Abstract
Some migratory procellariiform (tube nosed) seabirds can dive to depth yet the physiological mechanisms underpinning their dive performance remain poorly described. We compared dive capacity traits (total oxygen stores, theoretical aerobic dive limit ( t ADL) and muscle buffering) in three species of Procellariiformes that spanned a range of dive behaviour, i.e., grey-faced petrel ( Pterodroma gouldi , x̄ dive depth/duration: 1.6 m, 4 s), flesh-footed shearwater ( Ardenna carneipes , x̄ dive depth/duration: 3.5 m, 6.9 s) and the sooty shearwater ( Ardenna grisea , x̄ dive depth/duration: 6.9 m, 39.7 s). Our results show that the deeper and longer diving shearwaters have significantly higher total oxygen stores than grey-faced petrels i.e., 41.0 ± 3.1 mL O 2 kg − 1 for grey-faced petrels versus 46.2 ± 2.3 and 48.6 ± 2.2 mL O 2 kg − 1 sooty shearwaters and flesh-footed shearwaters respectively. This is mirrored in respective t ADL times with 44.2 ± 3.4 s for grey faced petrels, versus 49.6 ± 2.7 and 52.3 ± 2.4 s for sooty shearwaters and flesh-footed shearwaters respectively. Furthermore, dive logger data indicates that these species would rarely exceed t ADL. Myoglobin concentrations in pectoral muscles of our study species correlated strongly with diving ability. This myoglobin oxygen supply appears sufficient to keep metabolism of flight muscles aerobic as muscle buffering capacity differed minimally among species. Lastly, temporal differences in haematological parameters suggest a plasticity in blood oxygen stores among years. Our results show the degree to which physiological adaptations meet function, with Procellariiformes exhibiting traits that match their underwater performance.