Short-term behavioural response of polar bears (<Emphasis Type="Italic">Ursus maritimus</Emphasis>) to snowmobile disturbance

In this study the distance, at which polar bears detected and actively responded to approaching snowmobiles was measured and the behavioural response was recorded. The study was performed on Svalbard, an arctic island where human traffic has increased substantially in recent years. Fieldwork was conduced in April and/or May during the years 2003–2005. Polar bears were observed on ice with telescopes and binoculars. Undisturbed polar bears were observed continuously and their behaviours recorded, during the time when two snowmobiles moved toward the bear(s). Distances between the bear, the observer, and the approaching snowmobiles were measured using GPS positions taken on the track towards the bear. Data on the behavioural response of 20 encounters with bears were collected. On average, bears were alerted to the snowmobiles at 1,164 m. Mean distance at which the locomotive response occurred was 843 m, and there was a statistical significant difference in distance between sex and age classes [326 m (95% CI = 138–496 m) for adult males; 1,534 m (95% CI = 508–2,768 m) for adult females with cubs; 164 m (95% CI = 49–543 m) for two adult females without cubs; and 1,160 m (95% CI = 375–1,353 m) for single medium sized bears]. The responses of the polar bears to the snowmobiles were categorized according to intensity and persistence of reactions. Females with cubs and single medium sized bears tended to show more intense responses than adult males and lone adult females. Wind direction affects sound and odour transmission, and although an effect on response distance was not found, the response intensity was affected by wind direction. We conclude that female polar bears with small cubs in particular may have a greater risk to be disturbed, since they react at greater distances with amplified reactions; thus, users of snowmobiles should take particular care in areas where females with cubs are present.     

Population substructure and space use of Foxe Basin polar bears

Climate change has been identified as a major driver of habitat change, particularly for sea ice-dependent species such as the polar bear (Ursus maritimus). Population structure and space use of polar bears have been challenging to quantify because of their circumpolar distribution and tendency to range over large areas. Knowledge of movement patterns, home range, and habitat is needed for conservation and management. This is the first study to examine the spatial ecology of polar bears in the Foxe Basin management unit of Nunavut, Canada. Foxe Basin is in the mid-Arctic, part of the seasonal sea ice ecoregion and it is being negatively affected by climate change. Our objectives were to examine intrapopulation spatial structure, to determine movement patterns, and to consider how polar bear movements may respond to changing sea ice habitat conditions. Hierarchical and fuzzy cluster analyses were used to assess intrapopulation spatial structure of geographic position system satellite-collared female polar bears. Seasonal and annual movement metrics (home range, movement rates, time on ice) and home-range fidelity (static and dynamic overlap) were compared to examine the influence of regional sea ice on movements. The polar bears were distributed in three spatial clusters, and there were differences in the movement metrics between clusters that may reflect sea ice habitat conditions. Within the clusters, bears moved independently of each other. Annual and seasonal home-range fidelity was observed, and the bears used two movement patterns: on-ice range residency and annual migration. We predict that home-range fidelity may decline as the spatial and temporal predictability of sea ice changes. These new findings also provide baseline information for managing and monitoring this polar bear population.     

Population ecology of polar bears at Svalbard, Norway

The population ecology of polar bears at Svalbard, Norway, was examined from 1988 to 2002 using live-captured animals. The mean age of both females and males increased over the study, litter production rate and natality declined and body length of adults decreased. Dynamics of body mass were suggestive of cyclical changes over time and variation in body mass of both adult females and adult males was related to the Arctic Oscillation index. Similarly, litter production rate and natality correlated with the Arctic Oscillation index. The changes in age-structure, reproductive rates and body length suggest that recovery from over-harvest continued for almost 30 years after harvest ended in 1973 and that density-dependent changes are perhaps being expressed in the population. However, the variation in reproduction and body mass in the population show a relationship between large-scale climatic variation and the upper trophic level in an Arctic marine ecosystem. Similar change in other polar bear populations has been attributed to climate change, and further research is needed to establish linkages between climate and the population ecology of polar bears.     

