--- title: "Differing fortunes of Grey and White-chinned Petrels at South Africa’s Marion Island" --- # Differing fortunes of Grey and White-chinned Petrels at South Africa’s Marion Island Over the past 14 month’s field researchers, Ben Dilley and Delia Davis of the [Percy FitzPatrick Institute of African Ornithology](http://www.fitzpatrick.uct.ac.za/), University of Cape Town, have studied four species of burrowing petrels on South Africa’s [Marion Island](https://acap.aq/index.php/en/news/latest-news/1371-acap-breeding-sites-no-27-sub-antarctic-marion-island-a-research-laboratory-for-albatrosses-and-petrels). ![](https://acap.aq/images/stories/acap/Birds/Petrels/G/Grey/Grey_Petrel_by_Peter_Ryan2.jpg) Grey Petrel on Marion Island.  Photograph by Peter Ryan Research has been concentred on two summer-breeding species, the ACAP-listed White-chinned Petrel *Procellaria aequinoctialis* and the Blue Petrel *Halobaena caerulea* and on the winter-breeding ACAP-listed Grey Petrel *P. cinerea* and the Great-winged Petrel *Pterodroma macroptera*.  Breeding density and success information has been collected to compare with previous studies.  Burrow cameras have been used to ascertain what effects, if any, the island's introduced House Mice *Mus musculus* have on breeding success.  In addition, GLS trackers have been attached to (or recovered from earlier deployments on) the two *Procellaria* petrels to follow their movements at sea. Findings, set to continue on the island with new researchers during 2013, have shown that White-chinned Petrels have increased in breeding density since the 1980s, perhaps due to the elimination of feral cats *Felis catus* in 1991, and in 2012/13 had a breeding success of 68% - much higher than during and immediately after the cat era.  In contrast in 2012 the much rarer Grey Petrel had a zero breeding success (albeit on a small sample), worse than the 5-12% of earlier cat-era studies. The remote burrow cams have revealed mice entering Grey Petrel burrows in winter and interacting with chicks, although White-chinned Petrel chicks in summer months seem to have been left alone. The cameras have also recorded interactions between the two ACAP-listed species.  Because their breeding seasons at Marion Island overlap, White-chinned Petrels returning to breed may sometimes take over burrows occupied by Grey Petrels, leading to the death of a late-stage Grey Petrel chick in one case. Information collected at Marion Island on burrowing petrels helps inform progress towards dealing with the mouse problem.  It is planned that a mouse eradication feasibility study will be undertaken in 2014, as the next step towards their hoped-for eventual eradication. [Click here](https://acap.aq/index.php/en/news/news-archive/57-2012-news-archive/124-a-new-study-aims-to-assess-whether-burrowing-petrels-have-recovered-on-south-africas-marion-island-following-the-eradication-of-feral-cats-two-decades-ago) and [here](https://acap.aq/index.php/en/news/news-archive/57-2012-news-archive/1172-why-no-increase-now-no-more-cats-acap-listed-grey-and-other-petrels-get-to-be-studied-at-marion-island) for earlier news items on this study. For information on the deleterious effects of mice on the burrowing petrels, including the Grey Petrel, of Gough Island [click here](https://acap.aq/index.php/en/news/latest-news/1348-gough-island-s-killer-mice-have-reduced-the-island-s-burrowing-petrel-population-including-of-acap-listed-grey-petrels). **Selected references:** Berruti, A., Cooper, J. & Newton, I.P. 1995.  Morphometrics and breeding biology of the Whitechinned Petrel P*rocellaria aequinoctialis* at sub-Antarctic Marion Island.  [*Ostrich* 66: 74-80](http://www.tandfonline.com/doi/abs/10.1080/00306525.1995.9633764). Bester, M.N., Bloomer, J.P., van Aarde, R.J., Erasmus, B.H., van Rensburg, P.J.J., Skinner, J.D., Howell, P.G. & Naude, T.W. 2002.  A review of the successful eradication of feral cats from sub-Antarctic Marion Island, southern Indian Ocean.  *[South African Journal of Wildlife Research](http://www.sabinet.co.za/abstracts/wild/wild_v32_n1_a9.html)*[31: 65-73](http://www.sabinet.co.za/abstracts/wild/wild_v32_n1_a9.html). Cooper, J. & Fourie, A. 1991.  Improved breeding success of Great-winged Petrels Pterodroma macroptera following control of feral cats Felis catus at subantarctic Marion Island.  [*Bird Conservation International* 1: 171-175](http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7438568). Cooper, J. Marais, A.V.N., Bloomer, J.P. & Bester, M.N. 1995.  A success story: breeding of burrowing petrels (Procellariidae) before and after eradication of feral cats Felis catus at sub-Antarctic Marion Island.  [*Marine Ornithology* 23: 33-37](http://www.marineornithology.org/PDF/23_1/MO_1995_05.pdf). Newton, I.P. & Fugler, S.R. 1989.  Notes on the winter-breeding Greatwinged Petrel *Pterodroma macroptera* and Grey Petrel *Procellaria cinerea* at Marion Island.  [*Cormorant* 17: 27-34](http://www.marineornithology.org/PDF/17/MO_1989_04.pdf). Percy FitzPatrick Institute 2012.  [New project to assess petrel status](http://www.fitzpatrick.uct.ac.za/africa_birds/fitzas12.pdf).  *Africa Birds & Birding* 17(4): 16. Ryan, P.G., Dilley, B.J. & M. G. W. Jones, M.G.W. 2012.  The distribution and abundance of white-chinned petrels (*Procellaria aequinoctialis*) breeding at the sub-Antarctic Prince Edward Islands. [*Polar Biology* 12: 1851-1859](http://link.springer.com/article/10.1007%2Fs00300-012-1227-y). Schramm, M. 1986.  Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edward Islands.  [*Polar Biology* 6: 63-70](http://www.springerlink.com/content/j6870761m8806470/). With thanks to Ben Dilley for information. *John Cooper, ACAP Information Officer, 17 May 2013*