| Habitat and Ecology: |
Behaviour Although this species is largely sedentary some southern populations migrate north after the breeding season (del Hoyo et al. 1996). The species breeds between late-September and January (del Hoyo et al. 1996, Hockey et al. 2005) in colonies of up to several hundred pairs (occasionally nesting solitarily) (del Hoyo et al. 1996) and remains gregarious outside of the breeding season (Hockey et al. 2005). Habitat It inhabits sheltered coastal (Higgins and Davies 1996, del Hoyo et al. 1996) harbours, bays, inlets, estuaries, beaches and rocky shores (Higgins and Davies 1996), usually foraging within 10 km of the shore but also following fishing boats beyond the continental shelf (Higgins and Davies 1996, del Hoyo et al. 1996). It may forage and roost in near-coastal inland habitats including lagoons (Higgins and Davies 1996, Hockey et al. 2005), lakes, swampy basins, rivers, streams (Higgins and Davies 1996), reservoirs (del Hoyo et al. 1996), pastures (Higgins and Davies 1996, del Hoyo et al. 1996), cultivated land, tussock grassland, scrubland and cleared areas in pine plantations (Higgins and Davies 1996). It often also forages around abattoirs, fish- or seafood-factories and at sewage outfalls (del Hoyo et al. 1996). The species will form breeding colonies in a number of locations including headlands (Higgins and Davies 1996, del Hoyo et al. 1996), sea cliffs (Higgins and Davies 1996, del Hoyo et al. 1996, Hockey et al. 2005), rocky outcrops, stacks (Higgins and Davies 1996, Hockey et al. 2005), offshore islands (Higgins and Davies 1996, del Hoyo et al. 1996, Hockey et al. 2005), low sandy, pebbly or rocky beaches, spits or islands (Higgins and Davies 1996, del Hoyo et al. 1996) in estuaries and lagoons (Hockey et al. 2005), on reefs, peninsulas, mudflats, sandbanks (Higgins and Davies 1996) and occasionally on the roofs of coastal buildings or in salt and sewage works (Hockey et al. 2005). Locally (e.g. in New Zealand) it may also breed inland on flat rocky mountaintops near permanent water (Higgins and Davies 1996). Diet Its diet consists of molluscs (e.g. mussels, cuttlefish Sepia spp. and terrestrial snails), echinoderms (del Hoyo et al. 1996, Hockey et al. 2005), sponges (Hockey et al. 2005), arthropods (e.g. swarming termites, crabs, isopods, amphipods) (del Hoyo et al. 1996, Hockey et al. 2005), macrozooplankton (Hockey et al. 2005), fish, worms, reptiles (del Hoyo et al. 1996) (e.g. snakes) (Hockey et al. 2005), amphibians (del Hoyo et al. 1996) (e.g. frogs) (Hockey et al. 2005), small mammals (del Hoyo et al. 1996, Hockey et al. 2005), birds (del Hoyo et al. 1996) and berries (Hockey et al. 2005). The species also scavenges refuse, sewage and carrion (del Hoyo et al. 1996, Hockey et al. 2005). Breeding site The nest is a bulky structure of dried plants or seaweed (del Hoyo et al. 1996) placed on bare rock, sand or mud substrates (Higgins and Davies 1996, del Hoyo et al. 1996) in well-vegetated sites (del Hoyo et al. 1996) (with grasses, sedge, rushes and other herbaceous plants) (Higgins and Davies 1996) at the base of bushes, trees, rocks (del Hoyo et al. 1996), walls (Hockey et al. 2005) or other vertical structures (del Hoyo et al. 1996). Breeding habitats include headlands (Higgins and Davies 1996, del Hoyo et al. 1996), sea cliffs (Higgins and Davies 1996, del Hoyo et al. 1996, Hockey et al. 2005), rocky outcrops, stacks (Higgins and Davies 1996, Hockey et al. 2005), offshore islands (Higgins and Davies 1996, del Hoyo et al. 1996, Hockey et al. 2005), reefs, peninsulas, mudflats, sandbanks (Higgins and Davies 1996), the roofs of coastal buildings, salt and sewage works, guano platforms, shipwrecks (Hockey et al. 2005) and above the high water mark on low sandy, pebbly or rocky beaches (Higgins and Davies 1996, del Hoyo et al. 1996), spits or islands (Higgins and Davies 1996) in estuaries and lagoons (Hockey et al. 2005). Locally (e.g. in New Zealand) it may also breed inland on flat rocky mountaintops near permanent water (Higgins and Davies 1996). Management information Attaching high-visibility plastic cones to trawler warp cables can significantly reduce the mortality and bycatch of this species due to trawler fisheries (Gonzalez-Zevallos et al. 2007).
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