DOI: 10.5061/dryad.18931zd87
title: Data from: Parental control: Ecology drives plasticity in parental response to offspring signals

description: Bird species differ in their parent-offspring interactions, and these
 differences may be caused by environmental variation. When food is
 plentiful, the chicks that are begging the most are fed the most. When
 food is scarce, bird species instead feed the largest offspring. While
 this variation could be due to parents responding to signalling
 differently based on food availability, it could equally be due to
 offspring adjusting their behaviour, to variation in information
 availability, or to confounding factors not related to the environment. We
 tested between these competing explanations experimentally, by
 manipulating food availability in a population of wild great tits, Parus
 major, while standardising offspring size and behaviour by creating mixed
 cross-fostered broods just before filming. To simulate variation in
 ecological conditions, we experimentally manipulated food availability in
 an alternating pattern: half of the broods received supplemental food
 (mealworms and waxworms) in a feeding tray given to parents, while the
 other half experienced natural conditions. We wanted all parents to be
 exposed to equivalent information from their broods during filming, so
 that we could rule out the possibility that offspring are driving any
 differences in parental provisioning preferences. We therefore
 standardized brood size and offspring supplementation history across all
 broods immediately before filming on day 8. We measured chick body size by
 weighing chicks during the cross-fostering, and measured begging intensity
 from our videos. We painted all chicks with a dot of red, non-toxic
 acrylic paint on the head just before filming, so that we could
 individually identify chicks in the videos. All videos were coded by the
 same observer, blind to the experimental treatment and to chick weight
 ranks. The order in which the observer coded the videos was random
 concerning whether parents were supplemented and unsupplemented. Adult
 identity was determined by the difference in crown feather glossiness of
 males and females. This isolated the effect of parental strategies while
 holding offspring begging and size constant across treatments, but with
 sufficient variation within broods to generate usable information for
 parents. We found that when food was more plentiful, parents were: (1)
 more likely to preferentially feed the chicks that were begging the most;
 and (2) less likely to preferentially feed larger chicks. Overall, our
 results suggest that parents have more control over food distribution than
 suggested by scramble competition models, and that they flexibly adjust
 how they respond to both offspring signals and cues of offspring quality
 in response to food availability. Consequently, depending upon
 environmental conditions, parental plasticity and predictably different
 signalling systems are favoured.
description: # Parental control: Ecology drives plasticity in parental response to
 offspring signals **Video File Overview**\ The data and code refers to
 videos of Parus major parents feeding chicks. The complete collection of
 videos can be found on Zenodo in two data depositories. The first (DOI
 [10.5281/zenodo.15625055](https://doi.org/10.5281/zenodo.15625055)) has
 videos  from nests A, AA, B, BB, C, CC, D, DD, E, EE, F, FF, G, H, I, J,
 K. The second (DOI
 [10.5281/zenodo.15625465](https://doi.org/10.5281/zenodo.15625465)) has
 videos from nests L, M, N, O P, Q, R, S, T, U, V, W, X, Y, and Z. These
 files correspond to the variable "Blinded.film.file" which is
 the file name of the video data where each feeding visit can be found.
 They proceed in order, so C_2 is followed by C-3 and then by C-4, for
 example.  The first video for each nest "_1" is not included to
 give birds time to return to normal behavior after being disturbed during
 cross-fostering. **DATA & CODE FILE OVERVIEW** This data repository
 consists of one data file with two sheets, and this README document, with
 the following data filenames and variables. Missing data due to the
 camera's view being obscured are coded "NA" 1.
 **Field_Study_Date: Feeding Visits** Variables 1. unique.feeding.visit.ID:
 label for each row of the dataset 2. nest: ID of the nest 3. supplemented:
 whether the nest was in the supplemented (extra food) or unsupplemented
 (no extra food) treatment  4. hatch.date.since.march.1: when the first egg
 in the nest hatched, in days since March 1 5. clutch size: the number of
 eggs laid 6. nest.brood.size: the number of chicks that hatched in this
 nest 7. film.brood.size: the number of chicks during filming, after
 cross-fostering (7 or 6) 8. brood.size.change: the difference in the
 number of chicks in the original vs the filming brood 9.
 film.date.since.march.1: the date of filming, in days since March 1 10.
