Data from: Counting chicks before they hatch: Extending the observed lifetime to better characterise evolutionary processes in the wild
Data files
Nov 28, 2024 version files 19.80 KB
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Nest_data_(2008-09_Wytham_GTs).csv
17.49 KB
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README.md
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Abstract
Evolutionary theorists have emphasised for over half a century that population sampling must be conducted at the intergenerational boundary if the distinct effects of selection and inheritance are to be reliably quantified, with individuals recognised at the point of conception and lifetime reproductive success (LRS) defined as the total number of zygotic offspring produced per zygote. However, in those species whose ecology is otherwise well-suited to individual-level population studies, the prenatal part of an individual's life is often difficult to observe. While uncertainty has long surrounded the fertilisation status of unhatched bird eggs—hatching failure can arise through fertilisation failure or prenatal mortality—two recent studies show fertilisation failure to be extremely rare within two of the most popular avian study species. As such, unhatched eggs are highly reliable indicators of prenatal mortality. Although the generality of these results remains unclear, they demonstrate that prenatality can be incorporated into the observable lifespan of free-living animals. This allows zygotic LRS to be retrospectively quantified using historical nest observations and facilitates a more complete characterisation of the evolutionary dynamics of wild populations.
https://doi.org/10.5061/dryad.70rxwdc7c
Description of the data and file structure
Nestboxes in Wytham Woods (Oxfordshire, UK) were visited approximately weekly to observe progress of all breeding attempts, more frequently around the time of expected hatching. The archived file includes all recorded great tit nesting attempts from 2008-2009.
Files and variables
File: Nest_data_(2008-09_Wytham_GTs).csv
Description: Data derived from observations of great tit breeding attempts in nestboxes in Wytham Woods (Oxfordshire, UK). Nestboxes were visited approximately weekly to observe progress of all breeding attempts, and more frequently around the time of expected hatching. The archived file includes all recorded great tit nesting attempts from 2008-2009. Missing values are represented by NAs.
Variables
- Nest_ID: A unique identifier for each distinct breeding attempt
- year: Year of breeding attempt (2008 or 2009)
- clutch_size: Total number of eggs laid. If incubation was never started (such that the breeding attempt was potentially abandoned before laying was completed), the number of eggs in the nest is recorded, although it may not represent a completed clutch.
- hatch_day: The hatching date for the earliest-hatching egg in the nest. Values represent ‘Aprildays’, which are the number of days since 31st March (i.e., 1st April represents an Aprilday of 1). Hatching date is estimated based on the appearance of chicks and/or the weight of the largest chick(s) in the brood (both calibrated using data from high frequency visits).
- max_observed_brood_size: The maximum number of chicks in the nest that was recorded during post-hatching visits to the nestbox, including the ringing of chicks two weeks after the recorded hatch date (which can be the only occasion when the brood size was recorded.
- number_fledged: The number of confirmed fledglings. Chicks are ringed fourteen days after the clutch’s recorded hatch date, and the number of fledglings calculated as the difference between this and the number of dead chicks remaining in the nest after fledging has been completed.
Nestboxes in Wytham Woods (Oxfordshire, UK) were visited approximately weekly to observe progress of all breeding attempts, more frequently around the time of expected hatching. The archived file includes all recorded great tit nesting attempts from 2008-2009.