DOI: 10.5061/dryad.tqjq2bw5n
title: Exposure to humans and task difficulty levels affect wild raccoons (Procyon lotor) learning

description: Cognition helps wildlife exploit novel resources and environments.
 Raccoons (Procyon lotor) have successfully adapted to human presence in
 part due to their cognitive abilities. However, close interactions between
 humans and wildlife can create conflicts. A better understanding of the
 raccoon’s behavioral flexibility and learning ability could improve the
 mitigation of those conflicts. Learning can be evaluated over multiple
 exposures to a cognitive task. Our objective is to evaluate wild raccoons
 learning in contexts varying in terms of exposure to humans (recreational
 and preservation zoning within protected areas) and task difficulty. We
 used two food extraction tasks to measure how problem-solving performance
 varied between trials based on success probability and time to solve the
 puzzles.
description: <strong>Field work</strong> We
 conducted experiments in three protected areas located in southern Québec,
 Canada (all located around latitude 45.6° N and between longitude 72.6°
 and 75.2° W): Plaisance (28 km<sup>2</sup>),
 Îles-de-Boucherville (8 km<sup>2</sup>) and Yamaska (13
 km<sup>2</sup>) national parks. These parks are considered to
 have a high density of raccoons, causing “severe” nuisance problems (Denis
 2017; Dellarosa 2012). All these parks are relatively small, encompassed
 in mostly urban or agricultural territories, and border large bodies of
 water (river or lake). Two site categories are studied based on management
 zoning: intensive recreation and preservation zones. Recreation zones were
 defined by the presence of camping sites, vehicular circulation at low
 speed (&lt;20 km/h), campfires, dumpsters, and a mosaic of ground
 cover (gravel or paved roads, parking lots, forests, open fields,
 buildings, playgrounds). Preservation zones were strictly accessible to
 the public by walking and biking trails, with extensive forest cover. We
 ran the experiments for three summers (earliest-latest dates: May 31‒Sept.
 14) between 2019‒2021. Plaisance Park was not visited in 2021 because of
 its lower raccoon activity compared to the two other parks and its lower
 accessibility. We used species-specific baits, but all
 wildlife could interact with the devices (we only recorded eight
 interactions by stripped skunks in addition to raccoons). The experiments
 are non-invasive; animals voluntarily approached the apparatus and left.
 This ensured that only motivated animals participated. Raccoons were
 trap-shy, and although tested, capture-marking did not prove efficient in
 identifying individuals. Raccoons were identified solely by LL through
 careful observations of the video footage, based on their size relative to
 the puzzles, body characteristics (fur, tail, limbs), marking when
 available, and scars and injuries, in a similar manner to Chow et al.
 (2021a) with Eastern grey squirrels (<em>Sciurus
 carolinensis</em>). Juveniles were excluded because they showed very
 little initiative and were impossible to tell apart from the videos, often
 interacting together with the devices, therefore creating confusion to
 track one individual at a time. It was also impossible to identify an
 individual as a juvenile one year and as a grown adult on consecutive
 ones. To increase our confidence in the identification process, we
 conducted an intra-rater reliability test (Cohen’s kappa) on a small
 subset of recordings from the site with the highest activity level
 (Îles-de-Boucherville, recreation zone). We obtained an 87% agreement (κ =
 0.851) corresponding to an “almost perfect” agreement (Landis and Koch
 1977). We used two puzzle box tasks to test
 problem-solving abilities (Fig. 1). Raccoons trying to open food
 containers (e.g. plastic boxes, bags, bottles) is a common occurrence when
 they are exposed to humans, making this task contextually relevant (Knight
 2022). The first puzzle we used (hereafter, the Box) is similar to the
 model used with carnivore species in other studies (Benson-Amram and
 Holekamp 2012; Benson-Amram et al. 2016). Using the same type of puzzle
 facilitates the comparison of our results to similar experiments
 (Krasheninnikova et al. 2020). The Box measured 30 cm on each side and was
 made from steel mesh. To solve this problem, a raccoon had to slide a
 latch and pull on a door. The second puzzle (hereafter, the Tube)
 consisted of two horizontal plastic tubes (50 cm long in total and 7 cm in
 diameter), one sliding over the other. It required the animal to slide and
 turn the outermost tube to align two holes (approximately 5 x 10 cm) and
 access the food in the inner tube. Both puzzles necessitated two
 consecutive actions that can be performed with the paws, mouth, or muzzle
 of the animal. <strong>Video
 analysis</strong> We considered the puzzle to be
 solved when a raccoon opened it enough to have direct access to the food
 with its paw, even if it did not immediately reach in and consume the
 reward. An attempt began when an animal approached within one body length
 of the box and ended when the animal moved more than a body length away
 from the puzzle or when it opened the puzzle. A trial included all
 attempts at opening a puzzle within a single night, so the trial ended
 when the last attempt ended. We recorded interactions with night vision
 cameras (Argus 2, Reolink, Hong Kong) set up 3‒4 m away (see Supplementary
 Material for an example with each puzzle). We quantified cognitive
 performance in problem-solving ability from the videos. We used two
 response variables to quantify problem-solving efficacy: 1) success
 (binomial) when the subject opens the puzzle (or not) to have direct
 access to the bait and 2) time to solve (continuous), which is the
 cumulative time from the first attempt until the puzzle opening within a
 trial. Two discrete terms representing behavioral traits were included in
 our models: persistence is the sum of all attempts within a trial,
 including the one when the puzzle is solved, and exploratory diversity is
 the number of unique behaviors directed at the puzzles. We calculated
 exploratory diversity in a similar manner to previous studies
 (Benson-Amram and Holekamp 2012; Benson-Amram et al. 2013, 2014;
 Johnson-Ulrich et al. 2018; Daniels et al. 2019). The exploratory
 diversity score accounts for behaviors without contact that allow the
 gathering of information (circling around the puzzle and sniffing), as
 well as behaviors with physical contact (Table 1). NA ("not
 available") means it was not possible to determine from the video
 recordings. <strong>Data
 analysis</strong> We performed a generalized
 linear mixed-effect model (GLMM) to examine how success changed over
 successive trials. We used a binomial distribution with the logit function
 and included the fixed covariates zone and puzzle type in interaction with
 trials. Individual and year were included as random effects. To assess the
 effect of trial number on solving time, we ran a GLMM using only
 successful trial data. We used a Gamma distribution with the log function.
