Pre-nesting feeding selectivity of Pink-footed Geese Anser brachyrhynchus in artificial grasslands

The pre-nesting feeding ecology of Pink-footed Geese Anser brachyrhynchus was studied in southern Iceland in April and May 1989–1992. Extensive surveys showed that prior to movement to their nesting areas in the interior, Pink-footed Geese fed mainly on intensively managed grasslands of the southern lowlands. Faecal analysis showed that geese feeding in hayfields foraged almost exclusively on the most commonly reseeded species, Timothy grass Phleum pratense , which made up the majority (41% by number of green shoots) of new growth in studied hayfields. Dropping counts, as an indicator of goose use, were highly significantly correlated in all years with density of growing Phleum shoots in individual field units. Geese showed a response in feeding patterns to changes in Phleum density as a result of reseeding patterns. Analysis of forage quality in 1991 showed that Phleum shoots had a higher protein content than all other grasses present in hayfields, with the exception of Deschampsia caespitosa. The latter species showed similar levels of protein, but its tussocky nature precluded effective grazing by the geese. Phleum was similar in fibre content to other common grasses. Based on removal of tagged plants, geese grazed predominantly on the youngest leaves of Phleum , which also had higher protein content and lower fibre than older leaves and attached dead leaves, which were rarely taken by geese. Geese grazed shorter length classes of youngest leaves, which showed higher protein content than longer, older terminal leaves. Recently created grassland habitat has increased the opportunities for female geese to supplement their reserves during the crucial prelude to clutch initiation by selecting the highest quality plant species and the most nutritious parts of that forage.     

New choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Palaeocene, Alberta and Saskatchewan, Canada, and phylogenetic relationships of Choristodera

New choristoderan fossils from the Late Cretaceous and Palaeocene of Alberta and Saskatchewan, Canada, are described: incomplete maxillae and dentaries from the Upper Cretaceous Oldman Formation, Alberta, extend the range of the primitive Cteniogenys from the Jurassic in the North American Western Interior; an incomplete dentary from the Palaeocene Ravenscrag Formation, Saskatchewan, comprises the first occurrence of the crocodile-like Simoedosaurus in Canada and the earliest record of the genus; well-preserved skulls and mandibles from the Oldman and Horseshoe Canyon formations, Alberta, document a new species of Champsosaurus and clarify the status of previously known species of the genus. New information about Asian choristoderes supports a Tchoiria- ( Ikechosaurus + Simoedosaurus ) relationship, contrary to previous work. Choristoderes share no convincing synapomorphies with either Lepidosauromorpha or Archosauromorpha, but occupy a more basal position within Diapsida, possibly as a sister-taxon with Neodiapsida (Younginiformes + Sauria).     

Eutrophication and macroalgal blooms in temperate and tropical coastal waters: nutrient enrichment experiments with Ulva spp.

Receiving coastal waters and estuaries are among the most nutrient‐enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast‐growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth‐limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low‐ to high‐nutrient supplies. We carried out N and P enrichment field experiments on Ulva spp. in seven coastal systems, with one of these systems represented by three different subestuaries, for a total of nine sites. We showed that rate of growth of Ulva spp. was directly correlated to annual dissolved inorganic nitrogen (DIN) concentrations, where growth increased with increasing DIN concentration. Internal N pools of macroalgal fronds were also linked to increased DIN supply, and algal growth rates were tightly coupled to these internal N pools. The increases in DIN appeared to be related to greater inputs of wastewater to these coastal waters as indicated by high δ¹⁵N signatures of the algae as DIN increased. N and P enrichment experiments showed that rate of macroalgal growth was controlled by supply of DIN where ambient DIN concentrations were low, and by P where DIN concentrations were higher, regardless of latitude or geographic setting. These results suggest that understanding the basis for macroalgal blooms, and management of these harmful phenomena, will require information as to nutrient sources, and actions to reduce supply of N and P in coastal waters concerned.     

藏西北地区传统与现代狩猎模式变迁与野生动物保护调查分析

藏西北地区有近两万年的狩猎野生动物历史.人们的狩猎活动对当地野生动物的种群产生了重要影响.通过半结构式访谈、实地考察及文献资料收集等方式,对藏西北地区传统与现代狩猎模式进行了对比分析.结果 显示,两种狩猎模式在目的 、方法、工具等方面均存在较大差异,而且现代狩猎模式对野生动物种群的影响较大.