Volume 43, No. 2

Search by author or title:

First documented at-sea records of "intermediate morph" Soft-plumaged Petrel Pterodroma mollis and clarification of polymorphism in the species


1 10 Melrose Crescent, Menora, Perth, Western Australia 6050, Australia (
2 87 Falls Road, Lesmurdie, Western Australia 6076, Australia
3 Veterinary & Life Sciences, Murdoch University, Murdoch, Western Australia 6150, Australia


GRAFF, J.K., COLLINS, A. & CAKE, M.A. 2015. First documented at-sea records of "intermediate morph" Soft-plumaged Petrel Pterodroma mollis and clarification of polymorphism in the species. Marine Ornithology 43: 161 - 164

Received 20 February 2015, accepted 21 April 2015

Date Published: 2015/10/15
Date Online: 2017/02/28
Key words: Pterodroma mollis, Procellariidae, plumage polymorphism, Indian Ocean, Western Australia


The Soft-plumaged Petrel is a gadfly petrel that occurs widely across the southern oceans and exhibits plumage polymorphism. Pale-bellied individuals make up the vast majority of the species, while dark individuals are relatively rare. Intermediate forms are rarer still and, according to some authors, known only from museum specimens. We describe a number of at-sea records of intermediate-plumaged individuals seen off southwest Western Australia, including a previously undocumented streaked variant. Our observations indicate that plumage polymorphism within the species covers a continuous spectrum of variation between typical pale and wholly dark individuals.


BOURNE, W.R.P. 1957. Additional notes on the birds of the Cape Verde Islands, with particular reference to Bulweria mollis and Fregata magnificans. Ibis 99: 182–190.

BROWN, L.H., URBAN, E.K. & NEWMAN, K. 1982. The birds of Africa. Volume 1. London: Academic Press.

CLANCEY, P.A., BROOKE, R.K. & SINCLAIR, J.C. 1981. Variation in the current nominate subspecies of Pterodroma mollis (Gould) (Aves: Procellariidae). Durban Museum Novitates 12: 203–213.

CRAMP, S. & SIMMONS, K.E.L. (Eds.) 1977. Handbook of the birds of Europe, the Middle East and North Africa. The birds of the Western Palearctic. Volume 1 – ostrich to ducks. Oxford: Oxford University Press.

DEL HOYO, J., ELLIOT, A. & SARGATAL, J. 1992. Handbook of the birds of the world. Vol 1. Barcelona: Lynx Edicions.

ELLIOTT, H.F.I. 1954. On two new races and an undescribed variety from the Tristan de Cunha group. Bulletin of the British Ornithologists' Club 74: 21–24.

FLOOD, B. & FISHER A. 2013. Multimedia identification guide to North Atlantic seabirds: Pterodroma Petrels. Isles of Scilly, UK: Scilly Pelagics.

HARPER, P.C. 1973. The field identification and supplementary notes on the Soft-plumaged Petrel (Pterodroma mollis Gould, 1844). Notornis 20: 193–201. 

HARRISON, P. 1983. Seabirds – an identification guide. Beckenham, UK: Croom Helm Ltd.

HARROP, A.H.J. 2004. The ‘soft-plumaged petrel' complex: A review of the taxonomy, identification and distribution. British Birds 97: 6–15.

JOHNSTONE, G.M. & STORR, G.M. 2004. Handbook of Western Australian birds. Vol. I. Non-passerines (emu to dollarbird). Perth, Australia: Western Australian Museum.

MARCHANT, S. & HIGGINS P.J. (Eds.) 1990. Handbook of Australian, New Zealand and Antarctic birds. Volume 1: ratites to ducks. Melbourne, Australia: Oxford University Press.

O'CONNOR, F. 2010. Frank O'Connor's Birding Western Australia [Pelagics]. [Available online at:; accessed 6 December 2013]. 

ONLEY, D. & SCOFIELD, P. 2007. Albatrosses, petrels & shearwaters of the world. Princeton, New Jersey: Princeton University Press.

SCHRAMM, M. 1982. Recent records of the dark form of the Soft-plumaged Petrel Pterodroma mollis from the Subantarctic. Cormorant 10: 3–6.

SERVENTY, D.L., SERVENTY, V.N. & WARHAM, J. 1971. The handbook of Australian seabirds. Sydney, Australia: A.H. & A.W. Reed Ltd.

SHIRIHAI, H. 2008. The complete guide to Antarctic wildlife. 2nd ed. Princeton, New Jersey: Princeton University Press.

SWALES, M.K. 1965. The seabirds of Gough Island. Ibis 107: 17–42 & 215–229.

Search by author or title:

Browse previous volumes: