I.D. problems between EARED & HORNED GREBES
A photographic review
text © Don Roberson
photos copyrighted by photographer(s) credited
all photos taken in Monterey County, California
Eared Grebe is widespread throughout California, both inland and along the coast, and nests locally. Huge numbers appear in migration and winter. Horned Grebe is less common but still winters in reasonably good numbers on salt water bays and estuaries. It is rather rare inland or on fresh water. In Monterey County, for example, although many winter along the coast there are only 2 acceptable records on freshwater.

Two recent claims of Horned Grebe on fresh water ponds in MTY have proven to be Eared Grebes: one in fall 2003 and another in fall 2004. These mistakes were made by experienced birders. All the grebes in question were in non-breeding [=basic] plumage. Perhaps this is an over-looked problem?

Anyone beyond a beginning birder automatically identifies the birds at the top of this page as Eared Grebes on these characters:
  1. dark on face below a line drawn through the eye [yellow line here]
  2. concentrated white 'hot-spot' low on back of face
  3. peaked crown above the eye
  4. short, thin, straight or slightly upturned bill
  5. much dusky on neck, including on front of neck
  6. rear of bird often carried high [but not always, as in the front bird]
I think that experienced birders see all these points as the "jizz" of Eared Grebe, and hardly give it a second thought. Photo © D. Roberson, 16 Dec 1994 Moss Landing
The problem arises when a somewhat distant grebe (right) seems to show
  • crisply white cheeks, without any apparent dark below the line of the eye
  • a flat-looking crown
  • much white to front of neck, and
  • doesn't carry its rear end high
This photo is of an Eared Grebe that was on Crespi Pond from 14-24 Sep 2003. At least 3 good observers reported it as a Horned Grebe to the BirdBox, recognizing that a Horned Grebe on fresh water was of interest. The bird was often actively diving, making it hard to study. Photos right & below © D. Roberson, 18 Sep 2003
Here is a closer view of the Crespi grebe. What looked like clean white cheeks prove to be streaked with dusky and the auriculars are smudged a little, but it is easy to see how the whole lower face could look 'clean white' at a distance. This photo shows the bird perhaps a little more concerned about the nearby photographer, and the head shape looks more 'alert' and peaked above the eye.
For comparison, here is a real Horned Grebe in basic plumage. The cheeks (and everything on the face below the line of the eye) are really clean white. The front of the neck really is white. The crown is more rounded, and where the peak of the body is held on the back is well forward of the typical 'high rear end' of Eared Grebe. Also the flanks look white (not gray as above) but they also looked streaked here.

This Horned Grebe has a red eye while the Eared Grebe on Crespi has a yellow eye. This is age related (more below)

HOGR photo © D. Roberson 15 Nov 2004 Monterey harbor

Below are two shots of the other misidentified 'Horned Grebe' in MTY. It was on fresh-water Roberts Lake on 23 Oct 2004, and was reported by experienced birders. At a distance (below left) it does look to have white cheeks but up closer (below right) a lot of smudging or streaking appears in the cheeks and the top of the neck has a lot of dusky in the front. It's head looks rather rounded and it is not carrying its rear end high. Again, it is easy to see why a quick glance would bring a "Horned Grebe" response for this bird. It also has a yellow eye. Photos © D. Roberson
There are diagnostic character that seems to work on any Eared/Horned Grebe in any plumage: bill tip color and bill shape.
As illustrated below with enlargements on the heads of some of the above birds, all Horned Grebes have a distinctive white tip to the bill while Eared Grebes do not. The bill shape of Eared Grebe shows a very slight up-turn while that of Horned Grebe very slight turns down at the tip; these differences are exaggerated by the shape of the bottom edge of the lower mandible (slightly upturned from the gonys in Eared, rather straight in Horned) so that even when the culmen is actually straight in some Eared Grebes (like that on Roberts Lake) the slight up-turn of the curvature of the lower mandible gives a slightly upturned look.
The literature consulted (e.g., Palmer 1962, Cramp & Simmons 1977) stated that both grebes start life with dark eyes (gray in Horned, dark brown in Eared) but the eyes are red (Horned) or red-orange (Eared) by the time they breed, I have photos of red-eyed Eared Grebes so it seems that both can get nice red eyes. The literature did not explain the exact sequence of this eye color change. Clearly some Eared Grebes are yellow-eyed in fall; perhaps Horned Grebes can be as well. However, once eye color is obtained, it should remain basically reddish. So I make the presumption that yellow-eyed grebes are first-years birds.

