Svalbard Population Research Articles

Conservation Genetics and Population History of Betula nana, Vaccinium uliginosum, and Campanula rotundifolia in the Arctic Archipelago of Svalbard

Plant species defined as strongly thermophilous in Svalbard are rare and may be threatened by extinction due to suppressed sexual reproduction, small population sizes, genetic depauperation, and human activity. We examined isozyme diversity in three of these species—Betula nana, Vaccinium uliginosum, and Campanula rotundifolia—in Svalbard. Twenty-five to 60 ramets from each of two to three (sub)populations of each species were analyzed for eight enzyme systems. In B. nana, genetic diversity was low within sampling plots (D: 0.00–0.49) and intermediate within populations (mean D = 0.70, mean Hep = 0.119). Genetic diversity at the species level (Hes) was 0.141, and the differentiation among populations (FST = 0.193) was higher than the average for other species with similar life traits. In V. uliginosum, no variation was observed within plots, and genetic diversity within populations was low (mean D = 0.29, mean Hep = 0.082). Genetic diversity at the species level was also low (Hes = 0.152), and the differentiation among populations (FST = 0.493) was much higher than in most other species studied. The only Svalbard population of C. rotundifolia has 2n = 34 and is traditionally considered as diploid, but the observed enzyme banding patterns suggest polyploidy. In this species, genotypic diversity was low within plots (D: 0.00–0.33), intermediate within subpopulations (mean D = 0.74), and all multilocus phenotypes were local. The present populations of all three species in Svalbard are probably fragmented relics of larger populations in the postglacial warm period. On the basis of the observed distribution of genetic diversity and population sizes, we propose to conserve all Svalbard populations of V. uliginosum and C. rotundifolia, and at least one population of B. nana.

Contaminants in Svalbard polar bear samples archived since 1967 and possible population level effects

Blood plasma samples were collected in 1967 from 32 polar bears ( Ursus maritimus) in eastern Svalbard. These samples were stored frozen until 2001 and then analyzed for 33 polychlorinated biphenyls (PCB), two toxaphene congeners, DDTs, chlordanes (CHL), hexachlorobenzene, hexachlorocyclohexanes (HCHs), and polybrominated flame retardants (biphenyls and diphenyl ethers). The 1967 pollutant levels were compared with values from 1993 to 1994 for adult females and adult males to obtain insights into the historical development of pollution in the Norwegian Arctic. Differences in the OC levels measured between 1967 and 1993–1994 ranged from a decrease (PCB 187 and p, p-DDE) to unchanged in both sexes (PCBs 105, 118, 209, and HCH) to an increase in females (PCBs 99, 128, and CHL), to increases in both sexes (PCBs 138, 153, 156, 157, 170, 180, 194, and 206). The maximum change was a nine-fold increase in PCB 157 in adult females. Changes from 1967 to 1993–1994 in contaminant pattern expressed relative to PCB 153 could be explained by a combination of selective metabolism and accumulation of organochlorines in polar bears and temporal changes in the contaminant mixture being transported to the Arctic. Harvest of polar bears in Svalbard ended in 1973 and it appears that most pollutant levels were increasing at the same time that the population was expected to recover from over-harvest. The mean age of adult females in the Svalbard population was similar to other populations where pollution levels are lower but harvest is intense. Females with cubs-of-the-year ⩾16 years old are uncommon in the population for unknown reasons. The impacts of contaminants on the Svalbard polar bear population are inconclusive but there are suggestions of contaminant-related population level effects that could have resulted from reproductive impairment of females, lower survival rates of cubs, or increased mortality of reproductive females.

An examination of methods to estimate population size in wintering geese

We estimated the size of the Svalbard population of Pink-footed Geese Anser brachyrhynchus in 1991–98 using three different methods: (a) counts; (b) mark–resight estimates; (c) annual productivity and survival. Count data showed a slight increase of population size, from 33 000 in 1991 to 38 500 in 1998. Mark–resight estimates showed a larger fluctuation, but were almost always greater than counts. By contrast, estimates of survival and productivity suggested stability or at least a less pronounced increase in the population size, the discrepancy in the number estimated when compared to the other methods being especially large in the last two years of the study. A detailed examination of the assumptions underlying each of the methods reveals possible explanations for some, but not all, of the discrepancies. We conclude that goose population estimates derived from total population counts may be less reliable than commonly assumed, and moderate year-to-year trends should not be over-interpreted. Similarly, assessment of annual productivity and survival may be subject to undetected biases, and these uncertainties should be considered when interpreting results and trends in these parameters. Repeated cross-validation of parameter estimation methods in this and other populations is highly desirable.

