布氏田鼠肝毛细线虫感染率与其体重的关系

2005年5月和8月,在内蒙古锡林郭勒北部典型草原调查了肝毛细线虫对布氏田鼠种群的感染特征,分析肝毛细线虫对布氏田鼠的感染率与其性别、年龄、体重及种群密度的关系。结果表明：肝毛细线虫对布氏田鼠感染率没有性别差异,雄鼠与雌鼠的感染率相当;但是与布氏田鼠体重/年龄密切相关：幼鼠的感染率较低,成鼠感染率较高,感染率和平均感染度均随着个体年龄的增长而增高。布氏田鼠达到一定的年龄（或体重）后才可感染肝毛细线虫病,其最低感染体重为24.3g。布氏田鼠的种群密度对肝毛细线虫的感染率和平均感染度没有明显的影响,但同一样地不同季节感染率不同,本次调查显示,2005年5月份感染率高于8月份群体感染率,同一样地的春季感染率与秋季感染率之间呈现出显著的正相关。     

炔雌醚对长爪沙鼠种群数量和性比的影响

炔雌醚是一种激素类新型鼠类不育剂,已有研究表明,炔雌醚对某些鼠类种群繁殖具有良好的控制成效。为检验新型不育剂对长爪沙鼠种群的控制效果,2006年5月在内蒙古锡林郭勒盟锡林浩特市农牧交错带开展了炔雌醚对野外长爪沙鼠种群的控制实验,本次实验设投药区和对照区2个组别,5—8月开展逐月的夹线调查以及四分之一圆洞口计数法,对样地内长爪沙鼠进行系统的追踪调查,分析炔雌醚对长爪沙鼠种群数量以及种群性比的作用。结果显示:投药1个月之后,投药区雌鼠比例(16.3%)不及对照组雌鼠比例(51.9%)的三分之一,投药区的雌鼠比例(16.3%)仅为雄鼠比例(83.7%)的五分之一;与对照区相比,投药区长爪沙鼠的密度下降达60%以上。这表明:炔雌醚对野外长爪沙鼠种群的不育控制具有良好效果,且炔雌醚对长爪沙鼠的种群性比影响很大,过量投放炔雌醚可造成雌鼠死亡,单独使用炔雌醚可降低野外不育剂的药物成本。     

黑线毛足鼠年龄和种群密度与肝毛细线虫感染率的关系

2004—2005年,在内蒙古锡林郭勒盟阿巴嘎旗和东乌珠穆沁旗研究了肝毛细线虫病对黑线毛足鼠种群感染情况,分析肝毛细线虫对黑线毛足鼠的感染率与鼠体年龄以及种群密度的关系。结果表明,黑线毛足鼠达到一定的年龄(或体质量)才可感染肝毛细线虫病,最低感染个体体质量为14.6g。肝毛细线虫对低龄鼠的感染检出率比较低,而对成体鼠感染检出率较高,其感染率和感染度均随着个体年龄的增长而增高(感染率与年龄:r=0.97,P<0.05;感染度与年龄:r=0.93,P<0.05)。此外,黑线毛足鼠体质量与肝毛细线虫感染率和感染度也存在显著的相关关系(感染率与体质量:r=0.99,P<0.05;感染度与体质量:r=0.95,P<0.05),黑线毛足鼠的种群密度则对肝毛细线虫的感染率(r=0.27,P>0.05)和平均感染度(r=0.41,P>0.05)没有明显的影响,其感染率可能与地区不同有关。     

