Ground squirrels rattlesnakes and burrowing owls the legend

Ground squirrels, rattlesnakes, and burrowing owls: the legend of the “happy family” Matthew Rowe Michigan State University

My goals this morning…. . ✓ share… critters and questions ✓ demonstrate… sophisticated interactions ✓ convince… deserve our admiration ✓ inspire… a love of asking questions

The legend of the ‘happy family’ Illustration by Ernest Thompson Seton

Squirrels vs. snakes: the California players California ground squirrels (Spermophilus beecheyi) Photo by John Cooke Northern Pacific rattlesnakes (Crotalus oreganus) Photo by Ron Swaisgood

Squirrels vs. snakes: the New Mexico players Rock squirrels (S. variegatus) Photo by Larry Rabin Western diamonbacks (C. atrox) Photo by Wayne Van Devender

Squirrels at both sites do have other predators, including other snakes… Photo by Franco Folini

Background “stats” Rattlesnakes - principal predators of ground squirrel pups Adult squirrels - resistant to rattlesnake venom and, thus, are assertive in protecting pups So, rattlesnakes and adult ground squirrels are adversaries Consequently, squirrel-rattlesnake encounters are similar to a “boxing match” With associated opportunities for probing & assessment

When a snake is detected in a colony….

Snakes respond defensively to ground squirrel confrontation --- can include rattling and striking

Why work so hard to induce the rattlesnake to rattle? Photo by NGS/Chris Johns

Photo by Edward Rooks Photographer unknown

Evidence that smaller rattlesnakes are more vulnerable than larger rattlesnakes

Evidence that warm rattlesnakes are more dangerous than cold ones

Cues in rattling associated with rattlesnake body size

Cues in rattling associated with rattlesnake body temperature

Click rate – another view

Squirrels use size and temperature cues in rattling

Ground squirrels make subtle assessments about risk

Squirrels mediate their risk in other ways --- by transferring their young to other burrows -- by anointing with snake scent

What is the function of snake-scent anointing (SSA)?

Functional hypotheses of SSA 1. Antipredator 2. Ectoparasite defense 3. Conspecific deterrence

2. Ectoparasite defense SSA repels fleas Test: flea host choice

3. Conspecific deterrence SSA deters rivals Test: compare fights before & after SSA

1. Antipredator SSA disguises squirrel odor � Test: compare rattlesnake foraging behavior

What about burrowing owls?

The ‘happy family’ revisited Illustration by Ernest Thompson Seton

Special thanks:

What are we doing now?

Looking for a few good teachers!

Thanks!