DOI: 10.5061/dryad.gxd25480x
title: Seen in part, feared in full: conditional visibility enhances eyespot defenses without experience-dependent decay

description: Predation is a significant ecological pressure that shapes species
 evolution and community dynamics. Eyespots, as common anti-predator
 signals, are widely observed in various animals, particularly among
 lepidopteran species. These markings function by either mimicking the eyes
 of natural predators or acting as conspicuous warning signals to deter
 potential threats. However, eyespot effectiveness depends on environmental
 context (e.g., microhabitat structure) and predator experience. Here, we
 examined how partial eyespot concealment and short-term predator
 experience influence early-stage predation behavior using artificial prey
 and domestic chicks. We used artificial prey and manipulated eyespot
 visibility across microhabitat conditions. Our results show that
 partially occluded eyespots consistently delayed predation, with chicks
 taking longer to approach and exhibiting prolonged hesitation compared to
 prey with fully visible or absent eyespots. Short-term experience did not
 alter these behavioral responses, indicating that immediate learning plays
 a limited role in modulating reactions to salient deceptive signals.
 Together, these findings demonstrate that the concealment of the eyespots
 themselves, rather than habitat complexity alone which produces a
 measurable deterrent effect, likely through a combination of neophobia
 toward conspicuous stimuli and eye-mimicry processes. Our study highlights
 how microhabitat-mediated visibility shapes the functioning of visual
 defenses and offers new insight into the ecological and perceptual factors
 influencing the evolution of eyespots in avian predator–prey interactions.
description: # ”Seen in part, feared in full“: conditional visibility enhances eyespot
 defenses without experience-dependent decay ## Authors Yuwen Cheng et al.
 ## Description This dataset contains the raw behavioral data collected
 from controlled laboratory experiments testing antipredator responses of
 domestic chicks (*Gallus gallus domesticus*) to artificial prey bearing
 eyespot patterns. The experiments examined (1) how partial occlusion of
 eyespots influences predator behavior (Task 1), and (2) whether prior
 experience with different eyespot forms alters subsequent responses to a
 standardized eyespot prey (Task 2). The data support the analyses
 presented in the associated manuscript and are intended to enable
 transparency, reuse, and reanalysis of behavioral responses to
 antipredator visual signals. ## Experimental Design and Methods (Summary)
 Domestic chicks were used as a visually guided avian predator model. All
 individuals were naïve to eyespot stimuli prior to experimental exposure.
 Chicks were housed under controlled temperature and light conditions and
 trained to forage along a standardized runway apparatus. Each experiment
 consisted of three phases: 1. **Adaptation (Days 1–3):** acclimation to
 housing and environment. 2. **Training/Habituation (Days 4–6):**
 familiarization with the runway and acquisition of pecking behavior using
 blank prey (no eyespots). 3. **Testing (Day 7):** behavioral responses to
 experimental prey were recorded. Artificial prey consisted of mealworms
 mounted on gray triangular paper, bearing black-and-white concentric
 eyespots. All trials were conducted in a standardized runway with a
 vertical wooden post and leafy branches to simulate a structured,
 vegetation-rich microhabitat. ### Task 1: Eyespot Occlusion / Microhabitat
 Visibility This task tested whether occluding the eyespot signal itself
 alters antipredator responses. Four treatment conditions were used: *
 **POE**: Partially Occluded Eyespots (eyespot signal partly hidden by a
 leaf) * **EE**: Exposed Eyespots (eyespot fully visible; control for POE)
 * **WO**: Wing Partially Occluded (non-signal wing region partly occluded;
 eyespot unchanged) * **NO**: No Occlusion (entire prey fully visible;
 control for WO) ### Task 2: Experience-Dependent Effects This task tested
 whether prior experience with different eyespot forms affects responses to
 the same concentric-eyespot prey. Four experience conditions were used: *
 **N**: Naïve (no prior exposure to eyespot prey) * **EXP-diff**:
 Experienced with eyespots markedly different from the test stimulus *
 **EXP-sim**: Experienced with eyespots perceptually similar to the test
 stimulus * **EXP-id**: Experienced with identical eyespots used in the
 test Task 1 and Task 2 used independent cohorts of chicks and addressed
 different hypotheses. ## Data File Description ### File:
 `Supplementary_Materials.xlsx` This Excel file contains the raw behavioral
 measurements for all tested chicks from both Task 1 and Task 2. * Each row
 represents **one individual chick tested once**. * Only individuals that
 completed the testing phase are included. * No standardized (z-scored)
 variables are included; all values are raw measurements. ## Variable
 Definitions ### `Task_name` Experimental condition assigned to the chick.