肝毛细线虫对雌性布氏田鼠繁殖参数的影响

2005年5月,在内蒙古锡林郭勒盟阿巴嘎旗北部,研究了肝毛细线虫(Capillaria hepatica)对典型草原区雌性布氏田鼠(Lasiopodomys brandtii)繁殖参数的影响。采用标准夹线法捕获鼠类,对捕获的鼠类进行常规生物学解剖,根据虫卵有无确定肝毛细线虫病感染情况,记录鼠类名称、体长、体重、胴体重、繁殖特征以及肝毛细线虫病感染情况。由于体重是划分鼠类年龄的常用指标之一,结合布氏田鼠的繁殖特征研究数据,采用25.1~55.0 g之间的雌性个体作为本研究分析样本,并将其分为25.1~35.0 g、35.1~45.0 g和45.1~55.0 g体重(年龄)组。采用卡方检验比较分析同一体重(年龄)组内,肝毛细线虫病感染情况与雌性布氏田鼠妊娠率的关系,T检验分析感染情况与胎仔数的关系。结果显示,在各个体重(年龄)组中,感染肝毛细线虫组布氏田鼠雌鼠妊娠率均略低于未感染组,但感染情况与妊娠情况无显著相关关系(P0.05);感染肝毛细线虫布氏田鼠胎仔数低于未感染布氏田鼠,感染情况与胎仔数有显著相关关系(P0.05)。结果表明,肝毛细线虫病对布氏田鼠妊娠率无明显影响,但对布氏田鼠胎仔数有明显的负面影响。     

山东部分地区鼠类肝毛细线虫感染调查

本文对山东部分地区鼠类肝毛细线虫感染率进行了调查。山东地区鼠类肝毛细线虫总感染率为２７．３６％。不同地区感染率不同。各地均以褐家鼠为主。通过重点对褐家感染情况分析,结果肝毛细线虫感染率及感染强度与鼠龄呈正相关;肝毛细线虫感染以整个肝脏为主,右肝感染占第二位。本文还针对农田鼠类明显缺乏肝毛线虫感染的特点,提出肝毛细线虫用于控制农田鼠类种群密度的可能性。     

锡林郭勒地区肝毛细线虫病自然疫源地与鼠类分布的关系

2000~2005年,在内蒙古锡林郭勒地区开展了肝毛细线虫病自然疫源地的调查工作。采用夹线法捕获鼠类样本,解剖检视各个采样点鼠类肝毛细线虫病的感染情况。结果表明,锡林郭勒地区存在肝毛细线虫病自然疫源地。疫源地分布在锡林郭勒的北部和东北部地区,包括东乌珠穆沁旗、阿巴嘎旗、锡林浩特市、苏尼特左旗和西乌珠穆沁旗,2004年自然疫源地总面积为32932km2。肝毛细线虫病可感染疫源地的多种鼠类,其自然疫源地分布区与布氏田鼠分布区重叠程度很高,重叠度指数为1.37,而与其他鼠类的分布重叠度不高,这表明布氏田鼠可能是肝毛细线虫的主要宿主。     

大鵟对长爪沙鼠秋季的集群捕食策略

2003年9月10日—15日,在内蒙古东乌珠穆沁旗嘎达布其口岸附近的典型草原区鼠害草场研究了大鵟(Buteo hemilasius)对长爪沙鼠的捕食策略。鉴于秋季是长爪沙鼠的活跃期,直接采用鼠丘核心区的沙鼠洞口数作为衡量长爪沙鼠集群大小的指标,分析了大鵟对不同大小集群的长爪沙鼠家族集群的捕食选择偏好。实验涉及了3hm2的实验样地,样地中具有符合实验统计的长爪沙鼠洞群为87个。5d内作者观察到大鵟蹲守在样地中的长爪沙鼠29只次,共涉及23个沙鼠洞群。通过分析大鵟蹲守和没有蹲守过的沙鼠洞群的洞口数量,利用非参数的Mann-Whitney U检验法分析,结果表明:大鵟蹲守的洞群的洞口数量总秩和为2569.5,大鵟没有蹲守的沙鼠洞群的洞口数量秩和统计量为1258.5,统计量U值为489.5。校正之后的Z值为-2.37459,两组差异达到显著的水平(P=0.017574)。此外,分析还显示:沙鼠洞群洞口数量(S)与大鵟蹲守次数(F)呈显著的正相关关系,相关式为:F=-0.0559+0.023×S,(r=0.2707,P﹤0.05)。结果表明,大鵟会首先在洞口数量多的长爪沙鼠集群蹲守捕食,因此在越冬期间,长爪沙鼠的集群数量会被限制,进而可能形成一种最优化集群数量的模式。本文的研究结果从一定角度支持了鼠类通过形成最优集群以降低天敌捕食概率的理论。长爪沙鼠可能借助扩散行为,以及秋季的分群行为来降低集群密度从而降低被捕食风险。     

