绿瘦蛇捕食鳄蜥的现象

鳄蜥(Shinisauruscrocodilurus)是濒危的孑遗物种,生存遭受多方威胁。除人为猎杀和生境受到破坏之外,天敌也是其致命的威胁之一,但目前关于其被天敌捕食的研究非常匮乏。本文报道了绿瘦蛇(Ahaetullaprasina)捕食鳄蜥的现象,以全事件记录法观察了这一行为过程。鳄蜥面对的被捕食风险可能较广。除蛇外,鳄蜥的天敌也可能是鸟类等动物。在饲养繁育中,要注意加强防范举措,以免鳄蜥被天敌侵害。     

鳄蜥室内繁殖及幼体生长的观察

鳄蜥(Shinisaurus ercodilurus)是我国独有的珍稀爬行动物,过去一直认为仅分布在广西大瑶山一带,称为瑶山鳄蜥,1978年已列为国家第一类保护动物。近年来国内不少学者对其形态、生态、地理分布、内部解剖以及生理、生化等方面都做了不少的调查和研究工作,取得了一定的研究成果,然而到目前为止,对鳄蜥的室内饲养繁殖及幼体生长方面的研究,所见报道却不多,笔者从1979年开始对鳄蜥室内饲养和繁殖进行了试验和观察,现将观察的结果,报道如下:     

鳄蜥的食物识别机制

鳄蜥(Shinisaurus crocodilurus)食物识别机制的研究,对进一步了解鳄蜥的捕食行为和生态学习性有重要意义。使用棉棒分别沾上去离子水、香水、黄粉虫(Tenebriomolitor L.)和蚯蚓(Pheretima sp.)的气味(蚯蚓和黄粉虫处死后绞碎以便于棉花棒蘸上),观察11只鳄蜥对4种化学刺激的反应,每个个体对每种刺激均进行24次实验重复。实验结果显示：鳄蜥对4种刺激均有反应,对黄粉虫和蚯蚓刺激的舔舌次数显著高于香水和去离子水的舔舌次数(Wilcoxon test,所有P<0.001),表明鳄蜥能检测以及识别控制刺激和食物刺激。再又对鳄蜥进行4种处理实验：(A)空白对照;(B)蚯蚓气味;(C)密封着的活蚯蚓;(D)活蚯蚓。每个个体每种处理均进行5次实验。结果显示：鳄蜥在不同处理下的行为持续时间、探究频次和攻击频次有显著差异(Friedman test,所有P<0.001)。鳄蜥在仅有视觉刺激出现的处理C以及既有化学刺激又有视觉刺激的处理D比仅有化学刺激的处理B在持续时间、探究频次和攻击频次上显著要高（所有P<0.001）。在无视觉刺激的条件下,鳄蜥在处理B的行为持续时间以及探究频次均显著高于处理A 的（所有P<0.001）;而在视觉信息相同的条件下,鳄蜥在处理D中仅行为持续时间显著高于处理C（Z=3.95, P<0.001）,而探究频次以及攻击频次无显著差异（前者Z=1.53, P=0.13;后者Z=1.10, P=0.27）。结果表明鳄蜥主要利用视觉捕食,化学感觉有辅助作用。鳄蜥这种食物识别机制可能与捕食模式和种系发生有关,也可能受食物的影响。     

鳄蜥视神经的研究

鳄蜥是我国特有的珍稀动物,被列为一类保护动物。关于其视觉系统结构的研究,国内外至今未见报道。本实验用电子显微镜对其视神经结构进行了观察,并对视神经纤维的数量、纤维直径谱和髓鞘厚度等做了定量分析。同时将这些结果与某些种类动物的视神经做了比较,以探讨鳄蜥视神经的特点。     

人工繁育与野外鳄蜥幼体及亚成体形态和健康状况的比较

人工繁育是濒危物种保护的重要手段,但是也会改变物种的表型。为了探究人工繁育对于鳄蜥(Shinisaurus crocodilurus)形态和健康状况的影响,本研究比较了人工繁育鳄蜥与野外鳄蜥新生幼体及亚成体形态特征与细菌感染率。结果发现,人工繁育鳄蜥与野外鳄蜥的新生幼体体型无显著差异,而人工繁育鳄蜥亚成体体型显著大于野外鳄蜥;两个年龄段的人工繁育鳄蜥断尾率均显著低于野外鳄蜥;人工繁育鳄蜥亚成体细菌感染率最高,但是各年龄组种群间的差异不显著。本研究表明,人工环境促进了鳄蜥的生长,减少了鳄蜥被捕食的风险,但有增加鳄蜥感染疾病的可能性,因此在鳄蜥的饲养管理中需要加强疾病防治。     