Movements of satellite-monitored humpback whales on their feeding ground along the Antarctic Peninsula

Humpback whales were instrumented with satellite transmitters off the western Antarctic Peninsula in January of 2004–2006 to examine their movement patterns and habitat use. Whales were tracked from 4 to 80 days (mean = 36.5 days). Distance and travel rate estimates for nine individuals ranged from 223 to 4,356 km and from 17 to 75 km/day, respectively. Considerable individual variation was observed in direction, speed and range of movements. The overall pattern was characterized by short- and long-distance movements between presumed foraging areas with relatively short residency times. Travel rates were lower at these sites, characterized by erratic movements, than during traveling between them. Area usage for six individuals based on the 95% fixed kernel home range with least squares cross-validation ranged from 2,771 to 172,356 km². The management boundary between the feeding grounds associated with Breeding Stocks G and A needs revision, as current available data suggest it should be located to the east of 50°W. This study is the first to present detailed information on the movements of humpback whales in the Southern Ocean.     

Differences in growth,size and sexual dimorphism in skulls of East Greenland and Svalbard polar bears (<Emphasis Type="Italic">Ursus maritimus</Emphasis>)

Size, growth and sexual dimorphism of nine skull traits was studied in 300 East Greenland and 391 Svalbard polar bears (Ursus maritimus). Two traits were significantly larger in bears from East Greenland compared to Svalbard bears, and trait size was smaller after 1960 in five traits. For both localities and both age groups (subadult, adult), mean trait size values were higher in males than females (all: P < 0.05). Gompertz growth models showed trait size increasing with age in seven traits. Depending on the trait, males reached 95% asymptotic trait size at age 3–10, females at age 2–6. The females of both localities matured at approximately the same age, whereas the Svalbard males generally matured years later than their East Greenland peers. The differences found in the present study between the two polar bear subpopulations support the notion that East Greenland and Svalbard polar bears probably should be managed as separate units.     

Non-invasive detection of candidate pregnancy protein biomarkers in the feces of captive polar bears (Ursus maritimus)

Currently, there is no method of accurately and non-invasively diagnosing pregnancy in polar bears. Specific proteins may exhibit altered profiles in the feces of pregnant bears, but predicting appropriate candidate proteins to investigate is speculative at best. The objective of this study was to identify potential pregnancy biomarker proteins based on their increased abundance in the feces of pregnant polar bears compared to pseudopregnant females (controls) using two-dimensional in-gel electrophoresis (2D-DIGE) and mass spectrometry (MS). Three 2D-DIGE gels were performed to evaluate fecal protein profiles from controls (n = 3) and pregnant polar bears (n = 3). There were 2224.67 ± 52.39 (mean ± SEM) spots resolved per gel. Of these, only five proteins were elevated in the pregnant group (P < 0.05), and seven additional spots tended to be higher (0.05 < P < 0.10). All 12 were submitted for MS analysis and the identities of 11 were ascertained with a >99.9% confidence interval. The 11 spots represented seven distinct proteins, five of which were significantly more abundant in the pregnant group: IgGFc-binding protein, filamin-C, carboxypeptidase B, transthyretin, and immunoglobulin heavy chain variable region. To our knowledge, this was the first study that employed 2D-DIGE to identify differentially expressed proteins in fecal samples to characterize a physiological condition other than those related to gastrointestinal disorders. These promising results provided a strong foundation for ensuing efforts to develop a non-invasive pregnancy assay for use in both captive and wild polar bears.     

Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes

Polar bears (Ursus maritimus) in the northern Alaska region den in coastal areas and on offshore drifting ice. We evaluated changes in the distribution of polar bear maternal dens between 1985 and 2005, using satellite telemetry. We determined the distribution of maternal dens occupied by 89 satellite collared female polar bears between 137°W and 167°W longitude. The proportion of dens on pack ice declined from 62% in 1985–1994 to 37% in 1998–2004 (P = 0.044) and among pack ice dens fewer occurred in the western Beaufort Sea after 1998. We evaluated whether hunting, attraction to bowhead whale remains, or changes in sea ice could explain changes in den distribution. We concluded that denning distribution changed in response to reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season. In consort, these changes have likely reduced the availability and quality of pack ice denning habitat. Further declines in sea ice availability are predicted. Therefore, we expect the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the Alaska coast in advance of denning.     

