Thorny Trees and 20 Inch Tongues: A Case of Coevolution

A few days ago, I saw a very spiky-looking tree on the Bird of Prey Route near my house.  A few weeks ago, I saw another tree, much larger than this one, along the banks of Boulder Creek that had some enormous thorns on its branches as well, some of them easily six inches long, and super sharp on the end!  I don't know for certain what kind of tree this, or the Boulder Creek tree, is, but a good candidate I think is the honey locust (Gleditsia triacanthos), or some other tree closely related to the honey locust.  Below is the picture of the tree that I took on the Bird of Prey Route.

And here is the picture that I took on my iPhone at Boulder Creek of this tree.  The thorns look pretty similar to those of the honey locust, and I think that the trunk of the tree looks pretty similar, too.

Now why do these trees have such huge thorns?  When it comes to nature, everything evolves with a purpose.  There is no reason why a living organism would evolve something without a purpose, especially something as involved as giant, six-inch long thorns.  The question is, what purpose do these thorns serve?  Well that's a darn good question, and I am very pleased you asked.  Much like the "thorns" that you can see on the tail of a Stegosaurus, they likely were to help keep the organism from being consumed.  We see similar thorns on the branches of some trees in the genus Acacia in Africa today.  There, the thorns help protect the tree from attacks from one of the largest plant predators alive today, the giraffe.  This tree....well, suffice it to say that you probably won't see many activists hugging this tree.

"Oh, maybe these thorns look deceptively big," you're thinking.  Wrong.  These thorns do not look deceptively big.  If anything, they look deceptively small.  These thorns are frickin' HUGE.

So the real question is, why the long thorns, Goldilocks?  Many paleontologists believe that, during the Pleistocene Epoch (which lasted from between around 2.5 MYA to about 12,000 years ago), many of North America's mega-herbivores, everything ranging from mammoths and mastodons, to giant ground sloths and the North American camel Camelops, could have been preying upon these trees.  Selective pressures slowly caused these trees to evolve protection against these mammalian mega-herbivores.  Mastodons especially had very robust teeth, which would almost certainly have made them excellent bark-munchers.

In Africa, the acacia tree, also known as the whistling thorn, the thorntree, or (my personal favorite) the wattle, has a very similar defense.  Unlike the honey locust of North America, however, the acacia tree still has to deal with intense predation today, and from a wide variety of herbivores, everything from gerenuk to giraffe, elephants to more giraffes.

You see, the giraffes love the acacia tree.  If giraffes had Facebook, then they all would like the "I <3 Acacia Trees" page.  I remember reading somewhere that they can eat up to 60 or 65 pounds of acacia leaves per day.  (To understand this, try imagining a large hunk of butter that weighs 60 or 65 pounds.  Now you have an idea of how many pounds that is.)  They love it so much that, if the acacia tree hadn't adapted to keep up with the continual browsing pressure, the giraffes might have loved the acacia trees to death!  In response, the acacia trees convergently evolved these sharp thorns, just like the honey locust tree in North America.  (We talk about convergent evolution quite a lot as it is one of my favorite topics, so click HERE to learn more about it!)  

The giraffes love the acacia, though.  They aren't going to give up on those lovely leaves, just like that!  So while these acacia trees evolved their thorns to protect their leaves, the giraffes evolved something spectacular: a prehensile tongue!  Don't believe me?  Well, one of my favorite things about the Cheyenne Mountain Zoo is that you can feed the giraffes there.  And guess what: their tongues are HUGE!  Below, I have a video of my good friend Masaki Kleinkopf also feeding the giraffes!  Check out my gangsta hoodie, yo.  

So, yeah.  Suffice it to say, giraffes have frickin' long tongues.  And they use these TWENTY INCH LONG TONGUES to help circumnavigate through the acacia tree's poky and spiny maze of thorns to reach the leaves!  The acacia tree wasn't going to just take this lying down, though: no giraffe is going to be feeding on my leaves, yo!  So the acacia tree adapted again.  This time, by employing the use of tannins.

Long story short, tannins are used by humans in a variety of ways, including tanning, food processing, and making cocoa and wine.  They also apparently taste terrible.  Don't ask me, I've never tried it, but then again I don't have a 20 inch prehensile tongue, so it's a whole different ballgame.*

Not only do tannins taste terrible, but they inhibit the digestion of the leaf matter in a number of nasty ways, none of which would be all that fun for the giraffe.  So when a giraffe starts munching on the leaves of the acacia tree, that tree will release tannins to make the leaves taste like....well, leather I suppose.  (Again, haven't tried either.)  This tannin releasing is a pretty cool adaptation all on its lonseome.  The giraffe begins to move off to another acacia tree nearby.  However, if it's within 50 yards or so (especially downwind) of the original, now tanniny acacia, then the giraffe is out of luck: the nearby acacias react in turn, releasing their own tannins, and rendering their leaves almost indigestible to the giraffes, as well!  I would imagine that, because of this, giraffes have in turn developed the behavior of moving upwind as they eat, and a cursory glance over the Internet indicates that this does seem to be a behavior observed in giraffes!  Coevolution at its finest!

