Temporal Niche Switching By Grizzly Bears But Not American Black Bears In Yellowstone National Park
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Temporal Niche Switching By Grizzly Bears But Not American Black Bears In Yellowstone National Park
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Author : Jennifer Kay Fortin
language : en
Publisher:
Release Date : 2013
Temporal Niche Switching By Grizzly Bears But Not American Black Bears In Yellowstone National Park written by Jennifer Kay Fortin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Black bear categories.
Grizzly bears (Ursus arctos) have been reported as either nocturnal or diurnal in various studies, but have not been known to switch between the 2 times unless disturbed by humans. Black bears (Ursus americanus) are almost solely diurnal in studies unless human influences occur. Because human disturbance is often difficult to control, the relative temporal niche of both species remains ill-defined. Thus, the present study examined bears in Yellowstone National Park (Wyoming) where hunting does not occur, human activities are relatively benign, and bear species are sympatric to determine if niche occupancy was a stable feature of the species. Onset of activity was anticipatory of both sunrise or morning civil twilight (illumination sufficient for human vision) for individuals of either species. The peak hour of activity in black bears was consistently midday, but fluctuated in grizzly bears from midday during early spring, late summer, and fall to evening during late spring and early summer. Black bears did not temporally avoid the times when the more dominant grizzly bears were active. Mean activity levels were higher for male black bears than for both male and female grizzly bears. Together, results suggest that the foraging needs of black bears necessitate ingestion of less-digestible, lower-quality foods requiring longer foraging time during daytime hours, whereas grizzly bears adapt their diet to seasonally available food sources, necessitating greater temporal flexibility.
Niche Separation Of Grizzly Ursus Arctos And American Black Bears Ursus Americanus In Yellowstone National Park
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Author : Jennifer Kay Fortin
language : en
Publisher:
Release Date : 2011
Niche Separation Of Grizzly Ursus Arctos And American Black Bears Ursus Americanus In Yellowstone National Park written by Jennifer Kay Fortin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Black bear categories.
Yellowstone Grizzly Bears
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Author : Daniel D. Bjornlie
language : en
Publisher: National Park Service Yellowstone National Park
Release Date : 2017
Yellowstone Grizzly Bears written by Daniel D. Bjornlie and has been published by National Park Service Yellowstone National Park this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Bear populations categories.
Dietary Adjustability Of Grizzly Bears And American Black Bears In Yellowstone National Park
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Author : Jennifer Kay Fortin
language : en
Publisher:
Release Date : 2013
Dietary Adjustability Of Grizzly Bears And American Black Bears In Yellowstone National Park written by Jennifer Kay Fortin and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Black bear categories.
Grizzly bears (Ursus arctos) and American black bears (U. americanus) are sympatric in much of Yellowstone National Park. Three primary bear foods, cutthroat trout (Oncorhynchus clarki), whitebark pine (Pinus albicaulis) nuts, and elk (Cervus elaphus), have declined in recent years. Because park managers and the public are concerned about the impact created by reductions in these foods, we quantified bear diets to determine how bears living near Yellowstone Lake are adjusting. We estimated diets using: 1) stable isotope and mercury analyses of hair samples collected from captured bears and from hair collection sites established along cutthroat trout spawning streams and 2) visits to recent locations occupied by bears wearing Global Positioning System collars to identify signs of feeding behavior and to collect scats for macroscopic identification of residues. Approximately 45 ± 22% ([x bar] ± SD) of the assimilated nitrogen consumed by male grizzly bears, 38 ± 20% by female grizzly bears, and 23 ± 7% by male and female black bears came from animal matter. These assimilated dietary proportions for female grizzly bears were the same as 10 years earlier in the Lake area and 30 years earlier in the Greater Yellowstone Ecosystem. However, the proportion of meat in the assimilated diet of male grizzly bears decreased over both time frames. The estimated biomass of cutthroat trout consumed by grizzly bears and black bears declined 70% and 95%, respectively, in the decade between 1997?2000 and 2007?2009. Grizzly bears killed an elk calf every 4.3 ± 2.7 days and black bears every 8.0 ± 4.0 days during June. Elk accounted for 84% of all ungulates consumed by both bear species. Whitebark pine nuts continue to be a primary food source for both grizzly bears and black bears when abundant, but are replaced by false-truffles (Rhizopogon spp.) in the diets of female grizzly bears and black bears when nut crops are minimal. Thus, both grizzly bears and black bears continue to adjust to changing resources, with larger grizzly bears continuing to occupy a more carnivorous niche than the smaller, more herbivorous black bear.
Temporal Spatial And Environmental Influences On The Demographics Of Grizzly Bears In The Greater Yellowstone Ecosystem
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Author :
language : en
Publisher:
Release Date : 2006
Temporal Spatial And Environmental Influences On The Demographics Of Grizzly Bears In The Greater Yellowstone Ecosystem written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with Bears categories.
During the past 2 decades, the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem (GYE) has increased in numbers and expanded in range. Understanding temporal, environmental, and spatial variables responsible for this change is useful in evaluating what likely influenced grizzly bear demographics in the GYE and where future management efforts might benefit conservation and management. We used recent data from radio-marked bears to estimate reproduction (1983-2002) and survival (1983-2001); these we combined into models to evaluate demographic vigor (lambda [k]). We explored the influence of an array of individual, temporal, and spatial covariates on demographic vigor. -- Abstract, first paragraph.
Canadian Journal Of Zoology
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Author :
language : en
Publisher:
Release Date : 2014
Canadian Journal Of Zoology written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Zoology categories.
General Technical Report Int
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Author :
language : en
Publisher:
Release Date : 1986
General Technical Report Int written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with Forests and forestry categories.
Bears Of The World
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Author : Vincenzo Penteriani
language : en
Publisher: Cambridge University Press
Release Date : 2020-11-30
Bears Of The World written by Vincenzo Penteriani and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-11-30 with Nature categories.
Bears have fascinated people since ancient times. The relationship between bears and humans dates back thousands of years, during which time we have also competed with bears for shelter and food. In modern times, bears have come under pressure through encroachment on their habitats, climate change, and illegal trade in their body parts, including the Asian bile bear market. The IUCN lists six bears as vulnerable or endangered, and even the least concern species, such as the brown bear, are at risk of extirpation in certain countries. The poaching and international trade of these most threatened populations are prohibited, but still ongoing. Covering all bears species worldwide, this beautifully illustrated volume brings together the contributions of 200 international bear experts on the ecology, conservation status, and management of the Ursidae family. It reveals the fascinating long history of interactions between humans and bears and the threats affecting these charismatic species.
Proceedings Grizzly Bear Habitat Symposium
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Author :
language : en
Publisher:
Release Date : 1986
Proceedings Grizzly Bear Habitat Symposium written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with Forests and forestry categories.
Grizzly Bear Recovery Plan
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Author : Christopher Servheen
language : en
Publisher:
Release Date : 1997
Grizzly Bear Recovery Plan written by Christopher Servheen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Government publications categories.