Phenotypic plasticity in mass loss during chick-rearing in the European starling (Sturnus vulgaris)

Hodinka, Brett1 ; Williams, Tony1

Affiliations

Simon Fraser University

Research facility: Simon Fraser University

Forthcoming; Updated May 23, 2024 on Dryad. https://doi.org/10.5061/dryad.4j0zpc8jj

Cite this dataset

Hodinka, Brett; Williams, Tony (2024). Phenotypic plasticity in mass loss during chick-rearing in the European starling (Sturnus vulgaris) [Dataset]. Dryad. https://doi.org/10.5061/dryad.4j0zpc8jj

Abstract

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.

README: Phenotypic plasticity in mass loss during chick-rearing in the European starling (Sturnus vulgaris)

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.

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.
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)
repeatability.csv -- year 1 and year 2 data for all individuals as seen in rptr.csv but formatted specifically for a rptR 'repeatability' analysis
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
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 > 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 and/or 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.

Methods

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 (Sturnus vulgaris). 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).

Funding

Natural Sciences and Engineering Research Council, Award: RGPIN/03949-2018

Natural Sciences and Engineering Research Council, Award: RGPAS/429387-2012