Aim:The distribution of marine predators is driven by the distribution and abundance of their prey; areas preferred by multiple marine predator species should therefore indicate areas of ecological significance. The Southern Ocean supports large populations of seabirds and marine mammals and is undergoing rapid environmental change.The management and conservation of these predators and their environment relies on understanding their distribution and its link with the biophysical environment, as the latter determines the distribution and abundance of prey. We addressed this issue using tracking data from 14 species of marine predators to identify important habitat.Location: Indian Ocean sector of the Southern Ocean. Methods:We used tracking data from 538 tag deployments made over a decade at the Subantarctic Prince Edward Islands. For each real track, we simulated a set of pseudo-tracks that allowed a presence-availability habitat modelling approach that estimates an animal's habitat preference. Using model ensembles of boosted regression trees and random forests, we modelled these tracks as a response to a set of 17 environmental variables. We combined the resulting species-specific models to evaluate areas of mean importance. | METHODSThe Prince Edward Islands (46.9°S, 37.7°E) are situated in the southwest Indian Ocean sector of the Southern Ocean (Figure 1). The Results: Real tracking locations covered 39.75 million km 2 , up to 7,813 km from the Prince Edward Islands. Areas of high mean importance were located broadly from the Subtropical Zone to the Polar Frontal Zone in summer and from the Subantarctic to Antarctic Zones in winter. Areas of high mean importance were best predicted by factors including wind speed, sea surface temperature, depth and current speed. Main conclusions:The models and predictions developed here identify important habitat of marine predators around the Prince Edward Islands and can support the largescale conservation and management of Subantarctic ecosystems and the marine predators they sustain. The results also form the basis of future efforts to predict the consequences of environmental change. K E Y W O R D Sareas of ecological

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Since 2004 there has been mounting evidence of the severe impact of introduced house mice (Mus musculusL.) killing chicks of burrow-nesting petrels at Gough Island. We monitored seven species of burrow-nesting petrels in 2014 using a combination of infra-red video cameras augmented by burrowscope nest inspections. All seven camera-monitored Atlantic petrel (Pterodroma incertaSchlegel) chicks were killed by mice within hours of hatching (average 7.2±4.0 hours) with an 87% chick failure rate (n=83 hatchlings). Several grey petrel (Procellaria cinereaGmelin) chicks were found with mouse wounds and 60% of chicks failed (n=35 hatchlings). Video surveillance revealed one (of seven nests filmed) fatal attack on a great shearwater (Puffinus gravisO’Reilly) chick and two (of nine) on soft-plumaged petrel (Pterodroma mollisGould) chicks. Mice killed the chicks of the recently discovered summer-breeding MacGillivray’s prion (Pachyptila macgillivrayiMathews), with a chick mortality rate of 82% in 2013/14 and 100% in 2014/15. The closely-related broad-billed prion (P. vittataForster) breeds in late winter and also had a chick mortality rate of 100% in 2014. The results provide further evidence of the dire situation for seabirds nesting on Gough Island and the urgent need for mouse eradication.

ABSTRACT. The critically endangered Tristan Albatross Diomedea dabbenena breeds almost exclusively on Gough Island, in the central South Atlantic, where breeding success is much lower than other great albatrosses (Diomedea spp.) worldwide. Most breeding failures occur during the chick-rearing stage, when other great albatrosses suffer few failures. This unusual pattern of breeding failure is assumed to be largely due to predation by introduced house mice Mus musculus, but there have been few direct observations of mouse attacks. We closely monitored the fates of 20 chicks in the Gonydale study colony (123 chicks in 2014) using motion-activated cameras to determine the causes of chick mortality. Only 5 of 20 chicks survived to fledge, and of the 15 failures, 14 (93%) were due to mouse predation. One mouse-wounded chick was killed by a Southern Giant Petrel Macronectes giganteus; the rest died outright from their wounds within 3.9 ± 1.2 days of the first attack. Despite this high impact, most chicks were attacked by only 1-2 mice at once (maximum 9). The remaining 103 chicks in the study colony were checked less frequently, but the timing of failures was broadly similar to the 20 closely monitored nests, and the presence of mouse wounds on other chicks strongly suggests that mice were responsible for most chick deaths. Breeding success in the Gonydale study colony averages 28% from 2001 to 2014; far lower than the normal range of breeding success of Diomedea species occurring on islands free from introduced predators. Island-wide breeding success fell below 10% for the first time in 2014, making it even more urgent to eradicate mice from Gough Island. Tendances et tactiques de prédation par des souris sur les poussins d'Albatros de TristanDiomedea dabbenena à l'île Gough, océan Atlantique Sud RÉSUMÉ. L'Albatros de Tristan Diomedea dabbenena, espèce en danger critique d'extinction, se reproduit presque exclusivement sur l'île Gough dans l'océan Atlantique Sud, où son succès de reproduction est très faible comparativement à celui des autres grands albatros (Diomedea spp.) dans le monde. La majorité des échecs de reproduction surviennent durant l'élevage des oisillons, alors qu'il y a peu d'échecs de ce type chez les autres grands albatros. On pense que cette tendance inhabituelle d'échec de la reproduction est presque exclusivement attribuable à la prédation par la souris commune Mus musculus, espèce introduite, bien qu'il y ait eu peu d'observations directes d'attaques par celle-ci. Nous avons surveillé de près le destin de 20 poussins dans la colonie de Gonydale (123 poussins en 2014) au moyen de caméras à détection de mouvement afin de déterminer les causes de mortalité. Seuls 5 des 20 poussins ont survécu jusqu'à l'envol, et des 15 échecs, 14 (93 %) ont été causés par prédation de souris. Un poussin blessé par une souris a été tué par un Pétrel géant Macronectes giganteus; les autres poussins sont à l'évidence morts à la suite de leurs blessures en dedans de 3,9 ± 1,2 jours de la première attaque par les souris....

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