Morning-drive, evening-drive, and night spotlight surveys for deer (Odicoleus virginianus and 0. hemionus) were conducted each quarter on 3 National Park Service (NPS) areas in Texas and New Mexico from January 1987 to March 1988. Spotlight surveys resulted in a larger number of deer seen on all 3 sites. Spotlight surveys had significantly (P = 0.002) greater precision than morning or evening surveys. Increasing beyond 3 the number of consecutive days surveys were conducted did not significantly improve the precision of morning surveys (P = 0.328) or spotlight surveys (P = 0.719). A power analysis, generated for spotlight-survey data, indicated an increased probability of detecting differences in deer densities with increased survey effort. Weekly surveys are recommended.
