Chihuahuan Desert Lizard Abundance in Gunnisons Prairie Dog Habitat: Do Lizards Prefer Prairie Dog C

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Chihuahuan Desert Lizard Abundance in Gunnisons
Prairie Dog Habitat Do Lizards Prefer Prairie
Dog Colonies?
By Albert Davila Jr.
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Lizards Species
New Mexico Whiptail, Cnemidophorus neomexicanus
Little Striped Whiptail, Cnemidophorus inornatus
Lesser Earless Lizard, Holbrookia maculata
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Burrowing Rodent

• Gunnisons Prairie Dog (Cynomys gunnisoni)

Keystone species a species that plays an
important role in maintaining the structure of an
ecological community
For the Lizard -Mounds allow for an open space
to sun bathe - Mounds provide a resource of
protection -Mounds allow lizards to escape
from the heat (thermoregulation)
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Hypothesis

• Lizard abundance will be greater on plots with
  prairie dog mounds vs. plots with no mounds
• Lizards will more likely be found on mounds vs.
  off mounds
• The shrubbier a treatment plot is the higher the
  abundance of lizards

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Primary Objectives

• Observe the population abundance of Chihuahuan
  Desert lizard in areas with mounds created by
  Gunnisons Prairie dogs, Cynomys gunnisoni, and
  areas without mounds

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Objectives Cont.

• Compare shrub densities to lizard population
  densities to see if lizards prefer a shrubby
  habitat versus open grassland

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The Site

• East Mckenzie Flats grassland on Sevilleta
  National Wildlife Refuge (SNWR)
• - Short vegetation dominated by Blue Grama
  (Bouteloua gracilis)
• Sevilleta Gunnison's Prairie Dog Study Area
• Reestablishment of a colony of Gunnisons
  Prairie dogs
• April-August 2005 355 Gunnisons
  Pdogs (Cynomys gunnisoni)
  were released
• Populations were augmented through 2008

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Sevilleta National Wildlife Refuge
Sevilleta Gunnison's Prairie Dog Study Area
N
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The Site

• 6 plots each 100m x 100m
• 3 treatment plots with Prairie Dog mounds
• North Treatment (NT), Mid-Treatment (MT), South
  Treatment (ST)
• 3 control plots without Prairie Dog mounds
• North Control (NC), Mid-Control (MC), South
  Control (SC)
• 2 150m lizard transects on each plot (12
  transects)

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MC
NC
NT
MT
ST
150m Lizard Transect
SC
Plot layout w/12 150m lizard line-intercept
transect
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Methods

• Lizard Identification
• Fishing for lizards
• Three poles and dental floss

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Methods Cont.

• Walked during the morning (9am-11am)
• Alternated plot starts
• Walked earlier in June and later in July

N
B
A

• Recorded -Species -On a mound or off a
  mound -Movement

150m Transect Lines
N
B
A
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MC
NC
NT
MT
ST
150m Lizard Transect
SC
Plot layout w/12 150m lizard line-intercept
transect
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Methods Cont.

• Shrub Observations
• On each transect measure every shrub within 5m of
  the transect on both sides
• Record
• Species
• Point on transect
• Perpendicular distance
• Height and diameter

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Plants

• Yucca plant (Yucca glauca)
• New Mexico Thistle (Cirsium Neomexicanum)

• Yucca plant (Yucca glauca)

• Fourwing Saltbush (Atriplex canescens)

• New Mexico Thistle (Cirsium Neomexicanum)

Thread Leaf Groundsel (Senecio flaccidus)

• Cholla Cactus (Cylindropuntia imbricata)

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Results

• Transects walked a total of 14 times
• Two Sample T-Test
• P-value suggest significant difference between
  relative abundance of lizards on control vs.
  treatment plots

P0.02
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On or Off a Mound

• With a 90 confidence interval the p-value
  suggest that there is a significant difference

P0.07

• Lizards are more likely to be found off a mound

Two Sample T-Test
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Movement

• Preliminary data suggest that lizards prefer to
  distance themselves from disturbance

ObservatIon

• Lizards are more likely to run to mounds vs.
  shrubs

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Lizard Abundance compared to Shrub Abundance
NT
ST
MT

• Slight trend showing that as treatment plots
  become more shrubby then lizard abundance
  increases

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Conclusion

• Lizard abundance is greater on plots with prairie
  dog mounds vs. plots without mounds
• Lizards were found more off mounds then on mounds
  
• Slight trend of a higher abundance of lizards as
  plot becomes more shrubby

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Future Research

• Record how far mound and shrub are from lizard
• Record temperature underneath shade of various
  shrubs, inside mound, on top of mound, and in
  bare space
• Make more observations in Spring, Summer, and Fall

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Acknowledgements

• Sevilleta LTER
• National Science Foundation
• Sevilleta National Wildlife Refuge
• University of New Mexico
• US Fish and Wildlife
• Mike Friggens
• Jennifer Johnson
• Ginny Seamster
• Terri Koontz
• 2009 Sevilleta REUs
• 2009 Sevilleta Interns
• Diana Guzman

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Questions?