Barlow J.,Southwest Fisheries Science Center |
Calambokidis J.,Cascadia Research Collective |
Falcone E.A.,Southwest Fisheries Science Center |
Falcone E.A.,Cascadia Research Collective |
And 17 more authors.
Marine Mammal Science | Year: 2011
We estimated the abundance of humpback whales in the North Pacific by capture-recapture methods using over 18,000 fluke identification photographs collected in 2004-2006. Our best estimate of abundance was 21,808 (CV = 0.04). We estimated the biases in this value using a simulation model. Births and deaths, which violate the assumption of a closed population, resulted in a bias of +5.2%, exclusion of calves in samples resulted in a bias of -10.5%, failure to achieve random geographic sampling resulted in a bias of -0.4%, and missed matches resulted in a bias of +9.3%. Known sex-biased sampling favoring males in breeding areas did not add significant bias if both sexes are proportionately sampled in the feeding areas. Our best estimate of abundance was 21,063 after accounting for a net bias of +3.5%. This estimate is likely to be lower than the true abundance due to two additional sources of bias: individual heterogeneity in the probability of being sampled (unquantified) and the likely existence of an unknown and unsampled breeding area (-8.7%). Results confirm that the overall humpback whale population in the North Pacific has continued to increase and is now greater than some prior estimates of prewhaling abundance. © 2011 by the Society for Marine Mammalogy Published 2011. This article is a US Government work and is in the public domain in the USA.
Baker C.S.,Oregon State University |
Steel D.,Oregon State University |
Calambokidis J.,Cascadia Research Collective |
Falcone E.,Cascadia Research Collective |
And 15 more authors.
Marine Ecology Progress Series | Year: 2013
ABSTRACT: We quantified the relative influence of maternal fidelity to feeding grounds and natal fidelity to breeding grounds on the population structure of humpback whales Megaptera novae - angliae based on an ocean-wide survey of mitochondrial (mt) DNA diversity in the North Pacific. For 2193 biopsy samples collected from whales in 10 feeding regions and 8 breeding regions during the winter and summer of 2004 to 2006, we first used microsatellite genotyping (average, 9.5 loci) to identify replicate samples. From sequences of the mtDNA control region (500 bp) we identified 28 unique haplotypes from 30 variable sites. Haplotype frequencies differed markedly among feeding regions (overall FST = 0.121, FST = 0.178, p > 0.0001), supporting previous evidence of strong maternal fidelity. Haplotype frequencies also differed markedly among breeding regions (overall FST = 0.093, FST = 0.106, p > 0.0001), providing evidence of strong natal fidelity. Although sex-biased dispersal was not evident, differentiation of microsatellite allele frequencies was weak compared to differentiation of mtDNA haplotypes, suggesting male-biased gene flow. Feeding and breeding regions showed significant differences in haplotype frequencies, even for regions known to be strongly connected by patterns of individual migration. Thus, the influence of migratory fidelity seems to operate somewhat independently on feeding and breeding grounds over an evolutionary time scale. This results in a complex population structure and the potential to define multiple units to conserve in either seasonal habitat.© Inter-Research 2013. www.int-res.com.
Chenoweth E.M.,Glacier Bay National Park |
Gabriele C.M.,Glacier Bay National Park |
Hill D.F.,Oregon State University
Marine Ecology Progress Series | Year: 2011
In order to design marine protected areas that are ecologically meaningful, it would be useful to improve our understanding of headland wake foraging systems, which are commonly exploited by baleen whales and other mobile marine predators. We used humpback whale Megaptera novaeangliae sighting data from 1997 to 2008 in combination with tidal prediction software to investigate the effects of current direction (ebb vs. flood) and tidal amplitude on the distribution and abundance of humpback whales around 3 headlands and 5 non-headlands in Glacier Bay and Icy Strait in southeastern Alaska, USA. Headlands were defined as points of land that disrupt tidal flow creating distinct tideward and leeward conditions. We used an advanced tidal circulation model (ADCIRC) to identify these conditions. Current direction and tidal amplitude each significantly affected whale distribution at only one non-headland (χ 2 = 6.1, p < 0.01; χ 2 = 13, p = 0.002, respectively). At all 3 headlands, current direction significantly affected whale distribution (p < 0.0001). Whale abundance was greater in the leeward areas. Tidal amplitude significantly affected distribution at the 3 headlands (χ 2 = 97, p < 0.0001; χ 2 = 75, p < 0.0001; χ 2 = 6.1, p = 0.05) such that whales selected habitat that moderated, rather than maximized, the effect of tidal amplitude, suggesting that headlands also have the potential to be important features in areas with less extreme tidal exchange. © Inter-Research 2011.
