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Long‐term declines in multiple waterbird species in a tidal embayment, south‐east A ustralia
Author(s) -
Hansen Birgita D.,
Menkhorst Peter,
Moloney Paul,
Loyn Richard H.
Publication year - 2015
Publication title -
austral ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.688
H-Index - 87
eISSN - 1442-9993
pISSN - 1442-9985
DOI - 10.1111/aec.12219
Subject(s) - ecology , habitat , population , geography , wetland , biology , sociology , demography
Worldwide, local extinctions and severe declines in waterbird densities are being reported from many important waterbird sites. Waterbird sites often exist as a network, collectively providing crucial habitat for different life history stages of different species. Therefore, population changes at one site may strongly influence others. In A ustralia, many waterbird species are highly mobile, and move rapidly over long distances in response to rainfall. Large tidal wetlands often serve as drought refugia or alternative breeding habitat for these species. These sites are also the migration terminus of many species of shorebirds that spend their non‐breeding season in A ustralia. One such site in south‐eastern A ustralia is W estern P ort, a R amsar‐listed tidal embayment forming part of the E ast A sian– A ustralasian S horebird S ite N etwork. We measured waterbird population trends over nearly 40 years in W estern P ort to see whether changes showed consistent trends over time across multiple species. Thirty‐nine species were recorded often enough to allow an analysis of trends over time using dynamic linear models and, where appropriate, piecewise linear regression. Twenty‐two species had declined, including four species of duck, five species of fish‐eating bird (cormorants, terns and pelicans), one species each of grebe, gull and heron, and 10 species of shorebird. Only two species ( A ustralian pied oystercatcher H aematopus longirostris and straw‐necked ibis T hreskiornis spinicollis ) increased significantly over the same time period. Patterns of decline in non‐migratory waterbirds may reflect diminishing wetland availability, local reductions in fish prey, increased predation pressure and changes in inland wetland resources. Declines in migratory shorebirds are most likely related to loss of habitat elsewhere in their trans‐equatorial migration routes. These trends in waterbirds that use W estern P ort reflect widespread impacts on populations elsewhere in A ustralia and overseas, necessitating more than simply local management of this tidal embayment.