首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
F. Henrioux 《Bird Study》2013,60(3):250-257
Capsules Sites are selected as part of an antipredator strategy.

Aims To assess if site choice depends on habitat variables at nest sites and if habitat quality influences reproduction.

Methods Breeding density was explored in northwestern Switzerland from 1992 to 1996. Habitat variables were examined at 38 breeding sites and were compared with data collected from random sites. Habitat quality was estimated using the discriminant function scores of the nesting sites.

Results Breeding density was found to vary between years; more pairs bred and raised more young in 1993, a year of high vole abundance. Long-eared Owls tended to avoid the vicinity of buildings; they occupied sites with denser forest edges, greater canopy cover, and with more conifers than random sites. I found no statistical evidence that they used less optimal sites when the population was high. The number of fledglings increased with habitat quality, but did not vary with any of the habitat variables taken separately.

Conclusion Long-eared Owl selects nesting habitat as part of an anti-predator strategy, but the measures of territory quality did not seem to be a limiting factor for the population.  相似文献   

2.
【背景】传统引物延伸法常与放射性标记结合使用,但由于放射性元素半衰期短、危害人体健康及严格的操作要求等限制了其在一般实验室的广泛使用。因此,开发新型非放射性引物延伸法成为当前研究的热点。【目的】建立非放射性的引物延伸法,并利用该方法实现对细菌RNA剪切加工位点的鉴定。【方法】将包含RNA剪切位点的序列克隆至双荧光报告系统,然后利用荧光染料Cy5.5标记的特异性靶向mcherry寡核苷酸引物进行延伸,并辅以Northern blotting、RT-qPCR等技术,确定RNA剪切加工的精确位点。【结果】鉴定了来自解纤维梭菌cip-cel mRNA中的2个剪切加工位点均位于颈环结构下游的单链区域,且在剪切位点附近未发现保守序列。【结论】基于Cy5.5标记的引物延伸法能够精确鉴定RNA剪切加工位点,且与传统的放射性引物延伸法相比,该方法具有更高的安全性和更快的检测速度,能够满足一般实验室的实验要求。  相似文献   

3.
ABSTRACT

Capsule: Wintering Ruddy Turnstones Arenaria interpres occur in higher densities and their populations decline less on, or close to, offshore refuges than on mainland sites subject to greater levels of human disturbance.

Aim: To compare wintering densities of Ruddy Turnstones and changes in counts across time from sites with differing levels of human disturbance.

Methods: Long-term counts of Ruddy Turnstones (1998/1999 to 2015/2016) were used from 19 sites (two offshore refuges and 17 mainland sites subject to higher levels of human disturbance) in northeast England. No direct measure of human disturbance was available for our mainland sites; instead we used questionnaires (n?=?690) to understand how far people travelled to visit the coast and then used this distance with human population densities in a buffer around each site as a proxy for human disturbance levels.

Results: After controlling for the extent of their preferred habitat at each site (rocky shore) we found: (i) the closer each of the 19 sites was to the nearest offshore refuge the higher the density of Ruddy Turnstones and (ii) bird counts were stable at the two refuge sites, whereas, on average, counts declined at the 17 mainland sites. However, no relationship was found between Ruddy Turnstone counts from 17 mainland sites and human population densities within differing distances from each site (up to 10?km).

Conclusions: Our work suggests that Ruddy Turnstones made greater use of relatively undisturbed areas (offshore refuges) than those subject to greater disturbance by humans (mainland sites). Although the use of refuges and mainland in our study area was not well known, observations from 11 radio-tagged Ruddy Turnstones suggest that individual birds did use both locations. In a broader context, our work concurs with other studies that highlight the need for refuges with limited or no human access.  相似文献   

4.
ABSTRACT

Capsule: Duration and peak frequency of Wren Troglodytes troglodytes songs differ between Welsh islands (Skokholm, Flat Holm, and Sully Island) and a mainland site, suggesting random or cultural divergence.

Aims: The study tests for differences in bioacoustic traits in Wren song between four breeding sites.

Methods: Songs from breeding male Wrens were recorded from three Welsh islands and a representative location on the local mainland. Each sonogram was measured for six variables from the whole song and two distinct phrases from the beginning and middle. The variables were measured manually using an open source acoustic tool and compared between sites using generalized linear mixed-effects models.

Results: There was significant variation in song variables between island sites and the mainland. Skokholm Wren songs were significantly longer in duration than all other sites by up to 66%. Peak frequency was significantly different across all sites with Sully Island having the highest peak frequency and Skokholm the lowest.

