DOI: 10.5061/dryad.3j9kd51vz
title: Eyespot peek-a-boo: Leaf rolls enhance the antipredator effect of insect eyespots

description: Animal color patterns are often accompanied by specific, synergistic
 behaviors to most effectively defend against visual predators. Given the
 inherent context-dependence of color perception, understanding how these
 color-behavior synergies function in a species’ natural environment is
 crucial. For example, refuge-building species create a unique visual
 environment where most (or all) of the body is obscured unless closely
 inspected. How these built environments affect the perception of defensive
 color patterns by predators is not well understood. Using artificial
 caterpillars that resemble a refuge-building species with conspicuous
 markings (Papilio troilus; Lepidoptera: Papilionidae), I tested the
 hypothesis that leaf rolls amplify the antipredator effect of this
 species’ eyespots. I compared wild avian predation rates on 659 artificial
 swallowtail-like caterpillars from four treatment groups: eyespotted and
 non-eyespotted, and presented in leaf rolls or on open leaves of live host
 plants. In support of my hypothesis, eyespots only reduced predation for
 larvae in leaf rolls. On open leaves, eyespots had no antipredator effect.
 I also found that leaf rolls reduced predation in general for both
 eyespotted and non-eyespotted prey. These results highlight the importance
 of considering relevant behaviors in studies of animal coloration whenever
 possible, including behaviors that influence color perception indirectly
 (e.g. through habitat use or modification).
description: This project includes 3 datasets: 
 LRpred.csv: data from an artificial prey field experiment using
 hand-painted clay caterpillars (2021). Beyond
 treatment (color and roll vs no roll), this dataset also includes a
 considerable number of plant- and habitat-related variables.
 LRspectra.csv: spectral measurements for
 live and artificial swallowtails and host plant (Sassafras) leaves. Spectral data
 were collected with an Ocean Optics Flame Miniature (FLAME-S-UV-VIS-ES)
 spectrometer with Ocean Optics PX-2 Pulsed Xenon light source, calibrated
 with a 99% Labsphere reflectance standard at the University of Michigan
 Museum of Zoology. 
 LRsurvey.csv: data from surveys of naturally-occurring leaf
 rolls along transects at the same site as the field experiment
 (2022). All data were originally collected
 in google spreadsheets and downloaded as CSVs. I then cleaned, organized,
 and analyzed the data in R. All corresponding R scripts are available in
 the repository. The repository also contains
 supplemental materials associated with the manuscript
 (JAE_2024_00285_supp_materials.docx), including 3 supplementary tables of
 observational data, 3 supplemental figures generated from LRpred.csv, and
 1 supplemental figure generated from LRsurvey.csv.
description: # Eyespot peek-a-boo: Leaf rolls enhance the antipredator effect of insect
 eyespots Dates of study: * predation trials (07/03/2021-07/30/2021) * leaf
 roll surveys (08/23/2022-08/27/2022) Contributors: Elizabeth G. Postema
 Data files: ``` LRpred.csv: a csv file containing data from the artificial
 prey field experiment. LRspectra.csv: a csv file containing spectral
 measurements for live/artificial swallowtails and host plant leaves.
 LRsurvey.csv: a csv file containing data from surveys of
 naturally-occurring leaf rolls. LRpredation.html: full analysis of
 artificial prey field experiment in R. LRspectra.html: visual modeling of
 live/artificial swallowtails and host plant leaves in R using package
 pavo. LRsurvey.html: visualizing data from roll surveys in R.
 JAE_2024_00285_supp_materials.docx: a word document with supplemental
 tables and figures associated with the manuscript. ``` Description of data
 columns (LRpred.csv): ``` id: unique identity of each plant used in the
 study. treatment: treatment group of a specific artificial prey, based on
 whether prey was in a leaf roll/on an open leaf, had eyespots/no eyespots,
 and was oriented up or down. OE = open with eyespots, RE = rolled with
 eyespots, RNE = rolled with no eyespots, ONE = open with no eyespots,
 RE-Up = rolled with eyespots oriented up, RE-Down = rolled with eyespots
 oriented down. trial: which of the two predation trials (1 or 2) the data
 in this row were collected from. rolled: whether artificial prey were in
 leaf rolls (rolled) or presented on open leaves (open). color: whether
 artificial prey had eyespots (eyespots) or no eyespots (none).
 orientation: whether artificial prey was oriented up (up) or down (down).
 NAs represent artificial prey where orientation was not specifically
 manipulated. roll.opened: whether artificial leaf rolls was opened by a
 predator. Only applies to rolled prey. 0 = not opened, 1 = opened.
 attacked: whether artificial prey was visibly attacked by a predator. 0 =
 not attacked, 1 = attacked. pred.id: taxonomic identity of the predator
 that attacked the artificial prey, based on attack mark morphology. b =
 bird, m = mammal, u = unknown, NA = prey not attacked. found: whether the
 artificial prey was recoverable. y = prey recovered at end of trial, n =
 prey not recovered at end of trial. coords: geographic coordinates of the
 unique host plant, in decimal degrees (latitude, longitude). lat: latitude
 of the unique host plant, in decimal degrees. long: longitude of the
 unique host plant, in decimal degrees. deployed.date: day that the
 artificial prey was deployed (day-month format). collect.date: day that
 the artificial prey was collected (day-month format). hour.deployed: hour
 that the artificial prey was deployed, in standard time (HourMinute
 format). hour.collect: hour that the artificial prey was collected, in
 standard time (HourMinute format). exposed.hours: total number of hours
 that the artificial prey spent exposed to predators. exposed.days: total
 number of days that the artificial prey spent exposed to predators.
