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排序方式: 共有90条查询结果,搜索用时 15 毫秒
31.
TODD W. ARNOLD LEA M. CRAIG-MOORE LLWELLYN M. ARMSTRONG DAVID W. HOWERTER JAMES H. DEVRIES BRIAN L. JOYNT ROBERT B. EMERY MICHAEL G. ANDERSON 《The Journal of wildlife management》2007,71(8):2542-2549
ABSTRACT Dense nesting cover (DNC) has been a conspicuous component of habitat management for upland-nesting ducks for >30 years, but its benefits for nesting ducks have been contentious. During 1994–1999 we monitored 3,058 dabbling duck (Anas spp.) nests in 84 DNC fields located throughout the Canadian Parklands to examine sources of among-field variation in nest density and nesting success. Nest density averaged 1.51 (SE=0.15) nests/ha and overall nesting success was 20.4%, but there was pronounced annual variation in both estimates. Nesting success increased with increasing field size (range = 6–111 ha), but nest density remained constant. Nest density increased with percent wetland habitat within DNC fields and declined with percent perennial cover in the surrounding 2.4 × 2.4-km landscape, but these variables were not important for predicting nesting success. Nest abundance and nesting success roughly doubled in fields seeded with alfalfa (Medicago sativa) or sweet clovers (Melilotus spp.), but there was no benefit from using native as opposed to tame grasses. We recommend that waterfowl managers in the Canadian Parklands establish DNC with alfalfa in large fields in landscapes with abundant wetlands but minimal competing cover. 相似文献
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We isolated and characterized 11 novel microsatellite loci to study paternity in the Australian musk duck (Biziura lobata), using nonradioactive PCR‐based techniques to screen GA and GAAA repeats enriched genomic DNA libraries. Nine of 11 loci showed no evidence of null alleles and were variable (mean HE = 0.825, mean number of alleles = 9). This set of nine loci is suitable for paternity assignment (exclusion probability for nine unlinked loci = 0.9999). We also demonstrated that many of these loci cross‐amplify in various other waterfowl species. 相似文献
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Few genomic tools are available in ducks. To produce some new resources, we have designed Pekin (Anas platyrhynchos) and Muscovy (Cairina moschata) duck-specific primers for 22 genes involved mainly in lipid metabolism, and to a lesser extent in carbohydrate metabolism and other functions. Primers were designed according to duck sequences when available and otherwise from the corresponding conserved regions in chicken and human sequences. These primers allowed quantitative RT-PCR amplification of RNA from Pekin and Muscovy ducks. Amplified cDNA products from both species were sequenced and were found to be very similar to chicken sequences (about 94%). This work provides additional genomic resources and polymorphism information for some genes in duck species and represents a first step towards gene expression analyses in Pekin and Muscovy ducks. 相似文献
35.
目的应用5-HT抗血清研究40周HBK-SPF鸭胃肠道内的5-HT免疫活性细胞的分布密度及形态,并探讨其分布型的成因及细胞形态与功能的关系。方法免疫组织化学ABC法。结果5-HT细胞主要分布于十二指肠及其以下部位,腺胃偶见,分布密度近似呈波浪形,其中以直肠分布密度最高,小肠呈U形分布。5-HT细胞的形态多样,呈圆形、椭圆形、锥体形等,主要分布于胃肠粘膜上皮之间、上皮基部、固有膜以及腺泡上皮之间等。结论40周HBK—SPF鸭5-HT细胞分布型的形成与各部位消化功能有关;根据其形态,我们认为40周HBK—SPF鸭胃肠道内5-HT细胞具有内、外分泌两种功能。 相似文献
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Ornithological surveys conducted over the Pechora Sea (the southeastern part of the Barents Sea) in the 1990 s revealed huge
non-nesting flocks of marine ducks, the largest in the European North. Especially dense waterfowl aggregations are constantly
observed at the shallows near Dolgij Island during molting period and migration to wintering places. All the marine ducks
flocking there are specialized benthos feeders predominantly consuming mussels Mytilus edulis. At the same time, numerous previous benthic studies in the Pechora Sea did not reveal mussels near Dolgij Island where benthic
biomass was somewhat lower than in the adjacent areas (Denisenko in Mar Ecol Prog Ser 258:109–123. 2003) which left the food
source for these abundant bird flocks enigmatic. In the course of an expedition in summer 2007 we found subtidal populations
of M. edulis in shallows to the southwest of Dolgij Island. These populations were confined to a coastal zone and were characterized by
a highly disjunct distribution with the biomass reaching up to 4 kg m−2. We describe these subtidal populations as well as an intertidal mussel population on the western shore of Dolgij Island. 相似文献
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Matthew R. Pieron Frank C. Rohwer Michael J. Chamberlain Michael D. Kaller Joseph Lancaster 《The Journal of wildlife management》2013,77(4):663-671
Predator management regularly improves waterfowl nesting success, often beyond levels believed necessary for population maintenance. If recruitment, survival of breeding females, and/or breeding site fidelity is increased on predator-reduced sites, then local breeding populations may increase in subsequent years. During 2005–2008, we annually conducted breeding pair surveys on >600 wetlands at 6 township-sized (93.2 km2) trapped sites and 4 non-trapped sites for the 5 most common upland nesting ducks in eastern North Dakota, USA. For each species, we developed a series of competing regression models that related breeding pair abundance to wetland size, predator management, and upland habitats adjacent to sampled wetlands. In contrast to previous studies, we found limited and equivocal evidence that breeding populations increased following predator management. We discuss multiple potential explanations for this lack of effect and suggest that managers should not assume that increased production as a product of elevated nest success will be compounded over years. © The Wildlife Society, 2013 相似文献
40.
The new “Walk-through aviary” at the Opel-Zoo Kronberg, Germany, which was opened in September 2008 after a ten months construction period, is described. Covering around 1450m2 and being up to 12.5 m high this aviary is one of the biggest in German zoos. The technical innovation is the first use of a stainless steel mash, which was permanent darkened using a chemical reaction. This method is named: INOX-Spectral ® - technique.The author explains the decision-making for the construction and gives an overview of the first year of keeping the birds in this aviary. The public reaction to this building, which is unlikely for the overall animal keeping attitude at the Opel-Zoo, is also covered by this article. 相似文献