Polar Bear Reproductive Biology and Denning
Author: Jack W. Lentfer
Publisher:
Published: 1976
Total Pages: 36
ISBN-13:
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Author: Jack W. Lentfer
Publisher:
Published: 1976
Total Pages: 36
ISBN-13:
DOWNLOAD EBOOKAuthor: Randall W. Davis
Publisher: Springer
Published: 2022-07-05
Total Pages: 0
ISBN-13: 9783030667986
DOWNLOAD EBOOKSea otters and polar bears are carnivorous marine mammals that still resemble their terrestrial ancestors. Compared with Cetacea (whales and dolphins), Sirenia (dugongs and manatees), and Pinnipedia (seals, sea lions, and walrus), they are less adapted for an aquatic life and the most recently evolved among marine mammals. Sea otters are amphibious but seldom come ashore, and polar bears primarily occur on sea ice or along the shore. When at sea, both species spend most of their time swimming at the surface or making short, shallow dives when foraging or pursuing prey. Indeed, polar bears rarely pursue seals in water. Nevertheless, polar bears are powerful swimmers and will stalk seals from the water. As with many other large carnivores, they are solitary hunters. Although sea otters are gregarious and form aggregations at sea called rafts, they are primarily asocial. Except during mating, the principal interaction among sea otters occurs between a female and offspring during the six-month dependency period. In large carnivores (e.g., wolves and lions) that feed on ungulates, sociality and cooperation are favored because of the need to capture large prey and defend carcasses. Polar bears, which are the largest terrestrial carnivore, are solitary hunters of seals and are neither gregarious nor social. Males and females briefly associate during courtship and mating. During this time, males aggressively compete for females. At other times, males generally avoid each other except for aggregations of males that form while summering on land, and females with cubs avoid males, which are known for infanticide. As with sea otters, the interaction of polar bears outside of mating occurs between a female and her offspring during the 2-3 year dependency period. This interaction is critically important when altricial cubs are born in the winter den. This book provides new insight into the ethology and behavioral ecology of sea otters and polar bears. Each chapter reviews the discoveries of previous studies and integrates recent research using new techniques and technology. The authors also address historic and current anthropogenic challenges for their survival as climate change alters entire marine ecosystems.
Author: IUCN/SSC Polar Bear Specialist Group. Working Meeting
Publisher: IUCN
Published: 2006
Total Pages: 202
ISBN-13: 9782831709598
DOWNLOAD EBOOKThese proceedings provide an overview of the ongoing research and management activities on polar bears in the circumpolar arctic. Together with the previous 13 proceedings, they provide an historic record of international efforts in protecting, studying and managing polar bears. With recent documentation of how warmer arctic climate might affect the sea ice habitat of polar bears, the predictions of even warmer climate in the next decades, and documentation of effects on polar bears subpopulations, an evaluation of the red list status of polar bear subpopulations was followed by an increased conservation designation of vulnerable. In the complexity of possible interactions between climate change, local harvest, and in some areas high levels of pollutants, an increased level of international cooperation was advocated.
Author: Jay Wesley Olson
Publisher:
Published: 2015
Total Pages: 60
ISBN-13:
DOWNLOAD EBOOKLoss of sea ice due to global warming may affect the phenology and distribution of polar bear (Ursus maritimus) denning by altering access to denning habitats. We examined trends in the selection of maternal denning substrate (land versus sea-ice denning) in the southern Beaufort Sea (SB), addressing the potential influence of summer land-use and fall sea-ice conditions on substrate selection. We developed an algorithm based on statistical process control methods to remotely identify denning bears and estimate denning phenology from temperature sensor data collected on collars deployed 1985-2013 in the SB and Chukchi Sea (CS). We evaluated cub survival relative to den entrance, emergence, and duration, and examined differences in the phenology of land and sea-ice dens. Land denning in the SB was more common during years when ice retreated farther from the coast and off the continental shelf in September. All SB bears that occupied land prior to denning subsequently denned on land; however, only 29% of denning bears that summered on sea ice denned on land. Den entrance and duration in the SB and CS were similar, although CS bears emerged later. Land dens were occupied longer than those on ice. Bears later observed with cubs remained in dens 23 days longer and emerged from denning 17 days later on average than bears that denned but were subsequently observed without cubs, suggesting that den exit dates are related to cub survival. The increase in land-based denning in the SB when sea ice retreated farther from shore, along with the positive correlation between fall land-use and land denning, suggest that further sea-ice declines may result in continued increases of onshore denning. Growing numbers of denning females along the coast may increase the potential for human-bear interactions.
Author: C. Richard Harington
Publisher:
Published: 1968
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKAuthor: Andrew E. Derocher
Publisher: JHU Press
Published: 2012-03-08
Total Pages: 262
ISBN-13: 1421403056
DOWNLOAD EBOOKPresents an introduction to the polar bear, discussing its evolution, physical characteristics, life cycle, predatory behavior, habitat, and the threats to its existence from global warming.
Author:
Publisher:
Published: 1966
Total Pages: 84
ISBN-13:
DOWNLOAD EBOOKProceedings of the first International Scientific Meeting on the Polar Bear, held in Fairbanks, Alaska in 1965, to report on the current state of knowledge of the biology, ecology and conservation needs of the polar bear (Ursus maritimus) in Alaska, Canada, Greenland, Scandinavia and the Soviet Union.
Author: V. Richard Harington
Publisher:
Published: 1968
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOK"Common denning areas (core areas) for polar bears are northern Greenland, Svalbard, the archipelagos north of the Soviet mainland, and the islands of northern Canada. In autumn, bears are often rafted on broken pack ice to suitable denning places. Some experienced individuals probably find denning areas by their ability to navigate within a region"--Abstract.
Author: International Union for Conservation of Nature and Natural Resources
Publisher: IUCN
Published: 1985
Total Pages: 156
ISBN-13: 2880329000
DOWNLOAD EBOOKAuthor: Thor Larsen
Publisher:
Published: 1986
Total Pages: 60
ISBN-13:
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