Skull no. 6: Nutria

Myocastor coypus

Myocastor coypus


Description:  Nutria wiki

Nutrias are semi-aquatic creatures, spending half their lives in the water. Their webbed feet help make them excellent swimmers and they can spend up to five minutes under water without returning to the surface to breathe. Females have four pairs of mammary glands located on the side of the body, rather than on the belly, allowing them to breastfeed their young while swimming.

Nutrias are nocturnal animals, mostly active around midnight.

These critters have a huge appetite, able to eat about one quarter their of own weight every day.

They breed year round and are extremely prolific.

Nutrias are covered with two types of fur:  an outer coat made of shaggy hair that can be yellow or brown in color and an inner coat made of fine, grey fur. Nutria fur became very fashionable in the 1930s, and stayed popular through the ‘60s.  Faux nutria, made of rabbit fur was at one time branded as nutriette.

Where I got ’em:  Turkey Vultures are fascinating creatures; if you couldn’t tell by their name, they kinda look like turkeys.  Under the Migratory Bird Treaty Act of 1918, I cannot legally own a turkey vulture skull.  A permit might be obtainable, but I doubt I’ll ever know. I was leaving my office one morning when I saw a pair of them; one standing on a fence post and another one on the ground.  They’re pretty huge; about the size of a turkey (see above).  Normally, these raptors are soaring high in the sky, riding thermals; they use their incredible sense of smell to find smelly stuff.  When they touch ground, it’s for a reason.  I looked around and sure enough, almost right in front of my car was a nutria, and I wasn’t about to be the first person to run it over – more like the fifth or sixth.  I office in a great building, but it sits on a gravel road off highway 99, sandwiched between a yard debris composting facility and a lumber yard, so we’re a little ways out.  I pulled away, missing the carcass and careful not to upset the scene.  When I returned to my office a couple hours later, the vultures were gone. All that was left of the nutria was a greasy spot in the road.

These are not that nutria.

Nutrias (coypu if you’re Latino, beaver rat if you’re Dutch), are the South American equivalent of a beaver.  According to the guy I get my hats from, the pelts are virtually identical.  In an effort to combat extinction, and because their fur was desirable, nutria farms were established in the late 1800s through the 1930s and ‘40s. More often than not, the farms proved unsuccessful or unprofitable and the nutrias escaped or were intentionally released.  Those wild populations did just fine though.  Today, the state of Louisiana, in conjunction with the US federal government, is paying $5 a tail for hunters to help control (i.e. kill) nutria, with a goal of harvesting 400,000 nutrias annually in the state.  Just the tails; the rest of the carcass is your problem.  It is estimated that the animals have destroyed thousands of acres of wetland; they’ve migrated as far north as Canada in North America, and are invasive throughout much of Europe and many parts of Asia.  Global efforts are underway to eradicate this invasive species.  Efforts are also being made to convince you to eat them, but that’s a hard sell, since they look like rats.  Nutrias are, however, currently being used for dog food.

Nutria gestation is about 130 days, which means, if timed right, they can give birth three times a year; the number of young per litter averages five, but could be as many as a dozen.  Which means they can potentially produce over 30 young a year, but ten is normal.  They only live about three to five years in the wild, but they can live up to twelve years in captivity; they’re extremely docile and easily handled.  They’d make good pets, if they didn’t require a body of water – I don’t think they can live in your bathtub.

Nutrias are a common sight around my office.  In fact, there is a shed about the size of a single-wide trailer behind our building and I’ve seen nutrias enter through the bottom of a gate where the wood has decayed.  My guess is that they die and are then run over way more often than they are run over and then die.  They kind of look like beavers, because they have square heads and their eyes sit up so high on ‘em.  But they have rat tails.  That’s a turn-off for most people.  Think of the cutest animal you know, then put a rat tail on it; it’s a deal-breaker for sure.  They are definitely a little strange. And so are their skulls.  One peculiarity shared by many South American rodents is enormous infraorbital foramen.  I’m not a scientist, so a grain of salt here, but skulls have holes.  These holes are called foramen or foramina for more than one.  The biggest hole in your skull, where your spine comes in, is the foramen magnum.  Again, I’m no scientist, but every mammal skull, with one notable exception, has at least one foramen below each eye called an infraorbital foramen. Rabbits and hares are different: their bone is fenestrated, like a latticework on either side of the rostrum (not a scientist). I’m not aware of any other skull quite like it, but my knowledge is by no means exhaustive (more on rabbits later).  Anyhow, nutria infraorbital foramen are HUGE.  They also have a unique, alien-looking flare on their bottom jaw.

The first time I saw a dead nutria outside my office, I scooped up the entire body in a cardboard box and took it home.  Louisiana style, I took what I was after (in this case, the head, not the tail) and tossed the rest.  The skull turned out beautifully, and was my first overall success with skull processing.  I did lose a molar, but I found it a year and a half later.  About a year after processing my office nutria, I got a very large skinned nutria skull (along with a few others) from Promise Land Tannery in WA; buying skinned heads for processing is a lot less expensive than buying finished skulls, and I enjoyed learning the process of maceration (thanks again, Jana Miller!).  Both of these skulls were processed using maceration; the latter, I partially processed with a wild dermestid colony I inadvertently developed.

This is the first skull that came out looking beautifully; just look et them pitchers.

The above photos are set to random sequence, so the order will (usually) reorganize every time you refresh the page.

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