Habitat exploitation and interspecific competition of moulting geese in East Greenland

Jameson Land, East Greenland is a moulting area of c. 5000 non-breeding Pink-footed Geese and 5000 Barnacle Geese. Breeding populations of both species in the area are small and scattered. The moulting Pinkfeet originate from Iceland, and the Barnacle Geese from other parts of East Greenland. Both species arrive in the area at the end of June and moult their remiges in July. Moulting flocks of the two species seldom mix. Pinkfoot flocks are common along coastlines, in wide rivers and on lakes with open views to all sides, while Barnacle Geese predominate in smaller rivers and on lakes with surrounding hills. During moult the geese, and especially the Pinkfeet, are extremely wary and depend on a safe area of water serving as a refuge with nearby food supplies (sedge-dominated marshes). Barnacle Geese graze in a zone 0–100 m from the refuge, Pinkfeet up to 200–250 m from the refuge. The moulting sites fill up with geese according to available marsh areas, and the grazing pressure on average amounts to 594 goose-days per ha during the moulting period. Food intake is estimated at 149 g and 138 g organic material per 24 h by Pinkfeet and Barnacle Geese, respectively, [n 1984, which was sunny and warm, net above-ground primary production of a Carex subspathacea marsh (the prime feeding ground during moult) from the beginning of growth to the end of July was 13–15 g dw m², and it is estimated that the geese consumed 60–69% of the production. In 1983, which was cold, geese probably consumed the entire production. Goose grazing did not affect productivity, but nutrient levels were high in grazed compared with ungrazed shoots, and peaked in early July. When separate, the diet of both species comprises sedges and grasses. Where the species co-exist the amount of mosses in the diet increases, especially in Barnacle Geese. With respect to nutrient and fibre contents, moss is a suboptimal food compared to sedges and grasses. When separate, the geese spend 41–46% of the 24 hr grazing. Where they co-exist, Barnacle Geese spend 62% of the time grazing, while Pinkfeet seem unaffected by the presence of Barnacle Geese. It is argued that carrying capacity for moulting geese is reached. Geese compete for resources, the Barnacle Goose suffering from the presence of the other. The observed distribution pattern is suggested to result from (1) Pinkfeet being limited to certain sites due to extreme wariness, and (2) Barnacle Geese trying to avoid competition by utilizing sites which Pinkfeet are reluctant to use. The experience of older Barnacle Geese of stress when settling with Pinkfeet may be the segregation mechanism. Moult coincides with the onset of growth and peak nutrient levels in the vegetation. It is suggested that the geese undertake moult migrations to Jameson Land both to avoid competition for resources with breeding geese and because they gain advantage from a growing, nutritious vegetation.     

Spatial summation of heat induced pain within and between dermatomes

The aim was to study spatial summation within and between ipsi- and contralateral dermatomes at different painful temperatures. For heat stimulation we used a computer controlled thermofoil based thermode. The thermode area could be varied in five discrete steps from 3.14 to 15.70 cm2. When we applied the stimuli within a dermatome, the mean heat pain threshold decreased significantly from 45.6 to 43.5 C as the area was increased from minimum (3.14 cm2) to maximum (15.70 cm2). When the areas were increased involving different dermatomes (both ipsi- or contralateral), we found similar decreases in pain threshold. Spatial summation was also found within and between dermatomes at supra-threshold temperatures (46, 48, 50 C).The study shows that spatial summation of pain is most likely a mechanism acting across segments and is existing from pain threshold to tolerance.     

A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal

Mateus, O. & Milàn, J. 2009: A diverse Upper Jurassic dinosaur ichnofauna from central‐west Portugal. Lethaia, Vol. 43, pp. 245–257. A newly discovered dinosaur track‐assemblage from the Upper Jurassic Lourinhã Formation (Lusitanian Basin, central‐west Portugal), comprises medium‐ to large‐sized sauropod tracks with well‐preserved impressions of soft tissue anatomy, stegosaur tracks and tracks from medium‐ to large‐sized theropods. The 400‐m‐thick Lourinhã Formation consists of mostly aluvial sediments, deposited during the early rifting of the Atlantic Ocean in the Kimmeridgian and Tithonian. The stratigraphic succession shows several shifts between flood‐plain mud and fluvial sands that favour preservation and fossilization of tracks. The studied track‐assemblage is found preserved as natural casts on the underside of a thin bivalve‐rich carbonate bed near the Tithonian–Kimmeridgian boundary. The diversity of the tracks from the new track assemblage is compared with similar faunas from the Upper Jurassic of Asturias, Spain and the Middle Jurassic Yorkshire Coast of England. The Portuguese record of Upper Jurassic dinosaur body fossils show close similarity to the track fauna from the Lourinhã Formation. □Dinosaur tracks, Lusitanian Basin, Portugal, skin impressions, Upper Jurassic.     

