Hi Mike,
I must admit I found Jim Tate’s original posting interesting but somewhat open to interpretation. The only “big” tern with a red bill (in any stage of plumage) likely to be seen on the Brisbane that I can think of is the Caspian Tern. I imagine that it would be possible to see Whiskered terns on the Brisbane river at some time of the year but they are obviously small at half the size of the Caspian Tern. If there was two species of terns with red bills being seen and they were so different in size I would have thought that would have been mentioned. However, Jim seemed to be saying that the red-billed terns he was seeing were all large terns similar in size to Caspian Tern or, possibly, Crested Tern. I have recently seen Crested terns (still a large tern but smaller than Caspian Tern while obviously larger than Whiskered and Common Terns) in my area with bill colours ranging from lime-green to bright-ish orange-yellow but I have never seen a Crested Tern with a bill colour I would call ‘red’. So I was intrigued by the possible suggestion that there might have been two different species of “big enough” terns (but noticeably different in size) both with red bills. When I read Jim’s comment I assumed he was seeing Caspian Tern, very large with red bill, and Crested Tern, a little smaller but with ‘yellow’ bill. The fact that only the “dark red” bills were mentioned does have me wondering, though. I would classify Common Terns and Whiskered Tern as not simply “smaller” but “much smaller” than both Caspian and Crested Terns.
Jim said “Many of them [the terns observed on the river] appear to have dark red bills and look big enough to be Caspians or Crested.” Jim also said “But some are smaller – are these Commons?”. I wasn’t sure if Jim meant that only the “big enough” terns had red bills or if the “smaller” terns also had red bills. I would classify Common (and Whiskered) Terns as ‘small’ terns being very much smaller than Caspian Tern and obviously smaller than Crested Tern. Jim, by saying “Many of them appear to have dark red bills” appeared to me to be indicating that some of the other terns had bill colours other than “red” but what those colours were is not clear. I assumed that “smaller” meant noticeably smaller but not “small” – as in the size of Common or Whiskered Tern. It did cross my mind that there could also have been Gull-billed Terns (smaller than Crested and larger than Common) there as well; I saw one Gull-billed Tern (with full black-cap) fly over at Woorim when I was photographing those Common Terns the other day so they are around here at the moment. Of course, Gull-billed Terns have black bills so that wasn’t the red-billed species Jim was seeing even if it is a “smaller” species of tern.
As you said, the Common Terns in my photographs have “dark” bills as would be expected but some do have a reddish tinge. That is fairly common and does cause some confusion for many birdwatchers who are expecting to see only completely black bills on the Common Terns we get here. However, none of the Common terns I have ever seen in SE Queensland have had “dark red” bills as described by Jim. I assumed he was talking about the “deep red” colour that Caspian Tern bills can be in breeding plumage stage.
I am not aware of any sightings recently of Whiskered Terns on the Brisbane River as I don’t visit there and I don’t keep tabs on sightings from that area. Other observers from that area might be able to provide that information. I have not heard of any positive sightings of Whiskered Terns in SE Queensland this year so far but not all sightings are publically reported, unfortunately.
All of the above is not a lot of help in identifying Jim Tate’s terns but the discussion is interesting and it is to be hoped that Jim’s query has prompted some Brisbane bird observers who commute on the Brisbane River to check out the terns that are around there at the moment. It would also be ‘nice’ if those observations could be communicated to BirdingAus as well.
Bob Inglis Sandstone Point Qld
