<P> During the day, tammars stay close to scrub for shade and move out to more open grassland by nightfall . Like all macropods, the tammar is herbivorous . They are known to both graze and browse, but the latter is less effective, as they commonly drop leaves when chewing on them . When eating large leaves, tammars handle them with their forelimbs . This species spends more time chewing its food than other similar sized macropods, which likely aids digestion . Tammars commonly feed on acacia seeds . Other species consumed include heart - leaved poison (Gastrolobium bilobum), small - flowered wallaby grass (Austrodanthonia setacea), and marri (Corymbia calophylla). Tammars survive on several islands that have no fresh water, subsisting on seawater and the moisture in plants . </P> <P> The tammar rests in two positions: a "sitting tail forward" position, in which the hind legs are outstretched with tail brought forward in between, the body prone and the head above ground; and a "lying" position, in which the animal lies on its side with the head touching the ground . The former position is typically used during the day for long periods, and the latter position is used at night for brief periods . Tammars are known to live in stable groups, which lessens the chance of an individual being taken by a predator . As the group increases in size, tammars spend more time foraging, grooming and interacting and less time being vigilant and moving around . Predators of the tammar include dingos, feral cats, red foxes and wedge - tailed eagles . They may also have been preyed upon by the extinct thylacine . Tammars appear to respond more to the sight than the sound of predators . They can also use their acute sense of smell to detect a predator . When a predator is detected, a tammar will alert others by thumping its foot . When lost, young tammars are known to emit a coarse screeching call and adult females may respond with a similar call . </P> <P> The tammar wallaby has a promiscuous mating system . It is a seasonal breeder and births largely occur during late January and early February . During the breeding season, the male's prostate and bulbourethral gland enlarge . However, there does not appear to be any seasonal difference in the weight of the testes . Around two weeks before the first births, the males will begin sniffing the uro - genital openings and pouches of the females to determine their reproductive status . After giving birth, females enter estrus and allow males to mate with them . However, a male that attempts to mate with an estrous female may face aggression from other males . A male can achieve reproductive success by mate - guarding . During the estrous period, males establish a dominance hierarchy and the higher ranking males will try to prevent subordinates from mating with estrous females . Several males may pursue a single female . </P> <P> The female tammar can conceive shortly after giving birth . Tammars undergo embryonic diapause and the blastocyst remains dormant for nearly a year . For the first half of the year, the presence of the joey in the pouch prevents the blastocyst from developing and experiments have shown that removing the joey within this first half will stimulate the blastocyst's development . However, after this the blastocyst remains dormant even after the joey has left . It begins to develop by the summer solstice in the end of December and the female gives birth around one month later . After birth the newborn young climbs unaided by its mother from the birth canal to the pouch . </P>

When does lactational diapause end in the tammar wallaby