 We explored interactions between trials and zones, as well as between
 trials and puzzle types. Year and ID were included as random terms, and
 the model was optimized using the Nelder-Mead optimizer from the R package
 “nloptr” (Nelder and Mead 1965; Johnson 2014). To see
 if persistence (number of attempts) at a task changed over trials, we
 performed a GLMM with a Poisson distribution and log link function,
 controlling for repeated measures within an individual by including ID as
 a random term. We also calculated the success probability and mean number
 of attempts on unsuccessful trials (as a proxy of persistence) for each
 individual and tested for a correlation with a Kendall rank correlation
 coefficient. To see if exploratory diversity changed over trials, we
 performed a GLMM with a Poisson distribution and log link function,
 controlling for repeated measures within an individual by including ID as
 a random term. To assess the effect of year, we used a
 log-likelihood ratio test, comparing a model with year as a random effect
 to one without, while keeping the fixed effect structure constant (lmtest
 package; Zeileis and Hothorn 2002). We also performed McNemar’s Test (with
 continuity correction) to determine if the proportions of success
 significantly differed when matching pairs of subjects (Fagerland et al.
 2014) at their last trial of the year was different from the first of the
 next year. We used the program R to run all statistical analyses (4.2.3, R
 Core Team 2023).
description: # Data from: Exposure to humans and task difficulty levels affect wild
 raccoons (Procyon lotor) learning
 [https://doi.org/10.5061/dryad.tqjq2bw5n](https://doi.org/10.5061/dryad.tqjq2bw5n) Behavioral data of wild raccoons interacting with puzzle boxes to assess their learning ability. We have submitted our data (P lotor Learning QC). NA ("not available") means it was not possible to determine the value or outcome from the video recordings. Day: Calendar day of start of trial Month: Calendar month of start of trial Year: Calendar year of trial Time Start: Time of start of trial (HH:MM:SS) Park: National park where the study was conducted Zone: Zoning within the national park where the study was conducted * Recreational: presence of camping sites, vehicular circulation at low speed (&lt;20 km/h), campfires, dumpsters, and a mosaic of ground cover (gravel or paved roads, parking lots, forests, open fields, buildings, playgrounds) * Preservation: strictly accessible to the public by walking and biking trails, with extensive forest cover Species: Species observed during trial (all are *Procyon lotor *in this dataset) ID: Identification number of individual animals Conspecifics: Presence or not of conspecific individuals * 0: no other animal (same species) present * 1: at least one other animal present Puzzle: Cognitive task used in the trial * Box: measures 30 cm on each side and made from steel mesh; to solve, the subject had to slide a latch and pull on a door * Tube: consists of two horizontal plastic tubes (50 cm long in total and 7 cm in diameter), one sliding over the other; it requires the subject to slide and turn the outermost tube to align two holes (approximately 5 x 10 cm) and access the food in the inner tube Success: success in the cognitive task (Was the subject able to access the bait within the trial? yes or no) Attempts: number of attempts; an attempt began when an animal approached within one body length of the box and ended when the animal moved more than a body length away from the puzzle or when it opened the puzzle. TotTime: sum of time of the duration of all attempts within the trial (HH:MM:SS) Seconds: conversion of TotTime in seconds ExploDiv: number of unique behaviors directed at the puzzles; exploratory diversity accounts for behaviors without contact that allow the gathering of information (circling around the puzzle and sniffing), as well as behaviors with physical contact. Alternative: alternative behaviour used to access the bait, other than th eexpected method Trial: trial number; included all attempts at opening a puzzle within a single night, so the trial ends when the last attempt ends