Make sure to check back soon for our next episode in our coevolution series, all about a very fun little squirrel!  See you then!  In the meantime, you can read about what coevolution actually is, by clicking HERE.

*The second baseball metaphor that I believe has been used on this blog.  Refer to "23-Fact Tuesday: Prairie Falcon, Red-Tailed Hawk, and Great-Horned Owl at the Dino Hotel" and "Eye Black: What Works for Football Players Works for the Cheetah" to learn more about this sport.  

Works Cited:

Baby Prairie Dogs and Birdwatching on the Bird of Prey Route!

Today, with the summer weather and the lack of school, I decided to take my car over to what I like to call the "Bird of Prey Route," a little dirt road in between Superior and Boulder about ten minutes from my house here in Colorado.  You can usually see at least one or two different types of raptors there, and there are a number of other awesome animals that I have spotted there, as well!  Today, I saw a lot of really cool birds, as well as some baby prairie dogs, as you can see below!

This particular species of prairie dog is the black-tailed prairie dog (Cynomys ludovicianus).  Like the other species of prairie dog, the black-tail is a highly social little rodent.  Below you can see two pups "kissing" each other, a type of interaction that members of the same family group will employ.  I think this is just to help solidify familial bonds, but I'm not sure if anybody knows for certain.

Today, the bird of prey route did not disappoint!  Perched in the tree in the picture below is the red-tailed hawk (Buteo jamaicensis), definitely the raptor that I see most often when on the route.

I also saw a pair of American kestrels (Falco sparverius), the species of raptor that I see second most often.  I don't usually see the kestrels so close together, however, so perhaps this was a mated pair.  I did see one of them fly into a hollow in a tree, which might be where a nest is hidden away!

As I was watching the hollow in the tree where the American kestrel swooped off into, I noticed several European starlings (Sturnus vulgaris) flying into other hollows on the tree.  Then I realized that the angle of one of the hollows was just right, and that I could actually see the adult starling feed its young!  If you zoom in on the picture, you can see that the baby already looks pretty big, maybe even as big as the parent!

Black-billed magpies (Pica hudsonia) are especially abundant in the area, and I saw several of them as well.

This magpie looks like it is molting!

Now this particular tree presents a particularly provocative puzzle, as it is almost completely covered in some very sharp looking thorns.  A few weeks ago, I saw another tree, much larger than this one, along the banks of Boulder Creek that had some enormous thorns on its branches as well, some of them easily six inches long, and super sharp on the end!  I don't know for certain what kind of tree this, or the Boulder Creek tree, is, but a good candidate I think is the honey locust (Gleditsia triacanthos), or some other tree closely related to the honey locust.  Below is the picture of the tree that I took on the Bird of Prey Route.

Here is a picture of the thorns of the honey locust tree.

And here is the picture that I took on my iPhone at Boulder Creek of this tree.  The thorns look pretty similar to those of the honey locust, and I think that the trunk of the tree looks pretty similar, too.

Now why do these trees have such huge thorns?  That's a really good question.  I started answering (or at least trying to answer) the question here in this blog post, but everything rapidly started spiraling out of control and off focus as I started talking about giraffes, tiny squirrels, cheetahs, and extinct North American elephants.  For those of you who know me, it should come as no surprise that I spiraled so quickly off topic.  But regardless, what I had written ended up having enough material for at least three or more posts, so I have moved the answer to a different post, which I will hopefully be publishing soon.  Keep an eye out for that!  In the meantime, back to the future birds!  Here, we see a pair of barn swallows (Hirundo rustica) perched on a wire.

I'm not quite as sure about the identity of this particular bird.  Also a swallow, I am thinking that it might be a violet-green swallow (Tachycineta thalassina).

I believe this to be a vesper sparrow (Pooecetes gramineus).

A western kingbird (Tyrannus verticalis), another bird that I see all the time here, at least in the summer!

At last, we have one of the most exciting birds that I saw on the route today, the blue grosbeak (Passerina caerulea), a bird that I don't remember ever seeing before!

Remember to check back soon to learn all about those massively spiky trees!

Works Cited:

Robbins, C. S., Bruun, B., & Zim, H. S. (1983). Birds of North America. New York: Golden Press.

Stokes, D. W., & Stokes, L. Q. (2010). The Stokes field guide to the birds of North America. New York: Little, Brown.

Invasion of the Great Horned Owls

Throughout my entire life, I had not seen more than a handful of owls in the wild, but in the last month (actually exactly a month ago today, on November 16th) I have seen owls on three different occasions, all three of which were great horned owls (Bubo virginianus), not to mention the two times that I saw the great horned owl parent and chicks at my grandparents house in the few months preceding that!  The largest owl of Central and South America and the second largest in North America (following the snowy owl), the great horned owl is actually closely related to the snowy owl, despite their very different outer appearances.  Despite its name, the "horns" on the head of the great horned owl are really just tufts of feathers.  The great horned owl is labeled as "Least Concern" by the IUCN. Also, this post is a birthday post for Joseph M. Roessler, happy birthday big guy!

