Palmerston/Darwin NT Tern ID

Hi all…
Just at Palmerston treatment ponds today
I’ll be honest and say I struggle at a distance with some Tern species
I’d love some help with ID for this time of year from those in the know

What I could see/no pics sorry only had my scope
Was
– Terns flying with a dusting of blackish grey on their bellies that was obvious at a distance..
– Terns with a black cap that extended down onto their face under the eye but dark legs and reddish bill and white belly…

Never been to these ponds
I used to go to Leanyer ones years ago before they closed them to the public and saw Yellow wagtail and all sorts of ducks and some waders…not heaps at this one that I was expecting…although..as we progress closer to the end of the year…I imagine it will increase in activity

Anyways…
Any thoughts much appreciated before I complete my EBird checklist
(Heard Chestnut Rails calling nearby in mangroves at the back and Mangrove Robins very vocal and sweet while calling and were fairly close for viewing and male/female Black necked storks, Common Sandpipers & Pied stilts etc… still some lovely species here)

Thankyou for help with the Terns
Kirri ☺️

Neways34@yahoo.com.au
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