Today's Mystery Bird for you to Identify

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[Mystery bird] feet [I will identify this bird for you in 48 hours]

Image: [larger view].

Please name at least one field mark that supports your identification.

I have some questions about each foot depicted above. Can you tell me;

  1. what each foot is used for?
  2. for each foot type, can you tell me if its possessor walks or hops when on land?
  3. one foot type is found only in one genus worldwide, can you tell me which foot that is and the species that has that foot? This foot has a special character that it shares with another (much larger) taxonomic group of birds: can you tell me what that is?
  4. can you name three species of birds that have the other two feet types?

Upper left hand foot:

  1. what each foot is used for?

    This is a raptorial foot, used to grab prey. This particular foot, with its pointy scales and tremendously long claws (as long as, or longer than the actual toe) belongs to an Osprey, which is the only sort of bird to have it. In this case, the scales on the foot point "backwards" so struggling, slippery fish cannot escape after the bird has grabbed them.

  2. for each foot type, can you tell me if its possessor walks or hops when on land?
    Ospreys walk on land.
  3. one foot type is found only in one genus worldwide, can you tell me which foot that is and the species that has that foot? This foot has a special character that it shares with another (much larger) taxonomic group of birds: can you tell me what that is?
    This is the unique foot type I was referring to in my question. The special feature its possessor, Ospreys, has is the ability to switch from three toes pointed forward, one back (anisodactyly), to two toes pointed forward, two back (zygodactyly). This feature is shared with the owls (Strigiformes).

Upper right hand foot:

  1. what each foot is used for?
    This foot is used for swimming, diving and walking.
  2. for each foot type, can you tell me if its possessor walks or hops when on land?
    Birds with webbed feet walk on land, although some (loons and grebes, for example), tend to avoid land unless nesting, because they can walk only very clumsily. But this has everything to do with the structure and position of the legs on the bird's body and nothing to do with foot structure.
  3. can you name three species of birds that have the other two feet types?
    Instead of naming species, I'll just name a few taxonomic orders and leave you to suss out the species: Anseriformes, Procellariiformes, Gaviiformes and some taxonomic families within Charadriiformes. NOTE: Pelecaniformes are not included here because all four of their toes are webbed (totipalmate), and Podicipediformes (and the coots) are not included here because they have separate webs on each toe (lobate feet).

Lower foot, roughly centered:

  1. what each foot is used for?
    This foot is found among highly arboreal species and is used to attach the bird to a tree.
  2. for each foot type, can you tell me if its possessor walks or hops when on land?
    Most birds who have this toe arrangement (zygodactyly) walk on land. I say "most birds" because I cannot think of any zygodactyl birds that hop preferentially to walking, but there might be a few (I'll let you tell me, since I am drawing a blank at the moment). I am keenly aware that one group of zygodactyl birds, the parrots, and a few woodpeckers (such as Northern Flickers) will hop when they are trying to move quickly on the ground (although some parrots will run -- I've never seen a flicker run). This was actually a tricky question because "walking versus hopping" is a combination of leg length and leg position in relation to the bird's body, and overall foot/leg structure, with specific toe arrangement playing only a minor role.
  3. can you name three species of birds that have the other two feet types?
    Piciformes, Psittaciformes, some Strigiformes (owls) and the near-passerine (taxonomic "garbage can"*) family, Cuculidae (cuckoos and roadrunners).

*Taxonomic "garbage can": these are taxa where the precise evolutionary relationships for many of the birds are poorly known and generally are under dispute.

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Cool quiz!

Starting from the bottom: this looks like a woodpecker foot, but not a three-toed woodpecker foot. It's good at holding on to vertical surfaces (such as tree trunks). I think they usually hop on land. (Gosh, I think woodpecker, but now I'm wondering how a nuthatch foot looks in comparison?)

Upper left: this looks raptorish, except that I think most raptors have a toe on the back to grasp prey around. So I'm not at all sure. I think it's adapted to grasp prey of some sort, but maybe a special sort of prey?. But I'm guessing this is a pretty unusual foot, so maybe it's the unique genus foottype? I'm guessing it walks, but not sure.

Upper right: this looks goosish, adapted for swimming. I think it probably walks on land.

Nuthatches have typical songbird feet, Bardiac: three toes forward, one behind. That was a very good question, though. The two forward, two behind arrangement (called 'zygodactyl,' in case you're interested) is common to several genera of woodpeckers, so that type isn't unique to a single genus.

Likewise, the webbed foot works fine for lots of different genera of waterfowl, so that type isn't unique either.

That leaves the raptor foot. So I'm going out on a limb bere, and saying that this foot is unique to a single fish-catching genus because of the spiny undersides of the toes. The only member of this genus has a reversible toe, so it can switch back and forth from the three-toes-forward-one- behind arrangement to a two-and-two arrangement, the better to secure its slippery prey. It would thus share this feature with the Strigiformes (owls).

By Pete Moulton (not verified) on 11 Jun 2010 #permalink

So parrot toes would also be zygodactylic? (But my memory is that they're fleshier/thicker and that the short toes are way shorter than the long ones.)

Oh, I think I know the raptor of which you speak. Very cool!

I love this blog! I learn so much! Thanks, GrrlScientist!

Okay, now I've got a question. Woodpeckers that I see around hop. But parrots walk with fairly similar toe arrangements. Why the difference?

Toes 2&3 in front is zygodactyl, but when it's toes 3&4 in front that's heterodactyl - found only in the Trogons.

I learn so much while trying to figure out these mysteries!

Patty -- that was my first thought too, for question #3. We could also talk about pamprodactyl, as in the Mousebirds. Unfortunately, both of those families contain more than one genus. I think she's aiming at didactyl -- two toes -- which is only shown in Ostriches.

Excellent info, psweet - thanks - 2 toes for the Ostrich, and 3 for the Emus, cassowaries, etc.