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Variation in Black Bear Home Ranges in Relation to Preferred Foods in Sequoia & Kings Canyon Nat’l Parks. Rachel Mazur, Karen Folger, and Pete Klimley. Location of Sequoia and Kings Canyon, National Parks within California. Research Questions:
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Variation in Black Bear Home Ranges in Relation to Preferred Foods in Sequoia & Kings Canyon Nat’l Parks Rachel Mazur, Karen Folger, and Pete Klimley
Location of Sequoia and Kings Canyon, National Parks within California
Research Questions: • How much do the sizes of black bear home ranges vary by year? • Is it possible to explain any variation by measuring the availability of critical fall foods? • Are bears exhibiting preferences among habitat types or simply using them in proportion to their availability? • Are there fewer human-bear incidents when bears are foraging on higher quality foods?
Scenario 1 KEY = Summer Habitat Scenario 2 = Fall Habitat = Bear’s Range Scenario 3
GPS Radio Collars • Wild adult female bears • Store-on-board units – programmed to fall off • Locations recorded every hour (Aug-Oct) • 1 Bear in 2004 • 10 Bears each in 2005 and 2006 • 1 Bear had data for both 2004 and 2005 • 5 Bears had data for both 2005 and 2006
Core Area Mapping from GPS points • Kernals used to calculated home ranges using Home Range Tools extension to ArcGIS • Old days used VHF telemetry with a few points to estimate • Core areas are most used areas within Home Range
Total Habitat Area – All Bears Core Habitat Area – All Bears
Variation in annual acorn crops in Sequoia National Park 2004-2006
2005 2006 Relationships between food source availability and core use areas
Scenario 1 KEY = Summer Habitat Scenario 2 = Fall Habitat = Bear’s Range Scenario 3
Research Questions: • How much do the sizes of black bear home ranges vary by year? Depends on food. • Is it possible to explain any variation by measuring the availability of critical fall foods? YES! • Are bears exhibiting preferences among habitat types or simply using them in proportion to their availability? QUALITY! • Are there fewer human-bear incidents when bears are foraging on higher quality foods? YES!
2007 and 2008 Data • 9 Collars on in 2007 for 2 years • Collars to fall off October 31, 2008