DOI: 10.5061/dryad.tx95x6b73
title: Seed and color preferences of wild carrion crows

description: Birds can cause significant damage to agricultural fields, notably in
 Europe, where corvid species like carrion crows (Corvus corone) and rooks
 (Corvus frugilegus) target spring crops, posing challenges for
 conservation and wildlife management. Among targeted crops, sunflower and
 maize suffer the highest levels of damage from corvids’ foraging. While
 both lethal and non-lethal strategies are employed to mitigate bird
 damage, their effectiveness is limited and context-dependent.
 Consequently, there is growing interest in identifying natural bird
 repellents. To improve our understanding of corvid food selection and
 explore potential non-lethal management strategies, we conducted (1)
 cafeteria trials with five common seed types (maize, sunflower, soy, pea,
 and wheat) and (2) two-choice color tests with maize seeds in four colors
 (blue, green, orange and red) on an urban population of carrion crows
 accustomed to human presence. Results indicated a marked preference for
 sunflower and wheat, while soy and pea were largely avoided, and maize was
 moderately consumed. The crows also demonstrated a preference for
 green-colored maize over blue, orange, red, and natural maize seeds. These
 findings suggest that strategic planting of preferred crops like wheat
 alongside sunflower or maize may help mitigate damage. Further,
 incorporating colors into repellent seed coatings could reinforce the
 aversive learning process in birds, although color may play a less
 significant role in food selection when seeds are sown.
description: # Code and data for: Seed and color preferences of wild carrion crows from
 cafeteria experiments Reproducibility data for the manuscript "*Seed
 and color preferences of wild carrion crows from cafeteria
 experiments*", contains data and R script used in the main analysis.
 ## **Study aim:** * **SEEDS** * Determine the seed types that wild crows
 prefer using a using a negative binomial mixed-effects model (NBMM) *
 **COLORS** * Test if they display a particular aversion for a given color
 using a GLM with binomial error structure ## *Data Description* 1.
 `seeds.csv` `.csv` file with seeds' dataset , contains the following
 variables: * `$ID`: test ID * `$date` * `$n_indiv`: number (in categories)
 of individuals present at a test when available * `$type`: seed species;
 Wheat="B",Maize="M",Pea="P",Soy="S",Sunflower="T" * `$n_cons`: number of consumed seeds * `$ratio_cons`: proportion of consumed seeds * `$total_cons`: total of consumed seeds per test ID * `$julian`: julian date 2. `colors.csv` `.csv` file with colors' dataset , contains the following variables: * `$ID`: test ID * `$date` * `$duration`: test duration when available * `$n_indiv`: number of individuals present at a test when available * `$type`: maize color; Blue="B",Green="G",Red="R",Orange="O" * `$nat_cons`: number of natural maize seeds consumed * `$colour_cons`: number of colored maize seeds consumed * `$total_cons`: sum of colored and natural maize seeds consumed by crows * `$ratio_col_tot`: proportion of colored seeds consumed * `$julian`: julian date * `$julianscale`: scaled julian date ## **Code** * `color_seed_code.R` * R script for calibrating generalized linear models depicted in the manuscript, estimating marginal effects and, computing pairwise comparison of mean estimated parameters; and their associated figures.