肝毛细线虫的鼠体感染及虫卵扫描电镜观察

肝毛细线虫 Capillaria hepatica(Bancroft 1893)Travssos 1915属于毛细科Capillartidae毛细属Capillaria中的一种小型线虫,为世界性分布,是鼠类肝脏中常见的一种寄生虫。近年来发现可广泛寄生于多种哺乳动物,包括人体内。1982年12月在浙江天台县一公社对鼠类体内肝毛细线虫的感染进行了调查,以了解鼠体在冬季情况下对此种线虫的感染率,并对其虫卵进行了扫描电镜的观察,以与在外部形态上极为相似的毛首鞭形线虫(Trichuria trichiura)卵加以区別。     

炔雌醚对内蒙古农牧交错带长爪沙鼠种群繁殖的影响

炔雌醚对一些鼠类种群具有良好的控制效果。为探究炔雌醚对长爪沙鼠Meriones unguriculataus种群繁殖的影响,于2006年5—8月在内蒙古锡林郭勒盟白音锡勒牧场农牧交错带展开了炔雌醚对长爪沙鼠野生种群繁殖的控制实验。设置了投药区和对照区,5月初进行投药,实验期间采用夹线调查法逐月对样地内的长爪沙鼠进行系统的取样调查,分析炔雌醚对长爪沙鼠种群繁殖的影响。结果显示:在投药之后的6—8月,投药区成体鼠的子宫坏死率分别为75.3%、61.5%和48.7%,与对照区差异有高度统计学意义(P0.01);投药区成体鼠的怀孕率下降,与对照区差异有高度统计学意义(P0.01);投药区的胎仔数显著低于对照区(P0.05)。综上表明,炔雌醚对农牧交错带长爪沙鼠种群繁殖的控制具有良好的效果。     

炔雌醚对内蒙古农牧交错带长爪沙鼠(Meriones unguiculatus)家群大小和巢域行为的影响

为检验施用炔雌醚对农牧交错带长爪沙鼠家群大小与巢域行为的影响,于2006年5月至9月对内蒙古锡林郭勒盟锡林浩特市农牧交错区域分布的长爪沙鼠家群使用炔雌醚进行种群不育控制实验。分设投药区和对照区两个组别,分别于5月、7月与9月份采用1/4样圆面积有效洞口计数法,随机选取24个长爪沙鼠家群,调查对照区域和投药区内沙鼠的家群洞口数量以及家群大小。另在对照区和投药区,随机测定了30个沙鼠的家群活动范围,对比使用炔雌醚前后长爪沙鼠巢域平均半径和活动面积的影响。结果为:对照区家群平均洞口数58个,投药区仅23个,在炔雌醚投药区长爪沙鼠家群受炔雌醚影响,洞口数仅为23个,表明其对长爪沙鼠家群大小控制效果显著。投药区内长爪沙鼠家群密度在投药后连续下降,最大下降幅度较对照区家群密度低70%,表明炔雌醚对长爪沙鼠的家群密度影响较大,可显著降低长爪沙鼠家群密度(P<0.05)。炔雌醚对长爪沙鼠家群平均半径和活动面积的研究结果显示,施用炔雌醚后家群巢域半径与活动面积均显著缩小(P<0.05),与对照区巢域平均面积相比缩小15%、平均活动半径缩小30%。通过以上结果可得出:单独施用炔雌醚对控制野外长爪沙鼠家群以及降低长爪沙鼠巢域、活动面积效果显著。炔雌醚可有效降低农牧交错带长爪沙鼠种群数量和有效活动范围,这对于农牧交错带的鼠害防控,同时降低鼠源性疾病,包括鼠疫的传播都有一定的意义。     

