Browsing by Author "Jacobson, Andrew"

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    Brown Hyena (Hyaena brunnea) Distribution: Nuances in Modeling a Generalist Species
    (2020-04-24) Killea, Allison
    The brown hyena plays a critical role as a top carnivore across southern Africa alongside other megafauna including lions and cheetahs. However, because it is perceived to face fewer threats to its population, there are fewer research efforts aimed at understanding its distribution and spatial ecology. The Hyaena Distribution Mapping Project in partnership with the IUCN Hyaena Specialist Group is currently working to update the global range map of the brown hyena. A critical follow up to this work is the creation of a species distribution model to better understand the environmental factors that affect their spatial ecology. However, given the wide variation of habitat types within the hyena’s range, a single model may not be sufficient to capture the nuances within their global distribution. I created a global model of the brown hyena as well as two biome specific models, one for Deserts and Xeric Shrublands and one for Tropical and Subtropical Grasslands, Savannas, and Shrublands as defined by the World Wildlife Fund. I propose that brown hyena ecology varies based on the specific ecosystem of an individual and that by modeling their distribution at a biome level we can better predict potential habitat. However, a general model may still be informative as hyenas do range widely, and one individual can take advantage of a variety of habitats. By comparing these models and their performance, we can create a more robust description of how brown hyena ecology varies throughout southern Africa.
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    Prioritizing land for conservation purposes in East Maui, Hawai'i
    (2010-04-30T16:19:23Z) Jacobson, Andrew
    Hawai’i has 25% of the United States’ federally listed endangered species and nearly 75% of the nation’s recorded extinctions. Although no such list or datasets exists for cultural and historical landmarks, these resources may be similarly threatened. Of the eight major Hawaiian Islands, Maui is the second largest and has the third largest population. The average number of daily visitors has increased 333% to 51,222 people from 1980 to 2007. The history of grazing and agriculture along with increasing resident and tourist populations has placed pressure on Maui’s resources. East Maui is the least developed part of the island and may be in a critical time period before becoming over-developed. Therefore, this study seeks to identify the parcels with the most relevant and important resources in and for the region today. Using primarily local interviews and historical data, I developed a conservation dataset linked to the region’s tax parcels. The data were categorized into five resource groups: biological, recreational, cultural, historical and other. With the creation of a GIS-based tool, these categories can be given user-defined weights to highlight different conservation priorities. This will function as a decision support tool that will allow the land trust to explore different protection scenarios. This data, tool and document should provide a framework from which the land trust can base future conservation decisions regarding East Maui. I conducted eight different scenarios and selected parcels with the highest values, or greatest conservation importance. These parcels were compared across the scenarios. These analyses highlighted that historical resources are relatively under-protected, that many resources are concentrated in a limited number of parcels, and that many top parcels are proximate to county-designated growth boundaries. These results should incentivize the conservation community; protecting a few parcels can save a significant number of resources and that action should be taken soon before development is proposed.
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    The size of savannah Africa: A lion's (Panthera leo) view
    (Biodiversity and Conservation, 2013-01-01) Riggio, Jason; Jacobson, Andrew; Dollar, Luke; Bauer, Hans; Becker, Matt; Dickman, Amy; Funston, Paul; Groom, Rosemary; Henschel, Philipp; de Iongh, Hans; Lichtenfeld, Laly; Pimm, Stuart
    We define African savannahs as being those areas that receive between 300 and 1,500 mm of rain annually. This broad definition encompasses a variety of habitats. Thus defined, savannahs comprise 13.5 million km2 and encompass most of the present range of the African lion (Panthera leo). Dense human populations and extensive conversion of land to human use preclude use by lions. Using high-resolution satellite imagery and human population density data we define lion areas, places that likely have resident lion populations. In 1960, 11.9 million km2 of these savannahs had fewer than 25 people per km2. The comparable area shrank to 9.7 million km2 by 2000. Areas of savannah Africa with few people have shrunk considerably in the last 50 years and human population projections suggest they will likely shrink significantly in the next 40. The current extent of free-ranging lion populations is 3.4 million km2 or about 25 % of savannah area. Habitats across this area are fragmented; all available data indicate that between 32,000 and 35,000 free-ranging lions live in 67 lion areas. Although these numbers are similar to previous estimates, they are geographically more comprehensive. There is abundant evidence of widespread declines and local extinctions. Under the criteria we outline, ten lion areas qualify as lion strongholds: four in East Africa and six in Southern Africa. Approximately 24,000 lions are in strongholds, with an additional 4,000 in potential ones. However, over 6,000 lions are in populations of doubtful long-term viability. Lion populations in West and Central Africa are acutely threatened with many recent, local extinctions even in nominally protected areas. © 2012 The Author(s).