Puzzling out Red-throated Vs Pacific Loon on the Eastern shore of the US (New Jersey) (1 Viewer)

[tom baxter]

I understand if this photo is a lost cause, but its just barely good enough that I have a small hope that someone might have some insight. I have to wonder how someone would be able to pick out a Pacific Loon in flight on the East coast, unless it was a close flyby. Most migrants are viewed distantly through a scope, where subtleties like finer details of plumage, wing loading and bill shape are nearly impossible to be sure of.

This bird caught my eye as a candidate for Pacific Loon because to me it looked like it had larger feet than other Red-throated Loons. In the moment, it really stood out to me as being closer to the size of a Common Loon, but safely in between the size of Red-throated and Common. This impression I had in the field could have been wrong, but among the hundreds of Red-throated Loons I have seen in the past few days this one stood out to me in the moment. By way of its feet appearing large, it also appeared more evenly centered with respect to its wing loading, and I think of Red-throated as more rear loaded, is this an accurate starting point?

If you dont have an opinion on this bird, any general pointers would be appreciated.

 

[Joe H]

We have both regularly seen up in Alaska so I’ll add my .02 cents worth, but I’m no expert. As you say, the photos aren’t of ID quality but it’s good to have them. To my eyes it looks like an adult bird, so that helps. When were the pictures taken?

I see by some missing jpg numbers that a couple more shots were taken; it would be useful to get a picture of the bird with the wings below the body so you could try to see evidence of any white barring on the back (Pacific) versus a plain dark back (Red-throated). The Sibley Bird Guides have good in-flight illustrations and are worth a look.

My Impression is also that the head/neck area looks darker than the under body. If these pictures were taken in the past few days, then the non-breeding Red-throat ought to have the bottom of the head/neck the same color as the belly. Your pictures seem to appear as if the head/neck area is darker than the belly, an indication toward Pacific .

Also (and this is pretty iffy) the Sibley flight illustrations show a slight upward tilt to the bill in the Red-throat, while the Pacific bill is more in-line with the head like your pictures. Again, this is an impression Sibley wished to present when he painted the illustrations, not a guaranteed posture the bird will hold at all times.

Lastly, just to further confuse the situation, my old National Geographic Society Birds of N. America cautions that sightings of “Pacific Loons” on the East Coast may be Arctic Loons (Gavin arcica).

I hope some of that helps, good luck!

 

[nartreb]

The photos consistently show a mostly-dark neck and head, which (assuming nonbreeding plumage) is good for Arctic or Pacific but not Red-throated.
I'm not entirely certain Common can be ruled out from the photos, though. (Some seem dark all the length of the neck, but others look a little blotchy at the neck.) Size is notoriously hard to judge; if that was your only reason for discounting Common in the field, it's worth a second look. Would explain the impression of large feet (which the photos do support)...

 

[birdmeister]

Any photos are worth a try, in my opinion. I don't have any personal experience with Pacific Loon. I'd say your bird definitely does not look like a Common, but I can't say either way on Red-throated vs. Pacific.

My favorite guide for waterbirds in flight (by far) is the Peterson Seawatching Guide (Behrens and Cox 2013), so I took a look at their accounts for both species. I'm not sure exactly what you mean by "rear loaded" for Red-throated, but the guide describes Red-throated in flight as (paraphrasing here) tilted forward, with wings set farther back on the body. Pacific is supposed to be more evenly proportioned, as you mentioned, but I'm not sure which way to decide on these photos.

Another mark the authors list for Pacific is a shorter neck. This is the one feature that I doubt most in your photos, since your bird looks pretty long-necked to me. It could be a minor point, though.

It's tough to say much on plumage, especially given the backlit/poorly lit conditions.


I have to say, I don't know how people pick out Pacific Loon as a distant flyby on the East Coast, either, but somehow they key in on those finer details.

 

[tom baxter]

Any photos are worth a try, in my opinion. I don't have any personal experience with Pacific Loon. I'd say your bird definitely does not look like a Common, but I can't say either way on Red-throated vs. Pacific.

My favorite guide for waterbirds in flight (by far) is the Peterson Seawatching Guide (Behrens and Cox 2013), so I took a look at their accounts for both species. I'm not sure exactly what you mean by "rear loaded" for Red-throated, but the guide describes Red-throated in flight as (paraphrasing here) tilted forward, with wings set farther back on the body. Pacific is supposed to be more evenly proportioned, as you mentioned, but I'm not sure which way to decide on these photos.

Another mark the authors list for Pacific is a shorter neck. This is the one feature that I doubt most in your photos, since your bird looks pretty long-necked to me. It could be a minor point, though.

It's tough to say much on plumage, especially given the backlit/poorly lit conditions.


I have to say, I don't know how people pick out Pacific Loon as a distant flyby on the East Coast, either, but somehow they key in on those finer details.

that is what I meant by rear loaded, the wings are set further back. I have that guide, and I will have to take another look at it. Thank you.

So far I have gathered some very knowledgeable opinions here as well as offline, all of which are unsurprisingly hesitant to put out any claims to species. I know the commenters here to all be regular contributors on the forum whose opinions I value greatly, so thank you all. Several of the commenters have either stated that they can not rule out Common from these photos, or they question how I ruled out Common, which makes me pause to wonder about that. I’d be interested to hear more about why you say it definitely does not look like a Common to you.

