Megaleia Rufa Research Articles

NOTES ON SOME SPECIES OF NEMATODA FROM KANGAROOS AND WALLABIES, INCLUDING A NEW GENUS AND THREE NEW SPECIES.

A large number of nematodes from Protemnodon rufogrisea, P. bicolor, P. dorsalis, and Macropus canguru, from southern Queensland, M. robustus from Western Australia, and Megaleia rufa (? locality) have been examined. The species described in this paper are: Pharyngostrongylus macropodis Yorke & Maplestone, P. kappa, sp.nov. (syn. P. macropodis in part), P. eta Johnston & Mawson, P. lambda, sp.nov., Rugopharynx epsilon (J. & M.), R. delta (J. & M.), R. zeta (J. & M.) (syn. R. longibursaris (Kung)), R. theta (J. & M.), Coronostrongylus coronatus J. & M.; a new genus is proposed, Oesophagonastes, with type O. kartana syn. Spirostrongylus kartana Mawson to include O. parma syn. Pharyngostrongylus parma J. & M., O. gallardi syn. P. gallardi J. & M., and O. leptos, sp.nov.Most of the parasites were sent for examination by Dr M. J. Mackerras, then of the Queensland Institute of Medical Research. Those from Western Australia were from Dr T. Ealey of the Zoology Department, Monash University, Victoria, who was working on Macropus robustus in the north of that state. I am most grateful to both of these helpers.

The distribution of red kangaroos, Megaleia rufa (Desmarest), about sources of persistent food and water in central Australia.

Data from aerial surveys primarily designed to estimate the numbers of red kangaroos, Megaleia rufa (Desmarest), on about 4000 square miles of central Australia have been used to define the animals' distribution about sources of persistent food and water, both during severe drought and 6 months later after good rains had fallen. During the drought, 67.4% of kangaroos were sheltering in woodlands within 1/3 mile of open plains and water-courses (where food persisted), and only 17.4% were further than 1 mile away. After the rains, only 29.5% were within 1/3 mile of these drought refuges; 51.8 % were further than 1 mile away, but only 6% were beyond 6 miles out, i.e. beyond the mulga woodlands. Kangaroos were densest (seven-eight per square mile) during drought on land 2-4 miles out from bores and dams and within 2/3 mile of open plains because at that distance grasses on the plains respond to the grazing of cattle by sprouting green shoots which kangaroos prefer. Kangaroos drank at the bores and dams only during severe drought and may, therefore, get sufficient water from their food at most times. It is concluded that the kangaroos' distribution and changes in it are controlled primarily by their search for green herbage and shady trees.

Reproduction in natural populations of the red kangaroo, Megaleia rufa (Desmarest), in central Australia.

Reproduction in the red kangaroo, Megaleia rufa (Desmarest), in the arid environment of central Australia is highly opportunistic, and depends on the weather through its control of the food supply for its success. This conclusion is based on the study of 460 males and 1610 females between the years 1958 and 1962. Males and females matured sexually at an average age of about 2.5 and 3 yr, respectively. Drought significantly retarded sexual maturity in females by 6.24� 1.26 months. All females bred when green herbage was abundant after good rains. However, when food was scarce during drought, many females entered anoestrus, the proportion doing so being a probit function of the severity of the drought (measured in units of "drought index" explained in the text). Half of them became anoestrous after 3-5 months of drought in summer. Drought on the more scantily grassed of the two areas studied (they were 15-20 miles apart) was 1.57 times more effective in inducing anoestrus than on the other. All pouch-young survived if good conditions held for about 8 months, but many died during drought, the proportion doing so being a probit function of the increase in severity of drought after they were born. Half of them perished after 1.5-2.5 months of drought in summer. Only 28.7% of all joeys born survived life in the pouch because of the prolonged dry weather. Pouch-young were significantly lighter, and joeys-at-heel were 13.5 � 1.9 days older during drought than at other times. The birth of twin joeys was associated with an abundance of food. During severe drought, many females showed signs of having produced in quick succession one or more joeys which did not live long. Many of these females were anoestrous and suckling a small joey. Since most if not all females which became anoestrous did so during late pregnancy without aborting and subsequently suckled their pouch-young, it is suggested that the adaptive significance of delayed implantation is to ensure that females which have lost a joey and which are about to become anoestrous produce one more joey each. These joeys will be born well into any drought and therefore will have to live for a shorter time than older joeys to survive the drought. The advantage to the species can be gauged from the fact that 50 out of 145 females with young surviving the drought were anoestrous. The ages of their joeys averaged 60.1 � 7.6 days.

Form, weight, and indole content of pineal organs of red and grey kangaroos.

The pineal organ of the red kangaroo (Megaleia rufa) is shown to be distinguishable from that of the grey kangaroo (Macropus canguru) by being symmetrically bilobate instead of rounded distally. Pineal weights in the two species were similar. At least in M. rufa pineal size appeared to increase with age - from 6.4-15.6 mg in animals aged about 1 yr to 40.1 mg in a female 6+ years old. In comparison with the nocturnal indole contents of the pineal in rats, those of kangaroos have similar levels of 5- methoxy-N-acetyltryptamine (melatonin) and 5-hydroxyindole-3-acetic acid to the nocturnal values recorded in the literature for rats, but a lower level of 5-hydroxytryptamine (serotonin). Available information on vertebrate pineal weights and indoles does not provide evidence for any obviously distinctive evolutionary or functional status for the marsupial pineal organ as compared with that of some eutherian mammals or of some birds and reptiles.

