Daily changes in plant water content in western Queensland: implications for red kangaroo foraging times

Abstract

We measured daily changes in plant water content to see if red kangaroos (Macropus rufus), in foraging at night, may gain more water than foraging by day. If so, it could be influential in dictating their time of foraging. The study was stimulated by work in Africa which showed that, by choosing to feed at night, gazelles are able to take advantage of increased plant water content. Daily changes in water content of 15 known forage plants were examined at Idalia National Park in semi-arid western Queensland in February, April and July 2002, during progressive drying of the country in an extraordinarily dry year. Of 29 day-night comparisons of plant water content, thirteen showed no difference, two (both of red spinach, Trianthema triquetra) showed a substantial increase at night, eight showed small but statistically significant increases, and six showed small but statistically significant decreases. We conclude that the choice of red kangaroos to forage at night is unlikely to be explained by nightly increases in plant water content.