 location: general site where the unique plant was located; Bird Hills
 Nature Area (Bird Hills) or Nichols Arboretum (Nichols Arboretum).
 sublocation: more specific site where the unique plant was located. Within
 Bird Hills = mixed gully, sassafras patch, tulip ridge. Within Nichols
 Arboretum = hawthorn valley, heathdale. host.species: species identity of
 unique plant. Either tulip tree (Liriodendron tulipifera) or sassafras
 (Sassafras albidum). shape.leaf: shape of the leaf that the artificial
 prey was presented on/in. Either lobed (lobed) or ovate (unlobed).
 length.leaf: length of the presentation leaf, in centimeters. width.leaf:
 width of the presentation leaf, in centimeters. roll.length: for
 artificial prey in leaf rolls, the length of the roll, in centimeters.
 roll.prop: for artificial prey in leaf rolls, the length of the leaf roll
 divided by the total length of the presentation leaf. lengthwidth.leaf:
 the length of the presentation leaf multiplied by the width of the
 presentation leaf. area.leaf: the area of the presentation leaf, in
 centimeters^2. height.plant: the height of the unique plant (from ground
 to top), in centimeters. prey.height: the height of the artificial prey
 from the ground, in centimeters. height.prop: the relative height of the
 artificial prey (height.prop = prey.height/plant.height). diameter.1:
 diameter of the unique plant, in centimeters. Perpendicular to diameter.2.
 diameter.2: diameter of the unique plant, in centimeters. Perpendicular to
 diameter.1. radius.1: diameter.1 divided by two (in centimeters).
 radius.2: diameter.2 divided by two (in centimeters). plant.area: area,
 expressed as an oval, encompassing the unique plant in centimeters^2.
 open.prop: proportion of the canopy above the unique plant that is open
 sky. covered.prop: proportion of the canopy above the unique plant that is
 covered in vegetation(1 ? open.prop). canopy.status: whether canopy
 openness was successfully calculated (complete), missing (missing), or
 un-measurable due to lens flare (lens flare). data.complete: whether
 columns describing host plant and presentation leaf measurements are
 complete or incomplete. inclusion: whether to include the data in the
 analysis or not (include, exclude). prev.treatment: documents the previous
 artificial prey treatment group (OE, RE, RNE, ONE) for artificial prey in
 trial 2 that re-use a unique host plant. notes: any notes and/or data
 corrections. ``` Description of data columns (LRspectra.csv): ```
 wavelength.nm: light wavelength, in nanometers. modelgreen1 - modelgreen3:
 % reflectance of artificial caterpillar body for a given wavelength, 3
 measurements. realgreen1 - realgreen3: % reflectance of live caterpillar
 body for a given wavelength, 3 measurements. topleaf1a - topleaf10c : %
 reflectance of 10 sassafras leaves (top) for a given wavelength, 3 samples
 per leaf. bottomleaf1 - bottomleaf3: % reflectance of sassafras leaf
 (bottom) for a given wavelength, 3 measurements. modelyellow1 -
 modelyellow3: % reflectance of artificial caterpillar eyespot for a given
 wavelength, 3 measurements. realyellow1 - realyellow3: % reflectance of
 live caterpillar eyespot for a given wavelength, 3 measurements. ```
 Description of data columns (LRsurvey.csv): ``` plant.num: unique
 numerical identity of a plant being surveyed. transect: which transect
 (1-5) the plant was found on. sublocation: specific location of the plant
 (mixed gully, sassafras patch, tulip ridge, hawthorn valley, heathdale).
 date: date the plant was surveyed on (month-day-year format). roll.num:
 the individual leaf roll being surveyed (1, 2, or 3). NR = no rolls
 present on the surveyed plant. status.code: 0 = leaf roll is not occupied
 by something living, 1 = leaf roll is occupied by something living. NR =
 no rolls present on the surveyed plant. status: unoccupied = leaf roll is
 not occupied by something living, occupied = leaf roll is occupied by
 something living. NR = no rolls present on the surveyed plant. contents:
 the organism or type of debris present in the leaf roll. Nothing in the
 roll = empty. NR = no rolls present on the surveyed plant. plant.type:
 whether the surveyed plant is a host plant of Papilio troilus (host plant)
 or not (non-host plant). flight.behavior: whether the contents of the leaf
 roll jump, drop, or do nothing (none) in response to the roll being
 disturbed/opened. notes: any notes and/or corrections. ``` Description of
 Supplemental Matierals (JAE_2024_00285_supp_materials.docx): ``` Table S1:
 Visual/aural surveys of bird species present at the study sites (7/14/2021
 & 7/30/2021) Table S2: Observations and measurements of live spicebush
 swallowtail larvae and their host plants at the study sites, with dates
 for all observations. Table S3: Notes on the behavior of live spicebush
 swallowtail larvae in response to disturbance, observed throughout the
 main predation experiment. Figure S1: A map of the locations used in the
 field predation trials, with symbols for different host plant species and
 the locations of live spicebush swallowtail larvae. Generated with Google
 My Maps and LRpred.csv. Figure S2: A map of the locations of observed
 predator (avian, mammalian, and unknown) attacks on artificial prey.
 Generated with Google My Maps and LRpred.csv. Figure S3: Proportions of
 artificial prey attacked by mammal and unknown predators. Figures created
 in R (LRpredation.html). Figure S4: Method and results of surveys of
 naturally-occurring leaf rolls at the study sites. Figures created in R
 (LRsurvey.html) ```