高,冬季未捕获到怀孕鼠,仅捕获到有怀孕经历(有宫斑)的雌鼠。从繁殖指数看,春、秋季维持高峰水平,且秋峰高于春峰。雌性黄毛鼠总的参产率为71.58%,各季节间变化呈现单峰曲线,夏季最高,其次是秋季和春季,冬季停止怀孕。随着年龄的增长,平均胎仔数有明显增加的趋势,成体组胎仔数最高,而繁殖指数也是以成体组最高,说明成体组是种群中繁殖的主体。雄性黄毛鼠的睾丸下降率全年总计为81.36%,分四季平均为79.64%,春、夏、秋季都维持在较高水平,冬季最低。下位睾丸的大小季节性差异极显著(P0.01),春季与冬季相比,有显著性差异,说明开春后,雄性黄毛鼠在生殖潜能上已有明显变化。这些特征与雌鼠的繁殖高峰基本吻合。说明黄毛鼠主要在春、夏、秋季繁殖,繁殖盛期在春、秋季。从不同的年龄组看,幼体组个体不参与繁殖,亚成体组个体开始参与繁殖,繁殖主体是成体组个体。     

圈养大熊猫种群性比失衡现象产生机制的探究

大熊猫(Ailuropoda melanoleuca)的迁地保护工作已开展了近70年,基本实现了圈养种群的自我维持。根据2019年大熊猫谱系,现存圈养大熊猫种群(n=612)的总性比为1.22∶1 (♀336/♂276),与1∶1的性比有显著性差异(P=0.015),目前尚未开展性比失衡现象产生机制的探究工作。本研究以全国最大的圈养大熊猫种群为研究对象,梳理了该种群36年的出生性比、11年的分年龄雌雄个体数量和分年龄死亡雌雄个体数量,计算了出生性比和预期寿命等数据,旨在探究性比失衡的内在原因。结果显示,圈养大熊猫种群的出生性比为1.01∶1,与1∶1的性比无显著性差异(P=0.926);雄性大熊猫在幼年阶段死亡的比例高于雌性(♀38.24%/♂48.72%);圈养大熊猫的出生预期寿命中位数为21.4岁,其中雌性为23.5岁,雄性为19.8岁,雌性预期寿命比雄性长3.7岁。研究表明,圈养大熊猫种群性比失衡的内在原因是雄性大熊猫幼年阶段的死亡比例高于雌性,且雌性大熊猫预期寿命更长。本研究聚焦圈养大熊猫种群的性比失衡问题,首次计算了圈养大熊猫的预期寿命,可为圈养大熊猫种群的饲养管理和野外大熊...     

Male copulatory behavior and the induction of ovulation in female voles: a quest for species specificity.

Two experiments were conducted to investigate species specificity in the neuroendocrine responsiveness of female prairie voles to the copulatory patterns of males. In Experiment 1, prairie vole males mated for one ejaculatory series were not significantly more effective in inducing ovulation in prairie vole females than montane voles mated with prairie vole females for one series, two series, or to satiety. Mating with conspecific males did result in significantly more implanted embryos than did heterospecific matings. In Experiment 2, it was found that, when the amount of vaginal stimulation was both low and equated across groups, prairie vole males were significantly more effective in triggering ovulation in female prairie voles than were either meadow voles or montane voles. Although there appears to be some species specificity to the “vaginal codes” of these congeneric species, its biological significance is unclear.     

The effect of familiarity on social interactions in meadow voles,Microtus pennsylvanicus: a laboratory and field study

The role of familiarity in affecting the outcome of social interactions among meadow voles was investigated in both a laboratory and a field experiment. In the laboratory, captive meadow voles, Microtus pennsylvanicus, were exposed to a conspecific's odour. The voles were then placed into two groups: familiar and unfamiliar. Familiar voles were individuals who underwent staged dyadic encounters with the conspecific to whose odours they had been exposed. Unfamiliar voles were individuals who underwent paired encounters with conspecifics to whose odours they had not been exposed. In the field experiment, familiar voles were neighbours that were trapped within each other's home ranges over two consecutive bi-weekly trapping sessions. Unfamiliar voles were individuals that were trapped on different trapping grids. The results of the laboratory and field studies were similar. Encounters between familiar females resulted in less agonistic behaviour and more amicable acts than encounters between unfamiliar females. In contrast, encounters between familiar males resulted in more agonistic behaviour than encounters between unfamiliar males. Familiarity did not affect the outcome of male-female interactions. These results are discussed in the framework of the social system of the meadow vole.     

