Why The Killdeer Doesn’t Perch

  • Occasionally I rerun a favorite older post because many current blog followers have never seen it. This one was published on January 30, 2013. I’ve rewritten some of the text and edited the formatting.

More than half of all bird species (5000+) are classified in order Passeriformes and referred to as passerines. Passerines, sometimes known as perching birds or less accurately as songbirds, have four toes – three of them directed forward and one toe directed back. This arrangement allows for stable perching on structures such as small branches, herbaceous stems and wires because the hind toe is opposable to the others (much like our thumbs are opposable to our fingers) which allows “grasping”.

Interestingly, the tendon/bone anatomy of passerines and some other birds causes automatic closing of the foot (grasping) when the leg bends – such as when it lands on a typical perch. This arrangement also allows them to sleep on a perch without falling off and is responsible for the talon locking mechanism of raptors.

  • This information has practical application for me because of my track record of rescuing raptors in distress. It hasn’t happened yet but if I ever get “footed” by a raptor during the rescue process I know to follow the advice of blog follower and wildlife rehabber Mikal Deese: : “Remember that talon locking mechanism. Take a breath, stay calm, and straighten the (bird’s) leg before you try to peel the toes off of you one by one.”

 

Here we see the typical “three toes forward, one toe back” arrangement on this Savannah Sparrow that allows passerines to grasp narrow perches like small branches or wires and remain stable on them. Animals without something like this toe arrangement would be “walking a tightrope” but these birds have no problem with it.

 

 

Maintaining stability on a perch such as this would be virtually impossible without the ability to grasp, particularly in a breeze. Even with the ability to grasp this Loggerhead Shrike had some difficulty establishing and maintaining stability on the dried stem.

 

 

This shot of a juvenile White-crowned Sparrow gives us a better look at all four toes including the opposable rear toe.

 

 

Here’s a rear view of the opposable hind toes, this time on a Western Meadowlark.

Ok, now to my point. Many birds that do not typically “perch” (with exceptions) are waterfowl and shorebirds. The Killdeer is a plover but because of the habitats it prefers it’s often found with passerines and many of us associate them with the perching birds. But think about it, have you ever seen a Killdeer perched in a tree, on a branch, narrow stem or wire? I don’t think I have and I’ve spent a lot of time with them over the years.

 

 

And here’s why. Like most plovers, Killdeer lack the hind toe so they rarely perch, except on something like a relatively flat rock where grasping isn’t required. Because of their toe arrangement they simply do not have the ability to grasp a narrow perch for stability.

 

 

Another view of “the toe that isn’t there”.

This may be elementary information for most folks who are well-schooled in birds but I remember when I finally realized that I’d never seen a Killdeer perched and eventually figured out why.

Perhaps there are others in the same boat as I was…

Ron

 

 

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