BIRDING BY HINDSIGHT: A Second Look at Loons and Grebes

First, a word or two about hummingbirds. (And, not to worry, you'll see how this will segue seamlessly into the topic of loons and grebes.) It seems the most recent Hindsight article (http://mbwbirds.com/hummingbirds.html) erred about crediting South Dakota with records of Black-chinned and Broad-tailed hummingbirds. A website I had consulted was inaccurate, and I thank Doug Chapman for calling this to my attention. So, delete those two from the SD list; at the same time, though, you can add Anna's to their list, since Doug also reported there was a recent first state record of that hummingbird.

Some readers might also have found my article defective in failing to discuss sugar-water recipes (certainly a highly controversial subject), when to remove feeders in the fall (always good for a prolonged and heated debate), and the notion of how hummingbirds migrate south on the backs of geese. Of course, there's no evidence to support that popular but fanciful migration myth, especially since another theory is they actually ride on the backs of migrating loons and grebes!

Think about it. Why else would loons and grebes show their distinctive "humpbacked" flight profile, if it weren't to provide a perch for hitchhiking hummingbirds? And those feet you see trailing behind a flying loon/grebe – obviously, they're in ideal position to catch any clumsy hummingbird falling off the back. There's even research suggesting that certain hummingbird species actually select certain loon and grebe species. Accordingly, one way to learn your hummingbirds might be to brush up on your loon and grebe ID skills.

LOONS

Indeed, at the time of this writing in November, some recent loon reports demonstrate that this would be an opportune time for a discussion of their identification. Note that the following comments only apply to juveniles and adults in basic/winter plumage, since loons in alternate/breeding plumage are pretty straightforward (except for Arctic vs. Pacific loons, but an Arctic in that plumage here borders on the "impossible.")

You should refer to your Sibley field guide or one of the later editions of Geographic as you read this article, since it will not be repeating most of the information they illustrate. Nor will this pretend to be a comprehensively complete analysis. Not only isn't there enough time or space to do that here, but, more importantly, I'm just not that smart enough to pull it off – or dumb enough to try.

Flanks and Vents

Concentrating on any bird's undersides and rear end may not be for the squeamish, but with some loons it's exactly what needs to be done (especially, I suppose, if you're anal-retentive). Three of those recent loon reports mentioned above involved sightings on Lake Superior and Mille Lacs of loons with so-called flank patches. In other words, they all showed white above the water line as they swam, either as an elongated area along the flanks or as an oval patch back by the tail. Such a mark is said to be a diagnostic feature of the Arctic Loon, a rare-regular visitor to Alaska never before seen in these parts.

It's understandable, then, when the observers got excited, but equally understandable is they were apparently unaware of little-known Loon Lesson I: Any species of loon can have white flanks.

Over the years, I have often seen Commons, Red-throateds, and Pacifics with white on the flanks, and there are photos I can show you to illustrate this. The amount of white can simply depend on how high the bird is riding in the water as it swims and how its flank feathers are arranged. So white flanks alone do not necessarily indicate an Arctic Loon, although I'd definitely take a second look if there were lots of white along the sides and it flared up higher back by the tail. Conversely, by the way, an Arctic Loon riding low in the water might not show any white on the flanks: the only one I've ever seen in Alaska looked like this.  

But don't avert your eyes from that loon's hindquarters quite yet, especially if it's a Pacific-type loon which you suspect could be an Arctic. Try to see if it has a so-called "ventstrap" – i.e., a dark line across the white feathers of the vent or under tail coverts. Such a feature, unfortunately, would be impossible to see unless the bird flew overhead or rolled on its side as it preened, but a solid and complete strap would indicate a Pacific Loon and preclude an Arctic. A missing, partial, or faint strap, however, does not prove it's an Arctic Loon, since some Pacifics can look the same way. (Note as well that the reliability of this field mark is still under review.)  

Bill and Crown Profiles

It's time to move on to Loon Lesson II: Any species of loon can have an upturned bill.