One of the most notable features of the owls in general are their incredibly flexible necks.  Most birds of prey likes hawks, falcons, eagles, and vultures, have their eyes on opposite sides of their head.  Owls, however, like we humans, have binocular, or stereoscopic, vision.  This means that owls have to turn their heads a lot more than other birds of prey might in order to look all around.  In response to this, the owls have evolved the ability to turn their heads around 270 degrees, in either direction!

One of the great horned owls that my grandparents had in their backyard for a few months

Another interesting ability of the great horned owl, and owls in general, is their interesting method of digestion.  Birds nowadays don't have teeth, so they are unable to chew their food.  So most of the time, they (owls amongst them) swallow their food whole if they are unable to tear small chunks off of it.  This also means that the owl swallows the indigestible bits of its prey, such as the bones and the fur.  So after their meals, owls will regurgitate balls of the indigestible materials, colloquially referred to as "owl pellets!"

The great horned owl, more so than other owls, has an amazing crushing grip in its talons, around 300 pounds per square inch, which is more than the human hand is capable of!  There are also reports of cases in which the power exerted by the talons of the great horned owl matching those of much larger species of bird of prey, like the golden eagle.  The great horned owl is also capable of lifting prey that is several times heavier than they are.

What's on the menu for the great horned owl?  Where to begin!  Let's break it down by group, and give a few examples of each.  I am by no means including all of its prey items as that would take an immense amount of time. 

• Mammals
• Porcupines
• Skunk
• Domestic Cats
• Small or young domestic dogs
• Rabbits and hares
• Muskrat
• Squirrels
• Weasels and martens
• Shrews
• Lemmings
• Voles
• Bats
• Armadillos
• Mice
• Flying Squirrels
• Rats
• Marmots
• Birds: 
• Turkey
• Great blue heron and other herons
• Woodpecker
• Crows
• Pigeons
• Quail
• Gulls
• Ducks
• Other birds of prey, such as red-tailed hawks, snowy owls, and other great horned owls
• Misc.
• Young alligators
•  Amphibians
• Scorpions
• Worms
• Insects
• Crustaceans
• Centipedes
• Roadkill

Where did I see the owls?  The first one was exactly a month ago when my friend Masaki Kleinkopf and I were heading back from seeing the new James Bond movie, Skyfall, which was really really good (but not as good, in my opinion, as The Hobbit, which we saw last night and which was fantastic).  We decided to take the back way, the bird of prey route between Boulder and Superior where one can frequently see red-tailed hawks, kestrels, turkey vultures, and golden eagles.  Instead, we saw a great horned owl!

A picture of one of the red-tailed hawks that I took yesterday on the Bird of Prey Route.  Not only is it an amazing bird in its own right, but it is also potential prey for the great horned owl.

The next two sightings were actually yesterday and the day before.  The first one was when my other friend Mona Kamath and I were driving along West 120th Ave., and we saw a great horned owl perched in a tree!  Yesterday, on my way home from the Morrison Museum, I took a brief detour to see if the owl was still there, and he was!  Not in the same tree, but in another tree that was quite close by!  How exciting!  Enjoy the pictures! 

And remember, if you have a birthday coming up, just email me the date at cuyvaldar123946@gmail.com with the date and your favorite animal, and I will do my best to get a post in!  And remember, if you like what you're reading, make sure you LIKE US ON FACEBOOK, follow us (if you have a google or gmail account), or hit the subscribe button off to the right if you don't!

Birds of Prey on Marshall Road

Today, my friend Mona Kamath and I went out to find some birds of prey along a little side road off of Marshall Road between Boulder and Superior in Colorado.  We saw an abundance of them on this trip, perhaps more than on any other trip.  The only other trips that I can remember that could rival this one were one where I saw red-tailed hawks, kestrels, and turkey vultures, and another one where I saw red-tailed hawks, turkey vultures, and a golden eagle.

Today, we were rewarded with not one, but two golden eagles!  Below are some pictures taken by both me and Mona.

 

 

 

 

We also saw a number of turkey vultures circling overhead, and a pair of them perched on a fence nearby.  However, by far the most exciting vulture spot of the day was when a juvenile turkey vulture landed right behind us!  I stopped the car and Mona was able to snap a few pics.  Not quite as exciting as the time a few weeks ago when I was on this road, and saw a pair of turkey vultures and a bunch of magpies fighting over the remains of a small carcasses, maybe thirty feet from my car!  Note how similar the juvenile turkey vulture looks compared to black vulture adults.

 

I also saw a bird of prey perched upon a lamp post in the middle of Superior.  I don't know what kind it is, so if anyone can help me out with that, that would be awesome!  Anyways, here are a few pics of it:

 

 

One of my most favorite bird of prey moments on this road was perhaps a month or two ago when I saw a pair of hawks flying along calmly next to each other, and then they suddenly locked talons.  I'm not positive, but I believe that it might have been a courtship display!

Boulder on Dwellable