Conclusion: The differences in song duration and frequency do not directly suggest a trend associated with selective pressures such as habitat or noise, but instead may be explained by non-selective drivers such as cultural drift or local dialect formation.  相似文献   

5.
Capsule The nesting success of the Woodpigeon Columba palumbus in oak forests in Morocco is affected by human disturbance and nest-site characteristics.

Aims To determine factors affecting the nesting success of Woodpigeons subject to two levels of disturbance in a holm oak Middle Atlas forest.

Methods Woodpigeon nests were monitored in highly disturbed (n?=?30) and less-disturbed sites (n?=?60) over two years (2010–11). Logistic-exposure models were used to estimate daily nest-survival rate and evaluate mechanisms (altitude, temporal factors, nest location, nest-site habitat and degree of human influence) affecting nest survival.

Results Daily nest-survival rate was higher in less-disturbed sites (0.987; 95% CL: 0.980–0.991) than in high-disturbance sites (0.967; 95% CL: 0.949–0.978). Increasing density of trees surrounding nest sites and distance from the nest tree to the closest track increased daily nest-survival rate.

Conclusions Less-disturbed sites confer better nesting conditions than highly disturbed ones. Management measures should control the access of vehicles, especially trucks, in the forest of the Middle Atlas and introduce a grazing regime that will allow the forest regeneration, which would improve Woodpigeon nesting success by increasing the density of holm oak trees.  相似文献   

6.
Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites and nestling provisioning rate; when invertebrate availability is low, adults may take greater risks to provide food for their young.

Aims To investigate nesting and foraging ecology in a declining farmland bird whose fledging success is influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceived predation risk during foraging can be mediated by vegetation structure.

Methods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arable farmland. Foraging sites were compared with control sites of both the same and different microhabitats; provisioning rate was related to habitat features of foraging‐sites.

Results Foraging sites had low vegetation density, probably enhancing detection of predators, or high invertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasing vegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrate abundance was low, provisioning rate increased with increasing vegetation cover.

Conclusions Vegetation structure at foraging sites suggests that a trade‐off between predator detection and prey availability influences foraging site selection in Yellowhammers. Associations between parental provisioning rate and vegetation variables suggest that where invertebrate abundance is high birds increase time spent scanning for predators at higher vegetation densities; however, when prey are scarce, adults may take more risks to provide food for their young.  相似文献   

7.
【目的】为了研究泛素化对组氨酸转运及调控的影响。【方法】应用泛素化位点预测及定点突变等技术手段,Hip1p的3个潜在的泛素化位点K30、K42和K52被突变。这些突变的Hip1p被克隆到泛素化检测质粒中,检测泛素化位点突变对Hip1p的泛素化水平的影响。同时这些突变对细胞生长及组氨酸利用的影响也进一步做了检测。【结果】Hip1p的3个赖氨酸位点K30、K42和K52突变能有效降低其泛素化水平。同时,双重突变对其泛素化水平有明显的协同作用,并进一步影响了细胞生长和组氨酸利用。【结论】泛素化水平调控能有效调节组氨酸代谢,引起细胞对组氨酸利用的改变,为进一步研究氨基酸转运蛋白的调控机制提供了重要的依据。  相似文献   

8.
Capsule Foraging sites with low vegetation height and density, but with high arthropod biomass, are selected.

Aims To test the hypothesis that on intensively grazed moorland, breeding Meadow Pipits forage for nestling food where arthropod prey are most readily available, and therefore that foraging site choice is a function of prey abundance and vegetation structure.

Methods Observations of adults provisioning nestlings were made from hides positioned close to 19 nests within grazed, 3.3-hectare experimental plots at Glen Finglas, Scotland. Vegetation height and density and arthropod abundance from mapped foraging sites were compared with control sites. Prey items fed to nestlings were quantified and compared with their relative abundance.

Results Meadow Pipits selected foraging sites with significantly lower vegetation height and density, but with significantly higher arthropod biomass. Our data suggest that within foraging sites, Meadow Pipits select particular prey types to provision nestlings, in particular, Lepidoptera larvae, adult Tipulidae and Arachnida.

