Post on 22-Feb-2016
description
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:1. How much do the sizes of black bear home
ranges vary by year?
2. Is it possible to explain any variation by measuring the availability of critical fall foods?
3. Are bears exhibiting preferences among habitat types or simply using them in proportion to their availability?
4. Are there fewer human-bear incidents when bears are foraging on higher quality foods?
Scenario 1
Scenario 2
Scenario 3
= Summer Habitat
= Fall Habitat
KEY
= Bear’s Range
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
1 3 42
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
0
5
10
15
20
25
30
August September October
Month
Size
(km
2)
2004
20052006
0.0
0.5
1.0
1.5
2.0
2.5
3.0
August September October
Month
Size
of C
ore
Area
(km
2) 2004
20052006
Total Habitat Area – All Bears
Core Habitat Area – All Bears
05
1015202530
2004 2005 2006
Year
Cou
nts
acor
ns /
30 s
Canyon Oak
05
1015202530
2004 2005 2006
Year
Cou
nts
acor
ns /
30 s Int. Live Oak
05
1015202530
2004 2005 2006
Year
Cou
nts
acor
ns /
30 s Blue Oak
05
1015202530
2004 2005 2006
Year
Cou
nts
acor
ns /
30 s BlackOak
Variation in annual acorn crops in Sequoia National Park 2004-2006
Sugar Pine Habitat
Oak Habitat
2004 Bear
2005 Bear
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1 2 3 4 5 6 7 8 9
Weeks (September and October)
Log
Valu
esPercentage ofSugar Pine
Size of Core Area
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1 2 3 4 5 6 7 8 9
Weeks (September and October)
Log
of V
alue
s
Percentage of Oak
Size of Core Area
Relationships between food source availability and core use areas
2005
2006
Scenario 1
Scenario 2
Scenario 3
= Summer Habitat
= Fall Habitat
KEY
= Bear’s Range
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
1 2 3 4 5 6 7 8 9 10 11 12 13
Weeks (August - October)
Num
ber o
f Day
s w
ith In
cide
nts
2005
2006
Human-Bear Incidents
Research Questions:1. How much do the sizes of black bear home
ranges vary by year? Depends on food.
2. Is it possible to explain any variation by measuring the availability of critical fall foods? YES!
3. Are bears exhibiting preferences among habitat types or simply using them in proportion to their availability? QUALITY!
4. 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
Please save the bears.