The economics of scent marking with urine and feces in goitered gazelle (Gazella subgutturosa)

Abstract

Apart from the purely physiological excretion function, many mammals use their own urine and feces as reliable, odoriferous signals to indicate territorial occupancy. Marking is especially important for many antelopes, as territoriality is linked to reproductive success in these species. Scent marking with excrement, though, imposes physiological constraints in the amounts of urine and feces they can produce for these acts. Some male antelopes have been found to be able to regulate the size of their fecal marks, increasing marking frequency and decreasing the volume per defecation deposit compared to that of females. In this paper, we investigate quantitative characteristics of urination-defecation acts in goitered gazelles (Gazella subgutturosa), such as excretion frequency and duration, and explain potential differences in urine and fecal marking behavior for goitered gazelles based on sex, age, season, and territorial status. Our study found that frequency of urination-defecation acts in adult males fluctuated significantly over seasons and was highest in males during the rut, while subadult males urinated-defecated more rarely and with longer acts of urination than adults. In contrast, females (both adult and subadult) urinated and defecated at the same rate without significant seasonal changes. During the rutting period, urination duration in adult males decreased significantly with the rate increasing but even then, urination duration was longer than in females; defecation duration, on the other hand, remained relatively stable in adult males over months compared to urination duration, irrespective of rate. This finding is contradictory to the “material (urine and feces) saving hypothesis” as found for male oribi (Ourebia ourebi). We also discovered that in contrast to females and non-territorial males, territorial goitered gazelle males intensively ate snow during the rut, likely to compensate for water loss during their vigorous urination marking activity. The stability in defecation duration in adult and subadult males, however, regardless of seasonal changes in rate, was difficult to explain.