Tuesday, July 20, 2010

Suburban Safari

Most people seem to think that you need to go somewhere exotic to see wildlife, to see predators hunting, to witness life and death struggles.  I just look out my office window to my front garden.

It's fledgling season (fledglings are baby birds that have left the nest and are still learning life skills from their parents - like how to find food and avoid predators).  I was watching a group of fledglings bopping around the yard (that's a technical term - bopping).  Two of them were behaving oddly.  They would bop forward and then jump back and loooook, tilting their heads, bop forward, jump back, looooook.  So I decided I needed to look, too.  I'm too big to bop forward (plus there's my desk between me and the window) so I just leaned.  

There it was.  A shrew.  What was a shrew doing out in the middle of the day?

The fledglings were apparently trying to see if the shrew's stubby little tail was edible.

The shrew scampered off and after a minute the fleglings lost interest.  I didn't.

What was a small rodent doing out, fully exposed to predators, in the middle of the day?

I got up and went into the next room so I could watch.  The shrew was hunting. 
She1 would root around in the grass and under plants and occasionally I would hear crunch, crunch, crunch.  This makes her a beneficial insect.  No, wait.  Not an insect.  A beneficial rodent?

Slowly she moved across the front garden/yard.  So I moved, too.  Next room over.

This is the breezeway and it has a storm door so I opened the inner door for a good look.  The shrew did not dart into the bushes (normal shrew behavior, unless she knew there are snakes living there).  

Then she reached the edge of the driveway.  Did she turn back?  Did she rush across with great haste?  Did she hug the garage?  No, no and no.  She wandered across the driveway.  Something is not right with that shrew.

So I stepped outside.  She didn't flee.  Huh.

Then she went around the side of the garage.  Along this side there is a paved path leading to the backyard.  She walked right down the center.  Not along the edge of the garage, not in the neighbor's grass.  Out in plain sight of any predators (like me).
Then the word popped into my head.  Toxoplasma.2 

Wait, don't be scared by the big word!  Toxo is a parasite that infects rodents and felines (and it can infect humans, too.  This parasite is the reason pregnant women are told to avoid cleaning litter boxes).  This parasite has the ability to affect the behavior of the infected host (even in humans! The Wikipedia entry is actually very accurate and kind of creepy - you should read it).  In rodents this results in increasingly risky behavior.  Including a lack of fear (some rodents seem to actually seek out areas that smell like cats!). 

My guess is that this shrew is infected by Toxo.  Her behavior was just not normal.

Life and Death in the home garden.  That shrew is not long for this world.

1.  I don't always know the gender of the animal I observe, I don't like to use "it" for animals.  Animals are living beings, not household appliances.  So when I don't know the gender I randomly assign one.  All crows are "he," shrews are "she," Blue Jays are "he," birds of prey that I can't tell the gender are "she" etc.  
2. I learned a lot about Toxo during graduate school.  It's a very interesting parasite.  Research suggests that humans infected with Toxo also display reduced fear and an increase in risky behavior.  There appears to be some evidence suggesting that in some individuals Toxo can cause (or contribute to) schizophrenia.  It also has an effect on reproductive behavior and seems to skew the ratio of male:female births in favor of males.  Really.  Go ahead and read that Wikipedia article.  I don't usually recommend Wikipedia since their articles are not always accurate but this one is good enough for a lay audience.  You may never want to clean a litter box again!

1 comment:

  1. That may have been what afflicted the mouse that was posing for us on a fence post some weeks back. The poor thing let us take close-up photos. Thanks!