Spectacular!

The recovery of the Spectacled Petrel population

- Text and Photographs by Peter Ryan

Thanks to its white ‘spectacles’, the Ringeye or Spectacled Petrel is one of the more charismatic petrels. It breeds only at Inaccessible Island in the central South Atlantic Ocean, where it has been threatened by introduced mammals and accidental bycatch on tuna longlines. Peter Ryan explains why it is becoming an increasingly regular visitor to southern African waters.

Although originally described as a distinct species, the Spectacled Petrel was generally considered a subspecies of the Whitechinned Petrel until 1998, when it was shown that the two species have different calls (Bird Conservation International 8: 223-235). Both species utter a series of rattles, groans and squealing calls at their nest burrows and in flight over their colonies. However, Spectacled Petrels have lower-pitched calls than White-chinned Petrels and their groan calls in particular have a more complex harmonic structure that is more similar to calls of other Procellaria petrels. Playback experiments show that Spectacled Petrels are much less responsive to recordings of Whitechinned Petrels than to those of other Spectacled Petrels.

A subsequent study led by Mareile Techow in 2009 (Molecular Phylogenetics and Evolution 52: 25-33) confirmed that the two species are genetically distinct, having last shared a common ancestor about 0.9 million years ago. This is in contrast to the divergence among White-chinned Petrels, where the nominate subspecies P. a. aequinoctialis, which breeds at islands in the South Atlantic and Indian oceans, segregated from New Zealand’s