Fat-tailed Dunnart - Survival

Survival

The fat-tailed dunnart can survive in extreme, semi-arid environments. This is due to various physiological and behavioral characteristics. First, this marsupial is nocturnal and functions within a 24-hour circadian rhythm. During the nighttime it is protected from high temperatures that cause energy loss. While awake, it spends the majority of its time feeding. Every night it consumes approximately its own body weight of food. During periods of food shortage it decreases its duration of activity while also increasing its intensity of feeding. It uses specialized, sharp teeth to grind its prey into fine pieces. This increases its ability to obtain nutrients from its prey. It has a high rate of digestion and can use fat stored in its tail as an energy source.

Another survival technique that it uses is daily torpor. It lowers its body temperature and metabolic rate, in order to reduce energy expenditure. Torpor is unaffected by alterations in photoperiod but is greatly affected by environmental conditions. Two conditions must occur in order for the fat-tailed dunnart to use daily torpor: low ambient temperatures and food shortage. There are seasonal variations in torpidity. They use it more often in the winter because food is scarce and it requires more energy to maintain a high constant body temperature. During torpor, the body temperature can drop as low as 14.6 °C. This species does not use torpor for extended periods of time, thus the heart rate is variable and does not reach a steady state, such as seen in long-term torpidators. This species is unique in that it can use torpor during development and reproduction. Even during lactation a female is capable of entering daily torpor without affecting the offspring.

Coupled with the daily torpor is a process called re-warming. The re-warming process demands a high amount of energy in order to raise the body temperature. After awaking from a torpid state, these marsupials actively seek out areas in which they can bask in the sun to aid in this process.

Nesting is also used as a behavioral survival technique. During times of cold temperatures, the fat-tailed dunnart shares nests with rodent species such as the household mouse, Mus musculus, to conserve heat. This is unusual because the fat-tailed dunnart preys upon these mice during less extreme conditions. Group nesting is observed only during times of non-breeding.