DOI: 10.5061/dryad.vmcvdncts
title: Exploration speed in captivity predicts foraging tactics and diet in free-living red knots

description: Variation in foraging tactics and diet are usually attributed to
 differences in morphology, experience, and prey availability. Recently,
 consistent individual differences in behaviour (personality) have been
 shown to be associated with foraging strategies. Bolder or more
 exploratory individuals are predicted to have a faster pace-of-life and
 offset the costs of moving more or in risky areas, with higher energetic
 gains by encountering profitable foraging opportunities and prey. However,
 the relationship between personality, foraging, and diet is poorly
 understood. We investigated how exploratory behaviour in red knots
 (Calidris canutus) is associated with foraging tactics and diet by
 combining laboratory experiments, field observations, and stable isotope
 analysis. First, we developed a mobile experimental arena to measure
 exploration speed in controlled settings. We validated the method by
 repeated testing of individuals over time and contexts. This setup allowed
 us to measure exploratory personality at the field site, eliminating the
 need to bring birds into captivity for long periods of time. After
 releasing birds within days of their capture, we asked whether exploration
 speed was associated with differences in foraging tactics and diet in the
 wild. We found that tactile foraging red knots mainly caught hard-shelled
 prey that are buried in the sediment, whereas visual foraging knots only
 captured soft preys located close to or on the surface. We also found that
 faster explorers showed a higher percentage of visual foraging than slower
 explorers. By contrast, morphology (bill length and gizzard size) had no
 significant effect on foraging tactics. Diet analysis based on δ15N and
 δ13C stable isotope values of plasma and red blood cells confirmed our
 field observations with slower explorers mainly consumed hard-shelled prey
 while faster explorers consumed more soft than hard-shelled prey. Our
 results show that foraging tactics and diet are associated with a
 personality trait, independent of morphological differences. We discuss
 how consistent behaviour might develop early in life through positive
 feedbacks between foraging tactics, prey type, and foraging efficiency.
description: Isotope data: Red blood cell and plasma d13C and d15N isotopes
 collected from the blood samples of red knots.
 Exploration speed: Movement tracjectories were collected from the
 recordings of the top camera during experiments in the mobile arena. We
 used the distance between estimated positions to calculate speed. Errors
 in the positioning algorithm were filtered by excluding speeds higher than
 200 cm/s. An individual’s exploration speed was calculated as the average
 speed during each 20 min trial. The dataset includes four repeats of
 exploration speed. Proportion of explorative behaviour:
 Behaviours were collected from the recording of the side camera during
 experiments in indoor arena and mobile arena. Behavioural budget is
 calculated of the time that the focal bird spend exploring (walking and
 probing) the arena.  Foraging behaviour: Foraging
 behaviour was collected from the observations in the field. Focal birds
 were filmed for 20 min or up to the moment they flew away. Behavioural
 budget is calculated for two types of foraging tactics: ‘tactile foraging’
 when a bird is probing continuously with the bill into the substrate, and
 ‘visual foraging’ when a bird is scanning the area in front of it and
 pecking at items seen on the substrate surface. 
 Prey-foraging behaviour: In cases that we could identify the
 ingested prey in the field, categorized as hard-shelled prey (e.g.,
 cockles or Baltic tellins) or soft prey (e.g., brown shrimp or polychaete
 worms) to investigate the relationship between foraging tactics and
 diet.
description: GENERAL INFORMATION 1. Titles of the Dataset:
 Exploration speed (mean speed cm/sec) in mobile arena, exploration
 behaviour (behavioural budget walking and probing), isotope data (plasma
 and red blood cell), foraging behaviour collected from the observations in
 the field<br> 2. Date of the data collection: Catching between 14
 August - 19 September 2018, and 1 August - 6 September 2019, Field
 observations from August to October 2019<br> 3. Geographic location
 of data collection: Western Dutch Wadden Sea (53°15'N,
 5°15'E) <br> 4. Corresponding author information: Selin Ersoy,
 NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal
 Systems, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands,
 selin.ersoy@gmail.com <br> 5. Link to publication: Ersoy et al.
