The effect of The effect of arthropods on arthropods on Dipodomys Dipodomys spectabilis spectabilis food food stores and storing stores and storing behaviorbehavior

By: Amanda SchauppBy: Amanda Schaupp

Mentor: Jose Herrera Mentor: Jose Herrera

What is a kangaroo rat?What is a kangaroo rat?

Granivorous rodentGranivorous rodent Desert grassland ecosystemDesert grassland ecosystem Are distributed in Are distributed in

Southwestern U.S and Mexico Southwestern U.S and Mexico Ecosystem engineers Ecosystem engineers Evolutionary adapted to use Evolutionary adapted to use

only metabolic wateronly metabolic water Seed diet Seed diet Morphological adaptations Morphological adaptations

Kangaroo rats on Kangaroo rats on SevilletaSevilleta

Dipodomys ordiiDipodomys ordii Dipodomys merriamiDipodomys merriami Dipodomys spectabilis Dipodomys spectabilis (banner-tail)(banner-tail)

Biggest in SevilletaBiggest in Sevilleta White-tipped tailWhite-tipped tail

Dipodomys ordiiDipodomys ordii

Dipodomys Dipodomys merriamimerriami

Dipodomys Dipodomys spectabilisspectabilis

Storing behavior of Storing behavior of banner-tail banner-tail

Store seed caches in moundsStore seed caches in mounds Stashed vertically inside wall of moundStashed vertically inside wall of mound Store seed caches for hibernation Store seed caches for hibernation

But how do they do this But how do they do this and why?and why?

Den Seed Caches

Hypothesis on storing Hypothesis on storing behavior of banner-tailbehavior of banner-tail

Preliminary hypothesis: banner-tail stick the stalk in their mouth, push it back quickly, bite, and do this continuously

Added onto hypothesis later: spit seed caches out and push forward onto inside wall of the mound

MethodsMethods

Trapped using Trapped using Sherman trapsSherman traps

Place 3 stalks of Place 3 stalks of Sporobolus Sporobolus cryptandrus cryptandrus (sand dropseed) (sand dropseed) in terrarium in terrarium

Conducted video Conducted video recordings using recordings using red light from red light from 4am-7am4am-7am

VideoVideo

Why place the seeds Why place the seeds vertically?vertically? Fungal TheoryFungal Theory

Fungal growth caused by amount of Fungal growth caused by amount of moisture in denmoisture in den

Horizontally placed stacks containing Horizontally placed stacks containing seeds would imbibe waterseeds would imbibe water

Behavioral HypothesisBehavioral Hypothesis Vertically placed seed caches are more Vertically placed seed caches are more

difficult for ants and arthropods to difficult for ants and arthropods to harvest harvest

Den Seed Caches

What steals the seed What steals the seed caches?caches?

Ants are the primary seed stealersAnts are the primary seed stealers Watched them carry away seed Watched them carry away seed

stems and leave empty shellsstems and leave empty shells

Methods of behavioral Methods of behavioral hypothesishypothesis

Used kangaroo rat exclusion trap Used kangaroo rat exclusion trap and dug shallow hole in moundand dug shallow hole in mound

Seed caches placed in mound Seed caches placed in mound vertically, horizontally, and vertically, horizontally, and scatteredscattered

Kangaroo Rat Exclusion Trap

Vertical

Horizontal

Scattered

Hypothesis on arthropod Hypothesis on arthropod behavior behavior

Assumed that scattered seeds would be Assumed that scattered seeds would be taken first, followed by horizontal, and taken first, followed by horizontal, and then verticalthen vertical

Reasoning behind this is optimal Reasoning behind this is optimal foragingforaging

Results of arthropod Results of arthropod behaviorbehavior Used separate two-way ANOVAs Used separate two-way ANOVAs

with stalk orientation and den with stalk orientation and den activity as main factorsactivity as main factorsPercentage of Sporobolus cryptandrus caches taken

0

10

20

30

40

50

60

70

Vertical Horizontal Scattered

Orientation

Per

cen

tag

e ta

ken

Active

Inactive

Percentage of Sporobolus crytandrus caches taken

0

10

20

30

40

50

60

70

Vertical Horizontal Scattered

Orientation

Per

cen

tag

e ta

ken

Active

Inactive

Effect of orientation F=0.74, df=2, p=.48

Effect of den activity F=2.45, df=2, p=.1263

F=0.09, df=2, p=.9141

F=1.71, df=2, p=.1993

Trial 1 Trial 1 Trial 2Trial 2

ConclusionConclusion Kangaroo rats store seed caches Kangaroo rats store seed caches

vertically in moundvertically in mound Possible reasons arePossible reasons are

Fungal TheoryFungal Theory Behavioral HypothesisBehavioral Hypothesis Or maybe something else?Or maybe something else?

AcknowledgementsAcknowledgements University of New MexicoUniversity of New Mexico Sevilleta National Wildlife RefugeSevilleta National Wildlife Refuge Sevilleta LTERSevilleta LTER National Science FoundationNational Science Foundation US Fish and Wildlife ServiceUS Fish and Wildlife Service Jose Herrera and his studentsJose Herrera and his students Jennifer JohnsonJennifer Johnson 2009 Sevilleta REUs2009 Sevilleta REUs 2009 Sevilleta Interns 2009 Sevilleta Interns

Questions?Questions?