 number.dead.by.day.7: the number of dead chicks in the first 7 days after
 hatching 11. any. prior.mortality: yes/no (1/0) on whether at least one
 chick had died in the first 7 days after hatching 12. male.id: ID of the
 father  13. female.id: ID of the mother 14. Blinded.film.file: file name
 of the video data where this feeding visit can be found 15. hour.Entrance,
 min.Entrance, sec.Entrance: the time the parent entered the nest 16.
 parent.sex: whether the male or female performed this feeding visit 17.
 visit.number.for.parent: which number feeding visit this is for the parent
 (first visit recorded = 1, second = 2, etc) 18. fed.chick.ring.number: ID
 of the chick who received food on this feeding visit 19.
 fed.chick.beg.posture: begging posture (0-3, 0 is no begging, 3 is
 maximum) of the chick who received food on this feeding visit 20.
 fed.chicks.height.rank: height rank of the chick who received food on this
 feeding visit (highest chick to parent = 1, second highest = 2, etc) 21.
 fed.chicks.nearest.rank: proximity rank of the chick who received food on
 this feeding visit (closest chick to parent = 1, second closest = 2, etc)
 22. chick1.beg, chick2. beg, chick3. beg, chick4 .beg, chick5.beg, chick6.
 beg, chick7. beg: begging postures of all 7 chicks during that feeding
 visit.  23. missing .beg.number: number of chicks where we could not
 identify their begging posture 24. relative.beg.fed.chick.no.zero: how
 much a chick was begging, relative to the other begging chicks on that
 visit (1= same as nest mates, &gt;1 = more than nest mates) 25.
 mean.beg.brood.no.zero: the mean begging posture for the whole brood on
 that feeding visit, excluding chicks that were not begging 26.
 mean.beg.brood.with.zero: the mean begging posture for the whole brood on
 that feeding visit 27. max.beg.brood: the highest begging posture seen on
 this visit 28: total. brood. beg: the sum of all the begging postures on
 this visit 29: number.chicks.begging.higher: the number of chicks begging
 more than the fed chick on this visit 30:
 relative.beg.fed.chick.with.zero: how much a chick was begging, relative
 to all the other chicks on that visit (1 = same as nest mates, &gt;1 =
 more than nest mates) 28. fed.chick.beg.rank: the begging rank of the fed
 chick (1 = fed chick was begging the most (or tied) compared to nestmates,
 2 = one chick was begging more intensely than the fed chick, etc) 29.
 fed.chick.weight.rank: the size rank (based on mass in g) of the fed chick
 (1 = largest chick in the nest, 2 = second largest, etc) 30.
 fed.chick.relative.weight: the weight of the fed chick compared to the
 mean weight in the nest (1 = average) 31. film.brood.mean.weight: the mean
 weight of the chicks in the filming cross-fostered brood 32.
 film.brood.sd.weight: standard deviation of the weights of the chicks in
 the filming cross-fostered brood 33. sd.brood.beg.with.zero: standard
 deviation of the begging postures of the entire brood on that visit 34.
 sd.brood.beg.no.zero: standard deviation of the begging postures of
 begging chicks on that visit 35. unknown.id.chickx1.beg,
 unknown.id.chickx2.beg, unknown.id.chickx3.beg, unknown.id.chickx4.beg,
 unknown.id.chickx5.beg, unknown.id.chickx6.beg, unknown.id.chickx7.beg:
 begging postures of all chicks, in case the identity of a particular chick
 could not be recorded, although its begging could be seen. 2.
 **Field_Study_Data: Chick overview** 1. chick.ring.number: chick ID 2.
 natal. nest: the nest the chick was born into 3. filming.nest: the nest
 the chick was filmed in 4. foster .nest: the nest the chick was
 cross-fostered to 5. handfed_y_n: whether the chick was handfed or not
 prior to filming 6. survived_to_day_7: whether the chick survived the
 first 7 days or not 7. survived_to_day_14: whether the chick survived the
 first 14 days or not 8. survived_to_fledge: whether the chick survived the
 nestling period 9. survival_outcome: categorical descriptor of survival
 outcome or when death occurred 10. mass.day.7: How much the chick weighed
 in grams on day 7 after hatching 11. natal. nest.Supplemented: whether the
 chick came from a supplemented or unsupplemented natal nest.