Gyr Falcons, ptarmigan and microtine rodents in northern Sweden

A Gyr Falcon Falco rusticolus population in Northern Sweden (66°N, 17°E) was monitored from 1996 to 2002 in relation to its predator–prey interactions with its main and alternative prey species. Ptarmigan species Lagopus spp., and especially Rock Ptarmigan L. mutus , were the Gyr Falcons' most important prey and constituted more than 90% of the prey biomass. A 21-fold difference in ptarmigan abundance was found across Falcon breeding territories. However, this great variation in prey availability corresponded to only about a 10% shift in Gyr Falcon diet across territories, suggesting that the Falcons were reluctant or unable to compensate for declining ptarmigan availability by using alternative prey categories. Gyr Falcons did not respond functionally to microtine rodent abundance. Their diets were unaffected by a peak in the microtine rodent population cycle when Norwegian Lemmings Lemmus lemmus occurred in high numbers in the study area. Gyr Falcons responded numerically to their prey in two ways. First, there was a reproductive response with a significant relationship between the number of chicks fledged and the number of ptarmigan in the breeding territories. Secondly, although the Gyr Falcons did not utilize microtines as prey, there was a relationship between the microtine rodent abundance and the number of pairs that attempted to breed each year. This could be a result of an indirect community interaction, assuming that other predators switched from ptarmigan to microtines as prey, which could have had a positive effect on the breeding performance of the Gyr Falcons. The Gyr Falcons acted as true specialist predators, and their narrow food niche probably reflected a general lack of suitable alternative prey in the study area.     

VARIATIONS IN THE MORPHOLOGY OF EMU (DROMAIUS NOVAEHOLLANDIAE) TRACKS REFLECTING DIFFERENCES IN WALKING PATTERN AND SUBSTRATE CONSISTENCY: ICHNOTAXONOMIC IMPLICATIONS

Abstract:  Fossil footprints appear in a variety of preservational states, each revealing a different morphology that can give rise to misidentification and misinterpretations. Comparative ichnological work was conducted using living emus ( Dromaius novaehollandiae ). It was clearly demonstrated that the morphological variation that occurred in footprints of the same animal, walking in the same manner, was caused by variation in substrate consistency. Dry sand substrates are unlikely to preserve any anatomical details of the foot, whereas damp sand or mud of firm consistency preserves a high level of anatomical detail. The finest anatomical details, such as skin impressions, are only preserved in firm mud or clay. In semi-fluid to fluid mud the track walls collapse, destroying the shape of the footprint. Increased speed of progression affects the shape of the footprint dramatically as the distal ends of the digits become more deeply impressed in the substrate during acceleration. Plantigrade stance adopted by the emu while feeding produces highly elongated footprints. Applying these observations to the study of fossil footprints demonstrates that great care should be paid to the original sedimentary conditions at the time of track making, as well as to the stance and gait of the trackmaker.     

Impacts of disturbance on migratory waterfowl

It is well known that disturbance from human activities can cause temporary changes in behaviour and locally affect temporal and spatial distribution of migratory and wintering waterfowl. But it is also known that, to some extent, birds can compensate for disturbance by altering their behaviour or habituating to human activities. Comparatively little is known about how these reactions to disturbance may impact on the large-scale dispersion of waterfowl and, ultimately, on their population dynamics. To be able to answer these questions, a better theoretical framework, based on optimal foraging theory incorporating predation risk, and field experiments are required. Furthermore, we need to study the waterfowl throughout their winter ranges to interpret the overall impacts of disturbance. This paper examines two cases where the impacts of disturbance have been assessed from field experiments. In one study, disturbance effects of shooting were tested by setting up experimental reserves in two Danish coastal wetlands. Over a 5-year period, these became two of the most important staging areas for coastal waterfowl, and the national totals of key species were significantly increased. A national management plan which will establish more than 50 new shooting-free refuges on Danish coastal areas within the next 5 years is likely to boost waterfowl numbers even more. Such retention of birds at more northerly sites on the fiyway should result in a more efficient resource utilization and may positively affect the population dynamics where numbers are affected by winter resources. In a second study, the impacts of disturbance by farmers on spring fattening of Pink-footed Geese Anser brachyrhynchus were analysed. In undisturbed areas in northern Norway, abdominal profiles of the geese increased rapidly, whereas in disturbed sites they did not. Subsequently, geese that had used undisturbed sites reproduced better than geese from disturbed sites.     