Wood thrush nest success and post-fledging survival across a temporal pulse of small mammal abundance in an oak forest

1. Synchronized mass production of seed crops, such as acorns, produces a resource pulse that may have far-reaching consequences for songbird populations through its effects on avian predators. Seed production in these forests represents only the first of several pulsed events. Secondary pulses emerge as mast-consuming rodents numerically respond to seed production and tertiary pulses emerge as generalist predators, such as raptors, numerically respond to rodents. In turn, these two groups reduce nest productivity and juvenile survivorship 1 and 2 years, respectively, after the initial pulse in seed production. 2. At our study site in south-eastern New York, USA, autumn acorn abundance (primary pulse) largely determines rodent abundance (secondary pulse) the following spring. We tested the hypotheses that the population dynamics of a shrub-nesting passerine (wood thrush Hylocichla mustelina), is influenced by rodents through the: (a) direct effect of predation by rodents; (b) indirect effect of rodents on the abundance of raptors (tertiary pulse); and (c) indirect effect of rodent abundance on raptor diet. The latter specifically hypothesizes that a crash in the rodent population in the wake of region-wide failure of acorn production leads to an extreme diet shift in raptors that increases post-fledging mortality in birds. 3. We conducted a 3-year study to examine variation in wood thrush nest success and fledgling survival, using radio telemetry, across a pulse of rodent abundance (i.e. low, medium and high). We also updated and reanalysed regional wood thrush population growth rates as a function of the annual variation in rodent abundance. 4. Fledgling survivorship, but not nest success, varied in relation to annual rodent abundance. Raptors and eastern chipmunks Tamias striatus were the most commonly identified predators on fledglings. Fledgling survivorship was greatest at intermediate rodent abundance consistent with a shift in raptor diet. Regional rate of wood thrush population growth showed a unimodal relationship with rodent abundance, peaking during years with intermediate rodent abundance. This unimodal pattern was due to wood thrush population growth rates near or below zero during rodent population crashes. 5. The telemetry study, pattern of regional abundance and synchronized population dynamics of coexisting thrushes suggest a common mechanism of behavioural changes in raptors in response to declines in rodent prey, which in turn affects thrush population dynamics.     

Acorn mast drives long-term dynamics of rodent and songbird populations

Resource pulses can have cascading effects on the dynamics of multiple trophic levels. Acorn mast is a pulsed resource in oak-dominated forests that has significant direct effects on acorn predators and indirect effects on their predators, prey, and pathogens. We evaluated changes in acorn mast, rodent abundance, raptor abundance, and reproductive success of a ground-nesting songbird over a 24-year period (1980–2004) in the southern Appalachian Mountains in an effort to determine the relationships among the four trophic levels. In particular, we examined the following: acorn mast from red oaks (Quercus rubra) and white oaks (Q. alba), abundance of white-footed mice (Peromyscus leucopus) and deer mice (P. maniculatus), population estimates of seven raptor species from three feeding guilds, and nest failure and number of juveniles of dark-eyed juncos (Junco hyemalis). Finally, we recorded seasonal temperature and precipitation to determine the effects of weather on each trophic level. We found that weather patterns had delayed effects of up to 3 years on these trophic interactions. Variation in acorn mast, the keystone resource in this community, was explained by weather conditions as far back as 2 years before the mast event. Acorn mast, in turn, was a strongly positive predictor of rodent abundance the following year, whereas spring and summer temperature and raptor abundance negatively affected rodent abundance. Dark-eyed junco nests were more likely to fail in years in which there were more rodents and raptors. Nest failure rate was a strong predictor of the number of juvenile juncos caught at the end of the summer. Our results improve our understanding of the complex ecological interactions in oak-dominated forests by illustrating the importance of abiotic and biotic factors at different trophic levels. Ethan D. Clotfelter and Amy B. Pedersen contributed equally to the writing of this paper.     