News Article | September 7, 2016
Trees are dying across Yosemite and Yellowstone national parks. Glaciers are melting in Glacier Bay National Park and Preserve in Alaska. Corals are bleaching in Virgin Islands National Park. Published field research conducted in U.S. national parks has detected these changes and shown that human climate change – carbon pollution from our power plants, cars and other human activities – is the cause. As principal climate change scientist of the U.S. National Park Service, I conduct research on how climate change has already altered the national parks and could further change them in the future. I also analyze how ecosystems in the national parks can naturally reduce climate change by storing carbon. I then help national park staff to use the scientific results to adjust management actions for potential future conditions. Research in U.S. national parks contributes in important ways to global scientific understanding of climate change. National parks are unique places where it is easier to tell if human climate change is the main cause of changes that we observe in the field, because many parks have been protected from urbanization, timber harvesting, grazing and other nonclimate factors. The results of this research highlight how urgently we need to reduce carbon pollution to protect the future of the national parks. Human-caused climate change has altered landscapes, water, plants and animals in our national parks. Research in the parks has used two scientific procedures to show that this is occurring: detection and attribution. Detection is the finding of statistically significant changes over time. Attribution is the analysis of the different causes of the changes. Around the world and in U.S. national parks, snow and ice are melting. Glaciers in numerous national parks have contributed to the global database of 168 000 glaciers that the Intergovernmental Panel on Climate Change (IPCC) has used to show that human climate change is melting glaciers. Field measurements and repeat photography show that Muir Glacier in Glacier Bay National Park and Preserve in Alaska lost 640 meters to melting from 1948 to 2000. In Glacier National Park in Montana, Agassiz Glacier receded 1.5 kilometers from 1926 to 1979. Snow measurements and tree cores from Glacier National Park, North Cascades National Park, and other national parks contributed to an analysis showing that snowpack across the western U.S. has dropped to its lowest level in eight centuries. On land, climate change is shifting the ranges where plants grow. A global analysis that colleagues and I published in 2010 found that, around the world, climate change has shifted biomes – major types of vegetation, such as forests and tundra – upslope or toward the poles or the Equator. This type of research requires long-term monitoring of permanent plots or reconstruction of past vegetation species distributions using historical information or analyses of tree rings or other markers of the past. In the African Sahel, I uncovered a biome shift by hiking 1,900 kilometers, counting thousands of trees, reconstructing past tree species distributions through verified interviews with village elders and counting thousands of trees on historical aerial photos. Research has documented biome shifts in U.S. national parks. In Yosemite National Park, subalpine forest shifted upslope into subalpine meadows in the 20th century. In Noatak National Preserve, Alaska, boreal conifer forest shifted northward into tundra in the 19th and 20th centuries. Wildlife is also shifting. In Yosemite National Park, scientists compared the species of small mammals they captured in 2006 to the species originally captured along an elevation transect from 1914 to 1920 and showed that climate change shifted the ranges of the American pika and other species 500 meters upslope. Across the United States, the Audubon Society organizes its annual Christmas Bird Count in numerous national parks and other sites. Analyses of bird species results from 1975 to 2004 and possible local causes of changing distributions found that climate change shifted the winter ranges of a set of 254 bird species northward. Examples include northward shifts of the evening grosbeak (Coccothraustes vespertinus) in Shenandoah National Park and the canyon wren (Catherpes mexicanus) in Santa Monica Mountains National Recreation Area. Climate change is driving wildfires in and around many national parks in western states. Fire is natural and we need it to periodically renew forests, but too much wildfire can damage ecosystems and burn into towns and cities. Field data from 1916 to 2003 on wildfire