Just as white flanks can appear on any loon, I sometimes see Common and Pacific loons tilting their bills up above the horizontal, which naturally could lead to erroneous reports of a Red-throated. More diagnostic of a typical Red-throated Loon is its bill shape and bill-forehead-crown profile. The lower edge of the lower mandible angles slightly upwards, the culmen (i.e., top edge of the upper mandible) is straight, and there almost seems to be no forehead as the line of the culmen continues onto a relatively low and flat crown.  

Red-throated Loons can sometimes hold their bills level as well, and consequently lack that classic "field guide" up-tilted look, but that distinctive bill shape should still be there. It's also worth noting here that adult Yellow-billed Loons have a similar bill shape, with lower mandible angled upwards and a straight culmen, although juvenile loons may not yet have achieved the adult's bill shape.

Speaking of shapes and profiles, just as Red-throated Loons tend to show a relatively flat crown, Pacific Loons usually have a low, rounded crown shape, Arctics typically have a higher, squarer crown profile, more like that of Common Loons, while the square crown of a Yellow-billed is often accentuated by "bumps" on the forehead and at the hindcrown. Be sure to keep in mind, though, that these profiles are variable and just average differences, so alone they are not diagnostic.

Bill Colors

Two of the other reports from this fall which prompted this article involved purported Yellow-billed Loons, with one of these sightings of two individuals described as having yellow bills. The catch is that these birds were facing into the sun, so the apparent bill color may have been an artifact of the light conditions. More importantly, even if their bills were actually yellow, some Common Loons can show ivory-colored or even yellowish bills. (Indeed, it didn't take long for me to come across a couple of photos of yellow-billed Common Loons.)

The other sighting may not be any more convincing, but at least it's more interesting. First of all, this loon's bill is only described as "cream-colored" (not yellow), but the observer had the presence of mind to photograph it through a scope with a cell-phone camera. Though the photos are pretty marginal, they are good enough in my mind to suggest the loon was not a Yellow-billed, not even a Common, but actually a Pacific Loon! I'm fairly certain I can see a chinstrap and paler hindneck (both standard Pacific Loon field marks), and equally interesting is that one photo appears to show white flanks (see Loon Lesson I above), and another shows an up-tilted bill (see Loon Lesson II).

Just as a yellowish bill does not necessarily indicate a Yellow-billed Loon, be sure to note that many Yellow-billed Loons, especially juveniles, may have a non-yellow bill. Still, the most diagnostic feature on a Yellow-billed does involve its bill: rather than looking for yellow, though, examine its culmen and tip. If the distal half of the bill and culmen are pale, then it's a Yellow-billed (any darkness on its culmen is limited to the basal half). An all-dark culmen its entire length out to the tip would indicate a Common Loon.  

Facial Features

Almost as important as the bill pattern on a Yellow-billed Loon is its head pattern. Most individuals – but not all – show an isolated dark spot or smudge on the ear coverts, and, if present, this is fairly diagnostic. Sometimes this mark is connected to the crown, but it will still appear relatively well defined. A few Common Loons might show a suggestion of a smudge, but it tends to be less clearly delineated and typically merges with the nape. Again, though, remember that not all Yellow-billeds show this mark, so its absence can indicate either species.

As you smudge search on a suspected Yellow-billed Loon, take note of the generally paler (sometimes described as blond) overall appearance of its face, head, and neck when compared to most Common Loons. Be aware, however, that this paleness can be matched by some Common Loons, so alone it is not diagnostic.

The presence or absence of an eye ring is another facial feature worth considering on loons. For example, some references state that one way to distinguish a Pacific (or Arctic) Loon from a Common is whether or not there's a whitish eye ring. While it may be true that Commons "always" have an eye ring, it doesn't hold that all Pacifics lack one, so an eye-ringed loon could be either species. Yellow-billed Loons and juvenile Red-throateds have eye rings as well. An adult Red-throated in winter doesn't really have one, though, since its entire face and neck are white.

Collars and Chinstraps

As shown in the Sibley and Geographic guides, when separating a Pacific Loon from a Common (or, for that matter, an Arctic from a Yellow-billed), the best feature to examine is the pattern along the side of the neck. The Common's pattern is irregular, with a partial and usually rectangular  "collar" protruding forward a bit from the hindneck into the whitish foreneck. The Pacific's line of demarcation between gray hindneck and white foreneck is more sharply delineated, straighter or smoothly curved, and often narrowly outlined by black.

