Relative Contributions of Urine and Anal-Sac Secretions in Scent Marks of Large Felids

SYNOPSIS. A hypothesis generated from field observations oflions and tigers was tested in a zoo setting. The presence ofa whitish material in urine marks, detected by visual inspection,led to the surmise that analsac secretions were expelled alongwith urine. This hypothesis was evaluated by labelling anal-sacsecretions of various felids with an inert dye. The animalswere monitored thereafter for signs of dye in urine-marks, onfeces or in their enclosures. The failure to find anal-sac secretionsin urine or on feces led to a search for an alternate explanationfor the whitish material. A likely answer was found in the confirmationof considerable lipid in the bladder urine of lions and tigers,which separates to form a visible, whitish layer. Relative levelsof urinary lipid reflect general condition of an animal as theycorrelate with kidney fat reserves (Hewer et al., 1948), sothe amount of lipid in a scent mark could serve as an indicatorof condition. Furthermore, because lipid retards the releaseof volatile compounds (Regnier and Goodwin, 1976), lipid ina scent mark will extend release time of a pheromonal message.