Spatially explicit, individual‐based, behavioural models of the annual cycle of two migratory goose populations

1. Behaviour‐based models of animal population dynamics provide ecologists with a powerful tool for predicting the response of such populations to both natural and human‐induced environmental changes. 2. We developed this approach by addressing two outstanding issues in the application of such models: the need to adopt a large‐scale spatially explicit approach, and the need to consider the year‐round dynamics of animal populations. 3. Spatially explicit, year‐round, behaviour‐based models of two populations of arctic‐breeding geese, the Svalbard population of the barnacle goose Branta leucopsis and the dark‐bellied race of the brent goose Branta bernicla, were developed. Both populations have been the subject of serious conservation concern and are currently a source of increasing conflict with agricultural interests. 4. There was generally good agreement between empirically derived and model‐generated density‐dependent functions, and of seasonal patterns of the distribution and movement of populations within and between sites, and of energy reserve levels within a population. 5. Sensitivity analyses, however, highlighted the importance of accurate parameter estimation with respect to the predictions of such models, and the potential flaws in the predictions of existing models that have not adopted a spatially explicit approach when dealing with wide‐ranging migratory populations. 6. The effect of the removal of a given area of habitat on both populations was predicted to vary depending upon the spatial configuration of the change. This further emphasizes the need for a spatially explicit approach. 7. Both barnacle goose and brent goose populations were predicted to decline following habitat loss in their winter or spring‐staging sites. Simulations suggested that barnacle geese might be less vulnerable to winter habitat loss than brent geese. This reflected the relative strengths of the density‐dependence of productivity and winter mortality in the two models and provided a clear illustration of the need for a year‐round approach to animal population dynamics. 8. We believe that these models, and this approach to understanding the population dynamics of long‐distance migrants, will be beneficial in attempting to answer the increasingly urgent and frequent requests to predict the response of such populations to environmental change.

The Brief Period of Spring Migration, Short Marine Residence, and High Return Rate of a Northern Svalbard Population of Arctic Char

Abstract Arctic char Salvelinus alpinus, in the high-Arctic archipelago of Svalbard, entered the Dieset River (79°10′N) immediately after ice breakup in late June (1991–1993), and within 48 h almost half the migrating population had left the lakes where they spent the winter. The majority of the anadromous char descended into the sea within 3 weeks of the melt. The temporal pattern of emigration was independent of body size. The average residence time at sea of the char was 33.6 d, and the maximum was 56 d. The duration of the seawater sojourn was independent of body size. However, the combined time of downstream migration and marine residence was inversely related to body length in early migrating char. Fish that migrated to the sea early tended to stay there longer. The overall return rate ranged from 33.3% for the smallest (15.1–20 cm) to 75.0% for the largest (45.1–50 cm) char, averaging 51.5%. The average return rate for fish shorter than 25.1 cm (first-time migrants) was 42.5%. The upstream run star...

Exposure of spring‐staging pink‐footed geese Anser brachyrhynchus to pesticide‐treated seed

