Effects of environmental stressors on nest success of introduced birds

Understanding the influence of environmental stressors on daily nest survival of introduced birds is important because it can affect introduction success as well as the ability to evaluate introduction programs. For long-lived birds with low annual production, adjustment to local breeding conditions can take many years. We examined nest success rates of 2 introduced bird species, whooping crane (Grus americana) and trumpeter swan (Cygnus buccinator), in Wisconsin. Both species are long-lived with low annual reproductive rates. Trumpeter swans were established in our study area approximately 10 years before whooping cranes. We predicted that trumpeter swans would show less sensitivity to environmental stressors. We used daily nest survival rates (DNSRs) as our response variable to model several environmental parameters including weather, phenology, and ornithophilic black flies (Diptera: Simuliidae). Additionally, we examined the influence of captive history, age, release method, energetics, and nesting experience on whooping crane DNSRs. Daily nest survival of whooping cranes was the most sensitive to stressors. Trumpeter swan daily nest survival showed less sensitivity to the same stressors. Daily nest survival for both species peaked later in the nesting season, after 30 April and before 30 May. We also found that the daily nest survival rate (DNSR) for whooping cranes was potentially affected by captive exposure (measured by generations removed from the wild). Our results highlight the difficulties associated with conservation of long-lived birds with low annual productivity as they adjust to local breeding conditions and that nest phenology at the source location can determine how these conditions are interfaced. We recommend that the juxtaposition of source and introduction location nest phenology be considered prior to introduction site selection. Additionally, strategically selecting offspring from captive pairs with nest phenology similar to that of sympatric species at the introduction location should be considered. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

基于多源遥感的贵州草海国家级自然保护区黑颈鹤生境适宜性评价

生境适宜性评价是保护和管理濒危物种的重要途径。已有研究中用于物种生境适宜性评价的环境变量数据多存在分辨率低精度不高的问题,在研究小尺度物种生境适宜性时误差较大。为解决这一问题,本文根据黑颈鹤的出现点数据与光学、雷达遥感数据及地形辅助数据得出栖息地与觅食地特征,利用最大熵(MaxEnt)模型对草海越冬黑颈鹤细尺度的生境适宜性进行评价。结果显示：(1)运用多源遥感和地形辅助数据生成的环境变量结合MaxEnt预测黑颈鹤的栖息地与觅食地效果都较为优秀,两者受使用者工作特征曲线下的面积值(AUC)值均大于0.94;(2)距耕地距离、距水域距离、水深及距建筑距离是影响黑颈鹤栖息地主要环境因子,而影响觅食地分布的主要环境因子则是距耕地距离、优势植被、距建筑物距离和水深。(3)草海自然保护区黑颈鹤栖息地与觅食地的最适宜区和次适宜区面积较小,栖息地与觅食地最、次适宜区总和分别为6.404km~2与12.644 km~2,占比仅为研究区的6.43%和12.69%。通过调查发现,当前自然保护区的人为干扰源主要是游客和当地的居民,潜在地威胁着黑颈鹤的栖息地和觅食地。因此,为了避免保护区黑颈鹤栖息地与觅食地的退...     

An alternate and reversible method for flight restraint of cranes

Flight restraint is important for zoos, safaris, and breeding centers for large birds. Currently used techniques for flight restraint include both surgical and non-surgical approaches. Surgical approaches usually cause permanent change to or removal of tendon, patagial membrane, or wing bones, and can cause pain and inflammation. Non-surgical approaches such as clipping or trimming feathers often alter the bird's appearance, and can damage growing blood feathers in fledglings or cause joint stiffness. We observed microstructure of primary feathers of the red-crowned crane (Grus japonensis) and found that the width of barbs is a determinative factor influencing vane stiffness and geometric parameters. We hypothesized that partial longitudinal excision of barbs on the ventral surface of the primary feathers would reduce the stiffness of the vane and render the feathers unable to support the crane's body weight during flight. Furthermore, we hypothesized that this modification of barbs would also change the aerodynamic performance of feathers such that they could not generate sufficient lift and thrust during flapping to enable the bird to fly. We tested this hypothesis on a red-crowned crane that had normal flight capability by excising the ventral margin of barbs on all 10 primaries on the left wing. The bird was unable to take off until the modified feathers were replaced by new ones. Removal of barbs proved to be a simple, non-invasive, low-cost and reversible method for flight restraint. It is potentially applicable to other large birds with similar structural characteristics of primary feathers.     

Red coloration in young tropical leaves associated with reduced fungal pathogen damage

The adaptive significance of red coloration in tropical forest leaves remains unclear. In vivo assays show that there is a significant negative correlation between anthocyanin pigments in young leaves and fungal pathogen damage. This supports a previous hypothesis that anthocyanins may protect young leaves from fungal damage during the vulnerable period of leaf expansion.     

苏北地区丹顶鹤越冬种群数量及栖息地分布动态变化

利用资料追踪和历史时期土地利用变化数据深入研究了有资料记载以来苏北地区丹顶鹤越冬种群数量变化与栖息地分布的时空响应。结果显示,20世纪80年代之初,丹顶鹤越冬种群广泛分布于苏北地区,尤其是长江中下游的内陆湖泊、沼泽及江苏沿海滩涂湿地;20世纪90年代之后丹顶鹤分布区域逐渐向沿海滩涂湿地转移,主要分布于盐城市的射阳县境内;进入21世纪,丹顶鹤分布区域集中于盐城国家级珍禽保护区核心区。与此同时,丹顶鹤越冬种群数量也经历了十分明显的变化过程,与20世纪90年代相比,数量减少50%以上。丹顶鹤越冬种群数量及栖息地分布变化与栖息地分布点周围的土地利用方式及人为干扰有关,栖息地面积丧失和景观破碎化是丹顶鹤越冬种群数量减少的主要原因。     

丹顶鹤越冬栖息地数学模型的建立

利用地理信息系统及遥感卫片通过建立数学模型的方法来模拟及预测盐城自然保护区丹顶鹤越冬栖息地的分布。经验证,模型的正确预测率为７２．６３％,认为模型基本上能够反映丹顶鹤栖息地的分布情况。     

Genetic differentiation in a captive population of the endangered Siberian crane (Grus leucogeranus Pall.)

DNA fingerprinting, followed by multivariate analysis of data, was used to characterize genetic heterogeneity in captive populations of the endangered Siberian and sandhill cranes. The genetic structure revealed reflected the natural population and species distributions. The relevant groups differed not only from each other, but also from interspecies and inter-population hybrids bred in captivity. In this study we have tested an approach to the analysis of population structure based on individual genotypes. Interpretation of fingerprinting data by means of the analytical system applied here is a useful and reliable procedure for the estimation of genetic relationships between individuals.