DOI: 10.5061/dryad.6djh9w15g
title: Decoupling of growth, physiological state, and subsequent performance in a developmentally manipulated songbird

description: It is generally assumed that larger juveniles are more physiologically
 mature, hence their overall condition and subsequent performance are
 higher. Yet, some taxa face extreme workload transitions during
 development (e.g., nest departure in birds), which may select for
 non-linear growth profiles that decouple relationships between body size
 and physiological state, making associations between development and
 juvenile performance uncertain. We manipulated perceived mass in European
 starlings approaching fledging using 4.0 g weighted backpacks, measuring
 subsequent growth trajectories (mass, wing length) and physiological state
 (aerobic capacity, energy state, oxidative status) to test whether body
 size and physiology are developmentally coupled during a non-linear growth
 phase (pre-fledging mass recession). Nanotag radio transmitters were then
 used to track post-fledging performance (activity, activity-slope,
 dispersal). Weighted nestlings had greater pre-fledging mass recession and
 lower oxidative status than controls, but equal aerobic capacity and
 energy state. Haemoglobin and dROMs, as well as metrics of growth and body
 size, predicted post-fledging performance in control birds, whereas
 weighted birds showed no correlation between fledgling state and
 performance. Our data suggest mass-independent development of some
 physiological traits in species with non-linear growth profiles,
 potentially with a context-dependent oxidative cost, and that physiology
 (not just body size) may predict post-fledging performance.
description: # Decoupling of body size, physiological state, and subsequent performance
 in a developmentally manipulated songbird. **GENERAL INFORMATION**
 1.       Title of dataset: Decoupling of growth, physiological state, and
 subsequent performance in a developmentally manipulated songbird. 2.      
 Author information *Corresponding Investigator* Name: Joshua Allen
 Institution: Simon Fraser University, Burnaby, British Columbia, Canada.
 Email: [jmallen@sfu.ca](mailto:jmallen@sfu.ca) *Co-investigator 1* Name:
 Brett Hodinka Institution: Simon Fraser University, Burnaby, British
 Columbia, Canada. *Co-investigator 2* Name: Hannah Hall Institution: Simon
 Fraser University, Burnaby, British Columbia, Canada. *Co-investigator 3*
 Name: Kathryn Leonard Institution: Simon Fraser University, Burnaby,
 British Columbia, Canada. *Co-investigator 4* Name: Raven Barbera
 Institution: Simon Fraser University, Burnaby, British Columbia, Canada.
 *Co-investigator 5* Name: Genavieve Desjardin Institution: Simon Fraser
 University, Burnaby, British Columbia, Canada. *Co-investigator 6* Name:
 Tony Williams. Institution: Simon Fraser University, Burnaby, British
 Columbia, Canada. 3.       Date of data collection: May 2020 – August 2022
 4.       Location of data collection: Davistead Farm, Langley, British
 Columbia, Canada. 5.       Funding sources: Natural Sciences and
 Engineering Research Council Discovery grant (03949-2018) and accelerator
 grant (429387-2012). **DATA AND FILE OVERIEW** These data were collected
 to experimentally test the developmental coupling of traits relating to
 body size (body mass and wing length) and physiological state (aerobic
 capacity, energy state, oxidative status) in the approach to fledging in a
 species with a non-linear growth profile. In addition, radiotracking data
 was used to test how morphological and physiological traits correlated
 with post-fledging performance in control and experimentally manipulated
 birds. **METHODOLOGICAL INFORMATION** Morphological and physiological data
 were collected from a nestbox population of European starlings (*Sturnus
 vulgaris*) at our long-term field site of Davistead Farm, Langley, British
 Columbia, Canada, over the course of three breeding seasons (2020-2022).
 On day 15 post-hatching, we randomly selected four chicks from brood sizes
 of 4–6, two of which were fitted with 4.0 g lead-weighted backpacks, using
 a leg-loop harness, with the remaining two chicks receiving no treatment
 and acting as controls. Both weighted and control nestlings were
 subsequently measured (body mass, tarsus, and wing length) on days 17 and
 20 after hatching, while blood samples were also taken on day 20 to assess
 physiological state (aerobic capacity, energy state, oxidative status). In
 addition, between 2021-2022, after the removal of the weight treatment on
 day 20, nanotag radio transmitters (NTQB-4-2, Lotek Wireless Inc.,
 Newmarket, Ontario, Canada) were fitted to fledglings and post-fledging
 activity data were collected up to 49 days after nest departure.
