Importance of observer experience in finding desert tortoises

  • Freilich J
  • Larue E
  • 18


    Mendeley users who have this article in their library.
  • 20


    Citations of this article.


Because surveys for the desert tortoise (Gopherus agassizii) are usually conducted by experienced observers, we conducted 2 experiments in which observers of differing experience levels searched for desert tortoises and tortoise ''sign'' (burrows, seat) in replicated 1-ha plots. Each plot was seeded with a known number of tortoise seat, realistic-looking tortoise burrows, and 9 lifelike styrofoam tortoises of 3 size classes. When observers were divided into 2 groups, experienced and inexperienced, the groups did not differ (P greater than or equal to 0.17) in their ability to find tortoises of several size classes, total tortoises, seat, or burrows. Additional analyses divided experience into novice, beginner intermediate, and advanced levels based on previous survey experience. Again, tortoise-finding was unaffected tn experience level (Ps > 0.15). Observers overestimated numbers of burrows, mistakenly counted holes made by other animals, and consistently found fewer tortoises and seat than were actually seeded in plots, Tortoise-finding skill is probably part inclination and part aptitude, We cannot say which factors may affect a person's ability to find tortoises, but previous experience, in these experiments, did not.

Author-supplied keywords

  • 1998
  • Gopherus
  • agassizii
  • bias
  • desert
  • design
  • experience
  • observer
  • sampling
  • survey
  • tortoise

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • J E Freilich

  • E L Larue

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free