DOI: 10.5061/dryad.4j0zpc8jj
title: Phenotypic plasticity in mass loss during chick-rearing in the European starling (Sturnus vulgaris)

description: It has long been recognized that mass loss during breeding could be
 adaptive (e.g., by ameliorating the costs of increased parental activity).
 However, many studies still commonly interpret mass loss as evidence of
 “stress” or a cost of reproduction (a negative effect of high workload
 during chick provisioning). Despite several studies reporting evidence in
 support of both hypotheses, the ecological and/or life-history contexts
 under which mass loss may be viewed as a “cost” or an adaptive strategy
 are still unclear. Here, we used a long-term dataset from a breeding
 population of European starlings to investigate the natural annual and
 individual variation in body mass and mass loss and to test whether mass
 loss during chick-rearing represents a phenotypically plastic trait that
 varies predictably in relation to ecological context and individual
 quality. While there was significant annual variation in incubation mass,
 chick-rearing mass, and mass change, there were no systematic
 relationships between mass loss and (1) current breeding success or (2)
 future fecundity and survival. In addition, we found moderate
 repeatability of mass loss (R = 0.59) suggesting there might be additive
 genetic variation for this trait, though with considerable residual
 environmental variation. However, we found no covariation between this
 residual, intra-individual variation and other reproductive or
 life-history traits. We therefore found no support for the idea that mass
 loss reflects “reproductive stress” in our system: there were no negative
 relationships between mass loss and either current or future reproduction
 and survival (local return rate). Our results are consistent with mass
 loss being an individually plastic trait, potentially with moderate
 additive genetic variance, with individuals using mass loss to “level the
 playing field” and individually optimize reproductive effort and fitness.
description: Fieldwork was conducted at the Davistead Farm in Langley, British
 Columbia, Canada (49°10’N, 122°50’W) between April and July 2012–2022
 using a free-living population of European starlings (<em>Sturnus
 vulgaris</em>). The field site is comprised of approximately 150
 nest boxes mounted on fence posts around open pastures and on farm
 structures. In each year, a constant basic field protocol was followed:
 nest boxes were checked daily from April 1 to determine the laying date,
 clutch size, hatch date (day 0), and brood size at hatching, day 6, and
 fledging (day 21). Morphometric measures including mass, wing chord, and
 tarsus length were collected from adult females at day 6 incubation (6.3 ±
 1.3 d) and day 10 chick-rearing (9.6 ± 1.3 d). Here, “mass loss” is
 defined as the difference between day 6 incubation and day 10
 chick-rearing mass measures (approx. 15 days apart). Using tripod-mounted
 video cameras (Canon VIXIA HF R800), 30–60 min behavioral observations of
 chick-rearing parents were conducted at individual nest boxes from
 09:00–15:00 h when chicks were 6–10 days old. Data were obtained on the
 provisioning rate (number of visits/30 min) and the sex of the visiting
 adult. Chick quality metrics are derived from brood mean morphometric
 measures (mass, wing chord, tarsus length) that were obtained from all
 chicks on day 17. Upon capture, all females were fitted with individually
 numbered metal bands (Environment Canada Permit # 10646). After the
 fledging of the first broods, data collection was repeated for the second
 broods. In some years, we conducted experiments that potentially affected
 natural mass change via wing-clipping and/or attachment of
 radio-transmitters (e.g., Fowler and Williams, 2017; Serota and Williams,
 2019), so in this paper, we excluded these and restricted analysis to
 non-manipulated birds and controls. All protocols were approved by the
 Simon Fraser University Animal Care Committee (permit #
 1172B-96).
