Desert Tortoise Social Behavior, Mating Systems, and Dominance Hierarchies

Desert Tortoise Social Behavior, Mating Systems, and Dominance Hierarchies

USGS scientist Dr. Kristin Berry of the Western Ecological Research Center is conducting a research project on social behavior, mating systems, and dominance hierarchies in desert tortoises. The project is supported by the National Training Center at Ft. Irwin, as well as the USGS. The following photographs were taken at her study site in the Soda Mountains, central Mojave Desert, on April 26, 2006, by Dr. Steven Schwarzbach, USGS.

Adult Female No. 26 Adult female No. 26 is on a walk, foraging on dried annuals on a warm spring day.

Young Male No. 32 A young and rapidly growing male, No. 32 is a subordinate male and has never been observed to win an aggressive encounter with another male. His gular horn, an important weapon for battering an opponent during combat, was damaged by a predator and is unlikely to ever be useful in overturning a larger opponent or even a same-sized tortoise during a fight. Nevertheless, he is successful at courtship. Female No. 26 appears to prefer him over the local alpha male, No. 29.

Female No. 52 under a rock with an unmarked male Female 52 (with radiotransmitter) was found resting under a rock ledge at the edge of her home range with an unmarked, very large male tortoise. Face to face, the two had probably been courting earlier in the day. Female tortoises are polyandrous and can produce clutches of eggs with multiple paternities. They can also store sperm for more than one year.

-- WERC Home -- Who We Are -- Where We Are -- What We Do -- What's New -- Outreach -- Contact Us -- Search --

USGS Privacy Policy, Disclaimer , Accessibility
Comments to: webmaster@werc.usgs.gov
URL: http://www.werc.usgs.gov/tortoise/social_behavior.htm
Last update: 24 May 2006

	Adult female No. 26 is on a walk, foraging on dried annuals on a warm spring day.
	A young and rapidly growing male, No. 32 is a subordinate male and has never been observed to win an aggressive encounter with another male. His gular horn, an important weapon for battering an opponent during combat, was damaged by a predator and is unlikely to ever be useful in overturning a larger opponent or even a same-sized tortoise during a fight. Nevertheless, he is successful at courtship. Female No. 26 appears to prefer him over the local alpha male, No. 29.
	Female 52 (with radiotransmitter) was found resting under a rock ledge at the edge of her home range with an unmarked, very large male tortoise. Face to face, the two had probably been courting earlier in the day. Female tortoises are polyandrous and can produce clutches of eggs with multiple paternities. They can also store sperm for more than one year.