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Squirrel Science with Dr. Karen Monroe

1:40:43 recording · EN · 3 speakers

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Brief overview

Squirrels shape forests, outwit rattlesnakes and deceive rivals, yet 80% of the world's squirrel species are threatened.

  1. Squirrels plant most of our hardwood forestsMonroe's undergraduate work found acorns handled or half-eaten by squirrels germinate at equal or greater rates than intact ones.
  2. Most of the world's squirrels are in trouble80% of squirrel populations are threatened or endangered, and in Japan squirrels survive mainly around old sacred shrines with old-growth trees.
  3. Tail flagging is a precise anti-predator signalSquirrels heat their tails only for heat-sensing rattlesnakes, leaving the tail cold when the snake is a gopher snake.
Executive Summary AI
  • Dr. Karen Monroe, a mammalogist and biology professor at Baldwin Wallace University, tells Allie Ward she has studied squirrels since her freshman year at age 17, moving from cellular and molecular biology at Arizona State to a master's at Purdue and a PhD in wildlife conservation.4:14
  • Asked how many trees we owe to forgetful squirrels, Monroe answers almost all of them, because her undergraduate research showed an acorn handled or even half-eaten by a squirrel germinates better than one never touched.15:11
  • Only in the US are squirrels treated as pests to be managed and hunted, Monroe says, while 80% of the world's squirrel populations are threatened or endangered, the Mount Graham red squirrel being North America's most endangered mammal at a few hundred animals on one mountaintop.29:06
  • On mating, female gray squirrels are in estrus for only eight hours, may mate with up to 24 males in that window, males leave copulatory plugs that females simply remove, and litters run about two to three, though Monroe once recorded 13 in a round-tailed ground squirrel.37:51
  • In an added segment, rattlesnake expert Dr. Emily Taylor explains that California ground squirrels shunt blood into their tails to flash heat at rattlesnakes with infrared pits but not at gopher snakes, and that squirrel resistance drove the evolution of the rattlesnake's toxic venom.46:27
Key Quote
“Almost all of them.”
— Karen Monroe15:11
Key Quote
“80% of the world's squirrel populations are threatened or endangered.”
— Karen Monroe29:06
Key Quote
“The squirrels know this instinctively, and they shunt blood to their tails, and it lights up like a lightsaber in the rattlesnake's face.”
— Emily Taylor46:27