Understanding the bird’s toe arrangement
Birds are recognized as being the “superb flyers” of the world. Although their wings are what helps them fly . . . . it is their feet and bill that help distinguish what ecological niche that hey live in. By studying their feet we can understand unusual behaviors and where they spend most hours of the day (tree, ground, water). We can look at the birds of prey who have armor protecting it from being bitten and sharp talons for grasping its prey. The grebe toes are lobed which will expand or contract as the bird swims or dives under water. Chickadees will uses its toes for grasp sunflower seed and then peck through the shell to get to the meat of the seed. Although there are many obvious features of the birds feet that helps it survive (as listed above) . . . I plan to discuss the 5 different toe arrangements that our birds have that help make those obvious features work!
The 5 Different Toe Arrangements
Anisodactyl describes a foot having three toes in front and one behind. It is the most common arrangement of the avian toe and the one seen in songbirds and perching birds. Having the first digit in the back, it reminds me of how our human thumb works when we are “grasping something”.
2,3,4 (second, third & forth digit in the front)
1 (first digit in the back)
Zygodactyl foot has two toes facing forward and two facing backward. This is the second most common toe arrangement in perching birds. It is found in the osprey (Family Pandionidae) , most woodpeckers (Family Picidae), owls (Order Strigiformes), cuckoos, parrots, mousebirds, and some swifts. This foot pattern helps the bird grasping branches and moving around on branches.
2,3 (second & third digit in the front)
1,4 (first & forth digit in the back)
Pamprodactyl foot has all four toes in front, as seen in most swifts (Family Apodidae). The first and fourth digits pivot freely foreword and backward. Swifts often rotate all four toes forward and use their tiny feet as hooks to help hang while roosting on the walls of chimneys, caves, or hollow trees.
1,2,3,4 (first & forth digit can be moved to the front)
Syndactyl foot has two front toes (second and third digits) partially joined or webbed for much of their length. This foot pattern is common in kingfishers (Family Alcedinidae), hornbills (Family Bucerotidae), and rollers (Order Coraciiformes).
2-3,4 (second & third digits are fused together, forth is in the front)
1 (first digit is in the back)
Heterodactyl foot is similar to the Zygodactyl foot except that the inner (second) toe is reversed in the heterodactyl type. This is to help the short, weak first digit in gripping branches. This type is found only in trogons (Order Trogoniformes, Family Trogonidae).
3,4 (third & forth digit in the front)
2,1 (second & first digit in the back)
Sorry, I don’t have any photos of Trogons but you can see two good examples at Panama Birds’ Violaceus Trogon Photo and Willy Gil’s Masked Trogon photo for the Heterodactyl Arrangement.
Here is a birdQUIZ for everyone to try!
Your choices are: anisodactyl, zygodactyl, pamprodactyl, syndactyl, or heterodactyl.
Now take the time and really watch the birds feet when they are at your bird feeders!! Watch how some species are using their toes compared to some of the other species at your feeders. You probably will find anisodactyl and zygodactyl toe arrangements in your feeder birds (unless you have trogons or hornbills in your back yard). Have fun studying your birds!
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- Proctor, N.S. and P.J. Lynch. 1993. Manual of ornithology: avian structure and function. Yale Univ. Press, New Haven.