description: # Phenotypic plasticity in mass loss during chick-rearing in the European
 starling (*Sturnus vulgaris*)
 [https://doi.org/10.5061/dryad.4j0zpc8jj](https://doi.org/10.5061/dryad.4j0zpc8jj) **Overview** Included is a series of six datasets (.CSV files) from data collected from a breeding population of European Starlings in Langley, British Columbia from 2012 to 2022. Data herein were used specifically to test whether mass loss may represent a phenotypically plastic trait that varies predictably in relation to ecological context and/or individual quality. ## Description of the data and file structure ### Data files The names of each data file and a brief description of what each contains are shown below, followed by all column abbreviations used. 1. eust.data_2022.csv -- All starling data from 2012–2022 and reflects the "master file," meaning it contains all general field data including, but not limited to, body mass, tarsus and wing length, lay dates, clutch and brood sizes, etc. 2. rptr.csv -- a small sub-dataset from eust.data_2022.csv containing the change in mass (between chick-rearing day 10 and incubation day 6) for all individuals where more than one measure exists (i.e., two years of mass change data for a single bird) 3. repeatability.csv -- year 1 and year 2 data for all individuals as seen in rptr.csv but formatted specifically for a rptR 'repeatability' analysis 4. rptr.table.csv -- change in mass data as described above but including all residual values for current and future breeding success as well as provisioning data 5. eust_prov.csv -- a master file specifically for provisioning data from 2013–2022. This includes female/male and total provisioning rates. ### Abbreviations **eust.data.csv** * year - Corresponds to the field season year in which the data were collected * box - The physical nest box number attached to the nest boxes at Davistead Farms, Langley, BC * band - The federal metal band located on the Eur. starlings' right legs * brood - Value corresponding to the brood attempt for each female Eur. Starling ('1' = first brood attempt; '1.5' = relay, typically due to failed first attempts; '2' = second brood attempt) * ld - Value corresponding to the Julian lay date of individual female Eur. Starlings * treatment - Code representing the treatment experiment for the individual female Eur. Starling (any treatment that could affect body mass was not analyzed for this manuscript) * trt_other - Code representing additional treatment experiments on the nest (treatment overlap will be noted in the "NOTES" column) * inc_date - Date corresponding to the incubation weight collection date (note: dates do not reflect the Julian date) * inc_day - Value corresponding to the number of days since clutch completion (CC counted as "day 0") until female Eur. Starling weighed * inc_time - Time corresponding to the incubation weight collection time (note: times are in PST military time) * inc_mass - Mass (in grams) corresponding to the adult female Eur. Starling incubation mass (note: see individual protocols for each year, some years this mass reflects clutch completion incubation mass or day 7 incubation mass, etc.) * wing - Wing length (in millimeters) of adult female Eur. Starling * tars - Tarsus length (in millimeters) of adult female Eur. Starling * cs - Value corresponding to the clutch size of each adult female Eur. Starlings * bsh - Value corresponding to the brood size at hatch for each adult female Eur. Starling * bs6 - Value corresponding to the brood size at day 6 for each adult female Eur. Starling * bsf - Value corresponding to the brood size at fledge for each adult female Eur. Starling * fs - Did at least one nestling fledge (Y or N) in one year; FS stands for "fledge success" * days_inc - Value corresponding to the number of days the female Eur. Starling spent incubating (note: this includes the day for which the last egg was laid until the day before the majority of chicks hatched, i.e., majority hatch day was not counted) * cr_date - Date corresponding to the chick-rearing weight collection date (note: dates do not reflect the Julian date) * cr_day - Value corresponding to the number of days post-hatch day until female Eur. Starling was weighed (note: 'hatch day' is day 0, counted until (and including) the day in which the chick-rearing mass was collected) * cr_time - Time corresponding to the chick-rearing weight collection time (note: times are in PST military time) * cr_mass - Mass (in grams) corresponding to the adult female Eur. Starling chick-rearing mass 10−14 days post-clutch completion (unless otherwise noted in CR_DAY) * delt_bm - Value corresponding to the change in mass (in grams) between incubation and chick-rearing of the adult female Eur. Starling * b2_att - A binary value (Y or N) representing whether the bird returned for a second brood attempt in the same year * bsf2 - Value corresponding to the brood size at fledge during a second brood attempt in the same year * fs2 - Did at least one nestling fledge (Y or N) in a subsequent year; FS stands for "fledge success" * ret_1b - A binary value (Y or N) indicating whether the bird returned and made a breeding attempt during first broods in a subsequent year * ret_2b - A binary value (Y or N) indicating whether the bird returned and made a breeding attempt