I'd bet that most birders with loon experience are already aware of this difference, and that they also know a Pacific's crown, nape, and hindneck typically look paler gray than its back and darker forehead and lores, unlike a Common Loon. (By the way, a Red-throated's hindneck can also appear paler gray, and note an Arctic's hindneck tends not to look as pale as a Pacific's.)

I'd wager as well that these same observers have heard of something called a "chinstrap", although I suspect not all of them know what or where it is. It's a dark line across the throat or chin at the top  of the neck. Some observers probably get confused with the upper edge of a Common Loon's partial collar, which is up near the chin and could be mistaken for a chinstrap. It's also easy to mistake a crease or shadow in these feathers on any loon for a chinstrap.

And when dealing with the Pacific vs. Arctic problem, a genuine chinstrap – even if only partial – indicates you're looking at a Pacific Loon. However, as you my have already guessed, a lack of chinstrap doesn't really help you at all: not all Pacifics have one  – nor do any Arctics.

Other Thoughts

From the smallest to largest loon, as the field guides show, we have Red-throated, Pacific, Arctic, Common, and Yellow-billed. Yet, the overall size of any loon may not be very evident, especially if there's nothing around for direct comparison. Even with comparison it can be tricky, since on occasion I have seen a few Pacifics that didn't appear especially smaller than the Commons next to them. More helpful would be to concentrate on the shape or bulk of a loon's neck and bill. For example, the thinness of a Red-throated's bill and neck would be more noticeable than its shorter body length.

Another thought worth mentioning here is that non-birders and beginners will frequently mistake distant Common Mergansers for loons. This is understandable, since these ducks typically show a long and low and, well, loon-like profile as they swim. A merganser's long neck-head-bill profile in flight is also somewhat loon-like – although, of course, they lack the loon's humpbacked shape since they have no hitchiking hummingbirds to deal with!

Finally, with so many difficulties involved with loon identification, none of the field guides, even your Sibley and Geographic, have all the answers. Additional references will help, and one of these is the loon chapter in A Field Guide to Advanced Birding by Kaufman, part of the Peterson Field Guide Series, which is still in print. There are also a few other loon ID articles in the various journals, including Birding, which I'd be glad to refer the reader to upon request. (Beware, though, of what you find on your own: two widely-read loon ID articles are by those authors who also wrote unfortunate and counter-productive dowitcher articles – see

http://mbwbirds.com/dowitchers.html and http://mbwbirds.com/photographs.html.)

GREBES

Moving on to the grebes, this will be a shorter section since there are fewer difficult ID issues to deal with. As with the loon section above, the following applies just to juveniles and adults in basic/winter plumage (except for Western/Clark's grebes, which present problems as adults in summer), it will help to have your Sibley or Geographic at hand as you read this, and there will be no attempt to present a comprehensive analysis.

Pied-billed Grebe

Given any decent view of a Pied-billed in Minnesota, there's nothing really for you to confuse it with. Yes, I have seen birders initially mistake them for Least Grebes in Texas, but that's 1,500 miles away, and a second look will clear up any confusion. Pied-billeds in winter may lack a black bill ring and a juvenile's bill may look a bit thinner, but it is a generally brownish bird with dark eyes. On the other hand, Leasts are gray birds overall, their bills are thinner than on any Pied-billeds, and their eyes are pale: obviously bright yellow on adults, duller and more amber on juveniles (but not dark as on Pied-billeds).

Even in Minnesota, by the way, these differences are worth keeping in mind, since a lost Least Grebe has recently strayed in this direction as far as Arkansas. Thus, its potential to appear even up this far north may not be entirely out of the question.

Horned and Eared Grebes

In most cases, especially in fall, the first thing I notice on a Horned Grebe is how white its neck and face are, with the relatively straight upper edge of its white face cleanly delineated from the dark cap. An Eared Grebe, on the other hand, typically looks grayer or dirty on the neck and face, with only a distinctive whitish patch on the ear coverts, and its face-cap border is not as sharp or as straight. But I admittedly have been confused by some juveniles and by some adults in transition from one plumage to another, when their appearances can vary and overlap.

