Minton C.,Victorian Wader Study Group VWSG |
Dann P.,Phillip Island Nature Parks |
Ewing A.,Victorian Wader Study Group VWSG |
Taylor S.,Victorian Wader Study Group VWSG |
And 4 more authors.
Stilt | Year: 2012
Corner Inlet, Victoria, provides habitat for one of the largest and most diverse assemblages of shorebirds in southern Australia. Systematic counting commenced in 1981 and has continued, uninterrupted, to the present (2011). Standardised counts, along fixed boat routes, indicate that numbers in summer of all species combined have declined by 23% over the 30 year count period, from typically 35-40,000 in the earlier years to 25-30,000 in recent times. Ten species - Grey Plover Pluvialis squatarola, Ruddy Turnstone Arenaria interpres, Eastern Curlew Numenius madagascariensis, Red Knot Calidris canutus, Great Knot Calidris tenuirostris, Curlew Sandpiper Calidris ferruginea, Sharp-tailed Sandpiper Calidus acuminata, Common Greenshank Tringa nebularia, Greater Sand Plover Charadrius leschenaulti, and Lesser Sand Plover C. mongolus - have declined, while Sooty Oystercatcher Haematopus fuliginosus, has increased. Numbers of five other migratory species -Bar-tailed Godwit Limosa lapponica, Whimbrel Numenius phaepus, Red-necked Stint Calidris ruficollis, Sanderling C. alba and Double-banded Plover Charadrius bicinctus and one resident, species, Australian Pied Oystercatcher Haematopus longirostris - have not shown any significant change. Estimated declines in the abundance of individual species ranged from 47% to 95%. In contrast there was a significant increase in Sooty Oystercatchers of between 1.5 fold (winter) and 3.5 fold (summer). Numbers counted varied widely between years, most likely due to a combination of annual variation in demographic parameters, and possibly detection rates. The cause of longterm changes in abundance at Corner Inlet is not certain, but habitat destruction in staging areas, notably the Yellow Sea regions of China and Korea, is suggested as the main contributor with related changes in adult survival rates a more likely mechanism than changes in breeding success. Interestingly, declines in several species were most pronounced over one or two years. This study emphasises the benefit of using the same route and observers over long periods to identify trends in abundance.