White-winged Black Tern/s at Coopers Lagoon, Canterbury

[tom.b]

Hi All,
White-winged Black Tern/s seen at Coopers Lagoon yesterday evening, flying back and forth over the lagoon, periodically swooping down (presumably hawking insects) over the water.

Unfortunately I didn't stop to make an accurate count, but my impression was of about 8 or 10 birds. My initial thought was that they were young Black-fronted Terns, and only later identified at least one as White-winged Black Tern from a few average quality photos I'd fired off to check later (sent to Oscar Thomas to confirm the ID).
I understand 8-10 White-winged would be a large number for this location at one time, so it may be that a) I over-estimated the number and it was more like 2 or 3 or 4 that I'd seen flying back and forth, observed at different times as I was travelling round the lagoon, b) it was just 1 WWBT amongst a group of BFTs exhibiting similar behaviour (with expected similar size and plumage), or c) possibly an unusually large influx.

Update - confirmed at least 2 separate individual birds, (captured together in 1 photograph)

I may be able to return this evening or tomorrow, but thought I would post here if anyone wanted to go check it out.
Cheers,
Tom
https://ebird.org/atlasnz/checklist/S130565447

[wazzagonewild]

Two WWBT present this evening.

[Philip]

Hi Tom,
I went to kiatorete spit tip today, it is only 4 or 5km from coopers lagoon, i had 9 white-winged black terns roosting with black fronted terns, and 2 little terns to boot.
Looks like your first assessment was right.

Other high lights
427 banded dott
373 pied stilt
Godwit 2
Pectoral sandpiper 1
Sharp tailed sandpiper 5
Red necked stint 1
Wrybill 1
With al the other ducks and geese.

Regards
Phil

[Michael Szabo]

A flock of 8 or 9 WWBTs is a pretty unusual NZ sighting so it would be good to post any photos that either of you have of them either here or with your eBird checklists.

[Jan]

Phil is a pretty good observer and is down the spit counting birds all the time as part of his job. I don't think anyone needs to question his totals.

[tom.b]

Thanks All.
Good to have confirmation thanks Warwick. And sounds like a great visit to Kaitorete Spit Phil - very interesting.

I went back to Coopers Lagoon this afternoon and saw the WWBTs again (sorry you missed them Bev!), so will dig through the photos when I get a chance. No sign of them at 4-4.30pm, but by 5.30pm the wind had died down a bit and they were flying above the lagoon again.

There were certainly two, I think probably at least three and possibly more, but I found it difficult to get a good count. They were continually on the move working up the lagoon hawking insects, unfortunately they weren't particularly close to the shore and they were also joined by Black-fronted Terns doing the same thing in a mixed group. They would all work their way up the lagoon roughly in ones or twos, and then fly back to the beach-end of the lagoon to start again on the same cycle. I tried getting record shots of distinct individuals by i) starting with a shot of the port hills to begin the sequence, ii) then record shots of the bird at the 'front' of the procession, then iii) a marker photo of just the lagoon surface, then iv) shots of the second bird along, then v) a break with another water shot, and so on... trying to get through them before the first one rejoined at the back. So we'll see if it worked well enough to get some kind of count. And I'll aim to get some photos posted Michael

Good to see Noah there too, so he may have had better luck than me with the count. And if Phils terns at the spit were roosting then I'd trust his numbers much more than my Friday estimate.

So a little frustrating, but still good fun

[andrewcrossland]

Hi team, just confirming that the total is at least 11 comprising 9 seen (and photographed by Phil Crutchley) at Kaitorete Spit tip and 2 at present at approx the same time seen at Coopers lagoon by Tom B and Noah this arvo.

its great to see Kaitorete Spit Tip and Coopers Lagoon once again share a flock of White-winged Black Terns, as this was the case for 20+ years until about 5 years ago when they became very scarce and a small number switched wintering sites to the Bromley Oxidation Ponds (max count there has only been 3).

