Fig. 4. Three `typical' response profiles over time to pyrazine (filled circles)
and herring oil (open circles); control data are subtracted. Profiles are
illustrated for (A) Wilson's storm-petrels (Oceanites oceanicus), (B)
giant petrels (Macronectes sp.) and (C) white-chinned petrels
(Procellaria aequinoctialis) (see text).