一种濒危的珍稀动物——鳄蜥

鳄蜥(Shinisaurus crocodilurus)隶属蜥蜴目(Lacertiformes)鳄蜥科(Shinisauridae)。1930年经E,Ahl鉴定结果,认为是新科、新属、新种,从而引起国内外学者的重视。1978年被列为国家一类保护动物。作者于1979年至1983年,对鳄蜥的分布、栖息环境、生态习性及生长发育等方面,作了实地观察与研究,认为鳄蜥应列为我国的一种濒危的珍稀动物。 (一)名称鳄蜥俗名大睡蛇,又称落水狗。它头似蜥蜴,躯干圆柱形,尾长侧扁似鳄鱼,故名鳄蜥。     

龟嗜皮菌的快速鉴定及其在鳄蜥 皮肤病原检测中的应用

龟嗜皮菌(Austwickia chelonae)感染爬行类、鸟类、哺乳类等,造成野生动物和家养动物患皮肤病甚至死亡,近年来这种病原体在Ⅰ级保护动物鳄蜥(Shinisaurus crocodilurus)的救护种群中暴发。传统的病原检测方法费时耗力。本文基于龟嗜皮菌全基因组序列开发了特异性高、方便快捷的龟嗜皮菌检测方法,并应用于鳄蜥的皮肤病风险预测。本研究开发的3对检测龟嗜皮菌的特异引物中,AC3引物的使用效果最好。     

水蛭捕食两栖类卵

许多卵生动物具有对付食卵者的精巧策略以降低死亡率,因为早期发育阶段的捕食压力能显著影响具复杂生活史动物的生存。两栖动物卵被水蛭等很多物种所捕食。我们查阅了水蛭捕食两栖类卵的文献,发现27篇论文。在所报道的水蛭捕食两栖类卵的例子中,无尾类(3.6%,n=591)明显多于有尾类(1.6%,n=255)。此外,我们第一次记录到水蛭捕食四趾螈(Salamandrina perspicillata)卵,这也是西欧有尾类的第一例报道。我们没有发现两个两栖动物类群间存在差异。然而,当我们分别分析来自北美、欧洲和亚洲三个地区的数据时,发现北美的有尾类和无尾类间存在显著差异。水蛭可捕食各生活史阶段的两栖动物,因此,水蛭应归为一些两栖类的天敌。     

半自然状态下鳄蜥活动时间分配的初步研究

在半自然的条件下采用瞬时扫描法对鳄蜥活动时间分配进行了初步的研究,结果表明:在池养鳄蜥的活动时间分配中,静栖占69·09%,在穴占28·82%,移动占0·80%,捕食占0·28%,晒太阳占0·44%,其它占0·58%;比较了不同性别鳄蜥的活动时间分配,其中雄性鳄蜥用在移动的时间占1·15±1·22%,雌性为0·45±1·00%,经过单因素检验显示其差异显著(P<0·01),其它行为活动时间分配差异不显著;初步比较了不同生境中鳄蜥的行为差异,结果显示鳄蜥在池养的条件下弹性行为的表现频次正在下降。     

行为生态学(六):反捕食对策

动物有各种各样的对策防御捕食者的捕食。主要对策有警戒色、视觉色多态现象、尾斑信号、报警呜叫、以某种显示行为分散捕食者的注意力和群力围攻等。在我们分析动物反捕食对策的进化时,必须牢记以下几点:第一,被捕食动物的反捕食对策总是同捕食动物的捕食对策协同进化的(L.E.Gilbert和P.E.Raven,1975);第二,即使捕食不是作为一个密度制约因素在起作     

救护鳄蜥食物有害重金属和农药残留的检测北大核心CSCD

鳄蜥(Shinisaurus crocodilurus)为国家I级保护野生动物。近年来,我国广西大桂山鳄蜥国家级自然保护区北娄繁育基地救护的鳄蜥一直存在疾病困扰,但原因不明。为了探讨这些疾病的发生是否与其食物中的重金属及农药污染相关,本研究采用电感耦合等离子体质谱和色谱质谱分析技术来检测其主要食物中的重金属和农药残留含量。结果显示,与其食物(蚯蚓)相比,鳄蜥体内的重金属含量更低,同时,农药残留含量在鳄蜥及其食物中均未检测出,说明重金属和农药通过食物的生物放大作用而在鳄蜥体内累积的可能性较小。因此,重金属与农药这两类环境污染物对鳄蜥疾病发生的影响较小。本研究为鳄蜥的人工救护繁育工作提供一定的参考,有利于鳄蜥的保护工作。     