Conclusions In intensively grazed upland systems, it appears that Meadow Pipits select foraging sites that optimize total food abundance and accessibility. In order to understand how anticipated changes to livestock farming in Europe will affect grassland birds, we recommend that future studies should investigate the foraging and vigilance behaviour, diet composition and breeding success of a variety of bird species provisioning nestlings under a range of livestock management scenarios.  相似文献   

9.
【目的】筛选影响Ll.LtrB内含子编码蛋白(Intron encoded protein,IEP)反转录功能的关键催化位点,并获得无反转录活性的IEP突变体。【方法】首先,利用NCBI数据库,通过序列比对及同源建模方法筛选影响IEP反转录功能的关键氨基酸催化位点;然后,对筛选获得的关键催化位点进行定点突变,同时以Targetron载体为模板,构建无反转录功能的突变型Targetron打靶系统;最后,以大肠杆菌lacZ基因为例,体内验证IEP突变体的功能及其对Ⅱ型内含子"归巢"效率的影响。【结果】筛选到C164和G214两个位点是影响内含子编码蛋白反转录功能的关键氨基酸残基,并获得C164K和G214W两个突变体。体内功能分析表明,此两个位点突变完全失活了Ⅱ型内含子的"归巢"功能。【结论】筛选并获得了失活反转录功能的Ll.LtrB内含子编码蛋白突变体,为深入研究Ⅱ型内含子的结构和"归巢"机理奠定了基础。  相似文献   

10.
D.P. Whitfield 《Bird Study》2013,60(3):237-249
Capsule A minimum of 220 male Dotterel nested in Britain in 1999, which after correction for missed birds led to an estimated 630 breeding males.

Aims To provide a reliable population estimate of Dotterel against which past and future estimates could be compared.

Methods Over half of the potential breeding habitat in Britain, selected randomly and to cover protected sites and former breeding sites for Dotterel, was surveyed through a single visit when Dotterel had young chicks.

Results After correcting for missed birds, 750 males were estimated to be breeding in Britain in 1999. An alternative method led to an estimated 510 males. Both methods had their drawbacks – 630 males probably represented the best estimate. Almost 93% of males bred in three regions: central, east and north Highlands. Around a third of surveyed sites were occupied by breeding birds. The national population estimate was significantly higher in 1987/88 but numbers were probably greatest in 1989 and declined in the 1990s. In 1999 Dotterel distribution had contracted to those sites with the highest densities in the late 1980s.

Conclusion It is unlikely that changes in numbers between surveys were due to changes in the British breeding grounds. They may be due to adverse influences away from the breeding grounds or, because Dotterels can move across large distances between breeding attempts, a redistribution of birds away from Scotland to breeding sites elsewhere in the Palearctic.  相似文献   

11.
Capsule Lapwing nest predation was negatively correlated to nest density, while Lapwing alarm duration in response to foxes was positively correlated with the number of Lapwing broods present.

Aims To identify factors affecting Lapwing nest predation and Red Fox search effort.

Methods Lapwing nest success was monitored at four sites in 1996, seven sites in 1997 and six sites in 1998. In 1997 we mapped the position of all Lapwing nests in order to determine distances between nests, and the proximity of linear features and potential avian predator perches to each nest. From April to June 1998 we carried out 199 hours of nocturnal observations at six Lapwing nesting sites using night vision equipment.

Results The risk of nest predation was significantly higher for more isolated nests. Nocturnal observations showed that of all the nocturnal predators, foxes were the most active at Lapwing nesting sites. However, fox search effort in Lapwing colonies was relatively low, averaging 57 s/ha per visit. Foxes spent significantly longer foraging near breeding Lapwings (measured as duration of alarm calls) when more broods were present. Fox search effort (s/ha per hour of observation) tended to be greater in areas of high waterbird density.

Conclusion The lack of positive density-dependent nest predation, the relatively low search effort of foxes near Lapwing nesting sites and the high nest success sometimes achieved in areas with foxes all suggest that Lapwing nest predation by foxes is ‘incidental’. Lapwing chicks are probably more vulnerable to predation by foxes than clutches.  相似文献   

12.
BackgroundIdentification of wound-specific markers would represent an important step toward damaged tissue detection and targeted delivery of biologically important materials to injured sites. Such delivery could minimize the amount of therapeutic materials that must be administered and limit potential collateral damage on nearby normal tissues. Yet, biological markers that are specific for injured tissue sites remain elusive.MethodsIn this study, we have developed an immunohistological approach for identification of protein epitopes specifically exposed in wounded tissue sites.ResultsUsing ex-vivo tissue samples in combination with fluorescently-labeled antibodies we show that actin, an intracellular cytoskeletal protein, is specifically exposed upon injury. The targetability of actin in injured sites has been demonstrated in vivo through the specific delivery of anti-actin conjugated particles to the wounded tissue in a lethal rat model of grade IV liver injury.ConclusionsThese results illustrate that identification of injury-specific protein markers and their targetability for specific delivery is feasible.General significanceIdentification of wound-specific targets has important medical applications as it could enable specific delivery of various products, such as expression vectors, therapeutic drugs, hemostatic materials, tissue healing, or scar prevention agents, to internal sites of penetrating or surgical wounds regardless of origin, geometry or location.  相似文献   

