Roseate Terns

Adult Roseate Tern on Eastern Egg Rock, Maine, in June 2011.

From Oak Harbor, Ohio, Kenn writes: Terns may be the ultimate summer birds. They are related to gulls, but gulls thrive in cold weather, some even spending the winter north of the Arctic Circle. Terns, by contrast, love warm climates. In much of North America, they are most prevalent during the summer.

About ten days ago, thanks to the generosity of Dr. Steve Kress and his highly successful Project Puffin, Kimberly and I were able to visit Eastern Egg Rock, in the Gulf of Maine. We did see puffins there, and many other birds as well; maybe Kim will blog about the puffins (hint, hint). But I was most pleased by the opportunity to look closely at Roseate Terns.


Some treatments of tern identification focus on bill color. The mostly-blackish bill of Roseate Tern can be useful for quick ID, but it’s tricky, too: other terns have blackish bills for part of the year, and in transitional stages they can show color patterns much like that of the Roseate’s bill. The SHAPE of the bill is a better confirming point. It’s relatively long, thick at the base and tapered to a fine tip, with the gonydeal angle on the lower mandible located fairly close to the base of the bill.

Wing pattern is one of the best ID points.  Summer adults typically have dark outer vanes on only the outer three primaries.  When the wing is folded, this shows up as a limited dark area on the wingtip.

Here’s a closeup of the wingtip from the previous photo.  Looking at the top of the near wing (the one on this side of the bird!), we can see dark gray on the three longest feathers, while the rest of the primaries (stacked up toward the left) are paler silvery gray.

The wing pattern can be even more obvious when the wings are spread.  In this photo, on the far wing, the dark gray is clearly limited to only the three longest primaries.  On the nearer wing, we can see that there is no dark trailing edge to the wing at all.

Compare that underwing pattern to the one shown by this Common Tern, photographed at the same place and date.  The black trailing edge to the outer primaries is obvious at a glance.



Adult Common Tern in flight, Eastern Egg Rock, Maine, in June 2011.

Roseate Tern also has a noticeably long tail, and lacks any black or gray on the tail (Common and Arctic terns both have narrow black outer vanes on the outer tail feathers, and Forster’s Tern shows some gray on the inner vanes).   The faint rosy blush on the breast feathers, the source of the bird’s name, is a fleeting phenomenon of spring, and barely a hint of it shows in our photos from late June.  Regardless, Roseate Tern is still a beautiful bird, and well worth the effort to find and identify!  For those with a keen interest in the subject, more information on identifying terns can be found in two chapters of my new Kaufman Field Guide to Advanced Birding. 

Roseate Tern is a widespread species, found from the North Atlantic to the Indian Ocean, but it is not abundant anywhere.  Its North American populations have declined seriously, so it is now listed as Endangered in the northeastern USA and eastern Canada, and as Threatened in the southeastern USA.   The nesting Roseates on Eastern Egg Rock (along with about equal numbers of Arctic Terns, and many more Common Terns) are closely monitored and protected by Project Puffin, a great program that deserves the support of birders everywhere.

That Time of Year

From Oak Harbor, Ohio, Kenn writes: For several years now I've been very interested in the whole subject of molt. This is the process wherein birds develop a new coat of feathers, generally by dropping a few feathers at a time, with new feathers growing in their place. Birders may not notice the molt unless they look closely, but it's a universal phenomenon among birds. Especially among smaller birds, it's generally true that a healthy wild bird will replace every one of its feathers at least once a year. Birders may not notice, though, unless the new feathers are strikingly different in color from the old ones.

The timing of the molt for most species is quite predictable. Right now, for example, here in northern Ohio, the American Goldfinches are starting their spring ("prealternate") molt. It's most noticeable on the adult males, who molt from very dull to very bright colors. This bird was outside the windows at the Black Swamp Bird Observatory yesterday, the last day of March. The occurrence of molt is one of the reasons why we have to look at the calendar when we're considering the identification of an unknown bird: it may be some familiar species in the process of going through a change.

People sometimes ask us why this bird is called the "American" Goldfinch, when it also occurs in Canada and locally in Mexico. Why not just "Common" Goldfinch, or "Yellow" Goldfinch, or something like that? Well, there's a good reason. Remember, I said that the bird shown above was just starting to molt. When it finishes the process of molting into its full summer plumage, usually around July 4, it will look like this:

As I said, we have to look at the calendar when we're considering an unknown bird; for some reason, April 1 produces more than its share of weird reports.

