View From The Shed by Volunteer Shaun - TOE-TALLY PERFECT FEET

TOE-TALLY PERFECT FEET

Things that you never thought I’d start a blog with #1…

“I was cutting my toenails the other day…”  Bear with me, all will become clear.

So, I was cutting my toenails the other day and I suddenly thought to myself, “Do birds have fingernails and toenails?”

I mean, it’s easy to see how my toenails are equivalent to the claws or talons of a bird’s foot. The structure of their feet is recognisably similar to mine after all, But my hand is nothing like a bird’s wing. I can equate their toes to my own but their fingers? No. I can’t see that. I can’t see the grasping digits or opposable thumbs that I share with primates, so where are a bird’s fingers and fingernails?

The answer is simple. Most birds don’t really have any fingernails. However, they do still have the vestigial remains of fingers. That is, they have phalanx and metacarpal bones, much like you and I do, but their hand skeleton has pretty much fused together making far fewer individual bones with much less movement. No individual fingers means they have no individual fingernails in most cases. There are a few noticeable exceptions but seeing as these all live in the jungles of the Southern Hemisphere and we never see them in our Dearne Valley, I’ll ignore them and move a little south down the bird’s body to its toes.

Most birds can flex their toes to a much greater extent than I can. The best I can do is pick up a pencil from the floor with them when it’s too much trouble to bend my aching back. It’s quite an impressive feat for a man with such hairy feet. Sometimes I think I’m part Hobbit. But a bird uses its toes for so much more than I do. Mine are just for balance. Their feet and toes grasp and tear too. Colour me impressed. 

Most birds’ feet conform to one of several different basic patterns. Below I take a look at the most common types. For this week’s homework, see if you can think of some examples of each, beyond those that I’ve given. Aren’t you glad that the school holidays are over? 

ANISODACTYL FEET - Most birds have three toes pointing forwards and one pointing to the rear. Almost ninety percent of birds have this toe arrangement as it’s ideal for multitudinous uses. Woodland birds use them to hold themselves upright on branches. Some can scratch at the ground to uncover food or snatch a live meal from the air, ground or even water. And others can grasp that same foodstuff firmly while tearing chunks off to feed itself, its mate or its young. We’ve seen excellent examples of that with our Marsh Harriers here at Old Moor recently, first while courting their mates and later when feeding their young. A predator bird’s foot closely resembles that of a hunting dinosaur and it’s used in precisely the same sharp, strong way; three forward toes locked in with a fourth rear toe. Any prey that’s captured in those talons won’t last long.

ZYGODACTYL FEET - This means two toes pointing forwards and two pointing backwards. Birds such as Treecreepers have this toe arrangement, being ideal for clamping its body against the trunk of a tree, flattened tight against any strong wind. Woodpeckers climb with this kind of foot and Parrots toes also have this alignment. I’m sure we’ve all seen how dextrous they can be when holding their food up to their beaks. With my arthritic old toes and, I’d starve if I were a Parrot. This particular Polly wouldn’t be able to get a cracker past his belly-button. 

SEMI-ZYGODACTYL FEET - Some birds such as Ospreys and Owls can turn one of their toes to face to the front or back, thus being anisodactyl or zygodactyl as any particular activity requires. This is especially useful if they need to manipulate their food, such as when the Osprey turns a fish in mid-air to make it more streamlined when flying off with it

PALMATE FEET - If it spends much of its life swimming, the chances are that a bird will have palmate feet. This means that they have webbing between their front three toes that acts like a human swimmer’s flipper to increase thrust against the water. Look at the footprints of a Duck, Gull or Goose when it’s been walking through mud. Its three front toes all end in a small claw. Even these wettest of birds have fingernails.

TOTIPALMATE FEET - Birds with this kind of feet are even more at home on lakes but aren’t at all happy walking on land. All four of their toes have moved towards the front and are webbed, providing even more surface area for pulling them through the water. We see this in Cormorants here at Old Moor and the Gannets out at RSPB Bempton Cliffs. If you want to travel further afield you could notice it in the feet of Pelicans too.

LOBATE FEET - This is a further adaptation of the webbing and the best examples found at Old Moor are on our Coots. It is excellent for speed swimming as these birds have flattened lobes alongside each individual toe that open out on the swimming stroke to provide maximum paddle surface but close up on the recovery, forward movement. That’s an ingenious evolutionary adaptation.

These listed above are the main foot and toe arrangements in birds but there are several anomalies that I just don’t have space to detail. Thinking of the ones that we might see at Old Moor, Kingfishers, Avocets and Swifts all fit generally into one of the above categories but they have their own slightly specialised feet for their own requirements. If you want more details, ask me when you see me at Old Moor’s Welcome Shed. The important thing to remember is that every bird species’ feet are perfectly adapted to that bird’s individual needs. And they’re still changing in infinitesimally imperceptible ways as the world changes around them. Aren’t we all?