根田鼠的熟悉性及其自然动情下的配偶选择

报道了在室内雌鼠自然动情条件下根田鼠两性个体配偶选择的3种熟悉性效应的5组实验结果,包括雌性对熟悉和陌生雄鼠、配偶和陌生雄鼠、配偶和熟悉雄鼠的择偶行为实验 , 雄性对熟悉和陌生雌鼠、配偶和陌生雌鼠的择偶行为实验。在实验前, 将1对性成熟的雌雄鼠 (非亲缘关系) 每天关养8 h 共8 d 建立熟悉性; 配对雌雄鼠至少生育1胎则为配偶关系。在 Y 形迷宫内的30 min 实验中, 两个被选择鼠分别以项链拴在横跨选择箱顶端中央的一根铁丝上, 限制它们在各自箱内活动; 而允许异性选择鼠从中立箱自由进入两个选择箱。记录选择鼠对异性被选择鼠的访问、社会探究、攻击、交配和友好行为的频次和时间。经Wilcoxon 关联样本 T 检验发现, 除交配行为不显著外, 雌性根田鼠均选择熟悉性较高的雄鼠; 而雄鼠不具这种选择性。该结果提示雌雄根田鼠的不同择偶行为也许就是反映该种婚配制度特征的直接行为过程。因此, 在择偶行为中, 雌性根田鼠表现的单配性倾向和雄鼠的多配性倾向, 只能以其婚配制度为一雄多雌制的假设来解释。我们的实验还说明在多配制田鼠中, 一雄多雌制与混交制在雌鼠择偶行为上是不同的, 而与单配制的相似或相近, 故简单地比较多配制与单配制则不能反映田鼠亚科动物婚配制度的多样性。     

The influence of American mink odour on the spatial distribution and behaviour of water voles

The perception and assessment of predation risk often cause changes in the activities of animals and induce behavioural responses that may in turn affect their movements and distribution. To simulate high predation risk in a midfield pond riparian habitat, we used fresh faeces from ranch American mink Neovison vison and recorded behavioural responses of water voles Arvicola amphibius. In areas where mink odour was deployed, the numbers of captured vole individuals and their trappability were significantly lower than in control areas. Several voles migrated from the zones with deployed mink faeces to the areas without faeces, thus proving that increased predation risk affects the distribution of individuals in a population. The response to mink odour was much more pronounced in females than in males; in areas with deployed mink faeces, not a single female was trapped. We conclude that although American mink is a non‐native, invasive predator, water voles respond to mink odour by reducing their activity and/or by avoiding places with higher predation risk.     

Habitat selection and home range size of field voles<Emphasis Type="Italic">Microtus agrestis</Emphasis> in Słowiński National Park,Poland

Habitat preference, home range size and intra-specific overlap were investigated in summer 1998 among field volesMicrotus agrestis (Linnaeus, 1761) in Słowiński National Park (N Poland). Eight individuals (2 females, 6 males) were radio-tracked for one week in August. Field voles were shown to exhibit a marked preference for meadow and the ecotone between grassland and habitats with common reed, while avoiding alder forest and proper reedbeds. No significant differences between night and day in habitat-use of voles were noted. The results suggest that, at the end of the breeding season, it was food resources, rather than the risk of predation, played an important role in the voles’ utilisation of space. The home ranges of males were larger and more diverse than those of females; their sizes being correlated with body mass, such that heavier males had larger home ranges. This further suggests that intra-sexual competition exists between males for females. The low number of females influenced their spatial behaviour, as females had completely exclusive home ranges. Four males (out of six) had overlapping home ranges with other males; three of the overlaps were of less than 20%. Attributes of promiscuity (such as a 3.5:1 operational sex ratio of males to females, intra-sexual competition between males and the territorial exclusivity of females) influenced the social system. However, the period of radio-tracking during this study was too short to define accurately the social system in the field vole population.     

Comparison of the gonadal response of wild and laboratory field voles (Microtus agrestis) to different photoperiods

Weanling male and female field voles from laboratory stock and from the F1 generation of wild-caught animals were placed in a long (16L:8D) or short (6L:18D) photoperiod for 28 or 56 days. Both types of field vole showed the well-established effect of photoperiod upon sexual maturation, with animals in the long photoperiod having larger and more active gonads than animals in the short photoperiod. After 28 and 56 days laboratory stock females were more mature, sexually, and had a higher growth rate than did Wild F1 females. There was no difference between the two types of males at 28 days, but by 56 days laboratory stock males were more sexually mature and had a higher growth rate than did Wild F1 males. These differences between the two types occurred in the long and short photoperiods. There was no interaction between photoperiod and type of vole. The use of laboratory stock animals in experiments could lead to an incorrect assessment of the effect of photoperiod in the control of seasonal breeding in wild populations.     

