Sat-tagged godwits

[philbattley]

Hi folks, a bunch of us from various organisations (Max Planck Inst, Massey Uni, University of Groningen, Global Flyway Network, Pukorokoro Miranda Naturalists Trust) have just put out a swag of satellite tags out on godwits. 20 went onto adults at Miranda to track their international migrations, though one has moved to Raglan, which is presumably its true southern home. 38 went onto young birds - 37 juvs and one 2nd-year. These are to understand how young birds explore NZ and to determine when they settle down. We expect these birds to move around extensively, and the birds are starting to do so, with birds from the Manawatu/Ohau moving locally to the Rangitikei Rivermouth, Otaki and possibly Waikanae, and further afield to Mahia Peninsula and Lake Ellesmere. A bird from Miranda also went to Canterbury and was spotted this morning at Lake Ellesmere by David Thomas. This means that there will be colour-banded juveniles turning up in odd places, and at sites where historically you have not had banded birds. We are super-keen to get all records of these birds. The birds will all have found colourbands and a white flag above the bands on the right leg. They will have an antenna extending out the rear of the bird, though this may be hard to see with one tag type used. The code for the colourbands is a prefix of 4 to signify the flag position, then the L-leg bands followed by the R-leg band. So the bird below is 4RBYB.

We're looking into the best way to alert people when a bird may be at a new site. We'd like to know who the tagged birds are with - other juveniles in a flock of their own? Mixed in with a big group at an established flock? You can still tell juveniles by their plumage, though they are starting to lose their juvenile scapulars and are looking a bit messy.

Good luck - I look forward to great spotting success!

Phil

[philbattley]

4RYRB is probably at Waikanae estuary, if anyone is nearby. Ben Bell saw a banded godwit there 2 days ago but couldn't see all the bands, and it might well be this bird. Anyone on the Kapiti coast this weekend?

[Adam C]

Hi Phil is there anywhere we can see tracking maps of these birds etc? pretty interesting to follow.

[philbattley]

Hi Adam, we're just trying to decide an appropriate amount of details. Meanwhile... in the past week or so:
* The Manawatu bird at Lake Ellesmere got seen on the weekend.
* The Ellesmere bird that had come down from Auckland and taken a day trip to Otago then flew to Golden Bay, and then fairly promptly up to the Manukau Harbour.
* A Manawatu bird flew to Mahia Peninsula then up to Miranda via Coromandel.
* A different Manawatu bird flew to off Gisborne (today).
* A Manawatu/Horowhenua bird from the Ohau Estuary (4RYRB) was confirmed by Craig Steed yesterday at Waikanae estuary, though it may now be back up towards the Horowhenua district. It was in a small flock of juveniles.

It's going to be hard to keep up with them (he says hopefully!)... I'm confident we'll learn more in one year of tracking than we did in ten years of band resighting, though we did pretty well with that too.

Cheers, Phil

[Adam C]

Thanks Phil. This is going to be really interesting to follow!

Ive always wondered how godwits get enough food at freshwater sites like Ellesmere which Ive always presumed is massively weighted towards midge adults and lava which is fine for smaller waders but not the Godwits especially when they can shovel down 5-10 substantial yabbie or lobworm type food items a minute at estuary sites. If they were in nearby paddocks then earthworms would make sense but thats just not a Godwit thing to do...they are always in the lake shallows and pools. Ive watched them pretty closely at Ellesmere and never really noticed any major food items for all their work put in probing around. If anyone else knows more about this Id love to know what it is they're putting the work in for at Ellesmere. It would make sense they don't stay long at these sites but then with the repeated views of the Hudsonian & BlackTails in the same location over the last month or so (and I think the hudwit was there all summer last year) it would suggest that perhaps some do.
Anyway just thinking out loud (yawn) but pretty cool seeing these big shuffles around NZ during the season. Look forward to updates!

Adam

[Jim Kirker]

This study https://ir.canterbury.ac.nz/bitstream/h ... sequence=1 found that "Oligochaetes dominated 60 % of benthic sites" (page 24) and a map shows most of the sampling sites near the shore (page 16). I'm guessing that the godwits are feeding on oligochaete worms. I'd be tempted to sieve some of the bottom where the godwits are and see what turned up.

[philbattley]

They also feed on small mud snails on estuaries (as in the very small Potamopyrgus) from the surface. Observations of whether they pick or probe would be informative.
Phil

[Adam C]

Thanks for the link Jim. I wonder how things have changed since the study (I think 2007) with increasing nitrates entering the lake and lower and lower water flows. Like you say, it would be interesting to take a good metre cube of mud at a key feeding site and see exactly whats in it but I guess the birds are there for a reason and like you say probably aquatic oligochaete worms which Im assuming are an aquatic version of the good old earth worm. I'd just be keen to see the size of them and know the Godwits are getting large enough prey out there or if they need to visit estuary sites to really bulk up before departing on migration.

Sorry Phil Ive totally hijacked your post and gone way off topic.. :/

[Jan]

That's a very interesting MSc thesis on the benthic fauna of the lake, which I hadn't read before. She reveals that it is primarily a saline habitat, not a freshwater one but there are no saline-type invertebrates present for Godwit tucker and the turbid conditions limit the taxa to just 8 species, really low for any lake's fauna. Some years Godwits are at the lake all summer, so they evidently don't lack for food there. Godwits at the Avon estuary during winter [juveniles and those who haven't migrated] often feed in the Linwood paddocks and probe for earthworms and other pasture inverts. In China and Korea they feed in wet fields adjacent to the coast. They are not limited to estuarine situations.

[philbattley]

Hi folks, in case you are going to be anywhere near these birds, from north to south we currently have juveniles relocated to:
North Island
* Whangapoua Harbour, Coromandel (4RBRB)
* Mahia Peninsula (4RBRW) - probably at the lagoon at the start of the peninsula (Maungawhio Lagoon)
* Otaki (4RYRY), possibly just north of the township - this is a bird from the Ohau Estuary just a bit north
South island
* Riwaka (4RBYB)
* Motueka sandspit (4RYRB, seen by David Melville on 14/12)
* Lake Ellesmere, Embankment Road area (4RBWB)
* Ki Wainono (Lake Wainono), South Canterbury (4RBRY)

Any details of these birds, plus who they are with (age, numbers) would be great. Juveniles will be moulting out of their juvenile plumage now so you may have to look harder to see remnants of their original notched plumage. Our best traveller so far has been from Miranda to Canterbury to Otago to Canterbury to Golden Bay to Auckland to Miranda!

Good spotting, Phil