南充高坪机场土壤及草丛动物群落特征和鸟类的关系

机场鸟类是机场安全的重大隐患,减少机场附近鸟类数量是机场安全至关重要的一环.2007年4～12月,对南充高坪机场3种生境土壤动物和草丛动物群落组成、数量和季节性变化特征进行了初步的研究.调查共获得土壤动物25类,其中蜱螨目、原尾目、线虫纲为土壤动物群落优势类群,占年总捕获量的71.88%;常见类群有弹尾目、线蚓科、腹足纲、膜翅目、双翅目、鞘翅目、蚯蚓、蜘蛛目,直翅目9类,占总捕获量的22.84%.地表草丛动物21类,其中半翅目、蜘蛛目、双翅目、腹足纲为地表草丛动物的优势类群,占年捕获量的65.7%;常见类群有直翅目、鞘翅目、同翅目、膜翅目、鳞翅目、革翅目、弹尾目7类,占总捕获量的31.2%.将土壤动物群落、草丛动物群落与肉食性鸟类进行相关分析,结果显示土壤动物群落变化与肉食性鸟类群落之间有一定关系;草丛动物数量与肉食性数量鸟类呈现一定正相关性,机场肉食性鸟类数量与直翅目数量呈显著的正相关关系(r=0.910,P=0.032).结合机场区域鸟类食性观察、分析,直翅目、腹足纲动物是机场肉食性鸟类数量的主要捕食对象,通过定期割草、消除腐草和杂物、喷洒农药控制地表草丛动物是减少机场区域肉食性鸟类数量的有效方法和途径.     

Evidence for Convergent Evolution in Gape Morphology of the Bat Hawk (Macheiramphus alcinus) with Swifts,Swallows, and Goatsuckers

Gape morphology has been linked to feeding and breeding ecology in raptors, according to the ingestion rate hypothesis. Mammal feeding raptors have larger gapes, allowing them to ingest prey more rapidly than bird feeders, which have evolved smaller average body sizes and gapes to capture more agile prey. One highly derived raptor, however, the Bat Hawk (Macheiramphus alcinus), specializes on colonial bats and swiftlets concentrated daily in a limited temporal window by capturing and swallowing them whole in flight. We hypothesized that the gape of the Bat Hawk evolved to feed rapidly on agile vertebrates limited temporally. We predicted that the gape of the Bat Hawk would be significantly larger than the gape of other raptors, more closely resembling the gapes of swifts (Apodidae), swallows (Hirundinidae), and goatsuckers (Caprimulgiformes). We measured gape area of the lower mandible in museum specimens representing 138 bird species in six orders. We also compared gape area by prey type in over 100 raptor species in three orders. We predicted that insectivorous raptors would exhibit gapes similar to mammal feeders but would differ from bird feeders because insects are not agile prey. The Bat Hawk had the largest gape of any raptor and more closely resembled the gape of insectivorous birds, which also swallow prey whole in flight. The evolution of an enlarged gape may have permitted the Bat Hawk to exploit a previously unrealized ecological niche. Gapes of bird feeding raptors were smaller than in mammal and insect feeders, supporting the ingestion rate hypothesis.     

Breeding density, cuckoldry risk and copulation behaviour during the fertile period in raptors: a comparative analysis

