Polar Research (E-Journal)
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Food selection by barnacle geese (Branta leucopsis) in an Arctic pre-breeding area
No full textDetailed patterns of food selection by pre-breeding barnacle geese (Branta leucopsis) were investigated in Vårsolbukta, western Spitsbergen, Svalbard, in moss-dominated vegetation. This habitat is favoured by geese during the early Arctic spring when grass abundance is low. Grass is more profitable food than moss in terms of nutrient content and digestibility, and a five-fold higher proportion of grass in geese faeces compared with other vegetation indicated that geese selected grass in spite of its low availability compared with moss. As profitability may also depend on various properties that enhance searching efficiency, we studied the effects of grass tiller size, density and patchiness on goose selectivity in an experiment comparing ungrazed vegetation with vegetation where geese were allowed to feed for controlled periods of time. Large (two-leaved) tillers provided more biomass than small (one-leaved) tillers. The abundance of ungrazed large tillers relative to small tillers was lower in the grazed plots than in the ungrazed control plots, indicating that the geese preferred large tillers. Grass tiller density or spatial tiller distribution did not affect the degree of selectivity of geese for grass. Thus, we suggest that the feeding strategy of the geese in the early Arctic spring is primarily driven by the degree of tiller conspicuousness, as determined by tiller size. Furthermore, we suggest that an intense time allocation to feeding and an enhanced quality of grasses compared with mosses enabled geese to profit from feeding on the scarce grasses
Review of Arctic scientist, Gulag survivor: the biography of Mikhail Mikhailovich Ermolaev, 1905–1991, translated and edited by William Barr
No full textMikhail Mikhailovich Ermolaev (pronounced Yermolayev) —a Russian pre- and post-war geographer and geologist—is not a well-known scientist, neither in an international nor a Russian context. But he was an outstanding person in the lives of the many people he met during his long academic career. His difficult life in many ways reflects Russian scholarship during all stages of the Soviet era, from the Bolshevik Revolution to its dissolution, including the terrible years of Stalin’s reign of terror against academic society
Review of Otto Fabricius and the seals of Greenland. Meddelelser om Grønland: Bioscience 55, by Finn O. Kapel
No full textIn this three part volume Finn Kapel presents us with 1) a brief biography of Fabricius, 2) a translation of his treatise on the seals of Greenland and, fi nally, 3) a refl ection on the contribution of Fabricius as a seal naturalist/scientist. I concur with Dr Kapel’s belief that the key paper is the second one. This work on Greenland’s pinnipeds has until now been available only in Danish and German and certainly deserves to be more widely read and acknowledged. However, the first and last chapters are also an interesting read and give a nice basis for evaluating the biological and ethnographic material presented in the volume’s middle section, although now and again they are redundant. The book contains an interesting and eclectic collection of black and white illustrations including portraits, historical photographs, and technical and biological drawing
Modelling of polar bear populations by the Leslie matrix population model
No full textSome general doubts have been voiced regarding the soundness of using a Leslie matrix population projection on polar bear populations
Census of seabird colonies on Nordaustlandet, Svalbard, and in neighbouring localities in 1978 and 1979
No full textSeabird colonies were censused during the summer expedition of Norsk Polarinstitutt to Nordaustlandet. Svalbard, in 1978 and 1979, and to Kongs~yain 1979. An outline is givcn of thc distribution of the ,pecir, together with an estimate of the number of breeding pairs in the colonies. Twenty-five colonies were ccnsused; seven were visited both years. Four colonies with more than 1,000 breeding pairs of the most abundant species, Brunnich‘s guillemot and kittiwake, were found on Nordaustlandet
On testicular cooling in phocid seals
No full textTesticular and body core (intra-thoracic) temperatures were recorded in mature male harp seals (Pagophihs groenlandicuc) just prior to the mating season. In phocid seals the testicles are outside the abdomen but protected under 7-8 cm of insulating skin and blubber. The temperature of the testicles was found to be 14°C lower than body core temperature. Inspection of the veins of the pelvic and hind-flipper reglon of a male ribbon seal (Histrrophocafaciata) revealed that the testicles of phocid seals are enveloped in venous plexuses communicating with the veins of the hind flippers. It is suggested that cooling of the paraabdominal testicles of phocid seals is attained by passage of cold blood from the hind flippers through thc extra-testicular plexuses
