10,000 pythons breeding in Florida, says new USGS report

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Nine species of introduced giant snakes could pose risks to U.S. ecosystems, according to a report recently released by the U.S. Geological Survey. The giant species now present in the U.S. are descended from imported pets that have been released outdoors.  Already there are more than 10,000 Burmese pythons reproducing in the wild in south Florida.  Boa constrictors are also known to be reproducing in south Florida. The USGS says there's "strong evidence" that an African python may have a breeding population in Florida too.

Some snakes big enough to eat people
All nine potentially risky species are constrictors - nonpoisonous species that kill their prey by wrapping around them and squeezing until the prey can't breathe.  The USGS report says that "most...would not be large enough to consider a person as suitable prey."  But some of then are large enough to eat people, such as the reticulated python, which can grow longer than 26 feet.  This python is the snake "most associated with unprovoked human fatalities in the wild."  Reticulated pythons have been both sighted and captured in south Florida, but are not yet known to be breeding there.

Mature individuals of other species - Burmese python, northern and southern African pythons - have also been documented killing people in their native range, although unprovoked attacks are rare.

Invasive giant snakes threaten more states than Florida
Several species of giant snakes are considered more "high-risk species" for the U.S.than others because they
(1) tolerate cooler temps and could put larger areas of the U.S. mainland at risk - not just Florida
(2) are a major threat to native mammals and birds
(3) are common in the pet trade, hence likely to be released within the U.S.

Among these "high risk" species are the boa constrictors and yellow anacondas, which could breed north of Florida in areas with mild winters.  

Above, a boa constrictor in Manuel Antonio Parque Nacional in Costa Rica.  Photo by Sally Kneidel, PhD

Above, our friend Jose Luis holding up an immature boa on his farm near Limon, Costa Rica.  

Photo by Sally Kneidel, PhD

Nicole the resident biologist, Ken Kneidel and Sadie Kneidel examine an immature boa at Palo Verde Biological Station of OTS, in Costa Rica.  Photo by Sally Kneidel, PhD

Several species of anacondas have also been sighted or captured in south Florida. Anacondas can grow longer than 25 or 26 feet too, and I believe have been known to kill humans, although the USGS report didn't say that.  I've read that the record length on an anaconda is 28 feet.

Deep in the jungle, we found a beheaded anaconda 
Below are two anaconda pictures my son Alan took on a foray into the Amazon rainforest in 2008. We were slopping and tripping through a difficult swamp in an effort to spot hoatzins (birds) when we passed a family of indigenous Peruvians heading back toward the river, returning from a hunting/foraging trip. All of them, including grandma, were slogging barefoot through the most treacherous swamp I've ever experienced, having submerged 3" long thorns. (I stepped on two of those thorns; they went right through my rubber boots.) But the Peruvian family seemed unperturbed. The whole family had homemade packs on their backs, and one pack carried a chopped up anaconda they intended to eat. The head, as you see, they had left behind.

The head of an Amazonian anaconda, severed by an indigenous family hunting for food. Photos by Alan Kneidel.

Introduced snakes can devastate native wildlife
The USGS scientists who wrote the new report said that U.S. birds, mammals, and reptiles in areas of potential invasion have never been exposed to huge snakes before, snakes longer than 20 feet and weighing more than 200 pounds.  Said Dr. Gordon Rodda, a USGS scientist, "Compounding the risk to native species and ecosystems is that these snakes mature early, produce large numbers of offspring, travel long distances, and have broad diets that allow them to eat most native birds and mammals."  He also said that most of these snakes can live in a variety of habitats, including urban or suburban areas. Boa constrictors and northern African pythons are already thriving in metropolitan Miami.

"We have a cautionary tale with the American island of Guam and the brown treesnake," said Robert Reed, an invasive-species scientist with the USGS, and coauthor of the report.  "Within 40 years of its arrival, this invasive snake has decimated the island's native wildlife -10 of Guam's 12 native forest birds, one of its two bat species, and about half of its native lizards are gone."  Reed goes on to say that "these giant snakes threaten to destabilize some of our most precious ecosystems and parks, primarily through predation on vulnerable native species."

What can you do?
Don't keep snakes as pets, and if you must do so, don't get snakes that grow into large constrictors. If you have one, or know someone who does, there are alternatives to letting them go outdoors after they grow too large to keep at home. Google "reptile sanctuary" to find a facility near you that accepts unwanted pets. If googling doesn't help, call a nature center or zoo near you for referral to a nearby sanctuary for unwanted pets. Releasing non-native pets outdoors is never a good idea.

More snake pics by Sally, below

A coiled and wary Bushmaster, among the most venomous vipers in Latin America. Photo taken along a trail at La Selva Biological Station by Sally Kneidel, PhD

 

A coral snake at Arenal Volcano Parque Nacional in Costa Rica, photo by Sally Kneidel, PhD.

Sources:

Catherine Pucket (USGS) et al.  10/13/2010."Report documents the risks of giant invasive snakes in the U.S."  USGS Release. USGS: science for a changing world.

