Current research programmes involving Northern Hemisphere migrants that reach New Zealand are outlined below. Click on the links below to move down the page.
| Local movements | Large-scale tracking | Demography | Age ratios |
Migratory wading birds are an important component of New Zealand’s coastal biodiversity, but little is known of their movements while in the country. Whether birds are highly site-faithful, returning directly to one site where they reside for the non-breeding period, or more mobile, using a network of sites, affects the conservation management of these species. The Ornithological Society of New Zealand (OSNZ) has been contracted by the Department of Conservation to undertake a study of the movements of Arctic-breeding waders (Bar-tailed Godwit and Red Knot), to determine the extent to which individual godwits and knots use a network of estuaries while in New Zealand.
This is being studied by colour-banding birds at various sites around New Zealand, and enlisting the eyes of OSNZ wader watchers to search their local estuaries.
More on this project, including the first results
Eastern Bar-tailed Godwits are arguably the world's greatest migrant. Several lines of evidence suggest that birds refuelling in Alaska may migrate direct to New Zealand and eastern Australia across the Pacific Ocean (download PDF), and satellite tags have been deployed in attempts to discover the details of this flight. They are also being used to track birds migrating north from New Zealand to Alaska.
Survival rates in migratory birds are expected to differ depending on the relative stresses they encounter through the year. Birds migrating long distance will face higher physiological challenges and risks during flight than those that move only a short way. The flip side is that long-distance migrants will generally encounter warmer, and presumably more amenable, conditions for the non-breeding season. There may be a trade-off in survival rates between the risks of flight and the risks of winter, for Northern Hemisphere breeders. Whether these balance each other out, or whether one migratory strategy incurs a different overall mortality rate to another, is unknown. Different populations of Red Knot and Bar-tailed Godwit are being studied around the world in an attempt to discern the nature of these trade-offs. This information is also important for evaluating the population status of the different groups of birds around the world.
More on shorebird demography studies
Linked with the demographic monitoring is the need to assess the reproductive output of the populations using different areas. In bar-tailed Godwits, juveniles can be readily distinguished from adults by their plumage, which makes it possible to estimate the juvenile proportion in flocks on the staging or non-breeding grounds.