Fasting physiology of polar bears in relation to environmental change and breeding behavior in the Beaufort Sea

We examined the use of the ratio of serum urea to serum creatinine as a physiological biomarker of fasting to monitor temporal patterns in the feeding ecology of polar bears (Ursus maritimus). Blood was collected from 436 polar bears in the eastern Beaufort Sea during April and May of 1985–1986 and 2005–2006. The proportions of polar bears fasting were 9.6% in 1985, 10.5% in 1986, 21.4% in 2005, and 29.3% in 2006. We used stepwise logistic regression analysis to evaluate factors that could influence the binary response variable of fasting or not fasting. Significant predictor variables of fasting were: the 2005 and 2006 capture years, solitary adult male bears, and adult male bears that were accompanying an estrous female. The increased number of polar bears in a physiological fasting state from all sex, age, and reproductive classes in 2005 and 2006 corresponded with broad scale changes in Arctic sea ice composition, which may have affected prey availability. The higher proportion of adult males fasting from all years was attributed to spring breeding behavior.     

Modified method for external attachment of transmitters to birds using two subcutaneous anchors

ABSTRACT Of the transmitter attachment techniques for birds, the subcutaneous anchor provides a secure attachment that yields relatively few secondary effects. However, the use of subcutaneous anchors has been limited by transmitter size and retention time. Using a modified method of attachment that utilized two subcutaneous anchors, we deployed 69 GPS transmitters, plus 13 VHF transmitters that were similar in size and weight to GPS models, on Pacific Black Brant (Branta bernicla nigricans). Prior to our study, only harnesses were used for attaching GPS transmitters on birds, mainly because GPS transmitters are too large for other external attachment techniques and implantation in the body cavity attenuates the GPS signal. Thus, to increase the size capacity of anchor attachment and to avoid the well‐documented negative effects of harnesses on behavior and survival, we added a second anchor at the transmitter's posterior end. The double‐anchor attachment technique was quickly and easily accomplished in the field, requiring bird handling times of <10 min. Incidental recoveries of tagged Brant indicate a high degree of transmitter retention. Five recaptured birds (4–6 weeks after deployment) and eight killed by hunters (3–6 mo after deployment) retained their GPS transmitters. For studies involving the use of relatively large transmitters, the double‐anchor method appears to provide a viable alternative for external attachment.     

Movements and dive behaviour of two leopard seals (<Emphasis Type="Italic">Hydrurga leptonyx</Emphasis>) off Queen Maud Land,Antarctica

Two adult female leopard seals (Hydrurga leptonyx) were tagged with satellite-linked dive recorders off Queen Maud Land, Antarctica, just after moulting in mid-February. The transmitters transmitted for 80 and 220 days, respectively. Both seals remained within the pack ice relatively close to the Antarctic Continent until early May, when contact was lost with one seal. The one remaining seal then migrated north, to the east side of the South Sandwich Islands in 3 weeks, whereafter it headed east, until contact was lost at 55°S in early September. From mid-May to late September this animal always stayed close to the edge of the pack ice. Both seals made mostly short (<5 min) dives to depths of 10–50 m and only occasionally dove deeper than 200 m, the deepest dive recorded being 304 m. A nocturnal diving pattern was evident in autumn and early winter, while day-time diving prevailed in mid-winter. Haul out probability was highest at mid-day (about 40% in late February and more than 80% in March and April). From May till September the remaining animal mainly stayed at sea, in the vicinity of the pack ice, with only occasional haul outs. These data suggest that a portion of the adult leopard seals may spend the winter mainly in open water, off the edge of the pack ice, where they primarily hunt near the surface. In that case, it is likely that krill (Euphausia superba), as well as penguins, young crabeater seals (Lobodon carcinophaga) and a variety of fish are important prey items.     