Paul Rauber. Jan/Feb 2010. "Woe is us: ready, set, panic. Snakes on plains." Sierra magazine.

Some of my previous posts on the pet trade, invasive species, and snakes:

Why do girls fear snakes and spiders more?

Lawn is a dirty word.

Housecats are invasive species. 

Housecats kill hundreds of millions of species annually

How to convert a lawn to a lawn to a native meadow or woodland

Lawns are 5th largest "crop" in terms of lawn use 

Monkeys and parrots pouring from the jungle

Keywords: invasive species snakes threats to wildlife wildlife trade endangered ecosystems python anaconda, boa constrictor python predation by housecats predation on birds

Why do girls fear snakes and spiders more? Does it start in infancy?

Text by Sally Kneidel, PhD, of sallykneidel.com
Photos by Alan Kneidel
See Alan's blog at http://goodbykneidel.blogspot.com 

 Photo of gopher snake by Alan Kneidel

I love snakes. Every time I take a walk around the neighborhood, I stop and examine every squashed snake carcass I see on the road, of which there are many. I lament the loss of every one of them.

My parents, on the other hand, killed every snake they saw when I was a kid, and called all of them "copperheads."  They were protecting us young'uns, or so they thought. I didn't realize how many people kill all snakes until I spent three years teaching elementary science.  I used to bring a lot of snakes in to show my students. Every single time I did this, a dozen hands would shoot up begging to make a comment.  And almost every single comment was "My daddy killed a snake last week with a shovel" or "My granddaddy chopped a snake in half in the garden."  No one ever said that a snake their family saw was a welcomed or even a tolerated sight. And all of the snakes were allegedly "copperheads." After awhile, I began my snake lessons by banning stories about family members killing snakes; I couldn't take it anymore.  It's a miracle that the U.S. has any remaining snakes at all. 

Why are we so afraid of snakes? As a person partial to snakes, I have little patience with it.

Are girls genetically primed to fear snakes?
I read recently an intriguing study about fear of snakes, published in the journal Evolution and Human Behavior. That study is the subject of this post.  Researcher David Rakison of Carnegie Mellon University looked at differences in the way 11-month-old humans react to pictures of snakes and spiders.  Specifically, he looked at differences between male and female children. His findings surprised me.  

Rakison showed pairs of images to the youngsters in his study.  First he paired either a happy or a fearful cartoon face with a snake, a spider, a flower, or a mushroom.  After that, Rakison timed how long each baby looked at new pairings of images that were different from the orignial pairings they had viewed. He wanted to see if the new pairings would seem odd to them and would cause them to look longer, out of puzzlement or curiousity.

Here's what Rakison found
Apparently the girls more readily associated the snake or spider with a fearful face. When the girls were subsequently shown a happy face with the snake or spider, they looked at it a long time (as if trying to make sense of something surprising).  With the little boys, no pairings of images were more interesting than any others. The boys did not find the snake or spider paired with a happy face surprising or interesting.

Photo of tarantula in Amazon rainforest by Alan Kneidel

Rakison said that this finding (if confirmed by other studies) indicates that human females have evolved an aversion to snakes and spiders. That trait evolved because women in our evolutionary history were in charge of protecting their children from the bites of snakes or spiders. Another study in Sweden found that snake and spider phobias are four times more common in women than in men.

Photo of black-tailed rattlesnake by Alan Kneidel

Not so fast...
says Vanessa LoBue of the University of Virginia. She disagrees with Rakison's findings. If girls gaze longer at the pairing of a snake with a smiling face, it's because 11-month-old girls are better at recognizing facial expressions than male babies, and therefore understand the pairings better. This understanding would account for their surprise and longer gazes.

LoBue offers evidence from her own studies that 5-year-old girls recognize threatening and nonthreatening expressions faster than boys. Do 11-month-old girls have that capacity too? We need to find out! What do you think?

Maybe women are squeamish because of gender stereotypes
I personally don't believe that girls are "primed" genetically to be more fearful of snakes and spiders. I think it's cultural, that little girls learn to act squeamish and fearful by watching older females. I believe women often behave as though they're fearful and vulnerable because that's the sexy female prototype that's been promoted by our Western culture since who knows when. Powerful fearless women are, in popular culture, not widely admired. That's changing slowly. But women are still encouraged (often very subtly) to appear helpless and afraid like Olive-Oyl, while Popeye eats his spinach and beats the tar out of Brutus. I agree with LoBue. Rakison's results can be explained by female children's acuity in reading human facial expressions.

Or maybe girls already been affected by cultural expectations for their gender, at the age of 11-months!

I would love to hear reader comments.

 Photo of a hunting spider in Bolivia by Alan Kneidel

Sources:
David Rakison. "Does women's greater fear of snakes and spiders originate in infancy?" Evolution and Human Behavior. Volume 30. November, 2009.

Bruce Bower. "Girls but not boys may be primed for arachnophobia, ophidiophobia: Fear of crawly, slithery things could begin before first birthday. Science News, September 26, 2009.