上海农田泽蛙蛰眠状况初步调查

于2004～2005年冬季对上海农田泽蛙的蛰眠状况进行了初步调查。结果表明,农田中的路径、田埂和沟渠岸边地下洞穴是泽蛙的主要越冬场所。蛰眠洞穴共用率高达34.0%,超过62.2%的泽蛙与其它个体共用洞穴蛰眠,各共用洞穴内的泽蛙只数为2～6只不等。泽蛙主要利用已有的地下洞穴蛰眠。86.6%蛰眠期的泽蛙为1龄个体。     

青藏高原东缘高寒森林小型兽类地表洞穴选择与生境特征

高寒森林地表的小型兽类洞穴是生态系统重要的景观特征,对于认识小型兽类的分布格局及其生态功能具有重要意义.为此,以青藏高原东缘典型高寒森林生态系统小型兽类洞穴为对象,于2015年夏季(7—9月)研究了其地表分布与生境特征.结果表明: 小型兽类洞穴平均洞口密度为182.8个·hm^-2,不同森林植被类型显著影响洞穴密度,表现为针叶林(328.6个·hm^-2)>针阔混交林(160.0个·hm^-2)>灌木林(125.0个·hm^-2)>阔叶林(81.5个·hm^-2)>竹林(66.7个·hm^-2). Mann-Whitney U Test和主成分分析表明,小型兽类栖息样地的乔木郁闭度、乔木均高、乔木胸径、乔木密度、地表植被盖度、倒木密度、倒木覆盖度、灌木均高都显著大于非栖息样地;乔木因子是决定小型兽类生境选择的首要因子,贡献率最大(44.8%),其次是倒木因子(23.2%)和灌草丛因子(13.9%).说明高寒森林地表有明显的小型兽类洞穴分布,其分布格局主要受植被和倒木的影响.     

Strange bedfellows: Mammal burrow disturbances may provide thermoregulatory microsites for fossorial reptiles in densely vegetated dunes

Burrow excavation by mammals generates heterogeneity within landscapes. Globally, these disturbances are known to provide significant ecosystem benefits. Most investigations of native Australian burrowing mammal disturbances has focused on the role of burrows in landscape function and interspecific thermal refugia. Herein, we present a novel observation of the fossorial skink Lerista bougainvillii utilizing burrow mounds of the common wombat (Vombatus ursinus) for possible thermoregulatory gains. In the early morning, when thermoregulatory opportunities were limited, L. bougainvillii were detected in mounds that appeared hotter than adjoining vegetation. These observations suggest that in densely vegetated habitats thermal heterogeneity caused by mammal burrows may offer important thermoregulatory opportunities for fossorial species with limited climbing capacity.     

Cladichnus parallelum isp. nov. – a Mid- to Deep-Tier Feeding Burrow System

The ichnospecies Cladichnus parallelum consists of upper components characterized by downward branching, decreasingly inclined tubes, and lower components having horizontal, long, parallel tubes formed in the laminated part of a muddy, marly turbidite. The tubes of both components were successively produced, and the lower ones display an annulated fill. The producers of Cladichnus exhibit thigmotactic and phobotactic behavior in that the tubes are regularly spaced apart, do not cross over- or cross-cut, and their orientation is related to the fabric of the turbidite. The tube fill of both components is enriched in terrigenous material and organic matter suggesting selective feeding on the sediment surface, and the tubes do not show any grain sorting around them. The strong compression of the horizontal tubes suggests that the fill initially had high porosity. The producer of Cladichnus parallelum probably took advantage of burrowing in an anoxic setting; microbes likely played a role in converting organic material stored within the tubes or in processing dissolved compounds drained into the highly porous tubes.     

Hold your breath: Observations of the endangered pygmy bluetongue (Tiliqua adelaidensis) submerged in flooded burrows

Understanding adaptations to extreme weather events by endangered species is critical to inform conservation decisions, particularly when their adaptations relate to artificial habitat supplementation at translocation sites. Apnoea, temporary suspension of breathing, has been observed as an anti-predator adaptation by semi-aquatic reptiles that dive underwater for periods of time to avoid detection. This study reports on the observations of an endangered grassland skink, the pygmy bluetongue (Tiliqua adelaidensis), remaining submerged in rain-induced flooded artificial burrows at an experimental translocation site.     

Natural history and burrow system architecture of the silvery mole-rat from Brachystegia woodland

The silvery mole-rat Heliophobius argenteocinereus (Bathyergidae) is a solitary subterranean rodent, widely distributed throughout eastern and south-eastern Africa in a variety of habitats. Here, we provide the first data on its biology in a typical natural habitat, the Brachystegia woodland. The population density of mole-rats was low (4.6 ha⁻¹) and its distribution across the study site was random. Contrary to subadults and pups, the sex ratio of adult mole-rats was highly female biased (1:5.75), probably due to the higher mortality of males as a consequence of their mating strategy. Reproduction of Heliophobius is seasonal and pups are born at the beginning of the hot dry season. Burrow systems of the silvery mole-rat were long, highly branched, reticulated and comparable in fractal dimension to systems of social bathyergids. Variability in burrow architecture was related to the body mass of the burrow occupants, soil hardness and food supply when tested together. Burrow systems with a higher fractal dimension had inhabitants that had a greater body mass. Longer systems were less branched. Nests were typically deeper than foraging tunnels and experienced negligible temperature fluctuations. The microenvironmental characteristics of the subterranean niche including temperature, humidity and soil characteristics are provided for purpose of comparison with other mole-rat species.     

Depth of artificial Burrowing Owl burrows affects thermal suitability and occupancy

Many organizations have installed artificial burrows to help bolster local Burrowing Owl (Athene cunicularia) populations. However, occupancy probability and reproductive success in artificial burrows varies within and among burrow installations. We evaluated the possibility that depth below ground might explain differences in occupancy probability and reproductive success by affecting the temperature of artificial burrows. We measured burrow temperatures from March to July 2010 in 27 artificial burrows in southern California that were buried 15–76 cm below the surface (measured between the surface and the top of the burrow chamber). Burrow depth was one of several characteristics that affected burrow temperature. Burrow temperature decreased by 0.03°C per cm of soil on top of the burrow. The percentage of time that artificial burrows provided a thermal refuge from above‐ground temperature decreased with burrow depth and ranged between 50% and 58% among burrows. The percentage of time that burrow temperature was optimal for incubating females also decreased with burrow depth and ranged between 27% and 100% among burrows. However, the percentage of time that burrow temperature was optimal for unattended eggs increased with burrow depth and ranged between 11% and 95% among burrows. We found no effect of burrow depth on reproductive success across 21 nesting attempts. However, occupancy probability had a non‐linear relationship with burrow depth. The shallowest burrows (15 cm) had a moderate probability of being occupied (0.46), burrows between 28 and 40 cm had the highest probability of being occupied (>0.80), and burrows >53 cm had the lowest probability of being occupied (<0.43). Burrowing Owls may prefer burrows at moderate depths because these burrows provide a thermal refuge from above‐ground temperatures, and are often cool enough to allow females to leave eggs unattended before the onset of full‐time incubation, but not too cool for incubating females that spend most of their time in the burrow during incubation. Our results suggest that depth is an important consideration when installing artificial burrows for Burrowing Owls. However, additional study is needed to determine the possible effects of burrow depth on reproductive success and on possible tradeoffs between the effects of burrow depth on optimal temperature and other factors, such as minimizing the risk of nest predation.