真核基因启动子非依赖的功能转录延伸复合物的体外组装

真核生物RNA聚合酶Ⅱ的持续合成能力对基因转录过程中每一个阶段,包括启动子脱离、转录暂停、转录终止以及转录偶联DNA损伤修复过程的调节至关重要.在RNA聚合酶Ⅱ介导的转录延伸过程中,其和模板DNA及转录产物RNA紧密结合,形成一个非常稳定的延伸三维复合物(elongationcomplex,EC).此特征性“泡”状结构的形成是RNA聚合酶Ⅱ持续合成能力所必需的.在不依赖启动子及众多转录起始因子的条件下,利用人工合成的RNA与DNA寡核苷酸,在体外组装形成具有功能转录活性的延伸复合物.结果表明,长度为9个核苷酸的RNA与模板DNA形成的杂合分子对转录延伸复合物的形成是必需的,而非转录模板DNA链的加入导致最终活性转录“泡”状复合物的形成,并可转录形成与模板相关的转录产物,进一步通过在模板DNA的特定位置引入一个乙酰氧乙酰氨基芴修饰基团,可特异性地阻断转录延伸过程,从而显示该系统在研究真核基因转录及转录偶联DNA损伤修复机制中的潜在应用价值.     

The influence of rate of temperature change and peak stimulus duration on pain intensity and quality

An important aspect of experimental pain research is that the assessment methods can investigate the different aspects of pain perception. The aim of the present study was to investigate the influence of rate of temperature change and peak stimulus duration on heat evoked pain intensity and quality. All stimuli were applied within the medial aspect of the anterior forearm. The rate of temperature change was varied from 1 to 16 C/s without any effect on the pain threshold. The pain threshold decreased with an increasing peak stimulus duration from 0.1 to 2 s, but not from 2 to 3 s. The pain intensity for suprathreshold stimuli (46 C, 48 C, 50 C) increased for decreasing rates and increasing duration. The pain intensity was highly correlated with the energy of the stimulus. When the rates of temperature change (1-16 C/s) are varied, no differences between pricking and burning pain were present at either low stimulus intensity (46 C) or high stimulus intensity (50 C). At low stimulus intensity (46 C), the pricking pain was not influenced by the duration (0.1-3 s), but the burning pain was intensified when the duration was increased from 1.5 to 3 s. At high intensity stimuli (50 C), the pricking pain intensified with an increased duration, whereas burning pain did not. The heat pain threshold is influenced by the peak stimulus duration, and not by the rate of temperature change. If suprathreshold stimuli are used, both the rate of temperature change and the peak stimulus duration can strongly affect the pain intensity and the pain quality. Therefore, the same stimulus modality can be used to assess the modulation of different pain intensities and of the pricking and burning pain qualities simply by varying the stimulus configuration.     

Prediction of the distribution of Arctic-nesting pink-footed geese under a warmer climate scenario

Global climate change is expected to shift species ranges polewards, with a risk of range contractions and population declines of especially high-Arctic species. We built species distribution models for Svalbard-nesting pink-footed geese to relate their occurrence to environmental and climatic variables, and used the models to predict their distribution under a warmer climate scenario. The most parsimonious model included mean May temperature, the number of frost-free months and the proportion of moist and wet moss-dominated vegetation in the area. The two climate variables are indicators for whether geese can physiologically fulfil the breeding cycle or not and the moss vegetation is an indicator of suitable feeding conditions. Projections of the distribution to warmer climate scenarios propose a large north- and eastward expansion of the potential breeding range on Svalbard even at modest temperature increases (1 and 2 °C increase in summer temperature, respectively). Contrary to recent suggestions regarding future distributions of Arctic wildlife, we predict that warming may lead to a further growth in population size of, at least some, Arctic breeding geese.