The sugar glider is one of a number of volplane (gliding) possums in Australia. Gliders glide with the fore- and hind-limbs extended at right angles to their body, with their feet flexed upwards. The animal launches itself from a tree, spreading its limbs to expose the gliding membranes. This creates an aerofoil enabling them to glide 50 metres (55 yards) or more. For every 1.82 m (6 ft 0 in) travelled horizontally when gliding, sugar gliders fall 1 m (3 ft 3 in). Sugar gliders can steer by moving their limbs and adjusting the tension of their gliding membrane; for example, to turn left, a sugar glider will lower its left forearm below its right.
This form of arboreal locomotion is typically used to travel from tree to tree; the species rarely descends to the ground. Gliding provides three dimensional avoidance of arboreal predators, and minimal contact with ground dwelling predators; as well as possible benefits in decreasing time and energy consumption spent foraging for nutrient poor foods that are irregularly distributed. Young carried in the pouch of females are protected from landing forces by the septum that separates them within the pouch.
Torpor
Sugar gliders can tolerate ambient air temperatures of up to 40 °C (104 °F) through behavioural strategies such as licking their coat and exposing the wet area, as well as drinking small quantities of water. In cold weather, sugar gliders will huddle together to avoid heat loss, and will enter torpor to conserve energy. Huddling as an energy conserving mechanism is not as efficient as torpor. Before entering torpor, a sugar glider will reduce activity and body temperature normally in order to lower energy expenditure and avoid torpor. With energetic constraints, the sugar glider will enter into daily torpor for 2–23 hours while in rest phase. Torpor differs from hibernation in that torpor is usually a short-term daily cycle. Entering torpor saves energy for the animal by allowing its body temperature to fall to a minimum of 10.4 °C (50.7 °F) to 19.6 °C (67.3 °F). When food is scarce, as in winter, heat production is lowered in order to reduce energy expenditure. With low energy and heat production, it is important for the sugar glider to peak its body mass by fat content in the autumn (May/June) in order to survive the following cold season. In the wild, sugar gliders enter into daily torpor more often than sugar gliders in captivity. The use of torpor is most frequent during winter, likely in response to low ambient temperature, rainfall, and seasonal fluctuation in food sources.
ไม่มีความคิดเห็น:
แสดงความคิดเห็น