Alternation of nest visits varies with experimentally manipulated workload in brood-provisioning great tits

Baldan, Davide; Curk, Teja; Hinde, Camilla A.; Lessells, C. M.

doi:10.1016/j.anbehav.2019.08.004

Cited by 15 publications

(23 citation statements)

References 46 publications

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“…Outlier IVIs and IAIs may represent carers taking breaks from caring (e.g., due to self-foraging or disturbance), and hence are useful for characterizing and partitioning longer sample periods to avoid applying inappropriate analyses. When analyzing samples from longer periods of care, intervals (and hence analyses based on them) can be biased as the beginning and end of the sample periods are more likely to cut longer intervals; where possible studies should use either naturally bounded periods, or ensure their sample contains many events and acknowledge the bias (Baldan et al, 2019).…”

Section: Rate and Variancementioning

confidence: 99%

“…The rates at which individuals deliver care may vary across a sample period, driven by environmental variation (e.g., weather) or the states of parents or offspring (e.g., hunger). Such variation will affect parental care over the same period, and can limit the usefulness of randomizations used to infer interactions between carers (Baldan et al, 2019). To quantify trends, one simple metric is how strongly intervals are ordered in time (Schlicht et al, 2016), which will identify a linear increase or decrease in rate.…”

Section: Trendsmentioning

confidence: 99%

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What Can We Quantify About Carer Behavior?

Savage

Hinde

2019

Front. Ecol. Evol.

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In many species, individuals must contribute extensively to offspring care to reproduce successfully. Within species, variation in care is driven by local social, physiological, and environmental contexts, and this relationship has been a major focus of behavioral ecology since the inception of the field. The majority of existing studies on care, both theoretical and empirical, have focused on measuring the amount of care delivered by each carer as a proxy for individual investment, linking this investment to the local context, and investigating outcomes for offspring. However, more recently interest has grown in the finer-scale details of care, including how individuals respond to each other's behavior, and temporal variation in care both within and between stages. Simultaneously, advances in remote monitoring methods, such as video cameras and passive integrated transponder (PIT) tag systems, have vastly increased the ease of collecting large amounts of care data, providing opportunities to study carer behavior in much greater detail than previously possible. In this mini-review we provide an overview of the dimensions of carer behavior that can be quantified, illustrated using recent studies from a variety of taxa. We classify these analyses into three broad groups: (a) how parental care is distributed in time, (b) variation within care events, and (c) how carers interact when jointly providing care. Our aim is to encourage more in-depth analyses of parental care, to build a more complete picture of how animals rear their offspring.

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Section: Rate and Variancementioning

confidence: 99%

Section: Trendsmentioning

confidence: 99%

What Can We Quantify About Carer Behavior?

Savage

Hinde

2019

Front. Ecol. Evol.

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“…We used an alternation score which measures the deviation of the observed amount of alternation from that expected given the proportion of visits by the two parents (Baldan et al, 2019):…”

Section: Measures Of Alternation and Provisioning Cth Alternation Scorementioning

confidence: 99%

“…The ESS is remarkable in that it results in completely cooperative behavior, with each parent having maximum fitness. Johnstone et al's (2014) model has triggered studies on several avian species which have shown that alternation of nest visits does indeed occur at above the rate expected if the two parents provision independently at a constant rate (Johnstone et al, 2014;Bebbington and Hatchwell, 2016;Koenig and Walters, 2016;Iserbyt et al, 2017;Savage et al, 2017;Baldan et al, 2019). However, although this alternation of nest visits is consistent with a turn-taking strategy by the parents, other processes may give rise to alternation.…”

Section: Introductionmentioning

confidence: 99%

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Turn-Taking Between Provisioning Parents: Partitioning Alternation

