Cooperative feeding in common dolphins as suggested by ontogenetic patterns in δ ¹⁵ N bulk and amino acids

Understanding the effect of stage-specific traits on species feeding habits can reveal how natural selection shapes life strategies. Amino acid (AA) nitrogen stable isotopes (δ15N) provide multiple proxies habitat baseline values and diet that improve our understanding strategies relative to their animal metabolism. We evaluated body length as a proxy for stage sex common dolphin Delphinus delphis using δ13C δ15N in bulk tissue AAs from skin samples collected almost two decades. For data, we used SIBER analysis compare isotopic niches by stage. AA developed hierarchical Bayesian model (HBM) estimate indices trophic status (Δ15N position). The reflected structure data partitioning variability into three sources: between laboratory replicates, within dolphins among dolphins. Estimates Δ15N based all source were more precise each dolphin, less variable average 2.4‰ higher than single (Glx) (Phe) AAs. Precision was further increased when information shared individuals through random effects or regression models. position showed similar patterns. Both δ15Nbulk no difference sex, suggesting males females have may not segregate. However, lower weaning calves smaller juveniles discriminate them adults, whereas do not. A discrimination factor (TDFTro-Src) 3.1‰ required reasonable estimates these Together, lack differences sexes, low variation adults knowledge dolphins' social organization support intraspecific cooperation an important strategy feed highly dynamic marine environment. Our study also presents efficient way analyse complex HBM investigate foraging behaviour long-lived difficult wild.