Up to 13 or 14 have been recorded at Coopers Lagoon in the past (1980s-90s) so 11 birds is not as extraordinary there as it would be anywhere else in NZ. Infact, that's the main reason why this species has not been reportable as a rare bird in Canterbury for quite a number of years.

From memory, most WW Black terns on the kaitorete - Taumutu - Cooper's Lagoon - Rakaia Rivermouth coastline (whuch they move back and forth along) have been in Southern Hemisphere moult cycle. Its likely they breed on the Rakaia River and we've seen them on Rakaia riverbed surveys a number of times in the past (incl birds in full BP).

Any adults should be in dalmation plumage by now and their underwings colouring up, so it should be relatively easy to tell whether they're following a Northern Hemisphere or Southern Hemisphere moult cycle.

[tom.b]

Very interesting - thanks Andrew!

I'm confident of 4 WWBTs at Coopers Lagoon from around 5.30/6 to ~7pm on 12/3/23. There could have been more, but I was at least able to identify 4 separate individuals from my sequenced shots.
I noticed at least one with underwings clearly colouring up.

Update - 5 confirmed

[Michael Szabo]

It's good to hear that you both got some record shots - I've not seen a photo of more than a single bird before in NZ. According to Barrie Heather & Hugh Robertson's Field Guide, "Usually fewer than 10 reach New Zealand each year, except for occasional small influxes, eg 13 at Ahuriri Estaury in 1972." So, these latest reports of 8/9 and 11/13 birds surely qualify this as another small influx.

Looking back over the past few months (Nov-Feb) there have been more than 10 reports of single birds at: Waitangi Regional Park in Hawke’s Bay (6/11; 21/11; 3/12, 4/2 + 2 on 8/12); Rangaunu Harbour and Timaru Port (5/11); Tasman River delta (14/11; 8/12; 13/12); Waituna in Southland (11/11 & 2 on 15/2); Cass River near Lake Murray (24/11); upper Cass River (6/12); Tekapo River (28/11 carrying food); near Te Anau by Upukerora River (7/12); Lake Ruataniwha near Twizel (10/12); Wairau Lagoons wader roost (25/11); Clarence River in Molesworth (11/12); Aramoana Mole/Harbour entrance (22/1); and Weller’s Rock on Otago Peninsula (7/2). One was at Pūkorokoro Miranda from 1/1 to at least 29/1, and 2 were reported at Karikari Beach (Far North) on 21/12.

So, it seems that there has been a notable influx over summer, but no repeat of last year's Black Tern - yet ...

[andrewcrossland]

Here's some cell ph thru scope pics by Phil Crutchley at Kaitorete Spit tip yesterday with WW Black terns roosting with Black-fronted Terns.

Let's keep an eye on them over coming months and see which way their plumage goes? Is this an influx of migrants or an autumn flock of NZ resident birds sitting on a piece of coastline the species has frequented right back to Edgar Stead's day when he reported suspected breeding (90-130 years ago)?

Certainly most of the riverbed and inland records that Micheal has listed in the previous post are of birds that may be NZ resident rather than migratory.

For those interested , have a look through Classified Summarised Notes (CSN) from the 1980s and 90s if you want to get a good sense of abundance and distribution of species like WW Bl Tern, Little Tern, arctic waders in the recent past. It can be found online via the Notornis website. Its pretty helpful...............and its a pretty good way of accessing the "institutional memory" of OSNZ/Birds NZ prior to ebird.

also, here's our monitoring data for WW Bl Tern at Kaitorete spit tip from 2006 to present. Annual max count given. Birds most often seen through autumn and winter - most in Southern hemisphere mout cycles.

2006 4
2007 2
2008 1
2009 2
2010 4
2011 3
2012 0
2013 1
2014 1
2015 0
2016 0
2018 0
2019 0
2020 0
2021 0
2022 0

PC WWBL Tern 2.jpg (63.56 KiB) Viewed 973 times

PC WWBL Tern 1.jpg (32.58 KiB) Viewed 973 times