Today's Mystery Bird for you to Identify

Unfortunately I will again have to wait until at least 6pm tonight to be able to see the photo, but as the wingspan of the average Chipping Sparrow is around 25cm (Paul?), I'm going to say this is a pair of chippers, ± half a juvenile.

All right. That's what I call a mystery bird! :-)

It looks to me like the bird was hopping from upper left to lower right, and initiated takeoff in the middle hop, with the wingtips brushing the snow on the first flap, then clearing the snow on the second flap, corresponding to what I assume to be the final hop at the lower right. The left foot appears to have left a shallower impression in that last hop, indicating that the bird's weight was already being taken somewhat by the wings at that point.

It's all about the size. Wingspan of ~50 cm, converted into the ancient units my brain works in, gives 19.6". In terms of birds I'd expect to find hopping in the show in Colorado, my first thought is "chickadee", but this is too big for that. My second thought is "Steller's Jay", and Sibley gives its wingspan as 19", which is close enough for me. So: Steller's Jay.

(My third thought would have been Clarke's Nutcracker, but at 24" its wingspan is a couple of tads on the large side. I suppose Gray Jay is also a possibility, but its 18" wingspan seems a tad small. I guess Pinon Jay is a possibility too -- WS 19", per Sibley -- but I think a Steller's Jay is a much more likely bird to find hopping around near human habitation, and "near human habitation" seems like a much more likely place for someone to be snapping photos of birdtracks in the snow, rather than off in the pinon woods somewhere.)

Anyway, once again: Great mystery bird! Thanks!

My first thought was a grousey thing, but they walk rather than hop. A wingspan of 50-55cms is a small Crow, Jay or Magpie which was my next thought. So as none of my N. America books give wingspans I'll have to Google and come back later.

Now here's a challenge!

With the greatest respect to John Callender, I think it's going the other way (which is why the slots are thin at the front and thicker at the back), so what we have, particularly on the right wing (going my way, that is) is a pretty good wing formula. Note the very short and rather thin outermost primary and generally rounded wing. American Magpie should fit it pretty well (I know the estimated wingspan might be a bit on the short side, but we aren't told how it was measured and how allowance was made for the downward curvature of the wing as the impression must have been made on the downstroke).

Great mystery bird, as John says!

adrian: i also thought it was a galliformes due to the wingshape, but gave up that idea after i realized that the size was wrong (too small!) and grouse typically walk instead of hopping. i am also thinking it might be a corvid, possibly, as john proposes, a steller's jay.

david's guess of "a pair of chippers, ± half a juvenile" is interesting .. hadn't thought of that possibility. i should find a smokeless pub nearby so i can go there to work on the mystery birds alongside you, my good peeps.

I have absolutely no idea. But I have been keeping an eye peeled on my way to the mailbox each day for similar markings in the fresh snow. I've often seen impressions in fresh snow where an owl, I imagine, has plunged in after a vole or other small mammal. You can always tell if it succeeded, the 'liftoff' hole is much bigger and messier if there is an animal in the talons. I love the wingprints, often multiple sets. The first set of prints is usually a full impression of both wings, the second is a partial wingprint, the third, if it exists, is just the wingtips. I'll take my camera to the mailbox today just in case. rb

Steller's Jays are seen in that yard not so infrequently. I saw many Grey Jays at the ski lodge (especially the summit), but it was already some distance away and up high. I did not see any Crows around, actually.

I did not actually measure the wingspan imprint with a device (since I was concerned with falling and ruining the precious pattern), so maybe I should expand the uncertainty on that estimate.

I think that I agree with John Callendar's assessment of direction, since it can be seen where snow is sprinkled atop what would be the anterior end of the foot track. The suspect might have been headed toward the sunflower seeds remaining on the balcony . . .

So I gather there is no bird visible, just the wingprints in Colorado snow?

Based upon some of the discussion, 50cm or 20" is considerably wider than could be made by the jays mentioned, with average wingspans of the Blue Jay at 16" and Stellar's and Scrub Jays at 17"- the wingspans of the average Mourning Dove (17"), American Robin (17"), and the largest Colorado woodpeckers (18") are similarly too small... if the imprint is indeed 20" it could only have been made by a bird with at least a wingspan of 20" (on a down stroke a larger wingspan would imprint less than at stretch)... Magpies average 25", some of the small raptors are very close with the American Kestrel at 20" and a male Sharp-shinned also at 20"... scanning through some of the other Colorado bird families, other species coming in at about 20" are Killdeers, Eastern Screech and Burrowing Owls, and Rails; our Grebes at about 22", Common Nightjar at 23"... Crows come in at about 39", and mid-sized raptors such as a Red-tailed Hawk between 46-58"...

Presumably there are a few other clues such as landing imprints, assumed reason for touching down, etc. that can eliminate some of the above so I guess I will have to wait another 3 hours before I can actually see the photo!

Back after a nearly fruitless trawl through Google with no idea as to which bird made these marks. So on wingspan alone I have to go along with John and say it's a Jay, but which one I can't guess.

I thought of Kestral when I first saw the picture, but the snow dosen't seem 'messy' enough for a bird of prey strike.