during second broods in a subsequent year * ret_y - A value corresponding to the number of years after the first brood attempt a bird made another breeding attempt (e.g., first found in 2013 and then again in 2014; RET_Y would = 1) * bsf_ret1 - Value corresponding to the brood size at fledge during a return first brood attempt * bsf_ret2 - Value corresponding to the brood size at fledge during a return second brood attempt * ret_fec - Value corresponding to the total return fecundity (i.e., BSF_RET1 + BSF_RET2) * cq_m17 - A single value corresponding to the average day 17 mass (in grams; chick quality) for each adult female Eur. Starling brood * cq_tl17 - A single value corresponding to the average day 17 tarsus length (in millimeters; chick quality) for each adult female Eur. Starling brood * cq_wl17 - A single value corresponding to the average day 17 wing length (in millimeters; chick quality) for each adult female Eur. Starling brood * notes - Any notes about the collection of data along that .csv row **rptr.csv** * delt_bm - Value corresponding to the change in mass (in grams) between incubation and chick-rearing of the adult female Eur. Starling * inc - Mass corresponding to the adult female Eur. Starling incubation mass (in grams) **repeatability.csv** * The abbreviations in these two .csv files overlap entirely with the abbreviations listed above. **eust_prov.csv** * obs.id - Video observation ID -- year. Box#. Julian day of observation (e.g., 17.4.126 = 2017 Box 4, Julian day 126) * trt - Indicates any treatments done on the female and/or at this nest * hatch - Julian date when the majority of eggs hatch * bs.obs - Brood size at the time of the provisioning observation * age - Age of the chicks (days post-hatch) at the time of the provisioning observations * dur - Duration of the provisioning observation video (in minutes; the standard is 30 min) * f.count - Number of female provisioning visits to the nest * m.count - Number of male provisioning visits to the nest * u.count - Number of unknown (sex) provisioning visits to the nest * count - Total number of provisioning visits to the nest (male visits + female visits) * f.prov - Number of female visits/30 min; formula = f.count/dur * 30 * m.prov - Number of male visits/30 min; formula = f.count/dur * 30 * rate - Total number of visits/30 mins; male and female rate combined (f.rate + m.rate) * f.chkprov - Total number of female visits/chick/30 mins * m.chkprov - Total number of male visits/chick/30 mins * chk.prov - Total number of visits/chick/30 mins; male and female rate combined * xf.chkprov - Mean number of female visits/chick/30 mins over ALL observation days * xm.chkprov - Mean number of male visits/chick/30 mins over ALL observation days * x.chkprov - Mean number of total visits/chick/30 mins (male and female rate combined) over ALL observation days * m.help - Binary values (0,1) indicating whether the male was seen (1) or not seen (0) provisioning at the nest in any observations of the nest (Enns & Williams, 2022) * m.help2 - m.help binned into "none," "low," "medium," and "high" levels of help based on xmprov = 0 or &gt; 0, 3, 6, respectively * xfprov - Mean number of female visits/30 min over ALL observation days (e.g., D6–8 CR) * xmprov - Mean number of male visits/30 min over ALL observation days (e.g., D6–8 CR) * xprov - Mean total number of visits (male and female) in 30 minutes over ALL observation days **rptr.table.csv** * y1 - year corresponding to when y1_delt data were collected * y1_inc - first-year incubation mass (in grams) * y1_delt - first-year change in mass (between INC and CR; in grams) * y1_ld - first-year lay date * y1_corr_ld - first-year annual mean-corrected lay date * y1_cs - first-year clutch size * y1_corr_cs - first-year annual mean-corrected clutch size * y1_bsf - first-year brood size at fledge * y1_corr_bsf - first-year annual mean-corrected brood size at fledge * y1_fprov - first-year female provisioning rate (visits/video duration * 30) * y1_corr_fprov - first-year annual mean-corrected female provisioning rate * y1_mprov - first-year male provisioning rate (visits/video duration * 30) * y1_corr_mprov - first-year annual mean-corrected male provisioning rate * y1_fchkprov - first-year female mean provisioning rate per chick (visits/chick/video duration * 30) (across all obs) * y1_corr_fchkprov - first-year annual mean-corrected female mean provisioning rate per chick (across all obs) * y1_mchkprov - first-year male mean provisioning rate per chick (visits/chick/video duration * 30) (across all obs) * y1_corr_mchkprov - first-year annual mean-corrected male mean provisioning rate per chick (across all obs)\ These data repeat for year 2; i.e., any birds for which we have data in more than one year. These abbreviations will be identical to those above except "y1" will be replaced with "y2" All delt\_ headers indicate the (delta) difference between the named variables, following the naming conventions above. Any empty cells or cells labeled as "NA" indicate missing data. ## Sharing/Access information Please contact Brett Hodinka at [bhodinka@sfu.ca](mailto:bhodinka@sfu.ca) and/or [Brett.hodinka@gmail.com](mailto:Brett.hodinka@gmail.com) for queries. ## Code/Software The attached R file is annotated within and all attached .CSV files are called within the script.