DENSITY ESTIMATES OF RURAL DOG-POPULATIONS AND AN ASSESSMENT OF MARKING METHODS DURING A RABIES VACCINATION CAMPAIGN IN THE PHILIPPINES

We estimated the population density of dogs by distance sampling and a ssessed the potential utility of two marking methods for capture-mark- recapture applications following a mass canine rabies-vaccination camp aign in Sorsogon Province, the Republic of the Philippines. Thirty vil lages selected to assess vaccine coverage and for dog surveys were vis ited 1 to 11 days after the vaccinating team. Measurements of the dist ance of dogs or groups of dogs from transect lines were obtained in 10 88 instances (N = 1278 dogs; mean group size = 1.2). Various functions modelling the probability of detection were fitted to a truncated dis tribution of distances of dogs from transect lines. A hazard rate mode l provided the best fit and an overall estimate of dog-population dens ity of 468/km(2) (95% confidence interval, 359 to 611). At vaccination , most dogs were marked with either a paint stick or a black plastic c ollar. Overall, 34.8% of 2167 and 28.5% of 2115 dogs could be accurate ly identified as wearing a collar or showing a paint mark; 49.1% of th e dogs had either mark. Increasing time interval between vaccination-t eam visit and dog survey and increasing distance from transect line we re inversely associated with the probability of observing a paint mark . Probability of observing a collar was positively associated with inc reasing estimated density of the dog population in a given village and with animals not associated with a house. The data indicate that dist ance sampling is a relatively simple and adaptable method for estimati ng dog-population density and is not prone to problems associated with meeting some model assumptions inherent to mark-recapture estimators. (C) 1998 Elsevier Science B.V.