The Svalbard population of pink‐footed geese Anser brachyrhynchus is concentrated in western Jutland, Denmark, from early March to early May. During spring, the geese shift feeding habitat from grasslands and stubble fields to new‐sown fields. To avoid crop damage, grain bait is provided at five sites. The aim of this study was to quantify the exposure of geese to, and the ingestion rates of, pesticide‐treated seeds, and to evaluate the potential effects at the individual and the population level. During spring 1994, approximately 7% and 1 % of the total number of goose‐days were spent on new‐sown cereal fields and new‐sown pea fields, respectively. After the commencement of sowing, about 25% of all goose‐days were spent in new‐sown fields. Late‐departing individually marked geese made more frequent use of new‐sown fields than early‐departing individuals (P < 0.001). Geese foraged intensively in new‐sown fields early in the morning and sometimes late in the evening. Due to high feeding profitability of the new‐sown grain compared to grass, the geese obtained half or more of their daily energy intake by feeding on new‐sown cereal fields, even where bait grain was provided. Spring‐sown barley is treated with the fungicide Imazalil and peas are usually treated with Thiram. The daily Imazalil ingestion rate by an ‘average’ goose was estimated at 9–15 mg active ingredient (a.i.), or 3–‐5 mg a.i./kg body mass, which is two orders of magnitude below reported LD50 values for various species of test birds. Imazalil may have sub‐lethal effects, especially on geese using the new‐sown cereal fields for consecutive days, but the low toxicity and high mobility of the compound suggest that effects are minor and short‐lived. The daily Thiram ingestion rate by the geese was not quantified, but it is calculated that a goose would have to eat about 100 g of peas to reach a level of Thiram ingestion (200 mg/kg diet), which could have sub‐lethal effects on reproductive parameters. A goose foraging on new‐sown peas can accomplish this within less than one hour. Special management precautions should be taken to deter geese from exploiting new‐sown pea fields.

Distribution of polar bears (Ursus maritimus) in the Svalbard area

The distribution and movements of polar bears (Ursus maritimus) in the Svalbard area were studied, using mark and recapture and satellite raido‐telemetry in the period 1988 to 1994. A Total of 172 bears has been captured, mostly in the southern and south‐eastern parts of Svalbard, and 36 females have been tracked by satellite for more than 330 days. Two bears out of 389 tagged in the period 1966 to 1993 have been reported from the Greenland catches, which have been about 100 per year in the same period. About 95% of tracking days and 89% distance covered were from the Norwegian part of the area, the rest were from Russian territory. Minimum polygon home‐range estimates for 36 females, each tracked for more than 330 days, were 69468±79136 Km2. Twenty‐five percent (9/36) of the females have moved eastwards into Russian territory. Only two of them (6%), one of them in two different years, have landed at Franz Josef Land and one at Novaja Zemlja Information on Seasonal fidelity based on the distance from first spring capture location to spring locations in consecutive years exists for 38 female and four male bears. For 30 females, the average distance after one year was 149.3±143.2 km from the first tagging site. After two years the average distance was 78.9±82.5 km for 15 females, after three years the distance was 51.1plusmn; 29.5 km for nine females and after four years 32.0±31.9 km for four. The regression slope between distances and time is negative. The denning locations of 25 of the females were recorded based on satellite data. Twenty‐four of these were at Svalbard and one (4%) at Franz Josef Land. Satellite data combined with mark recapture data show that the polar bears have a very high degree of seasonal fidelity to Svalbard. This suggests that the migration of polar bears between Svalbard and Greenland and between Svalbard and Russia is relatively low and that the Svalbard population of polar bears can be managed as a local population.

Growth and reproduction in island and mainland populations of the vole Microtus epiroticus

The vole Microtus epiroticus was accidentally introduced from Russia to the high arctic archipelago of Svalbard between 30 and 70 years ago. Data on growth patterns were collected in the laboratory for animals originating from the unique Svalbard population and from a population in Finland, close to northern Russia. Gestation period, birth mass, litter size, and age at first reproduction were similar in both populations. Longitudinal growth data were analyzed using polynomial growth curve models. Growth was bimodal, with an early peak at 8–10 days and a later peak at 15 days. The Finnish animals differed from the Svalbard animals by a higher growth rate at 12–15 days. In the field, adult body masses were much greater on Svalbard than in Finland. This difference might have been due to a phenotypic response to the cold arctic climate. We discuss the lack of clear predictions regarding microtine adaptation to the unpredictable arctic environment, and emphasize that in terms of high reproductive rates in mammals, M. epiroticus represents an extreme case.