 (2021) Exploration speed in captivity predicts foraging tactics and diet
 in free-living red knots. Journal of Animal Ecology
 DATA & FILE OVERVIEW DATA &
 FILE OVERVIEW<br> 1. KnotData.csv: Metadata of individual red
 knots<br>          Column 1: CaptureDate: The date when the red
 knots were captured by means of mist-netting in the Western Duthc Wadden
 Sea (53°15'N, 5°15'E)<br>          Column 2: RingNr:
 Unique metal ring number of red knots. Ring were put on the legs<br>
          Column 3: Crc: Unique combination of color-rings of red knots.
 Rings were placed on the legs (two in right and two in left
 legs)<br>          Column 4: Bill: Bill lenght of the individual in
 mm.<br>          Column 5: Mass: Body mass of the individual in
 gr.<br>          Column 6: cell_d15N: Isotope value from red blood
 cell d15N. <br>          Column 7: cell_d13C: Isotope value from red
 blood cell d13C. <br>          Column 8: plasma_d15N: Isotope value
 from blood plasma d15N. <br>          Column 9: plasma_d13C: Isotope
 value from blood plasma d13C. <br>          Column 10:
 Expl_F01_MeanSpeed: Exploratory personality score of individual measured
 in mobile arena for the first time (mean speed cm/sec)<br>         
 Column 11: Expl_F01_Log10MeanSpeed: Log10 transformed of the exploratory
 personality score of individual measured in mobile arena for the first
 time (mean speed cm/sec)<br>          Column 12: Expl_Date: The date
 that exploratory personality assay was conducted 2.
 ExplorationSpeedRepeatibility.csv: Data on repeated measurement (max. 4
 repeats) on exploration speed (mean speed log10 cm/sec) measured in the
 mobile arena<br>          Column 1: RingNr: Unique metal ring number
 of red knots. Ring were put on the legs <br>          Column 2:
 MeanSpeed: Exploratory personality score of individual measured in mobile
 arena (mean speed cm/sec)<br>          Column 3: Expl_Date: The date
 that exploratory personality assay was conducted<br>          Column
 4: Condition: Whether the individual bird was wildly captured or it was in
 captivity<br>          Column 5: Repeat_Nu: Repeat number of the
 personality assay trials 3. ExplorationValidation.cvs:
 Data on personality measurements on both mobile (FU) and indoor (WU)
 arenas. Exploration is scored both mean speed and behavioural budget as
 proportion of walking and probing<br>          Column 1: RingNr:
 Unique metal ring number of red knots. Ring were put on the
 legs <br>          Column 2: Expl_Date: The date that exploratory
 personality assay was conducted<br>          Column 3: Setup:
 Whether the personality was measured in mobile (FU) or indoor (WU)
 arenas.<br>          Column 4: Condition: Whether the individual
 bird was wildly captured or it was in captivity<br>          Column
 5: PropExplBehaviour: Exploratory personality scored as behavioural budget
 as proportion of walking and probing<br>          Column 6:
 Mean_Expl_Speed: Exploratory personality scored as movement
 speed 4. ForagingFieldData.csv: Data on proportion of
 foraging tactics (tactile and visual) observed in the field. <br>   
       Column 1: RingNr: Unique metal ring number of red knots. Ring were
 put on the legs <br>          Column 2: Expl_F01_MeanSpeed:
 Exploratory personality score of individual measured in mobile arena for
 the first time (mean speed cm/sec)<br>          Column 3:
 gizzard_size: Gizzard size of the individual red knots measured through
 ultrasound (following Dekinga et al., 2001)<br>          Column 4:
 bill_length: Bill lenght of the individual in mm.<br>         
 Column 5: p_visual: Proportion of visual foraging observed in the
 field<br>          Column 6: p_tactile: Proportion of tactile
 foraging observed in the field 5. PreyForagingBehv.csv:
 Data on which foraging tactic (tactile and visual) result in catching what
 type of prey (soft and hard-shelled) observed in the field.<br>   
       Column 1: Obs_id: Field observation id. Combination of colour ring
 combination (crc) and the date of observation.<br>          Column
 2: totalingested_prey: Number of total ingested prey observed from that
 observation<br>          Column 3: prey_type: Identified type of
 prey (shellfish, worm, shrimp, cockle)<br>          Column 4:
 Foraging: What types of foraging behaviour was observed during that
 ingestion (tactile vs visual)<br>          Column 5: Prey: Whether
 that prey type is hard-shelled or soft prey