Lizards reduce food consumption by spiders: mechanisms and consequences

Summary To determine the effect of lizards on webspider populations, we conducted a long-term field experiment in the Bahamas. Numbers of spider individuals were about 3 times higher in lizard-removal enclosures than in control enclosures with natural densities of lizards. Dietary analyses showed that lizards ate spiders and that lizard and spider diets overlapped substantially. Lizards reduced biomass of prey consumed by spiders; details indicated that they reduced biomass of large (> 4 mm) prey consumed by spiders more than biomass of small (4 mm) prey. Similarly, lizards reduced biomass of large aerial arthropods caught in sticky traps but not biomass of small aerial arthropods. We found no evidence that the lizard effect on prey consumption by spiders was caused by a spatial shift from areas with high aerial arthropod abundance to areas with low aerial arthropod abundance. Lizards reduced adult female cephalothorax width and fecundity of spiders. In a separate experiment, food-supplemented spiders were more fecund than control spiders. This study indicates that the interaction between lizards and spiders includes both predation and competition for food.     

Lizards as a plant's 'hired help': letting pollinators in and seeds out

It is well-known that plants utilize many different kinds of animals for pollination and dispersal of their seeds, but an alternative kind of evolutionary relationship has attracted less attention: animals can facilitate pollen and seed transport without acting as a vector. We studied interactions between an epacridaceous plant (the honey bush, Richea scoparid) and a lizard (the snow skink, .Niveoscincus microtepidotus) near the summit of Mount Wellington, Tasmania. The lizards gain access to the plant's nectar by tearing the fused petals (the calyptra) from the flower, thus exposing the plant's reproductive organs. Snow skinks forage selectively on flowers with higher-than-average nectar content, suggesting that this behaviour has evolved in response to plant characteristics. Lizard foraging may benefit R. scoparia , because calyptra remain attached unless a lizard tears the flower open. Our experiments demonstrated that the lizard's calyptra removal dramatically increased the plant's seed release. In 60 fruits from flowers with their calyptra intact, no seeds at all were released. However, 57 out of 60 (87%) fruits from flowers with their calyptra removed by the lizards successfully released their seeds. This system appears to involve reciprocal evolutionary changes in the interacting species (behaviour in the lizards and reproductive morphology in the plant). Thus the system seems to provide an unusual case of coevolution.     

Spatial Use and Survivorship of Translocated Wild-Caught Texas Horned Lizards

The Texas horned lizard (Phrynosoma cornutum), a state threatened species in Texas, USA, appears to be declining throughout much of its distribution. Because of popular interest in restoring lizard populations, we conducted a 3-year radio-telemetric study to evaluate the feasibility of reintroducing Texas horned lizards into previously occupied areas with suitable habitat characteristics. We translocated lizards from natural populations in western Texas to the McGillivray and Leona McKie Muse Wildlife Management Area (MWMA) in the Cross Timbers and Prairies of north-central Texas, an ecoregion that has experienced apparent local extirpations of horned lizards. We translocated lizards after partly restoring a 32.5-ha portion of the MWMA from ashe juniper (Juniperus ashei)-honey mesquite (Prosopis glandulosa) woodland to mid-grass prairie. After a 10-day acclimation period and soft release, we tracked 57 horned lizards from March 2014 to October 2016 to evaluate daily movements, spatial use, sources of mortality, reproduction, and changes in body condition. Daily movement averages (1.16–174.18 m) and area used by individuals (<0.01–6.81 ha) were similar to those recorded for natural populations, with peaks in movement occurring in May and June. Annual survivorship for individuals (1.1–47.2%) was also similar to that reported from natural populations; however, survivorship declined across the 3 active seasons. Although mortality of translocated lizards was high, body condition remained relatively stable across active seasons, and reproduction occurred each year, indicating that translocation could be a viable option for restoring horned lizard populations to previously occupied parts of their range. © 2019 The Wildlife Society.     

Behavioural thermoregulation by the endangered crocodile lizard (Shinisaurus crocodilurus) in captivity

Understanding the factors that may affect behavioural thermoregulation of endangered reptiles is important for their conservation because thermoregulation determines body temperatures and in turn physiological functions of these ectotherms. Here we measured seasonal variation in operative environmental temperature (T_e), body temperature (T_b), and microhabitat use of endangered crocodile lizards (Shinisaurus crocodilurus) from a captive population, within open and shaded enclosures, to understand how they respond to thermally challenging environments. T_e was higher in open enclosures than in shaded enclosures. The T_b of lizards differed between the open and shaded enclosures in summer and autumn, but not in spring. In summer, crocodile lizards stayed in the water to avoid overheating, whereas in autumn, crocodile lizards perched on branches seeking optimal thermal environments. Crocodile lizards showed higher thermoregulatory effectiveness in open enclosures (with low thermal quality) than in shaded enclosures. Our study suggests that the crocodile lizard is capable of behavioural thermoregulation via microhabitat selection, although overall, it is not an effective thermoregulator. Therefore, maintaining diverse thermal environments in natural habitats for behavioural thermoregulation is an essential measure to conserve this endangered species both in the field and captivity.     