All seriousness aside (as the saying goes), the molt really IS going on right now, and it's affecting the appearance of many birds. The American Goldfinch is a great example to watch because it may come to feeders right outside your window and because the change of color on the males is so striking. But a high percentage of our small songbirds are going through some kind of molt of their head and body feathers at this season, and with a close study, you may be able to see the contrast between the crisp new feathers and the slightly older, worn, faded feathers. It's a part of the survival strategy of the birds and it's something we can witness for ourselves with just a little extra attention.

Antarctica, Day Two: I.D. At Sea

From home base, Kenn writes: (now that I've been so cutely interrupted by Kim's last post ... That's the thing about Kimmer, I can't stay mad at her for more than a few seconds at a time.) On January 8, when I got out on deck around 5 a.m., we had left the Beagle Channel itself but the islands of Tierra del Fuego were still visible off the stern. Dozens of Sooty Shearwaters and Greater Shearwaters, plus various other seabirds, were around the ship. The last of the land soon disappeared behind us but we would continue to see large numbers of seabirds all day. Most seabirds are beautiful creatures and amazing masters of flight, and in addition, many of them present fascinating challenges in identification.

Check this out. I know you can’t see much detail, but this is an unaltered photo taken from the rail of the upper back deck of the ship, with six seabirds captured in the same frame. From left, they’re a young Wandering Albatross, a Brown Skua, three Greater Shearwaters, and a Northern Giant-Petrel. I’m not saying every moment was like this, but it was common to have 30 or 40 individual birds visible at once.

Watching birds here was good practice for identifying them back in North America. This Wilson’s Storm-Petrel nests only on islands in the far southern oceans, but it’s common in the northern summer off the Atlantic Coast of the U.S. and Canada, and scarce off the coast of California.

Greater Shearwater is another bird we can see close to home in the northern summer. At that season it’s common off the Atlantic Coast of the U.S. and Canada, but it nests only on islands in the South Atlantic.

Identifying seabirds can be tough, partly because the viewing conditions at sea can be challenging, partly because the differences can be subtle. Even on very large seabirds, the best field marks can involve small differences. Take a look at this Southern Giant-Petrel ...

... and then at this Northern Giant-Petrel. Both species are variable in plumage, and the best way to tell them apart is by the color of the tip of the bill: green on the Southern, red on the Northern. Those who are red/green color-blind, as some excellent birders are, might note that the Northern's bill tip looks darker than that of the Southern. (These are poor names, incidentally, since both species live only in the Southern Hemisphere and their ranges overlap extensively.)

Variation reaches an extreme in the beautiful Wandering Albatross. It has five distinct populations, nesting on different island groups, that are thought by some to be separate species. All of them vary at least a little with age, so there are a vast number of different plumages possible on these birds. Add to that the fact that Royal Albatross can be very similar to Wandering, it has two distinct populations that also might be separate species, and it also varies with age. The richly colored brown bird above is one of the youngest Wandering Albatrosses.

This bird, extensively white above, is an older Wandering Albatross and may be an adult male, although some old males can become even whiter than this (and some adult females might duplicate the appearance of the bird in the photo).

This partially brown bird is in the Wandering Albatross complex and is almost certainly a young bird, although there are a few populations in which even the adults show a lot of brown. We saw many such variations today, and enjoyed discussing the identification of all of them.

Fortunately, we often got to look at Wandering Albatross individuals from very close range!

For this voyage, Victor Emanuel Nature Tours (VENT) had filled 85 of the 110 spaces on the Clipper Adventurer. You can’t have 85 participants and only one or two leaders, so VENT had recruited a team of leaders, all of them long-time friends of mine, starting with Victor Emanuel himself. Victor has been a friend of mine since the mid-1970s, when I was a teenager and he hadn’t yet started his tour company. Also along as leaders were Barry Lyon, a seasoned world birder and one of the professionals in the VENT office; Louise Zemaitis, great all-around naturalist, teacher, and nature artist; Michael O’Brien, a bird identification expert and lead author of The Shorebird Guide; and Lars Jonsson, from Sweden, probably the most renowned bird painter in the world today, and a leading authority on bird identification as well. Dr. John Fitzpatrick, director of the Cornell Lab of Ornithology, was supposed to have been a leader on this trip, and at the last minute he was unable to go. In his place, he sent Brian Sullivan, head of Project e-Bird for the lab, and another expert on bird identification, especially seabirds. Finally, the ship’s ornithologist, Geoff Carpentier from Canada, was also on deck, taking part in the discussions of identification from the perspective of his experience in these waters.

So a day at sea, looking at challenging or tricky seabirds, turned into a wonderful ongoing discussion and series of impromptu seminars in birding. For me, with my long-time interest in advanced bird identification, and for Kim, who is interested in all of these things and who was seeing some of these southern seabirds for the first time, this was a day of total fascination. Some people might imagine that all those hours on the open ocean could become boring, but for a birder, nothing could be further from the truth.