Keep in mind that the commenters are only going by these bad photos. I never considered Common in the field because it just didn’t look like one to me. I’ve been seeing tons of migrant Red throated lately, and very few Commons in flight as active migrants, like 1 for every 200-300 red throated, which is pretty typical for this time of year here. There are plenty of Commons around, but they’re all mostly loafing around, I usually see about 10, give or take at each site, each day sitting around in the surf, while migrating Red throated have been ranging from 50-500 a day over the past week, with 1-3 hour observation periods. I have a very good feel for the size of Red throated right now, they’re pretty engrained in my mind. This one came during the middle of an observation period, preceded by at least 100 Red throated and 0 Common in flight by that point in the watch. This bird really stood out immediately by its size. It definitely had bigger feet and maybe a slightly thicker neck, but the neck was very subtle, it was mostly the feet. While the feet did seem big, if I am not mistaken, usually Common Loon feet look bulbous. These looked safely intermediate, but large enough to be sure they were larger than the other birds seen to that point. I had a hard time in the field being completely sure it wasn’t a Red throated, whereas Common Loon feet usually are a fairly easy clincher in my experience. Among the tons of Red throated passing by, I frequently notice variations in their appearances, including the way they hold their necks, variations in plumage that can be accounted for mostly by various ages, and of course variations that I attribute to viewing conditions that make me settle for being 95% sure that Red throated is a safe ID. This bird had me feeling VERY unsure this was Red throated, but I have never had much of an issue with identifying Common Loons before. This absolutely could be a case of Common Loon, I have to wonder, especially now in photo review with that question being challenged by more than 1 respected contributor. I remain marginally confident of my original impression on that front, because in addition to the size, the color of the neck seems wrong. It never appeared to have much white on the chin, and as a matter of fact it, appeared to have even less white around the chin than I usually see on immature Red throated, which is substantiated by the photos I think.

 

[Butty]

I'm surprised by the repeated emphasis on size as a significant feature. In the field, one can judge size-related aspects - a bulky structure, proportions, powerful flight, speed of flapping, etc. - but not size itself. Judging the size of a lone bird is notoriously unreliable.

 

[jogresh]

First impression is Common Loon. I think those feet are a fairly good ID feature. 🤔

 

[tom baxter]

I'm surprised by the repeated emphasis on size as a significant feature. In the field, one can judge size-related aspects - a bulky structure, proportions, powerful flight, speed of flapping, etc. - but not size itself. Judging the size of a lone bird is notoriously unreliable.

I do agree to some extent. While it is not the ideal observation to use alone in identification, I think its usefulness varies. As you say, it should not be used without judging the size with respect to something else, proportions, powerful flight etc, which are all additional things that I noted in the field and of which I mentioned all of them aside from powerful flight in this thread. The reason I opted not to describe the flight here is because it is in my opinion less reliable and particularly difficult to describe beyond titling it as such. I did notice that everything about it felt different than Red-throated Loons. Also, I do think the experience of the observer makes a difference with respect to the reliability of these somewhat ambiguous assessments. For example, it is routine for experienced observers to note the size difference as a primary clue in identifying active migrants as subtle as flyover warbler sp. which is much more difficult than noticing the size difference in this case, and more relevant here, size difference between Common vs Red-throated Loon is usually a pretty immediately noticeable difference used in identifying them in my personal experience. It is often the immediate difference in size that is noticed, but you are correct that the subconscious mind is picking up more than just the size. It is also picking up proportions, flight style, and a lot more in those moments. When everything else seems normal, it is routinely a way that many experienced observers key in on different species. I have had explanations of this nature described to me by several of the United State's field guide authors at various points throughout the years. In summary, I definitely do agree with you to an extent, sometimes this approach will be misleading, and I think it deserves a cautious approach. Your point is a very big part of why I was hesitant to put a species to this bird. All I could personally conclusively determine from the photos and observation in the field, is that this bird seemed different than the others to me.

 

[Brian J Small]

First impression is Common Loon. I think those feet are a fairly good ID feature. 🤔

I agree. Though I see few GND/Common Loons, I am lucky enough to see 1000s of Redthroats (2300 in one seawatch recently) and the large, swollen -ended feet of this bird are not that of Redthroat or Black-throated/Pacific to my eyes.



Brian

 

[birdmeister]

So far I have gathered some very knowledgeable opinions here as well as offline, all of which are unsurprisingly hesitant to put out any claims to species. I know the commenters here to all be regular contributors on the forum whose opinions I value greatly, so thank you all. Several of the commenters have either stated that they can not rule out Common from these photos, or they question how I ruled out Common, which makes me pause to wonder about that. I’d be interested to hear more about why you say it definitely does not look like a Common to you.

Well, Tom, my initial claim was based on the apparent wing thickness of the bird. I considered the wings not to be broad enough for Common Loon, but I'm happy to retract that claim after comments above from the experts. It's not usually a good idea to call a distant photo on one feature, and that's just what I did!