A1 Refereed original research article in a scientific journal
Experimental support for partial compensation, not matched, partner response rules in blue tits
Authors: Brundl, Aisha C.; Lejeune, Lea A.; Deshpande, Purabi; Mulvey, Jessica E.; Thiney, Alice C.; Chaine, Alexis S.; Russell, Andrew F.
Editors: While Geoffrey
Publisher: Oxford University Press (OUP)
Publishing place: CARY
Publication year: 2025
Journal: Behavioral Ecology
Journal name in source: Behavioral Ecology
Journal acronym: BEHAV ECOL
Article number: arae059
Volume: 36
Issue: 2
Number of pages: 10
ISSN: 1045-2249
eISSN: 1465-7279
DOI: https://doi.org/10.1093/beheco/arae059
Web address : https://doi.org/10.1093/beheco/arae059
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/485108804
Outcomes of theoretical models on conflict resolution between investing partners in bi-parental care systems typically predict "partial compensation" or "matched" response rules, depending on underlying assumptions. Further, although experimental tests in birds suggest that care levels by pair members are largely associated with partial compensation responses, this outcome partly depends on the type of experiment used and its effects on model assumptions. To elucidate support for both the underlying assumptions and predictions of models predicting partner compensation versus matching, we performed temporary, bi-directional brood size manipulations during late nestling provisioning in blue tits (Cyanistes caeruleus) in the French Pyrenees. We found support for assumptions of both compensation and matching models. For example, females spent more time with the brood than males, leading to potential information asymmetries on brood demand as expected by matching models. Nevertheless, both pair members changed their provisioning comparably in response to brood size manipulations, suggesting that pair members have comparable cost-benefit functions in response to variation in brood demand, as assumed under partial compensation models. Despite support for the underlying assumptions of both models, we primarily found support for predictions of partial compensation models in provisioning responses. Notably, modest changes by one member of the pair on experimental days were met with larger changes by the other, after controlling for brood size and provisioning rates on control days. Our results corroborate previous findings in blue tits using alternative experimental approaches. We suggest that future studies could benefit from understanding when partial compensation responses dominate matched ones, despite apparent asymmetries in information over brood demand.When both parents care for their offspring, conflict is expected over their relative contributions. To investigate how such conflict might be resolved, we changed the number of nestlings in broods of blue tits. Although both parents responded, low-responding parents had higher-responding partners, consistent with models suggesting that conflict is resolved by partial compensation response rules. Further work is required to discover whether parents respond to each other's contributions directly or indirectly to changes in the number and begging intensity of offspring.
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