A comparison of the epidermis and pigment cells of the crocodile with those in two lizard species

Keratinization and pigmentation in Crocodilus niloticus skin were compared with the conditions in the lizards Lacerta viridis and Anolis carolinensis. The epidermis, both in the crocodile and in lizards, is arranged to form a surface pattern of scales and narrower intervening hinge regions. Similar keratin-bound substances were found in the crocodile and lizard stratum corneum. Nevertheless, the greater uniformity in histological structure and in distribution of chemical substances throughout the depth of the crocodile stratum corneum was in marked contrast to the lizards, which showed morphological differences, and differences in intensities of chemical reactions in the horny cells laid down early and late in each keratinization cycle. In the crocodile, keratin-bound S-S and SH are uniformly distributed in the horny scales, but in the lizards the superficial cells have most S-S and the lowermost keratinized cells most SH. The loosely arranged horny cells in the crocodile are shed in small flakes as in mammals, in contrast to lizards which undergo periodic sloughs of a compact stratum corneum. In the lizards, the intermediate layer between two horny layer generations contains no detectable S-S and is probably unkeratinized, so that when these cells die a fission zone is formed. The crocodile scales each contain a raised pigmented papule in which melanin is introduced into the epidermal cells, and keratinization is also different from the neighbouring area. Guanophores and lipophores are absent in the crocodile, although present in the lizards. All contain prominent dermal melanophores.     

Competition Between Insectivorous Lizards and Birds in Central Panama

The following evidence suggests that birds and lizards competefor their arthropod prey on islands in Lake Gatun, Panama: (1)there is extensive overlap between the diets of a representativebird and lizard, (2) at least one insectivorous lizard, Anolislimifrons, appears to be food-limited, (3) birds appear to havea major impact on arthropod abundances, (4) avian abundanceis negatively correlated with the physiological condition and,thus, with the fecundity of female A. limifrons, (5) bird andlizard population densities are negatively correlated. LakeGatun was formed in 1914. In the intervening years, a greatmany bird species have been lost from the smaller islands, butvery few lizard populations have gone extinct. Ninety-six percentof the between-site variation in avian abundances is accountedfor by the number of bird species present at a site. Sites withdepauperate avifaunas are characterized by low avian abundancesbecause the species present do not experience ecological release,and resources which are utilized by birds on species-rich sitesare not exploited by birds on species-poor sites. Thus, avianabundances are controlled by factors extrinsic to the bird-lizardinteraction, and lizards opportunistically increase their abundancesat sites with low avian abundances.     

Sex,Age, and Population Density Affect Aggressive Behaviors in Island Lizards Promoting Cannibalism

Island populations may evolve distinct behavioral repertoires as a response to the conditions of insular life. Strong intraspecific competition is typical in insular lizards and may include cannibalism. In this study, we investigated sexual and age patterns of aggression in two populations of the Skyros wall lizard (Podarcis gaigeae), one from the main island of Skyros (Aegean Sea, Greece) and another from the satellite islet Diavates. The latter is terrestrial predator‐free biotope, hosting a dense population of large‐bodied lizards that have been reported to exert cannibalism. In staged encounters, we examined the aggressive propensities of adult male and female lizards against their age‐peers and juveniles. Males from both populations were much more aggressive than females toward juveniles and other adults. Males from Diavates were more frequently aggressive to juveniles and other male lizards than males from Skyros. Diavates cannibals also captured their targets at shorter latency. We ascribe this distinct behavioral pattern to the high population density. Infanticide and intramale aggressiveness confer two great advantages to cannibals: food and elimination of future rivals.     

The Effect of Variation in Prey Movement on the Predatory Response of Jacky Lizards (Amphibolurus muricatus)

The sensory systems of animals have evolved to meet the demands of functionally critical events. Animals that rely on visual motion cues must ignore irrelevant movement and only attend to certain characteristics that warrant further consideration. For the Australian jacky lizard ( Amphibolurus muricatus ), movement is essential for detecting potential prey. Here we examine whether differences in the actual motion characteristics of a simulated prey item influence predatory behaviour. We begin with direct observations of responses to live prey items to define an ordinal scale for subsequent video playback experiments involving a synthetic prey item (an animated cricket). In expt 1, we show that the responses of lizards to the synthetic prey were matched to those given in response to video of an actual cricket. In expt 2 we manipulated the movement patterns of the synthetic cricket based on motion analysis of actual prey movement. Manipulating motion characteristics did not influence the level of predatory behaviour observed, however, lizards showed sustained predatory behaviour to stimuli with speed characteristics that were matched to those of real crickets. We discuss the possibility that recent experience of prey movement in captivity has influenced the foraging behaviour of these lizards.