Plasticity in diurnal activity and temporal phenotype during parental care in European starlings, Sturnus vulgaris

Abstract

We used an automated radio telemetry system to determine diurnal patterns of activity and temporal phenotype (onset and cessation of activity) in female European starlings (Sturnus vulgaris) during breeding. Parental care is thought to be the most "costly" part of reproduction with high rates of intense activity due to foraging and provisioning for chicks, so we predicted that variation in timing of activity should be closely related to breeding success. Diurnal variation in activity varied systematically with breeding stage in a way consistent with specific demands of each phase of parental care: incubating females were more active late in the day (16:00-18:00), while chick-rearing females were more active early in the morning (07:00-11:00). There was marked individual variation in timing of onset, and to a lesser extent cessation, of activity, e.g. chick-rearing females first became active between 7-127 min after morning civil twilight (CT), with low to moderate repeatability within-and among-breeding stages (individual explained 2-62% of total variation). On average, females were active later, and ceased being active earlier, during chick-rearing compared with incubation. Chick-rearing birds had a longer active day, but only by 2.3% (36% of the seasonal increase in total available day length). Thus, chick-rearing females were relatively less active ('lazier') which is consistent with the idea that parents work more efficiently rather than simply working harder. We found little evidence that chick-rearing activity was associated with variation in measures of current reproduction (provisioning rate, number and quality of chicks), future fecundity (initiating 2nd brood, cumulative 2-year productivity) or survival (local return rate).Our study demonstrates that timekeeping mechanisms show plasticity in response to reproductive state and can be modulated by 'biotic' (e.g. prey availability) or 'social' time (demands of parental care).

Mechanisms behind the Madness: How Do Zombie-Making Fungal Entomopathogens Affect Host Behavior To Increase Transmission?

“…Neuroactive chemicals like hormones and neuromodulators can activate and deactivate behavioral pathways in the central nervous system to allow for quick responses to unpredictable alterations in an individual’s direct surroundings ( 85 ). Additionally, behavioral outputs of the biological clock regulate activity patterns to anticipate predictable biotic and abiotic daily changes in the environment, ( 86 , 87 ) but do so flexibly enough to give rise to interindividual variation within a population (i.e., chronotypes) ( 88 , 89 ) and adjust to sudden changes in environmental and social cues ( 90 – 92 ). While such behavioral plasticity is of utmost importance for survival, it also provides opportunities for parasites to hijack and coopt ( 93 , 94 ).…”

Reproductive fitness is associated with female chronotype in a songbird

“…The only other study we are aware of that examined reproductive success relative to incubation chronotype did not find such an association (Maury et al . 2020).…”

“…Therefore, in this study, we leverage data from wild birds to i) disentangle particular factors that contribute to explain variation in chronotype, and ii) newly document links between chronotype and reproductive fitness. In a well-studied songbird, the great tit (Parus major), we inferred female chronotype through measuring behaviour during incubation, a critically important post-zygotic stage of avian reproduction, while monitoring reproductive success (Graham et al 2017;Capilla-Lasheras 2018;Gwinner et al 2018;Maury et al 2020). Because features of the environment can influence chronotype, we also included data from two habitat types, urban and forest, which often affect the diel rhythm of animals (Dominoni et al 2013;Gaynor et al 2018).…”

Time-course RNASeq ofCamponotus floridanusforager and nurse ant brains indicate links between plasticity in the biological clock and behavioral division of labor

“…In addition to being endogenous and entrainable, circadian clocks are also inherently plastic; the phase, amplitude and period length with which circadian processes oscillate can change with an organism's age or social environment [37][38][39][40][41][42]. Such changes give rise to phenotypes that differ in their exact timing of activity onset relative to sunset or sunrise, known as "chronotypes" [43][44][45][46].…”