My experience with misidentified Eared Grebes is with just these two fall birds in Monterey. Both were yellow-eyed birds. Thus I speculate that:

  • This i.d. problem is most prevalent during fall migration and is a problem in first-year Eared Grebes that look 'white-cheeked' at a distance. Maybe this appearance is lost by winter when they are fully in first-basic plumage? 
  • What percentage of first-fall Eared Grebes look like this, I don't know. Our attention was drawn to these two individuals because they were on fresh water where Horned Grebes are rare. It may not be that unusual?
Horned Grebes are rather rare inland anywhere in California. It has been my impression that they are most often reported in fall migration, particularly November. This leads one to wonder:
  • Could some claims of inland Horned Grebes be mistakenly identified first-fall Eared Grebes? Could this especially be true of birds scoped from some distance?
  • On the other hand, Horned Grebes are not that rare inland. I dug out my own notes and found that I saw "4-6 Horned Grebes" among "lots" of Eared Grebes on 13 Nov 1999 at Los Banos Creek Reservoir, Merced County. I have no other details but I was with Steve Glover and Rita Carratello; surely at least they got some of these right. So there is a movement, at least in November. Are claims in September or October more suspect?
  • Large lakes inland have plenty of records of wintering Horned Grebes. I find in my own notes that I saw "at least 15" among over 2000 Eared Grebes feeding on threadfin shad on Clear Lake, Lake County, on 28 Feb 1999. Surely the vast majority of inland records must be correct.
  • But assuming that there could be some error rate in claims of Horned Grebes inland, and maybe particularly in Sep-Oct, what error rate is acceptable? Should all inland counties (at least in northern California) have at least one Horned Grebe record adequately documented by written details (that include bill color), or photos (that show bill shape or color), or specimens? Or does it matter? 
  • These same questions apply to early dates of fall migrants from coastal locales. Should we be more skeptical of 'Horned Grebe' arrival dates in Sep or early Oct?
For what it's worth, on checking the Museum of Vertebrate Zoology, U.C. Berkeley, on-line data base, we find that of the 22 specimens there from California, only two are from fresh water: a February bird on Lake Merritt, Oakland, and one collected at Los Banos, Merced County, on 12 Apr 1912 [MVZ#21577]. So at least Merced County is clean! But what of other inland counties, especially the little counties where Horned Grebe may be the most scarce, in this day and age of emphasis of listing county birds? I dunno. But I am curious . . . .

Literature cited:

FOLLOW-UP: In response to this web page, Jeff Davis of Fresno County wrote:
I hadn't appreciated this problem until Jim Gain, Harold Reeve and I saw an odd grebe at the Madera sewage ponds during a 12 September 04 big day. It was quite close and showed  many features of a Horned Grebe: a clean white cheek, a mostly white foreneck, a low "stern," a smooth and nearly flat crown, and even an apparently straight bill with a white tip. Despite their initial skepticism I had pretty much convinced Harold and Jim that we were looking at a Horned Grebe. We all felt uneasy about this claim, however, as the bird didn't seem typical to us; it didn't have the bulky body of a Horned, and the white and dark of its plumage didn't contrast as crisply as it should have. I then found another nearly identical grebe, then two more, and two more. Only then was it obvious that we were looking at first-fall Eared Grebes.

So I'd say many if not all first-fall Eared Grebes have this confusing plumage before they complete their first prebasic molt, which according to the Birds of North America account by Cullen et al. (1999) "continues into October or later," and even birds at close range can be a problem.

That we thought the bird had a straight bill with a white tip, suggests even these features may not be foolproof: If fools like us can get it wrong, others can too. Head shape, and especially the slope of the rump, could vary with a bird's attitude, but I don't know what accounts for this bird's apparently straight and white-tipped bill. The bird was actively diving, so perhaps the bill looked as it did because it was wet. Or maybe the difference between slightly upturned and dark-tipped and slightly down-turned and white-tipped is just not obvious in many field situations.

We should always first consider Eared Grebe when we see a small Podiceps on fresh water, but it does seem especially prudent to do this in September- October. And based on the Madera experience, I think body bulk and  plumage contrast may be as important in distinguishing the two grebes as the features you suggested.

Use the following links to other portions of the MTY checklist:

Part 1: Waterfowl through Grebes
Part 2: Albatrosses through Frigatebirds
Part 3: Herons through Cranes
Part 4: Plovers through Sandpipers
Part 5: Jaegers through Alcids
Part 6: Doves through Woodpeckers
Part 7: Flycatchers through Larks
Part 8: Swallows through Pipits
Part 9: Waxwings through Warblers
Part 10: Tanagers through Sparrows
Part 11: Grosbeaks through Finches
or just the plain Checklist (no annotations)
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Page created 15-21 Nov 2004