The abundance of red kangaroos, Megaleia rufa (Desmarest), in central Australia.

Aerial surveys using stratified random sampling were used to estimate the numbers of red kangaroos, Megaleia rufa (Desmarest), on about 4000 square miles of central Australia, once during drought, and again 6 months later after good rains had fallen. Sampling involved varying width of transects along their lengths to suit viewing conditions over various types of vegetation. The method of statistical analysis is provided. The number of kangaroos on an area depended on the availability of green herbage and shady trees. During the drought, kangaroos congregated near open plains and watercourses where green grass (Eragrostis setifolia and Astrebla pectinata) persisted; they reached densities of eight-nine per square mile. After the rains, they dispersed into the surrounding woodlands where green herbage was temporarily abundant. There were never many kangaroos on spinifex tracts which have few shady trees. The kangaroos' nomadism is thus linked with their search for food and shelter. The tendency for kangaroos to cluster was highly correlated with their density on an area. The total numbers of kangaroos on 2642 square miles of the study area changed from 3927 during the drought to 4914 after the rain, probably as a result of immigration. The environment of kangaroos is ameliorated by cattle cropping the long dry grass of the open plains, causing it to sprout green shoots. Large areas where kangaroos can find food during drought have thus been provided for them.

A SURVEY OF THE ENDOPARASITES OF THE RED KANGAROO MEGALEIA RUFA (DESMAREST).

A survey of endoparasites of the Red Kangaroo (Megaleia rufa (Desmarest)) has been carried out in three geographically distinct areas of south-eastern Australia.During a period covering 22 months, 464 kangaroos of different sexes and ages were collected. Alimentary canals and tracheae of all of them and blood and organ smears from 333 were examined for parasites.A list of endoparasites of the Red Kangaroo encountered during the study and of others reported earlier is given. This includes three species of blood protozoa, two species of coccidia (Eimeria spp.), two species of cestode and twenty-one species of nematodes.The numbers of some nematode species are analysed in relation to season, sex of host and age of host as expressed by length of tibia.Two different patterns of age susceptibility of the Red Kangaroo to nematodes are recorded and it is suggested that these may be dependent upon the presence or absence of direct contact of the parasite with host tissue.Distribution of nematodes in the stomach of the Red Kangaroo has been studied. Different species were found to occupy separate niches within the stomach.A statistical test aimed at showing the correlation between severity of infection with some nematodes and condition of host expressed by the ratio: body weight — stomach content/tibia length showed only a very weak negative correlation.Alimentary canals of 100 sheep and thirty-five wild rabbits sampled simultaneously in the same area were found to be infected with only small numbers of worms.No parasites injurious to domestic stock were found in the kangaroos examined.

TRANSFERRIN VARIATION IN KANGAROOS.

INHERITED variation in the electrophoretic mobility of the serum protein transferrin (siderophilin) has been established for a number of mammalian species1–12 and for doves13. In other mammals14,15, several colubrid snakes and one amphibian species, variants exist16 and, although family data are not yet available, it is probable that they are also genetically determined. This communication reports the discovery of inherited variation in the transferrin of an Australian marsupial, Megaleia rufa (= Macropus rufus), commonly known as the red kangaroo.

COCCIDIA IN WILD POPULATIONS OF THE RED KANGAROO, MEGALEIA RUFA (DESMAREST), AND THE GREY KANGAROO, MACROPUS CANGURU (MUUELLER).

The incidence and prevalence of coccidia have been studied in populations of free-living red kangaroos, Megaleia rufa, and grey kangaroos, Macropus canguru, in four geographically distinct areas in Australia.Two new species of Eimeria—E. wilcanniensis and E. toganmainensis—are described from M. rufa, and five—E. cunnamullensis, E. gungahlinensis, E. purchasei, E. kogoni, and E. hestermani—from M. canguru.The incidence of coccidia ranged from 6 to 14% in populations of M. rufa and from 26 to 70% in M. canguru. The susceptibility of the animals to coccidia was analysed in relation to the tibia length. Red kangaroos with tibia approximately 360 mm. long and corresponding to an age of about 12 months were found to be most susceptible. No clinical cases of coccidiosis were seen in the field.Special thanks are due to the owners or managers of the properties on which the kangaroos were sampled; to members of the staff of the Regional Pastoral Laboratory ‘Gilruth Plains’ for their assistance in sampling, and to Messrs E. R. Hesterman, C. Kogon, and D. Purchase, who assisted in the field and the laboratory. Three species of Eimeria have been named after them in acknowledgement of their work. Messrs B. V. Fennessy and J. H. Calaby of this Division kindly read the manuscript.I wish to thank Dr G. B. Sharman for his permission to work with captive kangaroos in Canberra, and Mr E. Slater who took the photographs.