Kinda' silly question coming here, but if it was a Magpie, given the length of their tail feathers, wouldn't there be some kind of tail impression too?

I would go with some kind of jay or the nutcraker. The nutcraker seems more likely because there IS a slight contracting of the wingspan due to the downstroke of take off - certainly enough to account for ~4 inches.

Just a neophyte birder's input...

I think that I agree with John Callendar's assessment of direction, since it can be seen where snow is sprinkled atop what would be the anterior end of the foot track.

That was my thought just now - in addition, the one claw is entering the snow at a shallow angle - the exit angle would be steeper. I don't know how diagnostic that is, because I haven't watched birds taking off from snow that closely. I have a horrible feeling one of the regulars here has looked, though.

(Gotta do this in two parts just in case immigration calls me for secondary screening again!)

I think there is no doubt at all that the direction of flight is 11 0âclock to 5 oâclock because of the residual snow left on the downside of each foot furrow- i.e. snow is carried from the initial touchdown to the lift-off and then deposited on top of the surface of existing snow.

I think this is supported by the curvature of the flight feathers, the fanning forwards of the outer tips indicative of braking (the second furrows made by the feet being deeper than the first also suggesting deceleration) just prior to âjumpingâ forwards into the resumption of flight from the third furrow onwards.

It would perhaps be presumptive to assume this to be a jay because of their frequent hopping as I have seen several large bird species put down their feet while gliding over snow⦠I think other marks would have been left by a small bird or mammal had this been a raptorâs attempt at a snatch (a strike would obviously have left a different pattern) more indicative of an owl rather than a falcon or hawk.

The size estimate is the confounding variable so if we assume that the ± 5 cm is a realistic estimation of the 50cm, at 45cm or 18â we can pare down the list of possible suspects.

Although I argued that I would have expected another animalâs tracks if some kind of raptor was attacking, of the 13 species of typical owls found in Colorado, the wingspan excludes the too small Flammulated and Northern Pygmy, but does fit both the Western and Eastern Screech Owls and the Burrowing Owl; the remaining typical owl species (as well as the Barn owl) seem to be too big to have left such a narrow and light impression;

in addition, of the six species of Falconidae in Colorado, the wingspan would fit the American Kestrel and the Merlin, and of the 18 possible species of Accipitridae, only a male Sharp-shinned Hawk would be small enough, yet I am tempted to dismiss a raptor because I have only ever seen a dragging mark on a low-level glide and not a series of actual touchdowns unless in immediate pursuit of prey and in the absence of another animalâs marks, I remain unconvincedâ¦

I think we can exclude all of the mid-sized birds we would expect in this setting because their wingspnas are certainly too small, so none of the Picidae (about 18â), Turdidae (17â), Mimidae (15â), or Columbidae fit the profileâ¦

The lowest estimate of size at 45cm or 18â is at the extreme range of most of the 10 species of corvid found in Colorado, and because our bird is not in full flight (landing more solidly on the second set of furrows with braking wings) we therefore must exclude the Blue, Grey, Stellerâs, Western Scrub, and Pinyon Jays, as well as the Clarkâs Nutcracker; of the four remaining I think both raven species and the crow would have left broader and wider marks, so the Black-billed Magpie, Pica hudsonia is my prime suspect, so book 'em Danno!

A few photos of the flight mechanics of a magpie in support of why this could well be our bird:

note tail position just prior to landing in snow

note how the Magpie's tail remains upright when landing in snow

note forward curve and separation of flight feathers on down stroke (supports 11-5 o'clock flight direction and "splayed" imprint in mystery photo)

I think it's a magpie, for the following three reasons:
1) I like magpies
2) Magpies are cool
3) Magpies make really neat nests.

It's also possible that it wasn't a magpie, in which case I am wrong. Hope this helps clarify things.

Is this some sort of Net Twitch? Wait till you see the babe in "Avatar" pish her dragon-bird mount.

Rob Rachlin: those reasons work for me! i like magpies, too. BUT i beg to differ regarding their nests, which are (from my observations) anything BUT "neat".

At first, I thought that the tail of the Magpie should be evident in the imprint, but after studying posture and other images1,2, tail imprint is not requisite for Magpie tracks. Deflection of feathers under aeroelastic stress is not unique to Magpies, however.    

Steller's Jay wingspan can be as much as 48 cm. Are we sure that we can exclude him as a suspect, especially since one was spotted in the vicinity on that day?

 

Sara,

I feel relatively comfortable excluding the jays because 45-48cm is at the extreme limit of their wingspan which would have been measured from around P6 or P7 outstretched... (Paul, can you confirm wingspan meauring technique?)

as you noted above, most birds have this forward curve to the outermost primaries on a downbeat thereby reducing the imprint length by as much as several inches at that particular moment...

our imprint demonstrates that forward-curving signature and if one compares relative spread of the primariy edges that are imprinted across the width of the bird, these marks could really only have been left by a bird with a wingspan exceeding at least 20" and probably no more than 30" and that of Black-billed Magpies, ranging from 56-61cm or 22-24" seems the best fit...