 Possible values include: * **POE** – Partially Occluded Eyespots * **EE**
 – Exposed Eyespots * **WO** – Wing Partially Occluded (non-signal control)
 * **NO** – No Occlusion (control) * **N** – Naïve (Task 2) * **EXP-diff**
 – Experienced with different eyespots * **EXP-sim** – Experienced with
 similar eyespots * **EXP-id** – Experienced with identical eyespots ---
 ### `prey_type` Label indicating the type of artificial prey presented
 (e.g., concentric eyespot stimulus).\ This variable serves as a stimulus
 identifier and does not represent a behavioral measure. --- ### `ID`
 Unique identifier for each chick, corresponding to numbered leg bands. ---
 ### `weight` Body mass of the chick measured prior to testing.\ **Unit:**
 grams (g) --- ### `approaching_latency` Time from removal of the visual
 barrier to the chick’s first entry into the pecking zone. **Unit:**
 milliseconds (ms) If a chick did not approach within 30 seconds, the
 latency was right-censored and recorded as 30000 ms. --- ###
 `pecking_latency` Time from the chick’s first entry into the pecking zone
 to the first peck on the prey. **Unit:** milliseconds (ms) If no peck
 occurred within 30 seconds after entering the pecking zone, the latency
 was right-censored at 30000 ms. --- ### `initail_hesitation` Duration of
 the first pause (hesitation) during the approach toward the prey.
 **Unit:** milliseconds (ms) --- ### `average_hesitation` Mean duration of
 all hesitation events observed during the approach phase. **Unit:**
 milliseconds (ms) --- ### `total_hesitation` Cumulative duration of all
 hesitation events during the approach. **Unit:** milliseconds (ms) --- ###
 `tangential_approach` Binary variable indicating the chick’s approach
 trajectory toward the prey. * **0** = Direct approach * **1** = Tangential
 approach --- ## Notes on Data Analysis In the associated manuscript,
 continuous behavioral variables were standardized (z-scores) using the R
 function `scale()` prior to analysis. Linear mixed-effects models (LMMs)
 were fitted with experimental condition as a fixed effect and chick ID as
 a random intercept. However, the present dataset contains **only raw,
 unstandardized values** to facilitate flexible reuse. --- ## Software and
 Code All statistical analyses were conducted in R (version 4.1.3) using
 the packages `dplyr`, `lme4`, and `lmerTest`. Relevant analysis scripts
 are provided in the supplementary materials of the associated publication.
 
 
 ### File: `Rcod_eyespot.R` The R code was used to analyze behavioral
 responses of chicks using linear mixed-effects models (LMMs). Separate
 analyses were conducted for Task 1 and Task 2, corresponding to different
 experimental hypotheses. For each dataset, approach latency, pecking
 latency, and hesitation time were analyzed independently. ### Data import
 and inspection ``` data_long &lt;- read.csv("task1data.csv")
 str(data_long) head(data_long) ``` The raw behavioral data were imported
 from CSV files. The structure and first rows of the data were inspected to
 verify variable types and data integrity before analysis. ### Data
 standardization ``` data_long$approaching_latency &lt;-
 scale(data_long$approaching_latency) data_long$pecking_latency &lt;-
 scale(data_long$pecking_latency) data_long$average_hesitation &lt;-
 scale(data_long$average_hesitation) ``` All continuous behavioral
 variables were standardized using the R function `scale()`, which centers
 each variable to a mean of zero and scales it to unit standard deviation.\
 This standardization facilitates model convergence and allows effect sizes
 to be interpreted in standard deviation units. ### Linear mixed-effects
 models ``` mod1 &lt;- lmer(approaching_latency ~ Task_name + (1 | weight),
 data = data_long) summary(mod1) ``` Linear mixed-effects models were
 fitted using the `lmer()` function from the **lme4** package.\ In each
 model: * The behavioral response variable (e.g., *approaching latency*)
 was treated as the dependent variable. * Experimental condition
 (`Task_name`) was included as a fixed effect. * Body mass (`weight` or
 `bodymass7`) was included as a random intercept to account for
 individual-level variation. Separate models were fitted for: * approaching
 latency * pecking latency * average hesitation time The same modeling
 structure was applied consistently across all comparisons (POE, EE, POE
 vs. WO, and Task 2). --- ### Task-specific analyses * **Task 1 (POE, EE,
 and POE vs. WO):**\ Models were fitted using `weight` as the random
 effect. * **Task 2 (experience treatments):**\ Models were fitted using
 `bodymass7` as the random effect, reflecting body mass measured at the
 testing stage. Each task was analyzed independently because they involved
 different experimental cohorts and hypotheses. ### Summary In summary, the
 R code implements a standard and transparent analysis pipeline:\ raw data
 inspection → variable standardization → linear mixed-effects modeling of
 continuous behavioral responses → Fisher’s exact tests for categorical
 approach behavior.