The occurrence and performance of leucistic Barnacle Geese Branta leucopsis

The paper reports the occurrence of whitish ‘leucistic’ forms in populations of Barnacle Geese Branta leucopsis. A total of 15 (including 11 in the last 21 years) have been reported in the population breeding in Svalbard and wintering in the Solway Firth, northern Britain, whereas the two other populations, though much larger, have produced only one bird of the same type between them in the last 30 years. Leucism is controlled by a single, recessive allele.The median lifespan of leucistic birds is 2–3 years, compared to 8–10 years for normal plumaged birds. This is because they are sought out by (illegal) hunters. There is no evidence that there is any difference in pairing or breeding performance between white and normal birds, though one male, which is still alive aged 18 years, has produced 13 young; this performance is matched fay less than 2% of normal geese.It is suggested that the Svalbard population was established recently, from a few founders from the Siberian population; if one or two of these carried the allele controlling leucism, this would explain its much higher prevalence in this population than in the other discrete groups of Barnacle Geese.

Historical Records of Climate-Related Growth in Cassiope Tetragona from the Arctic

(1) Shoots of the circumpolar species Cassiope tetragona were collected on brief visits to three remote arctic and subarctic sites, two in Svalbard and one in Swedish Lapland. The shoots were subsequently analysed by measuring leaf lengths in strict sequence along individual shoots. (2) This evergreen species retained up to 232 leaves per shoot. Leaf lengths, plotted against leaf position on the shoots, revealed two trends: (i) more or less regular waves caused by the alternation of short spring and autumn leaves with long summer leaves, and (ii) an ontogenetic trend represented by a general increase in leaf length with increasing distance between the point of origin of the leaf and the origin of the shoot. (3) The seasonal trend of leaf length was used to delimit annual complements of leaves, of which up to twenty persisted. The number of leaves was counted for each year and the ontogenetic trend of leaf length was removed by statistical methods so that leaf length indices could be calculated and relative lengths compared, both between years within populations and between populations. Three indices of leaf length were derived: maximum, minimum and the total of all leaf length indices for each year. (4) Correlation analysis between the four measures of annual leaf performance showed several similarities between the two Svalbard populations, a few between the low altitude population from Svalbard and that from Swedish Lapland and none between the higher altitude Svalbard population and that from Swedish Lapland. (5) Correlation analysis between annual leaf performance and mean monthly temperature and monthly total precipitation showed that July temperatures and precipitation during May were particularly important for leaf development in the Svalbard populations. July temperatures represent mid-summer conditions during a very short growing season in Svalbard, whereas May is normally the driest month in this region of generally low precipitation. Ambient temperature is usually sub-zero for most of May and precipitation as snow is probably important in protecting the sensitive shoot apices of C. tetragona which lack true buds. (6) In Swedish Lapland, the number of leaves per year was correlated with summer temperatures but only negatively with precipitation which was greater at the Swedish site than in Svalbard. At the Swedish site, therefore, the protection of leaf primordia from frost is probably greater than in Svalbard because of a more persistent snow cover. (7) Correlations between the number of leaves per year and leaf length indices in the previous year, together with correlations between leaf performance and weather conditions in the previous year, were often significant. In general, the same weather variables were correlated with leaf performance as in the within-year comparisons. (8) The correlations between the number of leaves per year and the other measures of leaf performance and weather in the previous year were particularly strong in the Svalbard populations. This demonstrates the preformation of an annual leaf complement by the High Arctic Svalbard populations. This may be an important mechanism to buffer

Study of the breeding ecology and behaviour of the Svalbard population of Light-bellied Brent Goose Branta bernicla hrota

