January 03, 2004

Making Kang A Roo


Red kangaroos show the least complex courtship activities. As with other species, the most common sexual interaction is the sexual checking of the female by males. The male approaches the female and sniffs her cloacal region and occasionally her pouch opening. Young or mid-sized males may be aggressively rejected but with dominant males she usually just move away if she is unreceptive-and that is usually the end of it. It is rare for a male to touch or grasp an uninterested female. Red kangaroo females can be sparsely distributed and, with no breeding season, are likely to come into oestrus at any time. To be successful in breeding, the males must keep checking widely. Receptive females often urinate when being checked and the males perform 'flehem'. this occurs when the male sniffs the urine and or puts his nose in it. He then shakes his head and, with a lowered and stretched head, strongly sniffs again. Thus act is noticeably common among male antilopine kangaroos. When coming into oestrus a female also extends her area of activity so as to bring her condition to the attention of the males. The aim is to attract the biggest male available. Such signals from females presumably can picked up at a considerable distance.

As oestrus nears, males show increased attention. Red kangaroo and euro females at this time often have a large young that are about to finally leave the pouch. The male red kangaroo begins to follow, grasping and stroking at the female's tail, usually high near the butt. The full sequence: male approaches, male sniffs, female moves off, male grasps tail. This may be repeated several times, with the persistence of the male increasing as she nears oestrus. A soft clucking sound is often made by the male during this behaviour. Grey kangaroo and euro males follow this pattern and also often stand in front of the female, touching and grasping her head, or give a high-standing display with an erect penis while facing her. Antilopine kangaroo males may also move their body from side to side when standing in front or beside the female. 'Chesting', the make's grasping of the female's head and rubbing it against his chest is also done by the grey kangaroo but seemingly not by euros or red kangaroos.

When the female kangaroo is about to ovulate the male stay close by, generally within two or three metres. This consort relationship lasts for up to four hours days. Often more than one male is attendance; there have been reports of more than fourteen males. The dominant male, usually the largest, eventually copulates with her. The female stands crouched with her back arched. The male stands semi-erect behind the female, clasping her body with his forearms tucked inside her thighs. He gives a short sequence of thrusts, pulling the female back on his penis. There may be frequent pauses during the copulation, which generally lasts ten to fifteen minutes. Unlike other species, repeat copulations are rare among red kangaroos.

From this description it might seem that mating in red kangaroos is perfunctory. In fact, it can be anything but casual, due to continued aggressive interference of the attendant male or attempts to drive them away.

Copulatory behaviour in euros is more complex than in red kangaroos. They have been observed in the wild were extended bouts of copulation lasted over an hour. In one instance recorded, six acts of copulation were observed, each lasting between a minute or so and twelve minutes. two of the acts were terminated by interference from other males and once the copulating male was attacked and had to stop to fight off and chase the attacker. On another occasion the female struggled and broke free. During the intervals between acts of copulation the male often grabbed and pulled at the female's head. He thrust his head towards her and wiped it on hers and all along her body. Once the female lay down and the male attempted to pull her to her feet. The female was basically passive throughout and moved little except to break away from the male in order to terminate copulation. Her young at foot was nearby and twice tried to approach but was cuffed by the male. After the final copulation the male remained to guard the female for several hours but the young was allowed to reapproach the female and suckle.

The time over which large dominant males maintain their status may differ between different species of kangaroos. In the eastern grey kangaroos a dominant male achieves tenure and maintains it, though it rarely lasts much more than a year. It is not uncommon for a male to die if seasonal conditions deteriorate, because maintenance of his status and constant reproductive activity require considerable energy. Feeding time is also much reduced and body conditions fall. Much the same pattern is thought to occur in red kangaroos also, but the later stages of the life of a dominant male red are little documented. Old grey-nosed males in poor conditions have been observed as persistent and appear to live in relatively small areas. Their role in breeding, if any, is unclear. In areas where predation by dingos is significant these males may not last long.

The eastern grey's straightforward strategy may not be the most appropriate fro euros. During his PhD work Tim Clancy tracked a large male, of about fifty-two kilograms, for over two years. This euro seemed to take holidays from his duties as a dominant male. When he was in the hills he was clearly the successful consort male. However, on several occasions he left the hills and lived in the creek lines and flats. When he returned to the hills, sometimes after several months, he resumed his position as the dominant male. Unfortunately he was shot while raiding a vegetable garden so it was not possible to gauge how long he might have kept up this pattern.

The reason for this pattern of male euro breeding activity may be related to the fluctuating reproductive activity of female euros in the face of changing environmental conditions. At a large catch and release study at a water hole on the edge of the hills during a dry summer we found that about fifty percent of the euros were without pouch young and anoestrus as compared with only fourteen percent of red kangaroos. Vegetation conditions were not noticeably different throughout the area, nor were animal densities, and it appears that female euros withdrawal from reproductive efforts in dry conditions sooner than red kangaroos. It is during these conditions that the large males tend to leave both the hills and the female euros, who maintain their home-ranges in the rough country. Tim Clancy has suggested that the males may be extending their period of breeding success (but not the total number of copulations) in order to optimise their chances of producing young that survive to a reproductive age. In a poor season most young that are conceived die, and many females are not breeding. The large dominant males, who have higher feeding requirements, choose to survive these conditions by moving to where the feed is better and leaving chancy breeding to the smaller males.

Posted by Madfish Willie at January 3, 2004 12:01 AM | TrackBack
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