13.
Abstract

We have used one and two dimensional exchange 1H NMR spectroscopy to characterize the dynamics of the binding of a homodimeric thiazole orange dye, 1,1′-(4,4,8,8-tetramethyl-4,8-diaza-undecamethylene)-bis-4-(3-methyl-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene)-quinolinium tetraiodide (TOTO), to double stranded DNA (dsDNA). The double stranded oligonucleotides used were d-(CGCTAGCG)2 ( 1 ) and d(CGCTAGCTAGCG)2 ( 2 ). TOTO binds preferentially to the (5′-CTAG-3′)2 sites and forms mixtures of 1:1 and 1:2 dsDNA-TOTO complexes with 2 in ratios dependent on the relative amount of TOTO and the oligonucleotide in the sample. The dynamic exchange between preferential binding sites in the case of a 2:1 1 -TOTO mixture is an intermolecular exchange process between two binding sites on different oligonucleotides. In the case of the 1:1 2 -TOTO complex an intramolecular exchange process occur between two different binding sites on the same strand. Both processes were studied. The results demonstrate the ability of TOTO to migrate along a dsDNA strand in an intramolecular exchange process. The migration process (“creeping”) along the DNA strand is 6 times faster than the rate of intermolecular exchange between sites in two different oligonucleotides.  相似文献   

14.
A. Dyrcz  H. Nagata 《Bird Study》2013,60(2):166-171
CapsuleTwo populations of the Eastern Great Reed Warblers, one close to settlements and one far away, differed mainly in nest losses which were higher at the latter site.

Aims To compare the breeding ecology of two Japanese populations, and with breeding data from Polish sites.

Methods We studied two sites in 1996. The Seimei site comprises a natural reed-bed (Phragmites australis) (2.0 ha) c. 2 km from residential areas. The Sakura site occurs as smaller reed-bed (0.8 ha) close to residential areas. Field study comprised mainly nest searching and nest monitoring.

Results Breeding density, nest height, number of stems supporting nest, clutch size and brood size were not significantly different between sites. The proportion of nests built on reed stems standing in the water (60%) was significantly higher at the Seimei site (P < 0.001), and the warblers in this habitat experienced significantly higher nesting failure (P < 0.05). Predation was a principal cause of failure at both sites. Significantly more nests suffered from predation at Seimei (53%) than at Sakura (16%). Breeding density was higher at both sites compared with European populations but it fell within ranges of other Japanese populations. Mean first-egg date of first brood does not differ between our sites and Polish ones.

Conclusion The differences between the two Japanese populations and between Japanese and Polish populations were relatively small and were seen mainly in nest losses, breeding density and proportion of nests built over water.  相似文献   

15.
Júlio M. Neto 《Bird Study》2013,60(2):171-176
Capsule Savi's Warblers preferred sites dominated by high and dense Juncus and Rubus with thick litter, and avoided pure reeds; predation was higher in sites with less litter.

Aim To describe nest-site selection and identify which habitat and nest features influence predation risk.

Methods Comparisons were made between habitat characteristics measured at nest-sites and random points, and between predated and successful nests.

Results Total vegetation cover, litter thickness, habitat type, undergrowth height and undergrowth cover, which were higher or denser at nest-sites, were the most important variables influencing the distribution of Savi's Warbler nests. Nests were most often predated in sites with low litter thickness.

