Diurnal and Reproductive Stage-Dependent Variation of Parental Behaviour in Captive Zebra Finches

Parental care plays a key role in ontogeny, life-history trade-offs, sexual selection and intrafamilial conflict. Studies focusing on understanding causes and consequences of variation in parental effort need to quantify parental behaviour accurately. The applied methods are, however, diverse even for a given species and type of parental effort, and rarely validated for accuracy. Here we focus on variability of parental behaviour from a methodological perspective to investigate the effect of different samplings on various estimates of parental effort. We used nest box cameras in a captive breeding population of zebra finches, Taeniopygia guttata, a widely used model system of sexual selection, intra-familial dynamics and parental care. We investigated diurnal and reproductive stage-dependent variation in parental effort (including incubation, brooding, nest attendance and number of feedings) based on 12h and 3h continuous video-recordings taken at various reproductive stages. We then investigated whether shorter (1h) sampling periods provided comparable estimates of overall parental effort and division of labour to those of longer (3h) sampling periods. Our study confirmed female-biased division of labour during incubation, and showed that the difference between female and male effort diminishes with advancing reproductive stage. We found individually consistent parental behaviours within given days of incubation and nestling provisioning. Furthermore, parental behaviour was consistent over the different stages of incubation, however, only female brooding was consistent over nestling provisioning. Parental effort during incubation did not predict parental effort during nestling provisioning. Our analyses revealed that 1h sampling may be influenced heavily by stochastic and diurnal variation. We suggest using a single longer sampling period (3h) may provide a consistent and accurate estimate for overall parental effort during incubation in zebra finches. Due to the large within-individual variation, we suggest repeated longer sampling over the reproductive stage may be necessary for accurate estimates of parental effort post-hatching

Diurnal and Reproductive Stage-Dependent Variation of Parental Behaviour in Captive Zebra Finches

<div><p>Parental care plays a key role in ontogeny, life-history trade-offs, sexual selection and intra-familial conflict. Studies focusing on understanding causes and consequences of variation in parental effort need to quantify parental behaviour accurately. The applied methods are, however, diverse even for a given species and type of parental effort, and rarely validated for accuracy. Here we focus on variability of parental behaviour from a methodological perspective to investigate the effect of different samplings on various estimates of parental effort. We used nest box cameras in a captive breeding population of zebra finches, <i>Taeniopygia guttata</i>, a widely used model system of sexual selection, intra-familial dynamics and parental care. We investigated diurnal and reproductive stage-dependent variation in parental effort (including incubation, brooding, nest attendance and number of feedings) based on 12h and 3h continuous video-recordings taken at various reproductive stages. We then investigated whether shorter (1h) sampling periods provided comparable estimates of overall parental effort and division of labour to those of longer (3h) sampling periods. Our study confirmed female-biased division of labour during incubation, and showed that the difference between female and male effort diminishes with advancing reproductive stage. We found individually consistent parental behaviours within given days of incubation and nestling provisioning. Furthermore, parental behaviour was consistent over the different stages of incubation, however, only female brooding was consistent over nestling provisioning. Parental effort during incubation did not predict parental effort during nestling provisioning. Our analyses revealed that 1h sampling may be influenced heavily by stochastic and diurnal variation. We suggest using a single longer sampling period (3h) may provide a consistent and accurate estimate for overall parental effort during incubation in zebra finches. Due to the large within-individual variation, we suggest repeated longer sampling over the reproductive stage may be necessary for accurate estimates of parental effort post-hatching.</p></div

Consistency of parental effort over the course of the day using 1h and 3h sampling windows on day 3 and day 17 post-hatching, separately.

<p>Consistency of parental effort over the course of the day using 1h and 3h sampling windows on day 3 and day 17 post-hatching, separately.</p

Diurnal variation of parental effort in zebra finches on day 3 post-hatching.

<p>Mean ± SE proportion of 1h observation periods spent brooding between 7:00–19:00. Blue filled squares represent male, red filled circles female, grey filled triangles joint (male and female simultaneous) and grey open diamonds total brooding (when at least one parent broods).</p

Consistency of parental effort within reproductive stages in zebra finch parents.

<p>Consistency of parental effort within reproductive stages in zebra finch parents.</p

Division of labour and individual variation of parental effort in zebra finches during incubation.

<p>The figure shows proportion of 3h observation periods (10:00–13:00) spent incubating and inside the nest (nest attendance) during early, middle and late incubation (day 3, 8 and 13 of incubation, respectively). Blue filled squares represent male, red filled circles female, grey filled triangles joint (male and female simultaneous) and grey open diamonds total parental effort (when at least one parent incubates or attends the nest). Data from the same individuals are connected with lines.</p

Division of labour and individual variation of parental effort in zebra finches during nestling provisioning.

<p>The figure shows proportion of 3h observation periods (10:00–13:00) spent brooding and inside the nest (nest attendance) during early, middle and late nestling provisioning (day 3, 10 and 17 post-hatching, respectively). Blue filled squares represent male, red filled circles female, grey filled triangles joint (male and female simultaneous) and grey open diamonds total parental effort (when at least one parent broods or attends the nest). Data from the same individuals are connected with lines.</p

Parental behaviour of breeding zebra finches were recorded using small Mobius digital cameras.

<p>The wide field of view coupled with the ability to record videos in low light conditions and a pronounced sexual dimorphism in this species ensured that parental sex and activity inside the nest could be determined accurately.</p

Consistency of parental effort over the course of the day using 1h and 3h sampling windows on day 3 and day 13 of incubation, separately.

<p>Consistency of parental effort over the course of the day using 1h and 3h sampling windows on day 3 and day 13 of incubation, separately.</p