DOI: 10.5061/dryad.sn02v6xg0
title: Individual variation in spatial reference memory influences cache site choice in a wild bird

description: The spatial cognitive abilities of food-storing birds are well documented,
 but how individual variation in spatial memory influences natural caching
 behaviour is poorly understood. Here we tested wild toutouwai (Petroica
 longipes) on two spatial memory tasks and compared their performance with
 caching decisions. We found that birds with better performance on a
 spatial reference memory task also travelled further to cache food items.
 As widely distributed caches are thought to offer protection against cache
 theft, birds with better reference memories may therefore gain greater
 benefits from food-storage than birds with poor memories. Females
 outperformed males in the spatial reference memory task, and performance
 also declined with age. Birds also displayed marked individual differences
 in how they interacted with the reference memory task, with some
 potentially following a heuristic to locate the reward. By contrast, birds
 showed no evidence that they learned the contingencies of a working memory
 task. Our results provide empirical evidence that individual variation in
 spatial memory performance influences the choices that toutouwai make
 during caching. We recommend that researchers seeking to link cognition
 and behaviour in the wild take care to select ecologically relevant
 cognitive tasks that are likely to underpin fitness-linked behaviours
 targeted by selection.
description: # Individual variation in spatial reference memory influences cache site
 choice in a wild bird
 [https://doi.org/10.5061/dryad.sn02v6xg0](https://doi.org/10.5061/dryad.sn02v6xg0) ## Description of the data and file structure We assayed spatial reference memory and spatial working memory performance in toutouwai (Petroica longipes) and compared these to individual differences in food storage behaviour. We found that spatial reference memory performance was associated with the distance that birds chose to cache. We also found sex and age effects on spatial reference memory performance. ## Code/software Statistics were run with base R statistical software (R version 4.3.2 “Eye Holes”) Code version: Statistics were run with base R statistical software (R version 4.3.2 “Eye Holes”) To avoid interfering with the code, cells with missing data have been left blank (as opposed to being filled with 'NA'). In all cases where cells are blank, this is because data were not able to be collected (e.g. for weight, the bird was not able to be weighed using a scale hope). More details are available for each variable in the Variable descriptions section below. Overview: There are 4 CSV files containing the data used for analyses. The R code file provided (SpatialCaching2024FINAL.r) lists which dataset was used for which analyses. Descriptions of the files are as follows: **ReferenceMemoryTestTrialFINAL** is the raw data for the spatial reference memory task **WorkingMemoryTrialsFinal** is the raw data for the spatial working memory task **spatialcachingFINAL** contains the individual-level summary data for all individuals that participated in at least one of the spatial memory tasks **cache_memoryFINAL** contains the caching instance level data, where each row consists of one instance of caching. **Variable descriptions:** The following are descriptions of each variable in each data file. Units are included in the parentheses following the variable names: **ReferenceMemoryTestTrialFINAL:** id (indidivudal bird identity number): Each bird was assigned a unique identifying number bird (individual bird name): The name of each bird sex (0=female, 1=male): The sex of each bird cohort (year): the year in which the breeding season that the bird hatched began (i.e. a bird hatched in January 2020 was included in the 2019 cohort, as the summer breeding season began in late 2019) date (DD/MM/YYY): The date DD/MM/YYYY that the bird was tested weight (g): Weight of the bird during a sessions (measured by hopping onto a scale). If a bird was not able to be weighed this was left blank. tarsus (mm): The length of a bird's tarsus. If a bird was not able to be measured this was left blank body_cond (weight (g)/tarsus (mm)): Body condition of the bird found by dividing weight by tarsus length - higher number indicates better body condition. If a bird was missing one or both of the measures this was left blank trial (trial number): The test trial (1-30) in which the bird performed flipped (flip number): The number of lids flipped in the trial first_visit (position visited): the position on the board that was flipped first during that trial, read from left to right (e.g., a bird with a first visit of 2 flipped the second lid from the left as its first flip of the trial) rewarded (3=third tile rewarded, 6=sixth tile rewarded): Which side of the array was rewarded, read from right to left as tile number (3 if the third from the left was rewarded, 6 if the third from the right was rewarded) correct_side (1=correct side, 0=incorrect side): A binary score of whether the first visit a bird made was to the half of the board containing the rewarded position first_visit_figure (position visited): The position on the board in relation to the rewarded side of the array that the bird searched first (As half of birds