Incubation behaviour in a double-nesting alpine bird Alectoris graeca saxatilis: Similar nest attendance by males and females
Data files
Sep 17, 2025 version files 432.84 KB
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README.md
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recess-data_JAB.csv
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Abstract
In birds with double-nesting and uniparental incubation, such as the rock partridge (Alectoris graeca saxatilis), the male incubates one clutch, while the female incubates the other. A previous study found no significant difference in hatching and predation rates on Alpine rock partridge nests incubated by each sex. We therefore hypothesized that the incubation rhythms of both sexes would be similar. To test this, we monitored the incubation patterns of 40 nests incubated by females and 41 nests incubated by males in the French Alps between 2011 and 2020. Temperature loggers were installed within and outside the nests to record internal and ambient temperatures at 3-minute intervals. Incubation recess timing and duration were inferred from the analysis of temperature curves. We employed statistical modelling to assess the effects of the incubating bird’s sex, minimum ambient temperature, incubation day, clutch size and recess rank on various incubation parameters. The timing, total duration, and number of recesses, as well as nest temperature, were found to be similar between the sexes. On average, birds took 2.5 recesses per day, with each recess lasting approximately 75 minutes. Overall nest attendance was ≃ 88%. Recesses occurred throughout the day, with a peak after sunrise and a second, less pronounced peak before sunset. Nocturnal recesses were rare and resulted from disturbances to the incubating bird. Modelling results indicated only slight differences in the mean recess duration between the sexes throughout the incubation period. Further analysis showed that both sexes adjusted their incubation rhythms in a similar manner in response to the progress of incubation and to daily minimum temperatures. Cold temperatures may compel parents to spend more time foraging to meet their energy needs. Rock partridges exhibited lower nest attendance compared to grouse species inhabiting cold environments, likely due to their relatively lower body reserves.
Dataset DOI: 10.5061/dryad.hmgqnk9xb
Description of the data and file structure
File: recess-data_JAB.csv
Description: this file includes the data used for analysis of incubation rhythms of rock partridges. It consists of recesses as rows and identifiers along with variables as columns.
Variables
- oiseau: name of the incubating bird
- rang: rank of the recess within the day
- Duree_sortie: duration of the recess, in minutes
- date: number of days, counted from May 31st
- debut: recess start time from sunrise, in minutes
- Tmax_in: nest temperature, in °C, at recess initiation
- Tmin_in: nest temperature, in °C, at return time on the nest
- annee: monitoring year of the incubating bird
- oiseau_an_date: name of the bird_year_date
- oiseau_an: name of the bird incubating a nest_one year (used as nest identifier)
- sexe: sex of the incubating bird (male vs. female)
- annee_F: year
- Tminj: minimal daily ambient temperature, in °C
- ponte: complete clutch size
- PP: camera trap (1 if present, 0 if absent)
- deb_couv: day of nest incubation initiation, counted from May 31st
- mois: month
- aube.lever_soleil: time between dawn and sunrise, in minutes
- lever_soleil.crepuscule: Time between sunset and dusk, in minutes
- phase: nocturnal vs. diurnal
- lever_minute: time of sunrise, in minutes
- debut.aube: time between the start of the recess and dawn, in minutes
- debut_0h: time between the start of the recess and the start of the day, in minutes
- temps_jour: total duration of recesses throughout the day, in minutes, including both diurnal and nocturnal phases
- jour_couv: Incubation day, defined as the number of days since incubation began for a given nest
- temps_diurne: total recess duration, i.e. the cumulative amount of time spent off the nest during the diurnal phase
- temps_nocturne: total recess duration, i.e. the cumulative amount of time spent off the nest during the nocturnal phase
- nb_sorties_jour: number of recesses per day
- nb_sorties_diurne: number of diurnal recesses per day
Code/software
The data can be viewed using LibreOffice or R (version 4.4.1).