Population parameters and harvest risks for polar bears (<Emphasis Type="Italic">Ursus maritimus</Emphasis>) of Kane Basin,Canada and Greenland

We estimated demographic parameters and current harvest risks for a population of polar bears (Ursus maritimus Phipps) inhabiting northern Smith Sound and Kane Basin, Canada and Greenland. Our demographic analysis included a detailed assessment of age- and sex-specific survival and recruitment from 141 marked polar bears, using information contained within the standing age distribution of captures and mark-recapture analysis. Total survival rates for females were: 0.374 ± 0.180 (cubs), 0.686 ± 0.157 (ages 1–4), and 0.967 ± 0.043 (ages 5+). Mean litter size was 1.67 ± 0.08 cubs. Females did not reproduce until at least age 6, which is late compared to other populations of polar bears. The model-averaged, mark–recapture estimate of mean abundance (±1 SE) for years 1994–1997 was 164 ± 35 bears. We incorporated demographic parameters and their variances into a harvest risk analysis (i.e., a stochastic, harvested population viability analysis, PVA). Results suggest that polar bears in the region were severely over-harvested during the mark–recapture interval (1992–1997). The current status of the population is unknown.     

Estimating the energy expenditure of free‐ranging polar bears using tri‐axial accelerometers: A validation with doubly labeled water

Measures of energy expenditure can be used to inform animal conservation and management, but methods for measuring the energy expenditure of free‐ranging animals have a variety of limitations. Advancements in biologging technologies have enabled the use of dynamic body acceleration derived from accelerometers as a proxy for energy expenditure. Although dynamic body acceleration has been shown to strongly correlate with oxygen consumption in captive animals, it has been validated in only a few studies on free‐ranging animals. Here, we use relationships between oxygen consumption and overall dynamic body acceleration in resting and walking polar bears Ursus maritimus and published values for the costs of swimming in polar bears to estimate the total energy expenditure of 6 free‐ranging polar bears that were primarily using the sea ice of the Beaufort Sea. Energetic models based on accelerometry were compared to models of energy expenditure on the same individuals derived from doubly labeled water methods. Accelerometer‐based estimates of energy expenditure on average predicted total energy expenditure to be 30% less than estimates derived from doubly labeled water. Nevertheless, accelerometer‐based measures of energy expenditure strongly correlated (r² = 0.70) with measures derived from doubly labeled water. Our findings highlight the strengths and limitations in dynamic body acceleration as a measure of total energy expenditure while also further supporting its use as a proxy for instantaneous, detailed energy expenditure in free‐ranging animals.     

A wireless communication system for determining site fidelity of juvenile dusky groupers Epinephelus marginatus (Lowe, 1834) using coded acoustic transmitters

The value of marine reserves to protect threatened and vulnerable species, such as the dusky grouper (Epinephelus marginatus), is often uncertain because of a lack of knowledge about their ecology and habitat utilisation. To address this issue, a Wireless Communication System for location-based positioning of fish tagged with coded acoustic transmitters was installed to determine site fidelity of juvenile dusky groupers (mean total length = 30.4 cm, range: 20.5–40.0 cm; mean total weight = 470 g, range: 113–950 g) within a marine reserve (Island of Ustica, Sicily, Italy). The system was based on five wireless hydrophones distributed approximately 200 m apart along the coastline of the reserve, each monitoring acoustic signals from transmitters within a reception cell. The hydrophones retransmitted detected signals as a radio signal to a land-based receiver and data logger. Unique identifiers for each hydrophone permitted the identification of the detection cell containing the tagged fish. The wireless hydrophones had partly overlapping detection ranges, dividing the marine reserve into more than five different detection cells. The average detection range was 232 m, but coverage varied from site to site and with time, depending on many factors, such as ambient noise, wave action and signal strength of the transmitters. Despite some limitations, the Wireless Hydrophone System (WHS) combined with manual tracking provided a valuable tool for investigating site fidelity in the dusky grouper. Preliminary home ranges for the fish were estimated by the kernel method (probability level of 95%), based on a limited set of manual tracking data, to be a median 5312 m² (range 1673–18626 m²).