Foraging behaviour and feeding success of the black-necked stork (Ephippiorhynchus asiaticus) in Dudwa National Park, Uttar Pradesh, India

Foraging behaviour of the black-necked stork (BNS) Ephippiorhynchus asiaticus was studied in 1996 and 1997 in Dudwa National Park (DNP), Uttar Pradesh, India. The storks were observed using tactile and visual techniques to catch fish. Of the 929 fish seen caught in 2 years, 894 (96%) were caught by a tactile mode of feeding and the remaining 35 (4%) by a visual mode of feeding. The rate of foraging attempts by BNS fluctuates with that of season in DNP and coincides with prey abundance. Immediately after the monsoon when the water level was high, BNS had to search for prey more often, as the prey became widespread. Whereas in summer when the water level decreased, the concentration of the fish was higher, which helps BNS to catch fish in quick succession. Prey behaviour and the condition of the wetland determined the selection of the tactile foraging technique among the BNS in DNP. The black-necked storks were more successful in the early hours of the day (06:00–10:00) and they were generally more successful or preferred to feed on medium-sized fish (i.e. 5–10 cm) in DNP. Prey profitability was highest for larger size fish and decreased as the prey size decreased. Principal component analysis showed that prey size, handling time of each prey, the month and water depth determined foraging success in 1996 and 1997.     

丹顶鹤多尺度生境选择机制——以黄河三角洲自然保护区为例

生境在鸟类生活史中发挥着重要的作用,关系到鸟类的生存和繁衍。由于鸟类对环境变化的响应发生在等级序列空间尺度上,基于多尺度的研究更能深入刻画鸟类-环境之间关系。以丹顶鹤(Grus japonensis)为研究对象,以其迁徙和越冬的重要地区-黄河三角洲自然保护区为研究区域,应用等级方差分解法和等级划分法,分析丹顶鹤与微生境、斑块、景观尺度因子之间的关系,探求丹顶鹤生境选择的主要影响因素和尺度。等级方差分解结果表明,在第1等级水平,景观尺度因子与微生境、斑块尺度因子之间的联合效应大于独立效应,景观尺度因子的独立效应大于微生境和斑块尺度因子;在第2等级水平,景观尺度上的景观组成因子重要性大于景观结构因子,微生境尺度上的植被和水分因子为重要影响因素。等级划分结果表明,景观尺度上,翅碱蓬滩涂、水体面积大小是主要影响因素;微生境尺度上,植被盖度和水深为主要限制因子;在斑块尺度上,斑块类型对丹顶鹤生境选择最为重要。研究认为,在黄河三角洲自然保护区,景观尺度是影响丹顶鹤生境选择的主要尺度,景观尺度因子通过与微生境和斑块尺度因子的独立和联合作用制约着丹顶鹤在保护区的生境选择和空间分布格局。建议加强对翅碱蓬滩涂、芦苇沼泽、水体等湿地生境的保护和管理,规范和控制保护区内人类活动强度。     

The spatial–temporal pattern changes of the red crowned crane (Grus japonensis) population in Zhalong NNR and the related driving forces

Understanding spatio-temporal distribution patterns of a species is essential to successful species and habitat conservation. The fluctuations of the red crowned crane population were studied after collecting the data about breeding red-crown cranes from Zhalong National Natural Reserve (Zhalong NNR) since 1981; and their spatial distribution patterns were also quantified in variant time periods with the method nearest neighbor analysis (NNA); the main factors leading to the dynamics of the bird population were analyzed. The results showed the red-crown crane population had fluctuated dramatically from 1981 to 2005. The number dropped rapidly to the minimum of the bird population to endanger the existence of the population by the year of 2005. And the spatial distribution pattern changed from uniform distribution to aggregated distribution during 1996–2005. These changes reflected that the distributions of habitats had undergone a process of fragmentation, and the area of the suitable habitats suffered such a continuous loss that there were insufficient habitats to sustain the bird population any more. And consequently, the decline of the bird population occurred. The wildfire and the anthropogenic activities were the driving forces which accounted for the degradation of the habitats and hereafter the fluctuations of the red-crown population.     

The spatial–temporal pattern changes of the red crowned crane (Grus japonensis) population in Zhalong NNR and the related driving forces

Understanding spatio-temporal distribution patterns of a species is essential to successful species and habitat conservation. The fluctuations of the red crowned crane population were studied after collecting the data about breeding red-crown cranes from Zhalong National Natural Reserve (Zhalong NNR) since 1981; and their spatial distribution patterns were also quantified in variant time periods with the method nearest neighbor analysis (NNA); the main factors leading to the dynamics of the bird population were analyzed. The results showed the red-crown crane population had fluctuated dramatically from 1981 to 2005. The number dropped rapidly to the minimum of the bird population to endanger the existence of the population by the year of 2005. And the spatial distribution pattern changed from uniform distribution to aggregated distribution during 1996–2005. These changes reflected that the distributions of habitats had undergone a process of fragmentation, and the area of the suitable habitats suffered such a continuous loss that there were insufficient habitats to sustain the bird population any more. And consequently, the decline of the bird population occurred. The wildfire and the anthropogenic activities were the driving forces which accounted for the degradation of the habitats and hereafter the fluctuations of the red-crown population.     