2019

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How parents negotiate over parental care is a central issue in evolutionary biology because it affects the evolutionary outcome of sexual conflict. A recent theoretical model shows that "turn-taking" in provisioning visits by the parents can be an evolutionarily stable negotiation strategy, and empirical studies have shown that parental nest-visits do indeed alternate more than expected by chance. However, such alternation may also be generated by a refractory period, or by correlated temporal heterogeneity (CTH) in provisioning rates of the two parents driven by temporal environmental variation. Here we use a recently developed measure of alternation and a novel measure of CTH in the provisioning rates of pairs to clarify what can be concluded about the occurrence of turn-taking from the provisioning patterns of pairs. First, we show using a simulation model that turn-taking can, by itself, generate both a refractory period and CTH in provisioning rates. Second, we incorporate this insight into a conceptual framework that combines an existing randomization analysis with a novel analytical approach in which "pseudo-pairs" are created by analytically pairing the provisioning sequence of a parent at one nest with the contemporaneous provisioning sequence of the other-sex parent at a nearby nest. This allows us to partition the alternation score into different components. This approach confirms that isolating a component of alternation that can be unequivocally attributed to turn-taking is probably impossible. However, the pseudo-pairs analysis does isolate a component that can be unequivocally attributed to general temporal environmental variation [environmental variation that causes CTH in provisioning rates across (as well as within) pairs]. Third, we use these techniques to partition the alternation score of 17 pairs of great tits Parus major provisioning in the wild. Approximately 8% of the observed alternation score is due to the frequency distribution of the inter-visit intervals, 74% to nest-specific effects on the sequence of inter-visit intervals, and 18% to general effects on the sequence of inter-visit intervals. This last component can be unequivocally attributed to general temporal environmental variation, and is the first empirical demonstration of alternation by free-living provisioning parents being generated by temporal environmental variation.

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Visitation rate, but not foraging range, responds to brood size manipulation in an aerial insectivore

Madden

McDermott

Safran

2022

Behav Ecol Sociobiol

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Life history theory predicts that increased investment in current offspring decreases future fecundity or survival. Avian parental investment decisions have been studied either via brood size manipulation or direct manipulation of parental energetic costs (also known as handicapping). However, we have limited experimental data on the potential interactive effects of these manipulations on parent behavior. Additionally, we know little about how these manipulations affect spatial foraging behavior away from the nest. We simultaneously manipulated brood size and parental costs (via added weight in the form of a GPS tag) in wild female barn swallows (Hirundo rustica). We measured multiple aspects of parent behavior at and away from the nest while controlling for measures of weather conditions. We found no significant interactive effects of manipulated brood size and parental costs. Both sexes increased their visitation rate with brood size, but nestlings in enlarged broods grew significantly less post-brood size manipulation than those in reduced broods. Foraging range area was highly variable among GPS-tagged females but was unaffected by brood size. As such, increased visitation rate in response to brood size may be more energetically costly for far-ranging females. GPS-tagged females did not alter their visitation rate relative to un-tagged birds, but their mates had higher visitation rates. This suggests that GPS tagging may affect some unmeasured aspect of female behavior, such as prey delivery. Our findings indicate that investigation of foraging tactics alongside visitation rate is critical to understanding parental investment and the benefits and costs of reproduction. Significance statement Avian parental investment decisions have been studied by either brood size manipulation or direct manipulation of parental costs, but rarely both simultaneously. We simultaneously manipulated brood size and parental costs (via addition of a GPS tag) in a wild avian system, allowing us to examine interactive effects of these manipulations. Additionally, studies of parental investment often examine behaviors at the nest, but measurements of parental care behavior away from the nest are rare. Our study is unique in that we measured multiple aspects of parental care, including spatial foraging behavior tracked with GPS tags. We found no interactive effects of manipulated brood size and parental costs on visitation rate or nestling growth, and spatial foraging behavior of females was individually variable. Documenting foraging tactics alongside visitation rate is critical to understanding parental investment because the same visitation rate might be more costly for far-ranging females.

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Alternation of nest visits varies with experimentally manipulated workload in brood-provisioning great tits

Cited by 15 publications

References 46 publications

What Can We Quantify About Carer Behavior?

What Can We Quantify About Carer Behavior?

Turn-Taking Between Provisioning Parents: Partitioning Alternation

Visitation rate, but not foraging range, responds to brood size manipulation in an aerial insectivore

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