Polar bear hunt strategies evaluated by a Leslie matrix population model
No full textAn APL program for a Leslie matrix population projection is developed and applied to analysis of a Canadian polar bear population. Hunting specified with respect to sex ratio within a total quota may be included in the projections. Application to the lower central arctic islands’ polar bear population of 1100 animals indicates a growth to 1560 animals during ten years without hunting. Projection with two males taken for each female indicates that 54 animals may be taken from the population each year. However, the same sized hunt, but with a one-to-one sex ratio, caused a significant depression of the population
Regulation of annual weight cycles in reindeer and other cervids
No full textSeasonal changes in weight, food intake and metabolic rate are characteristic of reindeer and other northern ungulates. This article reviews relationships between endocrine and weight cycles in reindeer and other cervids, and the effect of manipulations with endocrine cycles upon the weight cycle. It appears that the secretions of most endocrine glands change throughout the year, either as a result of nutritional changes or of an inherent seasonal rhythm. It is suggested that the weight and metabolic cycles are secondary to an appetite cycle that is hormonally regulated. The hormonal control may include several hormones: sex steroids, thyroid hormones, and prolactin
Nocturnal hypothermia and its energetic significance for small birds living in the Arctic and subarctic regions. A review
No full textNocturnal hypothermia is demonstrated in a number of small northern birds. These birds utilize hypothermia among other energy-saving mechanisms and lower the body temperature by some 10°C. In most bird species hypothermia is utilized only in conjunction with a state of inanition. However, hypothermia has also been demonstrated in birds with satisfactory feeding conditions and body weight. For none of the small northern birds utilizing nocturnal hypothermia. is inanition necessary for the induction of a state of hypothermia. A seasonal effect on the hypothermic response has been demonstrated for two species of tits, the black-capped chickadee Parus atricapillus and the willow tit Parus monfanus, and also for an Andean hummingbird. The depth of hypothermia achieved significantly and linearly was correlated with the ambient temperature for the same two species of tits. By the use of nocturnal hypothermia, birds living in temperate zones can save as much as 75% of their energetic costs, compared with their energy consumption at normal body temperature. The reduction in the nightly expenditure of energy is considerable also in small-sized arctic and subarctic birds that utilize nocturnal hypothermia. The saving of energetic costs may easily represent the margin between life and death for such small birds living under the combined stresses of hunger, cold and long nights
A comparison of annual and seasonal carbon dioxide effluxes between sub-Arctic Sweden and High-Arctic Svalbard
No full textRecent climate change predictions suggest altered patterns of winter precipitation across the Arctic. It has been suggested that the presence, timing and quantity of snow all affect microbial activity, thus influencing CO2 production in soil. In this study annual and seasonal emissions of CO2 were estimated in High-Arctic Adventdalen, Svalbard, and sub-Arctic Latnjajaure, Sweden, using a new trace gas-based method to track real-time diffusion rates through the snow. Summer measurements from snow-free soils were made using a chamber-based method. Measurements were obtained from different snow regimes in order to evaluate the effect of snow depth on winter CO2 effluxes. Total annual emissions of CO2 from the sub-Arctic site (0.662–1.487 kg CO2 m–2 yr–1) were found to be more than double the emissions from the High-Arctic site (0.369–0.591 kg CO2 m–2 yr–1). There were no significant differences in winter effluxes between snow regimes or vegetation types, indicating that spatial variability in winter soil CO2 effluxes are not directly linked to snow cover thickness or soil temperatures. Total winter emissions (0.004– 0.248 kg CO2 m–2) were found to be in the lower range of those previously described in the literature. Winter emissions varied in their contribution to total annual production between 1 and 18%. Artificial snow drifts shortened the snow-free period by 2 weeks and decreased the annual CO2 emission by up to 20%. This study suggests that future shifts in vegetation zones may increase soil respiration from Arctic tundra regions