An incredible journey with the long-distance waders
(Part II of a three-part exclusive interview with ornithologist and author Keith Woodley by Natural Images founder, Tony Neilson.)
We’ve been banding birds for more than 400 years, and in some parts of the world the practice is so comprehensive that there are almost as many birds with ‘flags’ as without.
The little metal rings, plastic bands and flags used to identify and track migrating shorebirds in particular have enabled scientists and researchers to accumulate valuable in-depth knowledge about the birds – and why so many face extinction.
But there are others who say banding is now excessive, alleging that the process greatly stresses the birds, can cause infection and even limb loss, and is unnatural. Indeed, some purist wildlife photographers won’t shoot birds showing ID tags.
The first record
It is generally acknowledged that the first record of a metal band attached to a bird’s leg was about 1595 when one of Henry IV’s banded peregrine falcons was lost on a bustard hunt in France. It showed up 24 hours later in Malta, about 2173 km away, averaging about 90 km/h for the journey.
Ornithologist, author and shorebird migration expert Keith Woodley says being able to track waders over 20,000-plus km migrations to and from nesting grounds is of inestimable value.
Manager of the Miranda Shorebird Centre on the Firth of Thames in New Zealand for nearly 25 years, Woodley has witnessed dramatic expansion of international knowledge and understanding of the East Asia-Australasia Flyway
The vast flocks
“Until the 1990s, we knew little about the vast flocks of shorebirds that made annual migrations from New Zealand and Australia to breed in the Arctic summer. For instance, when I first came here [Miranda] it was generally thought that our bar-tailed godwit population nested in Siberia.
“It’s a [fallacy] that has become ingrained in New Zealand. But the truth is that virtually all of our godwits are a separate population and they breed in Alaska.”
Author of the widely acclaimed book Godwits – long-haul champions, Woodley says banding, flagging and the subsequent development of ultra-light-weight transmitters underpin these knowledge advances.
Knowing individual birds
“Primarily via work done by the Wildlife Service in Alaska, New Zealand researchers based out of Massey [university] and others, plus members of this [Miranda] trust, we probably know more about this [New Zealand] long distance migratory population than any other waders on the planet.
“It’s gone from being a little-known migratory population to something as in-depth as knowing individual birds, their timetables, when they will leave NZ [within 2-3 days] and what areas of Alaska they breed in. It is astonishing.”
Woodley says everything is the result of increased banding, particularly colour-coded and branded plastic leg flags, which brought an “exponential increase” in the number of birds that could be re-sighted. (Using the old, much smaller metal rings, researchers had to band 350 birds to get one recovery overseas.)
“The advent of colour banding in the early 2000s gave us some tremendous stories. Like one bird banded here [Miranda] in March 2004, seen at Yalu Jiang in China late April the same year and seen again in late August on a remote mudflat off the coast of Alaska. And by 8 October 2004 it was back at Miranda. One bird.
“That sort of [capability] confirmed the basic migration routes these birds were taking.”
Flags and bands remain the most widely used tracking system but the development of super-light transmitters – initially implanted but now strapped to the birds’ – has been a game-changer.
Initial trials in Alaska in 2005-06 failed and it wasn’t until Feb 2007 when transmitters were implanted in a few New Zealand bar-tailed godwits at Miranda that the researchers finally had success.
The fantastic E7
“That breakthrough ultimately gave us the fantastic story of ‘E7’, says Woodley with obvious pride. “She was tracked from the Firth of Thames [NZ] to Yalu Jiang in five weeks non-stop, and then non-stop to Alaska.
“And at end of August she set off from Alaska and was tracked back to New Zealand in a non-stop flight of eight days and four hours. Just astonishing.”
Woodley says wildlife research biologist Bob Gill from the Alaska Science Centre had long suspected the bar-tailed godwits were returning to New Zealand non-stop because they were getting so fat before they left.
“His theory was compelling but remained circumstantial, and there was much scepticism among some seasoned scientists who disputed that no animal was physically capable of doing something like E7 did. But satellite tracking in 2007 changed all that.”
Transmitters have since got smaller and researchers are using more solar-powered backpacks that can be strapped to the birds. They are more streamlined and don’t affect the birds to the extent that earlier models did.
Another transmitter-related finding that could be dubbed the ‘E7 factor’ is linked to stabilised bar-tailed godwit numbers in New Zealand.
Global wader populations are in free-fall and the main cause is massive land reclamation and habitat destruction, particularly along the Chinese and South Korean coasts of the Yellow Sea.
Alaska to NZ direct
“Our bar-tail numbers are down nearly 50 per cent from 20 years ago and red knots may be falling even more sharply,” says Woodley. “But the godwits in particular have stabilised and we are pretty sure that is because they come back direct to New Zealand from Alaska and don’t stop off to refuel on the Yellow Sea where food is now scarce.”
By contrast, waders returning from the Arctic that spend the non-breeding season in northwest Australia stop at the Yellow Sea to ‘refuel’ on both legs of the journey. And their numbers are falling more sharply.
In other words, the New Zealand-bound Alaska breeders pile on extra fat for the direct return flight, rather than take their chances at the threatened Yellow Sea feeding grounds.
( Click here to read Part I of the Keith Woodley interview. Part III, the final segment, will be posted in July.)
Story ©Natural Images 2017