in national parks and across the western U.S. show that, even during periods when land managers actively suppressed wildfires, fluctuations in the area that burned each year correlated with changes in temperature and aridity due to climate change. Reconstruction of fires of the past 2,000 years in Sequoia and Yosemite national parks confirms that temperature and drought are the dominant factors explaining fire occurrence. Climate change is killing trees due to increased drought, changes in wildfire patterns and increased bark beetle infestations. Tracking of trees in Kings Canyon, Lassen Volcanic, Mount Rainier, Rocky Mountain, Sequoia and Yosemite National Parks has contributed to a database that revealed how climate change has doubled tree mortality since 1955 across the western United States. High ocean temperatures due to climate change have bleached and killed coral. In 2005, hot sea surface temperatures killed up to 80 percent of coral reef area at sites in Biscayne National Park, Buck Island Reef National Monument, Salt River Bay National Historical Park and Ecological Preserve, Virgin Islands National Park and Virgin Islands Coral Reef National Monument. When the U.S. Congress established the National Park Service a century ago, it directed the agency to conserve the natural and cultural resources of the parks in ways to leave them “unimpaired for the enjoyment of future generations.” By altering the globally unique landscapes, waters, plants and animals of the national parks, climate change challenges the National Park Service to manage the parks for potential future conditions rather than as little pictures of a past to which we can no longer return. For example, Yosemite National Park resource managers plan to use climate change data to target prescribed burns and wildland fires in areas that will be different from the areas selected using estimates of fire distributions from the 1850s. At Golden Gate National Recreation Area, resource managers have examined stewardship plans resource-by-resource to develop actions that account for climate change. At Everglades National Park, managers are using sea level rise data to help plan management of coastal areas. It is in our power to reduce carbon pollution from cars, power plants and deforestation and prevent the most drastic consequences of climate change. In the face of climate change, we can help protect our most treasured places – the national parks. From Patrick Gonzalez, Principal Climate Change Scientist, National Park Service. This article was originally published on The Conversation. Read the original article.
Hoekman S.T.,University of Alaska Fairbanks |
Moynahan B.J.,National Park Service |
Lindberg M.S.,University of Alaska Fairbanks |
Sharman L.C.,Glacier Bay National Park |
Johnson W.F.,National Park Service
Marine Ornithology | Year: 2011
We assessed boat-based line transect sampling for monitoring population status and trend of the Kittlitz's Murrelet Brachyramphus brevirostris in Glacier Bay National Park and Preserve, Alaska. We used field experiments to compare efficiency of one versus two observers and to test the assumption that detection near the transect center line was 100%. Because coexisting Kittlitz's Murrelets and Marbled Murrelets B. marmoratus cannot always be distinguished on sight, we developed analytic methods to account for unidentified murrelets in density estimates. Relative to one observer, two observers had 56% higher encounter rates, a >20% higher probability of species identification, and better met the criteria for robust estimation of detection probability. More encounters also increase precision of estimated detection probability and group size. We estimated detection probability near the transect center line to be 0.94 (SE 0.03) and considered methods to relax the assumption of complete detection near the transect center line when estimating density. Relative to methods that exclude unidentified birds (53% of observations), analytic methods incorporating unidentified murrelets increased density estimates for both Kittlitz's and Marbled murrelets by >100% and reduced coefficients of variation by 9% and 15%, respectively. Failure to account for unidentified murrelets and for incomplete detection near the transect center line creates substantial and variable bias and error in density estimates, lessening the ability to assess population status and trend. We recommend the use of two observers, periodic calibration of detection near the transect center line and its incorporation into density estimates, and the use of skilled observers coupled with analytic methods to account for unidentified murrelets.