Wednesday, February 16, 2011

Armadillo in Winter

This last weekend we have been following an unusual creature across the snow.  A rather fat and prosperous armadillo has been patrolling our Bull Creek valley, digging through the snow in search of food.  The first day it escaped into the woods but the next day we caught up with it in the middle of the field.  It tried to hide in the melted grass beside a hay bale and let us come within 3 feet, acting as though we wouldn't see it if it stayed perfectly still.

Googling "armadillo winter" the very first hit turned out to be a story from about Dr. Lynn Robbins who was working the then SMS university field station in Taney County.  This undated article described his surprise in finding armadillos out and about after a severe winter.  We were also surprised, as the last winter armadillo we had found was frozen to death, its snout sticking two inches into the ground as if it was trying to dig its burrow too late.

Click to Enlarge
The Biogeography of the Nine-Banded Armadillo, coming from - of all places - San Francisco State University gave detailed information from 1999 on the migration of the nine-banded armadillo, including the attached map.  Its range was from Argentina to just across the border of Missouri.  The first US sighting was in 1849 but since then they seem to be steadily progressing northward, possibly due to the progressive warming over the last 50 years.

Armadillos are not designed for cold or dry climates.  They need moist soil to dig in for insects.  With their shell, heat means no sweat.  They control their temperature by circulating blood into their legs for evaporation to cool their body.  This circulation leaves them little protection from the winter cold.  The last two days of melting snow and sunshine was probably our friend's first chance to dig for food in a week and explained its willingness to ignore us.

Several things you might not know about armadillos:
  • They can "get across a body of water by two methods. The first method is the ability to float across by gulping air into their stomachs and intestines, and secondly, if the body of water is shallow enough, the nine-banded armadillo is able to walk across the bottom by holding its breath for up to five minutes." *
  • Females produce one fertilized egg which then divides into exactly four identical babies.  Implantation of their egg may be delayed as long as 4 months in unfavorable conditions.**
  • When startled, they can jump 3-4 feet in the air.  A good survival tool when facing a predator, this is a dangerous trait when encountering a car with a driver trying to avoid running over it.
  • They are as primitive as they look.  Related to sloths and anteaters, the first ones evolved 50 million years ago in South America.  When the submerged Panamanian strip of land emerged from the sea 2.5 million years ago, they were able to start toward what would become North America. *
Armadillo were occasionally seen in Missouri in 1995.  With our warming winters (hard to believe earlier this week), their high reproductive rate, and lack of natural predators except automobiles, they are now established in Missouri and are found as far north as Nebraska and Indiana.  Who knows, with a good pair of Carhartts they might eventually reach Minnesota.

Winter pictures on Bull Creek are at
*   The Biogeography of the Nine-Banded Armadillo
**  Wikipedia

1 comment:

  1. "The last two days of melting snow and sunshine was probably our friend's first chance to dig for food in a week and explained its willingness to ignore us."

    Oh, I guess he is really that hungry to remember to protect himself from any enemy or animals/people that may harm him. Reminds me of people who don't have food to eat and left to die in starvation and how they eat when given foods without shame or pride. Somehow, people and animals have their own similarities, eh. :)

    Thanks for sharing,
    Cathy@online scrubs