 Haematocrit (% packed cell volume) was measured (± 0.01 mm) using digital
 calipers after whole blood was centrifuged for 3 min at 13 000 g
 (Microspin 24; Vulcon Technologies, Grandview, MO, USA). Haemoglobin (g
 dl−1) was measured using the cyanomethaemoglobin method modified for use
 with a microplate spectrophotometer (BioTek Powerwave 340; BioTek
 Instruments, Winooski, VT, USA), measuring 5 μl whole blood diluted in
 1.25 ml Drabkin’s reagent (D5941; SigmaAldrich Canada, Oakville, Ontario,
 Canada) at 540 nm absorbance. Plasma triglycerides (mmol l−1) were
 measured with a colorimetric assay (Sigma-Aldrich Co.) following the
 manufacturer’s guidelines.  Reactive oxygen metabolites (mg H 2 O 2 dl−1)
 and total antioxidant titers (μmol HClO ml−1) were measured using dROMs
 and OXY kits from Diacron International (Grosseto, Tuscany, Italy). Red
 blood cells from 2021 and 2022 were sent to HealthGene Laboratory
 (Concord, Ontario, Canada) for sexing by polymerase chain reaction
 alongside known adult samples for quality control. Sexing data were not
 available in 2020 as red blood cell samples were lost due to a freezer
 malfunction during the COVID-19 lockdown. For radiotracking data, four
 automated radio telemetry towers (ART) were erected at typical foraging
 locations about the field site and scanned for nearby (approx. 1km) radio
 transmitters every 8 seconds. Each detection produced a power output that
 corresponded to the tag’s proximity to the tower (distance and angle to
 receiving antenna). Changes in power between successive detections were
 used as a measure of activity, with Δ power &gt; 10 corresponding to
 an ‘active’ detection. The ratio of active to inactive detections for each
 chick was used to calculate % daily activity. From this daily activity
 data, we calculated (1) average post-fledging activity, (2)
 activity-slope, and (3) day of dispersal. **DATA-SPECIFIC INFORMATION**
 Number of variables: 35. Number of rows: 706. Unique identifiers: Box
 (nest ID), chick ID, BS.ID (blood sample ID) and tag ID (radio
 transmitter). **‘NAs’** For physiological trait measurements, NAs for
 chicks of 15 and 17 days of age are due to blood samples not being taken
 until day 20. Similarly, NAs for chick ages 15 and 17 in relation to
 post-fledging radio telemetry data are because tags were not fitted until
 day 20. NAs for post-fledging data on day 20 in 2020 correspond to radio
 telemetry data not being recorded in that field season; NAs in 2021
 & 2022 on day 20 for post-fledging data indicate a chick that was
 not fitted with a radio tag. NAs for ‘sex’ in 2020 correspond to loss of
 red blood cell samples during the COVID-19 lockdown of that year. **Blank
 cells** For developmental data (morphological and physiological traits),
 blank cells indicate early fledgling (before 20 days of age). For
 post-fledging performance data overall (activity, activity-slope, and
 dispersal), blank cells indicate chick mortality (see ‘Fate). Empty cells
 specifically for activity and activity-slope data correspond to chicks
 that had too few recorded days of activity to calculate these metrics (see
 ‘Detec5’). In addition, empty cells in ‘Act10’ (see below) indicates
 chicks that dispersed before 10 days post-fledging. Blank cells in ‘Fate’
 mean no mortality was no observed via post-fledging data. **Variables,
 with abbreviations used (see above for unique identifiers):** ·      
 Brood ·       Year ·       Date ·       Time ·       Band; colour band.
 ·       Sex ·       Mass (body mass, g) ·       Wing (Wing length, mm)
 ·       Tars (Tarsus length, mm) ·       Masschange1517; change in mass
 between ages 15-17 (*also applies to ‘Wing’)*. ·       Masschange1720;
 change in mass between ages 17-20 (*also applies to ‘Wing’)*. ·      
 Masschangetotal; change in mass between ages 15-20 (*also applies to
 ‘Wing’)*. ·       Age; days after hatching. ·       Broodsize; number of
 chicks in the nest. ·       BP?; ‘Backpack?’ Yes/No (Y/N) for whether
 chicks received weighted backpack. L corresponds to a backpack that fell
 off during treatment. ·       Handling time; time between initial nest
 disturbance and weighing (days 15 and 17) or blood sampling (day 20).
 ·       HCT; haematocrit (% vol). ·       Hb; haemoglobin (g dl−1).
 ·       Trig; plasma triglycerides (mmol l−1). ·       dROMs; reactive
 oxygen metabolites (mg H2O2 dl−1). ·       OXY; antioxidant titers (μmol
 HClO ml−1). ·       Activity; average post-fledging activity (% of
 ‘active’ to ‘inactive’ detections) ·       Act10; average post-fledging
 activity in first 10 days after fledging. ·       Changeact;
 activity-slope. ·       Disp.yn; Y/N for whether chick dispersed prior to
 concluding data collection. ·       Disp.day; days after fledging that
 chick dispersed. ·       Fate; mortality. · Detec5; did chick have
 &lt; 5 days of activity data? Y/N.