食物可获得性对冬季丹顶鹤能量收支的影响——以扎龙自然保护区人工辅助繁育丹顶鹤为例

动物主要通过摄入食物和获得食物中的能量来维持其正常的生命活动。为论证食物获得性对冬季丹顶鹤能量收支的影响及为其越冬保护提供科学依据,以扎龙自然保护区人工辅助繁育丹顶鹤为研究对象,对分别供给鲫鱼、玉米和混合(鲫鱼+玉米)饲喂3组丹顶鹤的能量收支、体重及其行为变化进行比较。结果发现,丹顶鹤的能量收支受食物可获得性差异影响,鲫鱼、混合饲喂和玉米3组丹顶鹤的能量收支及排泄次数依次降低,玉米组丹顶鹤的体重降低显著(P0.01)及其行为谱中的静息时间分配明显增加。食物的可选择性、环境低温和短光照的交互作用使丹顶鹤的可摄食时间受限,丹顶鹤的能量收支随之发生变化。分析结果表明扎龙保护区冬季每日定时、定量供给鲫鱼和足量供给玉米的饲喂丹顶鹤的方法较为合理。     

Siberian crane chick calls reflect their thermal state

Chicks can convey information about their needs with calls. But it is still unknown if there are any universal need indicators in chick vocalizations. Previous studies have shown that in some species vocal activity and/or temporal-frequency variables of calls are related to the chick state, whereas other studies did not confirm it. Here, we tested experimentally whether vocal activity and temporal-frequency variables of calls change with cooling. We studied 10 human-raised Siberian crane (Grus leucogeranus) chicks at 3–15 days of age. We found that the cooled chicks produced calls higher in fundamental frequency and power variables, longer in duration and at a higher calling rate than in the control chicks. However, we did not find significant changes in level of entropy and occurrence of non-linear phenomena in chick calls recorded during the experimental cooling. We suggest that the level of vocal activity is a universal indicator of need for warmth in precocial and semi-precocial birds (e.g. cranes), but not in altricial ones. We also assume that coding of needs via temporal-frequency variables of calls is typical in species whose adults could not confuse their chicks with other chicks. Siberian cranes stay on separate territories during their breeding season, so parents do not need to check individuality of their offspring in the home area. In this case, all call characteristics are available for other purposes and serve to communicate chicks’ vital needs.     

基于冠层塔吊原位测定长白山温带阔叶红松原始林群落主要树种的光合特征

为了更好地理解温带阔叶红松原始林群落主要树种的生理生态学特征,为森林生态系统碳动态的模拟预测提供基础数据,本研究依托中国科学院长白山森林生态系统定位站,首次利用冠层塔吊原位测定了阔叶红松原始林群落4个主要树种成熟大树的CO₂响应曲线,并利用FvCB模型计算了一些重要的光合生理参数.结果表明: 红松的光合速率(A)、最大羧化速率(V_{c max})和气孔导度(g_s)均最小,而其气孔对光合的限制性(L_s)最大.水曲柳、蒙古栎和紫椴这3个阔叶树种的光合特征也存在显著差异.基于叶片面积的V_{c max}大小顺序为:水曲柳(83.2 μmol·m^-2·s^-1)、蒙古栎(89.3 μmol·m^-2·s^-1)>紫椴(68.4 μmol·m^-2·s^-1)、红松(68.8 μmol·m^-2·s^-1)(P<0.05),而基于叶片质量的V_{c max}大小顺序为:水曲柳(1.36 μmol·g^-1·s^-1)>蒙古栎(1.03 μmol·g^-1·s^-1)>紫椴(0.90 μmol·g^-1·s^-1)>红松(0.42 μmol·g^-1·s^-1)(P<0.05).7—9月,水曲柳和蒙古栎的A值显著降低,而紫椴和红松的A值变化不显著;所有树种V_{c max}都随季节发生显著下降.在温带阔叶红松林生态系统碳动态的模拟预测中,应该考虑V_{c max}的季节变化.     

基于MAXENT模型的丹顶鹤营巢生境适宜性分析——以扎龙保护区为例

明确物种繁殖栖息地的潜在分布对于受胁物种的保护与科学管理具有十分重要的意义。扎龙保护区是国际濒危物种丹顶鹤西部迁徙种群的主要繁殖地之一,近年来繁殖种群数量波动较大。通过GIS空间技术平台,利用MAXENT模型,结合2012—2013年丹顶鹤(Grus japonensis)营巢分布点和环境特征变量,对扎龙保护区丹顶鹤营巢生境的适宜性进行了分析。结果表明:模型的评价效果达到优秀水平(训练集AUC=0.901);绿度(34.9%)、距道路距离(17.1%)、土壤湿度(16.3%)、海拔(15.7%)是丹顶鹤营巢生境的主要环境特征变量;核心区中部和南部是丹顶鹤主要的适宜营巢分布区,缓冲区和实验区有少量的适宜营巢区分布,丹顶鹤适宜营巢生境面积为35857.35hm~2,占保护区总面积的17.07%。建议在重点管理核心区的同时,对缓冲区和实验区的小面积芦苇沼泽给予更多关注。