The capture of voles and shrews by male and female ermine Mustela erminea in captivity

The capture of meadow vole Microtus pennsylvanicus and short-tailed shrew Blarina brevicauda by male and female ermine Mustela erminea was observed in an indoor enclosure which simulated field conditions. We made 114 trials using 15 different male and 17 different female ermine. Each trial involved one ermine deprived of food for either 0, 10 or 20 h, and only one individual of either prey species. In most trials, the hunting efficiency (indicated by search and handling durations, and number of captures) of male ermine was greater than that of females. Females hardly ever captured shrews, whereas males hunted them successfully independently of the level of food deprivation. However, when deprived of food for 20 h, females spent less time than males in searching for voles. These results suggest that smaller females may be specialized and more effective at hunting meadow voles than larger males under severe food deprivation. This advantage may allow them to channel a greater proportion of energy into reproduction.     

Predation rate, prey preference and predator switching: experiments on voles and weasels

We studied the predation rate and prey selection of the least weasel ( Mustela nivalis nivalis ) on its two most common prey species in boreal environments, the bank vole ( Clethrionomys glareolus ) and the field vole ( Microtus agrestis ), in large outdoor enclosures. We also studied the response of weasels to odours of the two species in the laboratory. The enclosure experiment was conducted using constant vole densities (16 voles/ha) but with varying relative abundance of the two species. Weasels showed higher predation rates on bank voles, and males had higher predation rate than females. Females killed disproportionately more of the more abundant prey species, but they preferred bank voles to field voles when both were equally available. Overall, the predation rate also increased with increasing abundance of bank voles. Therefore our results are in agreement with earlier laboratory results showing preference for bank voles, even if no intrinsic preference for odours of either species was observed in our laboratory study. We suggest that the least weasel hunts according to prey availability, prey aggregation and suitability of hunting habitat, and that this causes the observed dependence of least weasels on field voles and emphasises the role of the field vole in the vole-weasel interaction in cyclic vole populations. Furthermore, our results suggest that predation by weasels may facilitate the coexistence of the two vole species via predator switching, and that it may cause the observed synchrony in dynamics between vole species.     

Meadow Voles (Microtus pennsylvanicus, Arvicolidae) Over-mark and Adjacent-mark the Scent Marks of Same-sex Conspecifics

Scent over-marking occurs when an animal deposits its scent mark on top of the scent mark of a conspecific; adjacent-marking occurs when an animal deposits its scent mark next to the scent mark of a conspecific. Given that male rodents usually scent mark more than females and that animals spend more time investigating the odor of the top-scent donor of an over-mark, I tested the following three hypotheses. First, male meadow voles deposit more scent marks than female meadow voles. Second, male meadow voles will deposit more over-marks and adjacent-marks in response to the scent marks of a same-sex conspecific than females would. Third, meadow voles spend more time investigating the odor of the second vole placed in the arena than that of the first vole placed in the arena. To test these hypotheses, two age-matched, like-sex conspecifics (first vole and second vole) were placed successively into an arena in which they were allowed to freely explore and scent mark for 15 min. The first hypothesis was not supported. The first and second vole, independently of sex, deposited a similar number of scent marks. The second hypothesis was also not supported by the data: more conspecific scent marks were over-marked by the second female than by the second male. The third hypothesis was supported by the data. After investigating a scented arena, males and females spent more time investigating the odor of the second vole than that of the first vole. Sex differences in scent-marking behaviors of meadow voles are unlike those reported for other species of rodents.     

Comparison of sociability,parental care and central estrogen receptor alpha expression between two populations of mandarin voles (<Emphasis Type="Italic">Microtus mandarinus</Emphasis>)

The socially monogamous mandarin vole (Microtus mandarinus) shows significant behavioral plasticity. We examined whether levels of sociability, parental care and central expression of estrogen receptor alpha differed between two populations with different ecologies. Our results show that males from the Chengcun population display significantly more amicable and less aggressive behaviors towards novel same-sex individuals compared to males from the second population of Xinzheng. Chengcun voles directed more licking behavior towards neonatal pups than did Xinzheng voles. Differences were also found in the number of estrogen receptor alpha-immunoreactive neurons. For example, Xinzheng males displayed significantly higher immunoreactivity than Chengcun males in the medial amygdala, medial preoptic area and ventromedial nucleus of the hypothalamus. Xinzheng females expressed higher levels of estrogen receptor alpha-immunoreactivity than Chengcun females in the medial preoptic area. Chengcun females exhibited significantly more estrogen receptor alpha expression than Xinzheng females in the bed nucleus of the stria terminalis. Our results indicate that mandarin voles from the Chengcun site possess monogamous traits, and animals from Xinzheng possess polygamous traits. It also appears that different social behavior and levels of parental care in these two populations may be associated with differences in estrogen receptor alpha-immunoreactive neurons.