The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the eVect of lay time and colony habitat on breeding success. SpeciWcally, we compared survival and growth parameters between A-and B-eggs and chicks from non-manipulated and artiWcially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to Xedge an A-egg (Wrst laid) than conspeciWcs elsewhere. Breeding was highly synchronous, with no signiWcant diVerence in the breeding success between early and late breeders or between pairs breeding in diVerent habitats. We demonstrate for the Wrst time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a Xedged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch.
The relationship between environmental variables and the occurrence of potential hollows and hollow-bearing trees in three dry forest types (dry Eucalyptus delegatensis forest, E. pulchella-E. globulus-E. viminalis grassy/shrubby forest and dry E. obliqua forest) in southeastern Tasmania, was examined using generalised linear modelling. The number of trees with potential hollows and the number of potential hollows was significantly higher in dry E. obliqua forest, compared with the other two forest types. The number of potential hollows per tree was best explained by tree species, tree form, degree of burn damage and the interaction between burn damage and tree species. There was no significant relationship between the number of trees with potential hollows per site and the environmental variables measured. However, the number of potential hollows per site was best explained by several environmental variables: vegetation type (highest in dry E. obliqua forest); topographic position; amount of dead trees on the ground; the age of the stand; the average total basal area of all trees; the height of the overstorey vegetation and various interactions between these variables and other variables, such as understorey cover. A model developed using a subset of the environmental variables measured was coupled with GIS data to develop a map of the predicted occurrence of trees with potential hollows throughout the study area. The use of such a predictive map for landscape level planning, in particular to assess the implications of land use scenarios on the hollow resource, is illustrated.
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