湖南长沙记录到绿背姬鹟

2019年10月3日,在湖南省长沙市烈士公园(112°59′55.74″E,28°12′48.08″N)内一池塘周边的阔叶林中观察并拍摄到一种鹟科鸟类。经查阅文献,对比该鸟的形态特征后,鉴定为绿背姬鹟(Ficedula elisae),为湖南省新纪录鸟种。     

Near-shore distribution of Heaviside’s (Cephalorhynchus heavisidii) and dusky dolphins (Lagenorhynchus obscurus) at the southern limit of their range in South Africa

Photo-identification surveys over three years along 390 km of coastline north of Cape Town, revealed that Heaviside’s dolphin distribution was consistent between years and higher in areas more exposed to swells and with greater long-term availability of small hake Merluccius capensis (their principal prey). Dusky dolphin sighting rates varied considerably between years, but were generally higher in areas with lower hake availability and sandier shores (mostly straighter coastline). Large groups of 50–200 dusky dolphins were only seen in St Helena Bay, the site of a wind-driven upwelling zone. Heaviside’s dolphins were found in shallower, cooler water than dusky dolphins and were more likely to be seen during brighter phases of the moon (when nocturnal light conditions may influence the vertical migration patterns of prey) and in areas of high hake abundance. Near-shore fishing activity was higher in the northern half of the study area and clustered around harbours. Set netting occurred only at Yzerfontein and St Helena Bay, but due to changes in the industry is currently thought to be a low threat to the population. Interactions between Heaviside’s and dusky dolphins were usually neutral and sympatry appears to be mediated by differences in overall range and the type and size of prey species taken.     

Measuring ecologically important quantities at relevant operational scales: An example using the dusky flycatcher in selectively logged forests in Idaho

Effective management of forest wildlife requires information about habitat features that can be altered by operations, if those habitat features promote reproductive success and survival, and if changes in organism density influence reproductive success and survival. Habitat selection studies often provide the first type of information, although relatively few studies examine how different selection decisions or densities of organisms influence fitness measures or measure habitat features at relevant operational scales. We examined patterns of habitat selection and estimated how habitat use, territory size, and conspecific density were associated with territory success (probability of a territory producing one or more fledglings) for the dusky flycatcher in 2002–2003 on eight study plots in managed grand fir (Abies concolor) forests in Idaho, USA. Flycatchers selected territories with greater cover of deciduous vegetation in two different height strata (1–2 and 3–4 m) and reduced cover of conifers less than 4 cm dbh compared to what was available. While flycatchers selected habitat characteristics at the territory scale, model selection results did not support any associations between vegetation features and territory success. Territory success had weak positive associations, for a given territory size, with conspecific density, although the relationship was highly variable. An interaction between territory size and density was not supported. These results are consistent with the view that avian breeding habitat selection occurs at multiple scales, and that the nest site scale may explain more of the variance in reproductive success than larger scales. Our results suggest that operational management of vegetation features, which often occurs at the stand scale, may not influence variation in critical demographic metrics. Increasing total shrub cover of commonly used plant species should benefit the dusky flycatcher, as well as other shrub-nesting forest birds, but stand-level habitat alterations alone cannot be relied upon to increase reproductive success, an important component of population change.     

Bird Responses to Removal of Western Juniper in Sagebrush-Steppe

We investigated bird abundance in response to western juniper (Juniperus occidentalis) removal using a short-term chronosequence approach and generated estimates of density and responses to management for the most abundant species. Stands targeted for tree removal were primarily in the middle stages of juniper encroachment (Phase II, 7 851 ha). Trees were removed using hand felling combined with either lop and scatter, single tree burning, or jackpot burning, which were carried out to minimize loss of shrub cover. Brewer’s sparrow (Spizella breweri) density was greater at treated versus untreated portions of the study area. At sites in the third year following tree removal, Brewer’s sparrow density was 23.6 (95% confidence interval [CI]: 19.4–27.8) territories per km² higher than locations that had not yet been treated. This equates to a net increase of 1 212 ? 1 737 nesting pairs within the project area. Green-tailed towhee increased by 4.6 (95% CI: 3.1–6.1) territories per km² for an estimated project-wide increase of 194–381 nesting pairs, and vesper sparrow (Poocetes gramineus) increased by 6.5 (95% CI: 4.6–8.4) territories per km² corresponding to an estimated increase of 460–559 nesting pairs within the project area. Density of gray flycatcher (Empidonax wrighti) was lower in cut areas, and over the entire project area we estimate a net loss of 183–486 nesting pairs as a result of juniper tree removal. This study demonstrates that conifer removal projects designed to retain shrub cover and structure can have benefits to multiple species of ground and shrub nesting birds, including several species of conservation concern.     

Evidence of improved water quality and biofilm control by slow sand filters in aquaculture – A case study

A rapid sand filter (RSF, 12 m³ m⁻² h⁻¹) and a rapid sand filter followed by slow sand filter (RSF-SSF, 0.1 m³ m⁻² h⁻¹) were compared to investigate whether the biological activity in the RSF-SSF would improve turbidity reduction and control of biofilm growth in seawater aquaculture of juvenile dusky grouper over a 31 days test period. The RSF-SSF combination produced water with lower turbidity than RSF, turbidity breakthroughs in RSF were effectively abated by SSF. Microbial growth potential (MGP) measured by a growth assay with Pseudoalteromonas spongiae in samples filtered through 0,2μm membranes was significantly smaller in SSF filtrate (MGP, 3.2 ± 0,1 logCFU) than in RSF filtrate (3.9 ± 0,6 logCFU). Turbidity in fish tanks fed with RSF-SSF and RSF effluent remained below 1 NTU and 6 NTU, respectively, inspite of the large amount of food not consumed by the fish and of the tanks remaining open to the atmosphere. Surface biofouling on PVC samples was assessed by protein and carbohydrate analysis. It was less pronounced on bottoms of tanks operated with RSF-SSF treated water but similar on tank walls for both types of water. Carbohydrates were present in much larger quantities than proteins in bottom biofilms, but the opposite occurred in wall biofilms. Diatoms were dominant in RSF but not in RSF-SSF tank biofilms. Dusky grouper survival and growth was similar for the two types of water. The benefit of reduction of microbial growth potential achieved in SSF pretreatment was successfully captured in lesser tank surfaces biofilm colonization and by lower water turbidity in the tanks.