Extrapair copulations (EPCs) and fertilizations (EPFs) occur in many socially monogamous bird species, including raptors. In this group of species, males invest heavily in reproduction through the feeding of female and young, so the cost of cuckoldry is particularly high. The feeding of females by males, characteristic of most species, conflicts with mate guarding, so raptors are expected to use frequent within-pair copulations (WPCs) for paternity assurance. In this study, I reviewed information on copulation behaviour of diurnal raptors, and used regression analyses and phylogenetic comparative analyses to investigate relations between density, EPC frequency and WPC behaviour. EPCs occurred in most raptor species studied (68%, N=19), mostly during the presumed fertile period of females. EPC frequency, measured as the percentage of females engaging in EPC but not the percentage of extrapair copulations, was positively related to breeding density. The rate and relative duration of WPCs were also positively related to breeding density, but only WPC rate was positively related to EPC frequency (percentage of females). Frequently copulating species had relatively larger testes, underlying higher sperm production capacities. The results support the hypotheses that sperm competition intensity increases with breeding density, and that male raptors rely on frequent copulations to ensure paternity. Despite the risk, EPFs rarely occurred in raptors, suggesting efficient paternity guards.     

典型草原啮齿动物密度与牧草损失量的关系

研究啮齿动物密度对牧草损失量的关系,对于计算草地经济损害水平至关重要,可以为草地畜牧业管理决策提供指导。本研究于2012 - 2016 年,在锡林郭勒典型草原(东乌珠穆沁旗),应用标志重捕法和样方法对啮齿动物密度以及9 月份植物地上生物量进行调查,用啮齿动物密度及其日食量来估算鼠类对牧草的损害程度,确定牧草损失量。研究结果表明:(1)啮齿动物密度与牧草损失量的最佳拟合曲线是三参数S 型曲线,为:Loss = k/(1+e ^{a - rdensity});(2)当啮齿动物密度>906 个标准鼠单位/hm² 时,牧草产量发生最大损失(牧草产量损失比=23.30% );(3)根据所拟合的曲线,得出该类型草地啮齿动物对牧草损害的危害阈值为174 个标准鼠单位/hm² 。     

Natural and experimental West Nile virus infection in five raptor species

We studied the effects of natural and/or experimental infections of West Nile virus (WNV) in five raptor species from July 2002 to March 2004, including American kestrels (Falco sparverius), golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), barn owls (Tyto alba), and great horned owls (Bubo virginianus). Birds were infected per mosquito bite, per os, or percutaneously by needle. Many experimentally infected birds developed mosquito-infectious levels of viremia (>10(5) WNV plaque forming units per ml serum) within 5 days postinoculation (DPI), and/ or shed virus per os or per cloaca. Infection of organs 15-27 days postinoculation was infrequently detected by virus isolation from spleen, kidney, skin, heart, brain, and eye in convalescent birds. Histopathologic findings varied among species and by method of infection. The most common histopathologic lesions were subacute myocarditis and encephalitis. Several birds had a more acute, severe disease condition represented by arteritis and associated with tissue degeneration and necrosis. This study demonstrates that raptor species vary in their response to WNV infection and that several modes of exposure (e.g., oral) may result in infection. Wildlife managers should recognize that, although many WNV infections are sublethal to raptors, subacute lesions could potentially reduce viability of populations. We recommend that raptor handlers consider raptors as a potential source of WNV contamination due to oral and cloacal shedding.     

Raptors and "campo-cerrado" bird mixed flock LED BY Cypsnagra hirundinacea (Emberizidae:Thraupinae)

Bird mixed flocks including Cypsnagra hirundinacea and Neothraupis fasciata as species with sentinels were studied in "campo-cerrado" in order to investigate the possible relationship between alertness and the mixed flock leadership. This study was conducted from March to September 1996 and mixed flocks were observed on average for 2:30h. The time with sentinels were recorded for C. hirundinacea and N. fasciata. The sentinels of Cypsnagra hirundinacea performed most of the vigilance (time with sentinel was on average 42 +/- 17%, 41 +/- 17% of which by C. hirundinacea, whereas only 1.2% by N. fasciata) and gave all the alarm calls recorded (54% of the encounters with raptors stimulated alarm calls). A relationship was verified between time with sentinel and the rate of encounters with raptor (ANOVA, F = 3.0. P < 0.05). The results of this study are an evidence for the anti-predatory function of mixed flocks, in campo-cerrado, and the alertness as a major feature of a leader species, since C. hirundinacea always led those flocks.