A comparison of the olfactory abilities of three species of procellariiform chicks.

Most studies investigating olfactory sensitivities in procellariiform seabirds have concentrated on adults, but little attention has been paid to how olfactory behaviours develop. We took a first step towards understanding the ontogeny of these behaviours by testing the olfactory abilities of the blue petrel Halobaena caerulea, the thin-billed prion Pachyptila belcheri, and the common diving petrel Pelecanoides urinatrix. We scored the responsiveness of chicks in a sleep-like state to puffs of odours presented near their nostrils. We tested reactions to dimethyl sulphide (DMS, a prey-related odourant) and phenyl ethyl alcohol (PEA, a novel odourant); distilled water was used as a control. Scores for blue petrel chicks were significantly greater for DMS and PEA than for control presentations, while scores for thin-billed prions were significantly greater only for PEA. Common diving petrels did not respond significantly to either odourant. These results are consistent with what is known of adult olfactory behaviours. A negative correlation between the mass of blue petrel chicks and their mean responsiveness to odours indicates that older or recently fed birds are less responsive to these stimuli.