Predicting the distribution of a suitable habitat for the white stork in Southern Sweden: identifying priority areas for reintroduction and habitat restoration

The loss of wetlands and semi-natural grasslands throughout much of Europe has led to a historic decline of species associated with these habitats. The reinstatement of these habitats, however, requires spatially explicit predictions of the most suitable sites for restoration, to maximize the ecological benefit per unit effort. One species that demonstrates such declines is the white stork Ciconia ciconia , and the restoration of habitat for this flagship species is likely to benefit a suite of other wetland and grassland biota. Storks are also being reintroduced into southern Sweden and elsewhere, and the a priori identification of suitable sites for reintroduction will greatly improve the success of such programmes. Here a simple predictive habitat-use model was developed, where only a small but reliable presence-only dataset was available. The model is based on the extent and relative soil moisture of semi-natural pastures, the extent of wetlands and the extent of hayfields in southern Sweden. Here the model was used to predict the current extent of stork habitat that is suitable for successful breeding, and the extent of habitat that would become suitable with moderate habitat restoration. The habitat model identifies all 10 occupied nesting sites where breeding is currently successful. It also identifies ∼300 km² of habitat that is predicted to be suitable stork habitat, but that is presently unused; these sites were identified as potential areas for stork reintroduction. The model also identifies over 100 areas where moderate habitat restoration is predicted to have a disproportionate effect (relative to the restoration effort) on the area of suitable habitat for storks; these sites were identified as priorities for habitat restoration. By identifying areas for reintroduction and restoration, such habitat suitability models have the potential to maximize the effectiveness of such conservation programmes.     

The feeding strategy of dab Limanda limanda in the southern North Sea: linking stomach contents to prey availability in the environment

The feeding strategy of dab Limanda limanda was investigated within a predefined research area in the southern North Sea for 2 years. The aims were: 1) to establish the relationship between prey availability and dab abundance, distribution, body condition and prey selection, and 2) to determine the underlying functional processes of prey choice in dab. Temporal and spatial trends of prey availability in relation to dab abundances, distribution, condition and prey selection were analysed. Temporal trends in dab condition, percentage of empty stomachs and numbers of ingested prey were apparent. In particular in the winter period 2000–2001 dab were in poor condition and prey items were only rarely found in stomachs. Similarly prey availability decreased in the environment while the abundance of dab increased. Thus, temporal changes in the nutritive state were partly thought to be attributed to density‐dependent effects. The stomach composition of dab during the two consecutive summers was mainly dominated by Pariambus typicus and Ophiura albida while in the winter period only O. albida made a significant contribution to the stomach content. Analysis of prey characteristics indicated that only prey densities in the environment significantly influenced prey choice in dab, while other characteristics such as the position of the prey in the habitat, its palatability or mobility did not have significant effects. The feeding strategy of dab thus was highly opportunistic, although trends were apparent that suggested that buried living fauna was less likely to be ingested, which was also observed in previous studies.     

Do Predators Condition the Distribution of Prey within Micro Habitats? An Experiment with Stoneflies (Plecoptera)

The selection of habitat by macroinvertebrates living in running waters may be influenced by the physical characteristics of the substratum, as well as by the presence of other species. In this study, an artificial river with three different substrata (pebbles, detritus, and leaves) was utilized to analyze the microhabitat preference of two Plecoptera prey species (Amphinemura sulcicollis and Brachyptera risi), both in absence and in presence of a Plecoptera predator species (Perla marginata). In the absence of predators, both prey species showed a clear preference for the leaf microhabitat. When the predators were present, only Brachyptera risi showed a change of microhabitat selection, with a decrease of leaves and an increase of pebbles and detritus utilization. Amphinemura sulcicollis did not change their substratum utilization. This study demonstrates that the presence of a predator may affect microhabitat selection through a switch from the preferred to the less preferred substrata, although not all species change their habitat utilization in response to predator presence. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Validation of a randomization procedure to assess animal habitat preferences: microhabitat use of tiger sharks in a seagrass ecosystem

1. Tiger sharks Galeocerdo cuvier are important predators in a variety of nearshore communities, including the seagrass ecosystem of Shark Bay, Western Australia. Because tiger sharks are known to influence spatial distributions of multiple prey species, it is important to understand how they use habitats at a variety of spatial scales. We used a combination of catch rates and acoustic tracking to determine tiger shark microhabitat use in Shark Bay. 2. Comparing habitat-use data from tracking against the null hypothesis of no habitat preference is hindered in Shark Bay, as elsewhere, by the difficulty of defining expected habitat use given random movement. We used randomization procedures to generate expected habitat use in the absence of habitat preference and expected habitat use differences among groups (e.g. males and females). We tested the performance of these protocols using simulated data sets with known habitat preferences. 3. The technique correctly classified sets of simulated tracks as displaying a preference or not and was a conservative test for differences in habitat preferences between subgroups of tracks (e.g. males vs. females). 4. Sharks preferred shallow habitats over deep ones, and preferred shallow edge microhabitats over shallow interior ones. The use of shallow edges likely increases encounter rates with potential prey and may have profound consequences for the dynamics of Shark Bay's seagrass ecosystem through indirect effects transmitted by grazers that are common prey of tiger sharks. 5. Females showed a greater tendency to use shallow edge microhabitats than did males; this pattern was not detected by traditional analysis techniques. 6. The randomization procedures presented here are applicable to many field studies that use tracking by allowing researchers both to determine overall habitat preferences and to identify differences in habitat use between groups within their sample.     

栖息地演变与人为干扰对升金湖越冬水鸟的影响

2002年10月—2003年4月,选择安徽升金湖6个不同干扰程度和栖息地质量的固定监测点,研究人为干扰对升金湖越冬水鸟分布格局的影响;同时结合前期调查数据,研究栖息地演变对升金湖越冬水鸟的影响.结果表明:同一越冬期不同监测点水鸟种类和数量与栖息地质量无显著相关关系,但水鸟数量与栖息地干扰程度显著负相关;不同年份升金湖越冬水鸟种类和数量与栖息地质量显著相关.升金湖越冬水鸟存在的主要威胁包括栖息地丧失、人为活动干扰以及生物杀灭剂的影响.提出了一些保护升金湖越冬水鸟的建议.     

鸟类夜栖地选择研究进展

夜栖地可以为鸟类提供安全、舒适、温暖的夜间栖息场所。昼行性鸟类夜间视觉能力较差,对夜栖环境中潜在的威胁感知程度较低,导致其夜栖时常常处于被动和危险的环境中。鸟类通过选择适宜的夜栖地,进而达到充分利用夜栖地空间资源的目的。本文从鸟类夜栖地选择的行为适应性以及保温性、食物因子和安全性(隐蔽性)等3个影响因素,对国内外鸟类夜栖地选择相关研究进行综述,为今后该领域的研究提供更多思路。