David, I have no idea how wingspan is measured -- when banding birds, you measure the wing chord on the folded wing. (On chickadees we measured the wing arc, but that also uses the folded wing.)

Everyone seems to have forgotten one of the most important questions to ask in Colorado -- what is the elevation?

Paul, I believe the elevation at Pagosa Springs is 7,126ft or 2,172m, certainly within a magpie's range...

Wow, cool information. Thanks, David.

I know what I'm going to do the next time I see a bird leave some wing impressions in the snow: Run out and measure the wingspan, and compare to Sibley's WS figure.

@David Hilmy

Several inches? We do not know how deep the snow is (or rather how deep he landed in it), and we do know whether or not the bird modified his downstroke to accommodate the snowy substrate.

Furthermore, it is not even clear to me what was he doing there. So he alights on snow, and leaves no trace of wings. Hops. In the new spot, he flaps and sort of drags his feet a bit leaving the last foot tracks?

Sara,

the "several inches" did not refer to the depth of snow but the probable difference between wingspan as recorded in the literature (i.e. fully stretched measurement from P7 across the body to the opposite P7) and the actual wingspan of the bird's shortened downwards and forwards thrusting wingspan as evidenced by the snow imprint.

In other words, if the bird has a span of 20" fully stretched, then one could conservatively subtract a couple of inches from either side to account for the shortened forward/downwards shape, therefore could only make an imprint around 16".

Conversely, if the measured mark in the snow as 20" (your 50cm), knowing that to be shorter than the actual wingspan would put the bird at a measured wingspan of 24"+.

Unfortunately, although one of my graduate degrees is indeed in Biomechanics, it did not involve avian physiology nor the kinematics of flight!

For some reason I am having trouble loading the current (Tuesday, January 12th) "Today's Mystery Bird" from different computers and through different servers and so I am unable to comment at that link...

but of the three albatross species present on Midway (Laysan, Black-footed, Short-tailed), this could only be the Laysan Alabtross, Phoebastria immutabilis, because of the black "smudge" at the eye... although there are hybrids between the Laysan and the Black-footed (about 1:100,000), this particular albatross hybrid photo shows that it would have a dusky look to the plumage around the head, which ours lacks... I also understand that hybrids have a hard time breeding because they have "two left feet", neither fully conversant with the mating dance of the Laysan, nor with that of the Black-footed!

I assume if you have a Facebook account you can access my "open to everyone" Photo folder, so if you would like to view some of the photos I borrowed from photographer Chris Jordan, who documented the devastating toll that plastics take upon the albatross chicks on Midway, feel free to click here.

@David Hilmy: I just think that the deflection angle is too small to constitute such a significant change to imprinted wingspan, but I do not really know. I cannot even use wing set position relative to claw tracks as a clue, since there is broad uncertainty in determining the center. We need information in the third dimension, since the snap-shot projection will not do.

And how do you think I feel? I am supposed to be getting a PhD in feather structure and mechanical properties, and I cannot solve this!

The problem I have is what kind of bird claw would make marks like that...the're really narrow - as if the front toes and rear toes are really close ...

Ashok, I don't have a problem with the width of tracks- if you imagine the outline of the bird using the wingprints, it appears to me that the width of the tracks (not just at a single point but consistently dragged through the snow) is entirely consistent with a bird that sort of size, even a large-taloned raptor...

Sara, as to the thinking of this bird, I wouldn't be surprised if it was coming in to forage, touched down and realisisng the snow was deeper than it anticipated or because there really was a raptor lurking, switched plans and took off for safer environs... and given what I'm sure you will have studied concerning magpie wing-gait at altitude, a magpie could certainly touch down and with one wingbeat resume an airborne state...

I found the following research somewhat relevant and certainly interesting:

Tobalske, B.W. and Dial, K.P. (1996) Flight kinematics of Black-billed Magpies and pigeons over a wide range of speeds. Journal of Experimental Biology, 199, 263-280

Lecture Notes on Bird Flight by Gary Ritchison, Professor of Biology at Eastern Kentucky University

Grrl, please put us out of our agony!! What was it??

No kidding. Whatwhatwhat?

She's just admitted to me that it's that damn Chipping Sparrow again.

like any whip-cracking .. um, momma bird .. i love it when my peeps beg, but alas, i cannot stuff a wriggling worm down your throats this time because the photographer doesn't know the ID of this bird. so i guess i can give you an existential answer and say; "this bird can be whatever you wish it to be." or, since you've all done such a fine job at discussing the various aspects of the image and the relevant scientific data, it seems you've all more or less IDd the bird yourselves.

right?

Yup! It's an owl, right gang? Uh, Chipping Sparrow? No, wait, albatross! Ah hell...

So I'll have to get out into the snowy UK countryside and start measuring bird tracks now. If I freeze to death it's your fault!!
BTW there is a folklore here that if Magpies put a roof on their nests it's going to be a wet spring. I can't say if it's true or not.

I spend much of my time with ravens--drawing them and collecting stories of science and spirit. The wing imprints here do have that distinctive "fingerprint" pattern seen on certain corvids. The foot prints are, as has been said here,"mysterious."