Conclusion Savi's Warblers are dependent on the presence of dense low vegetation and litter for nesting, which should be maintained close to or within reed-beds for their benefit.  相似文献   

16.
17.
SettingWorld Health Organization advocates for integration of HIV-tuberculosis (TB) services and recommends intensive case finding (ICF), isoniazid preventive therapy (IPT), and infection control (“Three I’s”) for TB prevention and control among persons living with HIV.ObjectiveTo assess the implementation of the “Three I’s” of TB-control at HIV treatment sites in lower income countries.DesignSurvey conducted between March-July, 2012 at 47 sites in 26 countries: 6 (13%) Asia Pacific, 7 (15%), Caribbean, Central and South America, 5 (10%) Central Africa, 8 (17%) East Africa, 14 (30%) Southern Africa, and 7 (15%) West Africa.ResultsICF using symptom-based screening was performed at 38% of sites; 45% of sites used symptom-screening plus additional diagnostics. IPT at enrollment or ART initiation was implemented in only 17% of sites, with 9% of sites providing IPT to tuberculin-skin-test positive patients. Infection control measures varied: 62% of sites separated smear-positive patients, and healthcare workers used masks at 57% of sites. Only 12 (26%) sites integrated HIV-TB services. Integration was not associated with implementation of TB prevention measures except for IPT provision at enrollment (42% integrated vs. 9% non-integrated; p = 0.03).ConclusionsImplementation of TB screening, IPT provision, and infection control measures was low and variable across regional HIV treatment sites, regardless of integration status.  相似文献   

18.
Capsule: The nesting habitat of the Common Buzzard Buteo buteo and Lesser Spotted Eagle Clanga pomarina extensively overlap, indicating that they exploit similar resources.

Aim: We aimed to determine the overlap in the nest platforms, nest trees and nest stands used by these raptors, find any evidence for the avoidance of the larger Lesser Spotted Eagle by the smaller Common Buzzard, and provide conservation implications for habitat protection of the former species in habitats that overlap extensively.

Methods: Nest sites were mapped during 2012–2014 in the Bir?ai Forest Spatial Protection Area, northern Lithuania. Fifty-three nest sites occupied by Common Buzzards and 26 by Lesser Spotted Eagles were compared.

Results: The nest platforms of both raptors were similarly placed in the tree canopies. Most Lesser Spotted Eagle nests were built in spruce, while the Common Buzzard usually nested in birch. The nest stands of the eagles were on wetter soil and located closer to the forest edge than those of the buzzards, otherwise, the nest stands did not differ significantly. There was no evidence for spatial avoidance of the larger raptor by the Common Buzzard.

Conclusions: The different components of the nesting habitats extensively overlapped, and the distribution of the interspecific pairs lacked spatial avoidance. We suggest that the nest sites of both raptors were a largely shared resource, especially if located close to the forest edges. We propose, as a rule of thumb, applying protection by way of buffer zones around buzzard nest sites if they are located close to eagle nest sites and the forest edge.  相似文献   

19.
ABSTRACT

Capsule: Non-breeding waterbirds are more likely to respond to drone approach when in larger flocks, and responses are more likely in arable and coastal habitats than at inland lochs.

Aims: To investigate the extent to which drones are a potential source of disturbance to non-breeding waterbirds.

Methods: Using a commercially available quadcopter drone, we approached waterbird flocks of varying sizes in coastal, freshwater, and arable habitats following a standardized protocol.

Results: Waterbirds at coastal sites and in arable fields were more likely to respond to drone approach than those at inland freshwater bodies. Larger flocks were more likely to respond to drone approach and responded at a greater distance than smaller flocks.

Conclusion: Repeated drone use at coastal and arable sites with large aggregations of feeding or roosting waterbirds could cause energetically costly flight responses, increased stress, and effective loss of available habitat. At such sites, it may be beneficial to regulate recreational and commercial drone use to minimize potential disturbance effects.  相似文献   

20.
Capsule Redshank used more sites and had larger ranges at night than during the day.

Aims To determine whether there were differences in how wintering Redshank used intertidal feeding grounds during the day and night.

Methods The movements of 38 Redshank caught and radiotagged at two neighbouring sites on the Severn Estuary were monitored during four different study periods between January 1997 and October 1999.

Results Individuals used a greater number of sites at night than in the day (on average, two as opposed to one). Kernel home range analyses also indicated that individuals used larger core areas and home ranges at night. In addition, there was a significant difference between the sizes of ranges of birds caught at two neighbouring sites. One foraging site was almost entirely avoided during the day, probably due to disturbance from an adjacent heliport, but was used by the majority of individuals at night when the heliport was unused. This site was rich in invertebrates as a result of the high organic and nutrient input from a sewage outfall pipe. Redshank also used riverine mudflats less during the night, preferring more open mudflats – perhaps to avoid nocturnal predators.

Conclusions Comparison with previous studies suggests that the importance of sites predominantly used at night and the total extent of the areas used by waders may be underestimated by studies that rely on daytime surveys alone. It is important, therefore, that information on nocturnal distributions should be available to inform decisions on site management and protection.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号