Then it's time to try Plan B and look at head shape, an important feature which will resolve most ID difficulties. A Horned Grebe has a relatively flat crown, with no more than a slight peak towards its hindcrown; a more peaked crown profile is typical on the Eared Grebe, with its peak farther forward above the eye.

Still, there remain those juveniles with ambiguous crown profiles, since their head shapes may have not yet fully developed. Don't worry, though, since there is a Plan C, but it only works if you're close enough to the bird. If you can see a tiny whitish tip on the bill, it's a Horned Grebe; on the other hand, if you're sure quite sure that the tip is dark, then it should be an Eared. Also look to see whether or not there's a whitish patch on the lores (something easier to see than bill tip color): if there is, it's a Horned Grebe. Unfortunately, it doesn't follow that all-dark lores identify the grebe as an Eared, since some Horneds lack this patch.

Another point worth mentioning is that birders unfamiliar with Horned Grebes in fall can mistake a distant one for a Western, since both grebes look dark gray or blackish above and contrastingly white below, and size may be hard to determine. In such cases, it would be a Western Grebe only if the bill is obvious and visible; the tiny bill on a distant Horned (or Eared) Grebe would be difficult to see at all.

Red-necked Grebe

A large bill would also serve as a good way to distinguish a Red-necked Grebe from a Horned/Eared Grebe when you're confronted with long distances or poor light. But otherwise, under reasonable conditions, Red-necked Grebes should present few ID difficulties, though I suspect at times they are mistaken for juvenile or molting adult Red-throated Loons. This confusion is not too surprising if the birder is concentrating too much on plumage and not enough on overall shape and posture, since both have dusky necks, often with a reddish wash, and are somewhat whiter on the cheeks.

Western and Clark's Grebes

If you still have some old copies of The Loon lying around, like maybe from 19 years ago, it's worth getting out the Fall 1989 issue with its article on Western vs. Clark's Grebe identification (61:99-108). Kaufman's Advanced Birding guide also has a brief chapter on these grebes. Even without these references at hand, your Sibley and Geographic guides stress bill color and face pattern as the two most important field marks: duller yellowish-green bill and black around the eye on a typical Western; brighter orange-yellow bill and white around the eye on a normal Clark's.

One thing to point out is that bill color is usually easier to see, less variable, and more straightforward than the facial pattern, even though it seems many birders tend to pay more attention to the latter. (By the way, I would add that the bill color on one of the Clark's Grebes in the Geographic guide is too dull and Western-like.)

There are other average differences between these two grebes, but none of those features alone would be diagnostic, since all are variable and overlapping. Still, these field marks can be worth noting as supporting characteristics: the whiter flanks, paler back color, narrower hindneck stripe, longer white wing stripe, and one-syllabled call on most Clark's Grebes; darker flanks and back, wider hindneck stripe, duller and shorter wing stripe, and a two-syllabled call on typical Westerns.

The main difficulty is when grebes with intermediate (hybrid?) characteristics are encountered, and such individuals can be impossible to identify with any certainty, especially when there are in-between or inconsistent face patterns (a disturbingly common occurrence) and bill colors. On a few occasions over the years, I have even seen grebes with one side showing Clark's-like orange-yellow bills, white around the eyes, and pale flanks – and then the grebes have turned around to reveal Western-like yellowish-green bills, eyes surrounded by black, and darker flanks on the other side!

Hybridization is not be the sole source of the problem, and I suspect that basic/winter-plumaged birds and juveniles tend to show the most problematic features. Whatever the case, be prepared to leave some of these grebes as unidentified. I'm sorry, but you're on your own. I'm afraid I can't help you.

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Admit it – you're still skeptical about hummingbirds migrating on the backs of loons and grebes, aren't you? Well, ever wonder why you don't see grebes in flight very often? Simple: grebes are generally smaller than loons and naturally would have a harder time flying around carrying hummingbirds. If pressed into service, though, a grebe could manage with a tiny Calliope, though probably not with a big ol' Blue-throated. In fact, consider that there's never been a documented record of any grebe with a Blue-throated Hummingbird on its back!