Offspring provisioning represents a major reproductive cost. However, evidence suggests that parents sometimes feed unrelated offspring. Several hypotheses could explain this puzzling phenomenon. Adults could feed unrelated offspring that are (1) of close social associates to facilitate these juveniles’ integration into their social network (resulting in social inheritance), (2) potential extra-pair offspring, (3) at a similar developmental stage as their own, (4) coercing feeding by begging, or (5) less-developed and who’s enhanced survival would benefit the adult or its own offspring (the group augmentation hypothesis). Colonial breeders are ideal for investigating the relative importance of these hypotheses because offspring are often kept in crèches where adults can exhibit allofeeding. Using automated monitoring of replicated captive zebra finch (Taeniopygia guttata) colonies, we found that while parents selectively fed their own offspring, they also consistently fed unrelated offspring (32.48% of feeding events). Social relationships among adults prior to breeding did not predict allofeeding, nor was provisioning directed towards unrelated offspring directed to potential genetic offspring. Instead, adults preferentially fed less-developed non-offspring, despite these not begging more frequently than larger ones did. Our study suggests that allofeeding is consistent with group augmentation, which could be beneficial through colony maintenance or increased offspring survival.

dataChickID_toPublish20200223.csv: dataset containing the information about each chick.

dataParentsID.csv: dataset containing information about adults (parents).

dataQ.csv: dataset of observed feeding visits/events identified in the videos, including information of attendees and the occurrence of begging behaviour.

Event_All_Count.csv: dataset of observed feeding visits where parents fed non-offspring. This dataset was created by transforming “dataQ.csv” based on $EventID and the relationship of fed chicks (i.e. “unrelated” to the focal adult, $AdultID).

massChecksChicksCross-foster.csv: dataset for chick ID, body mass, and age (i.e. days old).

2018_AX_prebreedingMtx.RData: data on social interactions in each of the aviaries (1 to 4) during the pre-breeding period. These data were collected via an automated tracking system, 8-megapixel Camera Module V2 (RS Components Ltd and Allied Electronics Inc.) controlled by a Raspberry Pi3 Model B (Raspberry Pi Foundation), and individuals were identified by a backpack containing a 2D-tag (see Alarcón-Nieto et al 2018).

Adult_towards_potential EPoffspring.R: Code to report the numbers of feeding visits/events where adults feed to potential extra-pair offspring.

Figure1a_Chick_masses.R: Code for the relationship between age of chick and body weight.

Figure3a_Adult_towards_OwnSocialOffspring.R: Code for testing (1) whether parents selectively fed their own social offspring or not and (2) whether social offspring begged more towards social parents or not.

Figure3b_Adult_towards_GeneticOffspring.R: Code for testing (1) whether parents selectively fed their own genetic offspring or not and (2) whether genetic offspring begged more towards genetic parents or not.

Figure4a_Adult_towards_Under-developedNonOffspring.R: Code for testing whether parents selectively fed non-offspring based on their developmental stages.

Figure4b_Adult_towards_BeggingNonOffspring: Code for testing whether parents selectively fed begging non-offspring or not.

SupplInfoSec15_MantelTest_AviaryX.R: Code for testing whether adults in each aviary (1 to 4) selectively fed offspring of close social associates or not.