Of Fur and Feathers

So we’ve looked at footprints and scat, but there are still other big things that let us know who has been in our yard: features, fur, and skin, for starters.  Humans shed hair and skin all day, though usually flecks and strains small enough to not notice much.  But, look over your shoulder and perhaps there’s a hair or two.  This happens to other animals too.  Even if no scat or prints are left behind, and they haven’t dug anything up, I can often tell when there have been chickens in my yard because they occasionally leave behind feathers.  There are three different colors of chicken at our neighbor’s house.  I can narrow down which chicken may have been the trespasser.  White feather, white chicken.  Brown feather, brown chicken.  Easy enough, yes?

Wildlifers can rely on these things as well.  When we are banding birds we take a feather from certain species to add to a large data base.  Like scat, fur and feathers can contain DNA as well as chemicals from the environment.  And obviously, if you have fur from an animal, you know their general location.  I’m not going to find some panda fur up here in New York, and if I do, I better call the local zoo to see if they had an escapee.

I know of a trap or two where the goal isn’t to snag an animal, but a bit of their coat.  Lures such as food are placed in one area, and nearby there is something to catch on fur.  It could be a bit of wire that the animal has to walk through.  It could be a sticky pad that the animal may lean against in order to reach their prize.  Either way the goal of the biologist is to get a fur sample.

Birds and mammals aren’t the only ones leaving behind evidence of their passage either.  Snakes and other reptiles shed their skin as they grow, for example.  If you happen to find this in your yard, you may be able to figure out which snake neighbor you have, as well as their size.  I’ve even found some insect exoskeletons around that let me into the world of insects in a way that I hadn’t really thought of before.  I found this particularly interesting and used to collect them.  And how about a snail or crab shell?  Who hasn’t gone to the beach and wandered around looking for unoccupied shells to bring home?  They each tell a story.

You know what other evidence you can find while walking about?  Bones.  Yes, sometimes whole skeletons, sometimes just pieces.  During my Vermont field course we found a skull and had an improvised discussion around it and its owner’s identify.  Sometimes by looking at the bones you can determine if it died from a predator attack or something else.  Experts can point out age, past injuries, possible illness, and more.

These little physical things are something many people can enjoy, not just scientists.  Anyone walking in their yard or taking a hike can come across feathers or shells.  Kids especially love to find these little treasures.  It’s a great way to get them to connect with the world around them, to inquire and feed their natural curiosity.

One thing I need to note, though, is that sometimes state and federal agencies have rules about collecting and being in possession of certain wildlife parts.  Migratory bird feathers, for example, are under the regulation of the federal government here in the United States.  It’s actually a part of the Migratory Bird Treaty Act, an international treaty.  Basically, if you want to collect them you need to apply for a permit.  Applying for permits and licenses from multiple local, state, and federal agencies is one of the things that keeps biologists busy even before they can begin a project.  It’s not all fun and games! 

This isn’t to say that men in black suits are going to appear at your door because your kids brought home a feather they found at the park, but it’s something to keep in mind.  A bald eagle feather, for instance, is a valuable thing, but it’s not something you should bring home.   There’s been a history of poaching and selling of animal parts, pushing species to the point of population decline, so it’s all for a good reason.  We have to keep our neighbors safe too.

Defensive Adaptations: Armor

Detachable body parts aren’t the only defensive mechanisms out there.  Actually, the first thing I think of is armor.  Humans have made various kinds of armor to protect themselves for thousands of year, but many animals have evolved to have their own built-in versions.  Millions of years ago there were some serious heavy-hitters in the armor department.  Animals with thick body plates and spikes roamed both the land and the sea.  We no longer have giants like triceratops running around, but we still have armored neighbors.

Crustaceans are an obvious fit in this category, as are most arthropods.  Crabs, lobsters, barnacles, as well as spiders, ticks, insects, etc. have their own armor.  They are all covered in plates of strong exoskeleton.  That’s right, outside skeleton instead of inside.  The strong upper exoskeleton is called the carapace.  In order to grow these animals must shed their skin, or the hard layer of exoskeleton, that they have outgrown.  During this molt the animal is actually quite vulnerable until its new exterior hardens, but when it does it creates some serious protection.

Barnacles are a bit more like turtles and snails in that their bodies, such as head and limbs, are soft flesh but they have a shell that they can pull into.  These shields protect the organs all the time, and the head and limbs when necessary.  The shell is part of the animal in this case, unlike a hermit crab’s shell, which can be replaced with other found shells and at the animal’s discretion. 

A big difference between all of this body armor is the material it is made with.  A turtle shell is actually made of boney plates.  The carapace fuses to the vertebrae of the spine and ribcage.  The exoskeleton of arthropods and crustaceans is made of chitin.  Molluses shells are composed of calcium carbonates.  In all cases it evolved to encase and protect the animal within.

Not to be outdone, there are mammals and reptiles with similar armor.  The New World armadillo has a back full of protective plates meant to defend against predators.  Similar to the turtle, these plates are made of bone and covered with overlapping epidermal scales called “scutes.”  Unlike the turtle, however, armadillos are not covered in an inflexible shell nor are their bellies exposed; their plates are more individualized to allow for more movement and the stomach is soft flesh and fur.  Though the armadillo is known for rolling up into a ball to leave no soft skin exposed, only a few species can actually do this feat, whereas others cannot.

Similar to the armadillo, the pangolin is covered with armor too, but instead of plates it has individual scales that cover its back as well as its limbs and head.  These are not made of bone but of keratin (the same stuff that makes a rhino’s horn or human fingernails).  Like the three-banded armadillo, the pangolin can roll up into a ball as a defense against predators, leaving only it’s hard, pointed scales exposed.

Some lizards, such as the alligator and crocodile, have armored backs.  Here we find both the boney scutes as well as horny scales.  Instead of overlapping like the pangolin scales, the crocodile’s scales are individual square-ish scales set in rows on the body.

A different type of armor altogether is neither scale nor plate but spike.  Several species of lizards have evolved to be covered in spikes, which are actually similar to the crocodile’s scale armor.  These spikes are long, smooth, and pointy, much like those thorns found on a cactus.  Some pufferfish and porcupinefish are similarly covered in spikes.  However, a main differences is that most pufferfish have spikes that lay down flat and only stick up when threatened, as the fish will inhale enough water to make themselves swell into a pointy ball.

This, of course, leads us back into the mammal category where we find the porcupine and hedgehod.  Just like it’s fishy friends, the porcupine has quills/spines that lie flat until the animal is threatened.  These spikes are modified hair made of keratin.  Imbedded in the skin musculature, the animal can raise these quills as needed.  They cannot, however, shoot them like arrows, which is a common myth.  This is armor, after all, which can be used as weapons but is first and foremost for defense.