Nesting ecology and behaviour of the Light-bellied Brent Goose was studied on Luroya and adjacent islands in the Tusenoyane group, SE Svalbard, from 13 June to 30 July 1987. On Luroya 38 pairs attempted to nest, and in the whole study area 98 pairs. Estimated median data of laying of first egg was 10 June, and median hatching date 7 July. Mean clutch size in the middle of the incubation period was 4.0 eggs. On Lurtfya nesting success was 25.7%, hatching success 28.6%, and hatching success for the whole study area was c. 24%. Most losses were attributed to predation (62% of all eggs), polar bears being the most severe predators. Until mid July the islands were surrounded by drift ice, and bears occurred regularly. Bears not only damaged nests but also created disturbance in the nesting colony, offering Arctic Skuas opportunity to take eggs from deserted nests. Other losses were due to female nest desertion during late incubation. Post-hatching losses were negligible. 17 pairs of Barnacle Geese nested on an island adjacent to Luroya, and pairs were nest prospecting on Luroya, but were effectively expelled by territorial Brent males. During nesting, territorial Brent males spent most of the time in vigilance, followed by grazing and resting. Intruding avian predators and other geese were vigorously chased out of the territories. On average females were attentive to their nests 91% of the time. The rest of the time was spent foraging and preening in the territory. During nesting, time off the nest increased. Food resources on the islands were poor. Moss constituted the staple part of the diet during nesting and post-hatching, but the geese selected Cochlearia and Saxifraga. In wet moss carpets where most foraging took place, Cochlearia was almost completely depleted. The high predation pressure observed may be the prime factor responsible for the general low reproductive output of the population, as observed in the Danish wintering quarters. It seems that the Barnacle Goose population on Tusenoyane is expanding, and interspecific competition for nest sites and food may arise.

Study of the breeding ecology and behaviour of the Svalbard population of light-bellied brent goose Branta bernicla hrota

Nesting ecology and behaviour of the Light-bellied Brent Goose was studied on Lurøya and adjacent islands in the Tusenoyane group, SE Svalbard, from 13 June to 30 July 1987. On Lurøya 38 pairs attempted to nest, and in the whole study area 98 pairs. Estimated median data of laying of first egg was 10 June, and median hatching date 7 July. Mean clutch size in the middle of the incubation period was 4.0 eggs. On Lurtfya nesting success was 25.7%, hatching success 28.6%, and hatching success for the whole study area was c. 24%. Most losses were attributed to predation (62% of all eggs), polar bears being the most severe predators. Until mid July the islands were surrounded by drift ice, and bears occurred regularly. Bears not only damaged nests but also created disturbance in the nesting colony, offering Arctic Skuas opportunity to take eggs from deserted nests. Other losses were due to female nest desertion during late incubation. Post-hatching losses were negligible. 17 pairs of Barnacle Geese nested on an island adjacent to Lurøya, and pairs were nest prospecting on Lurøya, but were effectively expelled by territorial Brent males. During nesting, territorial Brent males spent most of the time in vigilance, followed by grazing and resting. Intruding avian predators and other geese were vigorously chased out of the territories. On average females were attentive to their nests 91% of the time. The rest of the time was spent foraging and preening in the territory. During nesting, time off the nest increased. Food resources on the islands were poor. Moss constituted the staple part of the diet during nesting and post-hatching, but the geese selected Cochlearia and Saxifraga. In wet moss carpets where most foraging took place, Cochlearia was almost completely depleted. The high predation pressure observed may be the prime factor responsible for the general low reproductive output of the population, as observed in the Danish wintering quarters. It seems that the Barnacle Goose population on Tusenøyane is expanding, and interspecific competition for nest sites and food may arise.

Relations between Change in Spring Habitat Selection and Daily Energetics of Pink-Footed Geese Anser brachyrhynchus

During the month prior to spring departure to the breeding grounds the Svalbard population of Pink-footed Geese staging in west Jutland, Denmark shifts from pasture to grain feeding on newly sown fields. This paper compares the daily energy expenditure and net energy intake in the two habitats. On pastures the geese spent 80% of the feeding day feeding vs 54% on newly sown barley fields, but due to more frequent disturbance flights in the latter habitat, the estimated daily energy expenditure on pastures was lower (1088 kJ vs 1280 kJ). Daily food intake on pastures was estimated at 158.5 g organic matter and on newly sown fields at 229.8 g organic matter, equivalent to a daily net energy intake of 1267 kJ and 2824 kJ, respectively. The net energy intake per peck during a feeding bout was 14 J on pastures and 219 J on newly sown fields. Thus, from an energetic point of view, feeding on newly sown fields was advantageous compared with feeding on pastures, and the observed habitat shift can be seen as a choice of the most profitable food source. The grain provides sufficient carbohydrates to build up fat reserves for later reproduction, but not sufficient protein.