Question about Birds and Cactus Spines (1 Viewer)

[WTXaviphile]

Not desert here on the South Plains though some think so. Some of the birds -- my fav birds -- are better known as desert species and here in Lubbock we are on the fringes of or outside their normal range.

Two in particular I like to feed and watch: the Pyrrhuloxia and the Curvebilled Thrashers. Curvebulls have been living here year-round for at least 3 years.

Heavy snow on the ground this morning and the female pyrrhuloxia I've been feeding for a week or so was hungry. She perched on the very thorny stem of a scotch rose, then moved to my most fearsome cactus, a pencil cholla with incredibly sharp spines. I saw her a minute later with a cactus fruit in her beak.

The Curvebilled Thrashers get in the big cholla cactus all the time, nest there,
though I never saw them around the little pencil cholla.

My question is, how do these birds keep from getting spitted on the cactus? and are their feet adapted to perching on spiny plants?

BTW in early summer I found a fledgling mockingbird impaled and dead on my cholla. Apparently blown there by the wind.

 

[fugl]

From what I can gather it's mostly a combination of agility & keen eyesight. Google "how do birds avoid being impaled by cactus spines?" for examples.

 

[WTXaviphile]

From https://arizonadailyindependent.com/2013/12/22/cactus-wrens-arizonas-very-noisy-state-bird/, quote:

"The birds can stand the spines because their feet are covered with tough scales and have few nerves."

Then fromhttp://archive.azcentral.com/arizonarepublic/local/articles/2009/06/07/20090607clay0607.html#ixzz3vesewkzF, there is this, quote:

"There are a couple of reasons birds are so good at perching on cactuses.

"A little bird, such as a cactus wren, doesn't weigh enough to exert enough pressure on the spine to pierce the skin.

"Larger birds, such as hawks, have learned the trick of spreading their weight out over lots of spines. It's sort of like that sleeping-on-a-bed-of-nails thing. One other thing to remember: Most birds have very few nerve endings in their feet and lower legs."

These birds are very light and certainly they have tough scaled feet. But cactus spines can be extremely sharp. Anybody dissected the foot of these species to see if there are embedded spines?

 

[Nutcracker]

What about the glochids of e.g. Opuntia microdasys? Barbed, and detach very easily from the plant.

 

[WTXaviphile]

The little brown spines of the prickly pear that come out so easily? I'm not sure they are as sharp as the pencil cholla spines. Easy to check; I've got microscopes. I'll do that and post a pic.

The cholla are Opuntia as well. All have joints or pears that break off and are capable of growing a new plant. I have a lot of prickly pears growing, up to 7 feet high, on fencelines, but nearly all are spineless, possibly being the variety developed by Luther Burbank.

The Curvebill Thrashers are not pets but they are used to my presence. One will perch on a branch outside the kitchen door to remind me to bring out food. (Either I've conditioned it to do that or it's conditioned me!) I've looked at their feet from under 10 feet with 10X binocs. There look to be knobby foot pads -- or perhaps swollen feet in response to injury. That's what promped my question.

And I was startled this morning to see that pyrrhuloxia perching on the pencil cholla. Never saw a bird on it before, or any eating the little red fruits.