Migratory movements of individual humpback whales photographed off the eastern coast of Australia

Humpback whales (Megaptera novaeangliae) migrate long distances each year on a return journey from low‐latitude breeding grounds to high‐latitude feeding grounds. Migration is influenced by subtle and complex social behaviors and the assumption that whales transit directly through the migratory corridor off the east coast of Australia requires further investigation. From 2003 to 2005, we followed the movements of 99 individual whales within one migratory cycle from three locations, off Byron Bay during the whales' northern migration and in Hervey Bay and at Ballina during the southern migration. The median sighting interval of whales between Byron Bay and Hervey Bay (n = 26) was 52 d (IQR = 42.5–75.5); between Byron Bay and Ballina (n = 21) was 59 d (IQR = 47.0–70.0); and between Hervey Bay and Ballina (n = 33) was 9 d (8.0–14.0). The overall pattern observed from these resightings suggests that Group E1 humpback whales spend approximately two months in the northern quarter of their range during the austral winter months. Intraseason resightings of whales at Ballina (n = 13, median sighting interval = 7 d) also suggest that some individuals, particularly adult males, may circle back north during their general southward journey along this part of the coast, perhaps in an attempt to increase mating opportunities.     

毕节试验区石漠化时空演变过程和演变特征

基于RS和GIS技术,解译了2000、2005和2010年3期毕节试验区石漠化数据,利用空间分析和数理统计分析方法,在探讨石漠化时空演变总体特征的基础上,选取演变方式、演变方向和演变速率等指标,重点分析了不同石漠化强度之间的内部转移特征,演绎了10年间毕节试验区石漠化演变过程。研究表明:(1)10年间,石漠化总面积呈现先增加后趋稳的演变态势,石漠化扩张趋势虽然初步遏制,但局部地区还在恶化,防治形势仍很严峻;(2)石漠化演变方式以渐变式为主,跳跃式为辅,返变式最少;(3)石漠化演变的方向既存在改善也存在恶化,且轻度改善和轻度恶化的面积均比较大,一边治理、一边破坏的现象还没有根本遏制;(4)非石漠化与石漠化相互转换非常活跃,潜在石漠化虽被定义为非石漠化,但并不稳定,容易转变为石漠化;(5)石漠化演变速率分为转入速率、转出速率和综合速率,中度石漠化综合速率最高,转入速率大于转出速率,潜在石漠化和轻度石漠化是中度石漠化增加的主要来源;(6)石漠化时空演变特征与生态环境建设及社会经济发展具有一定的相关性。该研究成果为喀斯特山区生态环境保护和石漠化防治提供了有益的参考。     

Evaluation of Harmonic Direction-Finding Systems for Detecting Locomotor Activity

Abstract: We conducted a physical simulation experiment to test the efficacy of harmonic direction finding for remotely detecting locomotor activity in animals. The ability to remotely detect movement helps to avoid disturbing natural movement behavior. Remote detection implies that the observer can sense only a change in signal bearing. In our simulated movements, small changes in bearing (<5.7°) were routinely undetectable. Detectability improved progressively with the size of the simulated animal movement. The average (±SD) of reflector tag movements correctly detected for 5 observers was 93.9 ± 12.8% when the tag was moved ≥11.5°; most observers correctly detected tag movements ≥20.1°. Given our data, one can assess whether the technique will be effective for detecting movements at an observation distance appropriate for the study organism. We recommend that both habitat and behavior of the organism be taken into consideration when contemplating use of this technique for detecting locomotion.     

INFLUENCE OF VEGETATION,TOPOGRAPHY, AND ROADS ON COUGAR MOVEMENT IN SOUTHERN CALIFORNIA

Abstract: Models of individual movement can help conserve wide-ranging carnivores on increasingly human-altered landscapes, and cannot be constructed solely by analyzing the daytime resting locations typically collected in carnivore studies. We examined the movements of 10 female and 7 male cougars (Puma concolor) at 15-min intervals during 44 nocturnal or diel periods of hunting or traveling in the Santa Ana Mountain Range of southern California, USA, between 1988 and 1992. Cougars tended to move in a meandering path (mean turning angle ∼54°), and distance moved (mean and mode ∼300 m) was not correlated with turning angle. Cougars used a broader range of habitats for nocturnal or diel movements than for previously described daybed locations for this same population. Riparian vegetation ranked highest in a compositional analysis of vegetation types selected during movement; grassland, woodland and urbanized sites were least selected. During periods of stasis (we presume many of these were stalking locations), patterns of selection were less marked. Cougars spent a disproportionate amount of time in highly ranked vegetation types, and traveled slowest through riparian habitats and fastest through human-dominated areas. Our results suggest that travel speed may provide an efficient index of habitat selection in concert with other types of analysis. Hunting or traveling individuals consistently used travel paths that were less rugged than their general surroundings. Traveling cougars avoided 2-lane paved roads, but dirt roads may have facilitated movement. Maintenance and restoration of corridors between large wildlands is essential to conserving cougars in southern California. Our results indicate that riparian vegetation, and other vegetation types that provide horizontal cover, are desirable features in such corridors, that dirt roads should not impede cougar use of corridors, and that corridors should lie along routes with relatively gentle topography. Our results suggest that cougars do not key in on highway-crossing structures in a way that creates a prey trap. Our empirical frequency distributions of distances and turning angles, along with cougar responses to vegetation, topography, and roads can help parameterize an individually-based movement model for cougars in human-altered landscapes.     

Orientational and directional selectivities of visual neurons in the superior colliculus of the cat

Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.     

国家公园研学旅行适宜性评价指标体系构建与实证研究

国家公园兼具自然生态系统保护与教育、游憩等社会文化功能,是自然性、体验性和课程性研学旅行的潜在活动场所之一。研学旅行为国家公园的教育、游憩价值实现提供路径参考。基于"内在价值-外在条件"分析框架,根据独立性、全面性、科学性及可操作原则,选择教育价值、游憩价值、环境条件、相关设施及服务等4个因子构建国家公园研学旅行适宜性评价指标体系,并以钱江源国家公园为例进行实证分析。结果表明,国家公园的研学旅行利用应首先考虑教育价值,在完善教育、游憩等相关设施及服务的同时兼顾环境承载力及利益相关者态度等环境条件,最后考虑游憩价值;钱江源国家公园的研学旅行利用具有良好的教育及游憩价值基础,中小学生的研学旅行需求与利益相关者的支持态度等提供了外在环境条件保障,但在教育、交通及安全等方面的设施及服务有待改善。研究结果可为国家公园及其他场地的研学旅行利用规划与管理提供参考。     

龙角山林区维管植物物种多样性

以龙角山地区216个样方的调查资料为基础,用Shannon-Wiener多样性指数和Sφrensen相似性指数,研究了龙角山林区野生维管植物物种多样性的空间分异规律及其原因。结果表明,乔木层物种多样性比较低,而灌木层和草本层的物种多样性则比较高;野生维管植物物种多样性随海拔高度的升高而降低;不同坡向的野生维管植物物种多样性存在着差异,北坡>东坡和西坡>南坡;坡向和海拔是影响该地区野生维管植物物种多样性空间分布的主要因子。坡向对当地的野生维管植物物种组成成分也有明显影响,其中北坡与南坡之间的野生维管植物物种组成差异最大,东坡与西坡之间的野生维管植物组成差异最小;海拔高程的变化对野生维管植物物种组成也有影响,但影响不明显。