Bridled or Sooty Tern? Dry Tortugas NP, Florida Keys (8 Viewers)

[esrpiano]

Visited Dry Tortugas National Park in the Florida Keys today - was hoping to find a bridled tern or two among the hundreds of sooty terns. I got the one picture (very blurry, argh apologies!) of the attached...might it be possible with potentially paler undersides of flight feathers or impossible to determine due to photo quality?

Thanks in advance for any thoughts!!

 

[Butty]

As you say, plus black cap contrasting with grey upperparts = bridled tern.