Because studies estimating density of gray squirrels (Sciurus caroline
nsis) have been laser intensive and costly, I demonstrate the use of l
ine transect surveys to estimate gray squirrel density and determine t
he costs of conducting surveys to achieve precise estimates. Density e
stimates are based on four transects that were surveyed five times fro
m 30 June to 9 July 1994. Using the program DISTANCE, I estimated ther
e were 4.7 (95% CI = 1.86-11.92) gray squirrels/ha on the Clemson Univ
ersity cam pus. Eleven additional surveys would have decreased the per
cent coefficient oi variation from 30% to 20% and would have cost appr
oximately $114. Estimating urban gray squirrel density using line tran
sect surveys is cost effective and can provide unbiased estimates of d
ensity, provided that none of the assumptions of distance sampling the
ory are violated.