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Rainfall Influence on Lizard Activity Patterns in a Piñon-Juniper Woodland Vivien Enriquez Beloit College Summer 2013. Introduction. Focal species 1) Chihuahuan Spotted Whiptail (Aspidoscelis exsanguis) 2) New Mexico Whiptail (Aspidoscelis neomexicana) Natural History
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Rainfall Influence on Lizard Activity Patterns in a Piñon-Juniper Woodland Vivien Enriquez Beloit College Summer 2013
Introduction Focal species 1) Chihuahuan Spotted Whiptail (Aspidoscelis exsanguis) 2) New Mexico Whiptail (Aspidoscelis neomexicana) Natural History 1) Native to the North American southwest 2) All female species 3) Active foragers 4) Active in the early morning and late afternoon
Introduction • Sensitive to changes in habitat structure and function • Altered whiptail abundance in response to climate change/drought stress
Introduction 2011 Precipitation and lizard abundance May 27th-August 9th Red = rainfall plots Green = drought plots Blue = weekly precipitation Grah: Ryan, 2011
Introduction • Rainfall pulses impact lizard abundance and activity • Using this data to form new questions about what drives lizard behavior • Using activity time budgets to illustrate daily behavior and habitat use
Introduction Questions: 1) How does long term artificial drought and rainfall addition influence lizard behavior and habitat use?
Methods Research took place at the Sevilleta National Wildlife Refuge New Mexico
Methods Rainfall Manipulation Experiment, Piñon-Juniper Woodland, Los Piños Mountains
Methods 30 minute surveys per plot, 2 times a week • Start at 8:30 a.m. • Drought and rainfall treatment plots are surveyed at every visit. • Various plots are substituted for others throughout the week.
Methods Behavioral observation and recording: 12 minute observational period, 22 individuals • Videos recorded and then analyzed • Individual behaviors timed (in seconds) and categorized • Behaviors and habitats organized in a template • Activity time budget calculated
Methods Behavior & Habitat Codes: BA - basking OH - open habitat AF - active foraging SH - shaded habitat • searching • digging • scratching WA - walking PC - prey capture CL - climbing
Methods Activity Time Budgets: a measurement of time spent on each behavior. • Total time of each activity divided by the total amount of time spent observing (in seconds), then multiplied by 100.
Basking Active foraging Results Drought: Rainfall:
Results AF (OH) AF (SH) BA (OH) BA (SH) WA (OH) PC (OH) Drought Treatments ID: 0836.ASPEXS.PJ1.6
Results AF (SH) AF (OH) BA (SH) WA (OH) WA (SH) PC (SH) Rainfall Plots 0936.ASPEXS.PJ4.8
Results Active-Foraging by Treatment (Aspidoscelis exsanguis) Active-Foraging in open habitat Active-Foraging in shade Kruskal-Wallis Test Chi-Square 8.9219 Chi-Square 1.6694 DF 1 DF 1 Prob>Chisq 0.0028 Prob>Chisq 0.1963
Results Basking by Treatment (Aspidoscelis exsanguis) Basking in open habitat Basking in shade Kruskal-Wallis Test Chi-Square 2.9413 Chi-Square 1.2172 DF 1 DF 1 Prob>Chisq 0.0863 Prob>Chisq 0.2699
Discussion Question: How does long term artificial drought and rainfall addition influence lizard behavior and habitat use? • Affects the amount of time lizards spend performing certain behaviors in the shade vs. open habitat • Promotes different common behaviors depending on which treatment the lizard is located in
Discussion • Future directions: project replication after rainfall manipulation experiment ends. - Other factors: vegetation cover/health, soil quality, prey abundance 1) Will we see similar results? 2) If drought landscape recovers, will lizard behavior adapt?
Acknowledgements I would like to thank: Mentor - Mason Ryan Elizabeth Gallagher REU Program - Amaris Swann and students Sevilleta National Wildlife Refuge