Sleeping under pressure: Sleep site selection in urban brown anoles (Anolis sagrei)
Data files
Feb 04, 2026 version files 35.62 KB
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morphology_perches.csv
9.94 KB
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random_sampling.csv
3.33 KB
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README.md
3.78 KB
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Sleeping_Under_Pressure_Site_Selection.Rmd
18.58 KB
Abstract
Daytime microhabitat selection is shaped by both physiological traits and environmental pressures, yet nocturnal microhabitat selection remains poorly understood in many species. In urban brown anole lizards (Anolis sagrei), daytime perch selection is influenced by morphology, thermoregulation, and competition, but the factors shaping nocturnal perch selection in urban populations are less clear. We examined sleep site selection at night in adult male, adult female, and juvenile brown anoles in an urban population in New Orleans, Louisiana. Larger individuals perched marginally higher than smaller conspecifics, though perch height did not differ significantly across groups. Within juveniles, higher body temperatures were associated with lower perch heights, a pattern not observed in adults. This difference may reflect active thermoregulatory behavior on the part of juveniles, or passive heat gain resulting from lower thermal inertia. Most lizards slept facing the stem of the plant, suggesting a defensive posture toward potential ground-based predators. Individuals also slept in dark sleeping perches, with most observed at light levels below 1 lx, microhabitats that may reduce predator detection or exposure to artificial light at night (ALAN). Overall, sleep site selection in this urban population of A. sagrei exhibits marked variation within the studied population, and likely reflects the combined influence of morphology, light exposure, predation risk, and age-specific constraints.
Description of the data and file structure
These data were collected to investigate sleep site selection in an urban population of the brown anole lizard (Anolis sagrei) in New Orleans, Louisiana. Sleeping individuals were located at night and measured for morphology, body temperature, perch characteristics, and ambient light levels. Morphological traits were included to examine relationships between individuals and sleep site use.
Randomly available perches were also sampled at the same sites to evaluate whether observed sleep sites differed from randomly available habitat. These data accompany the published article "Sleeping Under Pressure: Sleep Site Selection in Urban Brown Anole Lizards (Anolis sagrei)" in Ethology (DOI: https://doi.org/10.1111/eth.70035)
Files and variables
File: random_sampling.csv
Description: Measurements of randomly available perches sampled at the same urban site as sleeping brown anoles (Anolis sagrei) in New Orleans, Louisiana. Each row represents one randomly sampled perch used to characterize habitat availability.
Variables
- Perch ID: Unique identifier for each randomly sampled perch
- perch height_m: Height of the perch above ground (meters)
- perch width: Width of the perch (centimeters)
- perch length_m: Length of the perch segment (meters)
File: morphology_perches.csv
Description: Data collected from individual sleeping brown anole lizards (Anolis sagrei) in an urban population in New Orleans, Louisiana. Each row represents a single sleeping individual measured during nocturnal surveys.
Variables
- ID: Unique identifier for each individual lizard
- category: Individual category (adult male, adult female, or juvenile)
- tb: Body temperature at the time of observation (°C)
- mass: Body mass (grams)
- svl: Snout-vent length (millimeters)
- head width: Head width (millimeters)
- head length: Head length (millimeters)
- head depth: Head depth (millimeters)
- humerus: Humerus length (millimeters)
- radius: Radius length (millimeters)
- longest front toe: Length of the longest front toe (millimeters)
- femur: Femur length (millimeters)
- tibia: Tibia length (millimeters)
- longest back toe: Length of the longest back toe (millimeters)
- tail length_cm: Tail length (centimeters)
- perch height_m: Height of the perch above ground (meters)
- perch width: Width or diameter of the perch (centimeters)
- perch length_m: Length of the perch segment used by the lizard (meters)
- lux: Ambient light intensity at the sleep perch (lux)
- position: Body orientation on the perch relative to the stem (toward, away, or perpendicular)
File: Sleeping_Under_Pressure_Site_Selection.Rmd
Description: R Markdown script containing all data cleaning, transformation, statistical analyses, and figure generation associated with this study. The script reproduces all results reported in the associated Ethology publication.
Code/software
All data files can be viewed using standard spreadsheet software capable of reading CSV files.
All statistical analyses and figure generation were conducted in R (version 4.3.1). Analyses were performed using the R Markdown file Sleeping_Under_Pressure_Site_Selection.Rmd, and all required R packages are loaded within the script. Running the R Markdown file in RStudio will reproduce all analyses and figures.
Access information
Other publicly accessible locations of the data:
- No additional public repositories host these data.
Data was derived from the following sources:
- The data were generated by the authors through original field observations and measurements.