experienced the 3rd position from the left as rewarded, and the other half experienced the 3rd position from the right as rewarded, this was necessary in order to provide a standardized visual of heuristic performance) edge_start (1=first flip to closest edge, 0=first flip not to closest edge): A binary score of whether a bird's first flip of the trail was at the edge tile closest to the reward. **WorkingMemoryTrialsFINAL** bird (indidivual bird identity number): each bird was assigned a unique identifying number name (individual bird name): The name of each bird sex (0=female, 1=male): The sex of each bird cohort (year): the year in which the breeding season that the bird hatched began (i.e. a bird hatched in January 2020 was included in the 2019 cohort, as the summer breeding season began in late 2019) weight (g): Weight of the bird during a sessions (measured by hopping onto a scale). If a bird was not able to be weighed this was left blank. tarsus (mm): The length (mm) of a bird's tarsus. If a bird was not able to be measured this was left blank body_cond (weight (g)/tarsus (mm)): Body condition of the bird found by dividing weight by tarsus length - higher number indicates better body condition. If a bird was missing one or both of the measures this was left blank date (DD/MM/YYY): The date DD/MM/YYYY that the bird was tested time (hh/mm): The time (24h) at which the bird's trial began trial (trial number): The test trial during which the bird performed first_six (positions visited): the number of novel positions searched during the bird's first six visits to the array **spatialcachingFINAL:** bird (individual bird name): Each bird's name sex (0=female, 1=male): The sex of each bird cohort (year): the year in which the breeding season that the bird hatched began (i.e. a bird hatched in January 2020 was included in the 2019 cohort, as the summer breeding season began in late 2019) total_sites (number of unique sites created): The total number of unique sites that a bird cached in across all caching sessions mean_distance (m): The mean distance that each cached food item was stored at total_distance (m): The total summed distance that each cached food item was stored at ref_memory (number of flips): The summed number of flips across all test trials of a bird's reference memory sessions mean_bodycond (weight (g)/tarsus (mm): The mean body condition of each bird across caching sessions work_memory_participation (1=participated, 0=did not participate): a binary score of whether each bird participated in the working memory task work_memory (number of positions visited): Each bird's working memory score (sum of the number of unique positions searched in the first six visits of each trial). If the bird did not participate in the working memory task this cell was left blank. heuristic (1=majority of first visits to near edge, 0=majority of first visits not to near edge): A binary score of whether the majority of a bird's first visits were to the edge of the array in the reference memory task number_edge (positions visited): The number of trials for which a bird's first flip in the reference memory task was at the edge of the array closest to the reward **cache_memoryFINAL:** bird_id (individual bird identity number): each bird was assigned a unique identifying number bird (individual bird name): The name of each bird year: The year in which the bird received its sessions (2020 or 2021) sex (0=female, 1=male): The sex of each bird cohort (year): the year in which the breeding season that the bird hatched began (i.e. a bird hatched in January 2020 was included in the 2019 cohort, as the summer breeding season began in late 2019) age (years): Age of the bird (in years) at the time of testing ref_memory (positions visited): The summed number of flips across all test trials of a bird's reference memory number_edge (number of trials): The number of trials for which a bird's first flip in the reference memory task was at the edge of the array closest to the reward work_memory (positions visited): Each bird's working memory score (sum of the number of unique positions searched in the first six visits of each trial). If the bird did not participate in the working memory task this cell was left blank. total_sites (number of unique sites): The total number of unique sites that a bird cached in across all caching sessions total_sites_session (number of unique sites within a single session): The total number of unique sites that a bird cached in during one session handling (s): The number of seconds that a bird had the mealworm in its beak prior to caching, minus flight time session (session number): The session (1-3) during which the item was cached trial (trials number): The trial during which the item was cached (1-15) in_ses_trial (trial number): The trial within the session that the item was cached (1-5) cumul_site (number of sites): The cumulative site that the item was cached in (i.e. the identity of the unique site that the item was stored in) reuse (1=reused site, 2=not a reused site): A binary score of whether the site stored in had been used previously distance (m): the straight-line distance at which the food item was cached angle (degrees out of 360): the compass angle, measured from the feeding location, at which the food item was cached. height (m): The height above ground that the item was stored at