Studies of the cutaneous glands and hair follicles of some species of Macropodidae

Histological studies were made on skin samples from wild red kangaroos, Megaleia rufa (Desmarest), grey kangaroos, Macropus canguru (Miiller) syn. M. giganteus and M. major of three colour variants, euros, Macropus robustus Gould, and one swamp wallaby, Protemnodon bicolor (Desmarest). The hair cover was densest in the mid-dorsal region of the body, on the cheeks, and on the shoulders and the thighs. The density decreased ventrally. On the tail the hair follicles were less dense on the ventral than on the dorsal surface. The red kangaroo had the densest hair cover. The thickness of the hair fibres varied inversely in relation to the density of hair cover. Hair follicle grouping on the ventral surface of the tail was characteristic for each species and the hairs there uniformly resembled bristles. Males of all species, except the euro, were found to have consistently thicker skin on the ventral surface of the body but in females the skin was thicker on the back. In the tails of both sexes of all species the skin was thicker on the ventral than on the dorsal side. The thickness of the papillary layer on the ventral surface of the tail was correlated with the size of the animal and it is suggested that it may possibly be used as a measure of age. The complete absence of a reticular layer was noted in the skin of all species of macropods examined. The type and distribution of sweat glands was studied and sex, age, and species differences were demonstrated. Euros were found to have sweat glands with a characteristically bulbous lower part, in addition to the types of sweat glands present in the other species. In males of all species highly convoluted apocrine glands occurred in the breast and axillary regions while in females they were most common in the cloaca-pouch area. The behavioural importance of the secretion of these glands is suggested. Histological differences in the skin of the three colour variants of the grey kangaroo are described and the taxonomic value of skin characteristics is suggested.

Mobility of the Red Kangaroo, Megaleia rufa

The distribution and abundance of red kangaroos was studied in inland New South Wales by a series i f aerial surveys. Thro'ughout the study the population density of kangaroos fell sharply in each area studied and there is little doubt that a drastic decline occurred in the number of red kangaroos in in!and New South Wales during the period April 1960 to January 1963. Possible causes are discussed. The distribution of kangaroos was determined by the abundance of short green grass; long herbage was avoided as were dry pastures. The greatest abundance of animals occurred on Danthonia and Stipa grasslands, especially where shade was available from clumps of timber and where local movements were controlled by the availability of forage. In the study area with the milder climate, red kangaroos were very sedentary, but in the more arid area rather more extensive movements occurred in response to the changing distribution of green herbage. It is suggested, however, that red kangaroos were, on the whole, not stronlgly nomadic in the period studied.

Reproductive behaviour in the Red Kangaroo, Megaleia rufa, in captivity

Female red kangaroos in captivity became sexually mature at 15-20 months and males at about 2 years of age. 'I'he oestrous cycle averaged 34-35 days in length and the gestation period was 33 days. The interval from fertile mating to post-partum oestrus was not significantly different from the length of the oestrous cycle. The oestrous cycle was accompanied by changes in the cell composition of the vaginal smear, by changes in the urogenital sinus and the area surrounding the urogenital opening, and by changes in the pouch and teats. The approach of oestrus could not always be predicted but the immediate post-oestrous condition could always be recognized even if mating had not occurred at oestrus. Pre-mating and mating behaviour is described. Breeding in the red kangaroo in captivity was virtually continuous but there was evidence that some females showed a slightly reduced fecundity in the winter months. The births of 18 young were closely observed. At the approach of parturition most females cleaned away the scale inside their pouches by licking. For parturition females assumed the "birth position" with the back usually supported, the hind legs extended straight forwards, the tail passed forwards between them and the trunk inclined forwards. Females adopted the birth position up to 20 or more times before birth occurred. They licked the urogenital opening before birth occurred but no female licked a path in the fur which the young followed to the pouch. Birth was preceded by the appearance of yolk sac fluid and usually by the embryonic allantois which appeared in the form of a fluid-filled sac. The young were born in the amnion and climbed unaided by the mother up a generally dry route in the fur to the pouch. During the first part of the journey they were attached by the umbilical cord to the ruptured yolk sac which was still in the birth canal. Birth was followed by the appearance of blood, viscous fluid, and the yolk sac all of which were carefully licked up and eaten by the mother. Seventy-six young born in captivity were made up of 42 females, 32 males, and two of unknown sex. All behaviour associated with birth occurred in non-mated females. Non-rnated parous and virgin females which had newborn young transferred to their teats at the appropriate stage after oestrus produced milk and the foster young were reared normally. Growth rates of foster young did not differ significantly from that of control young reared in their mothers' pouches.

The female reproductive system of the Red Kangaroo, Megaleia rufa

The reproductive system of the female red kangaroo consists of paired ovaries, Fallopian tubes, and uteri. The uteri open on separate papillae into the anterior vaginal sinus. An incomplete septum divides the right and left halves of the vaginal culs-de-sac at the first oestrus. Size changes in the parts of the reproductive system of females in the immature, oestrous, post-oestrous, luteal, post-luteal, pro-oestrous, and quiescent stages of the reproductive cycle are described and illustrated, and measurements of the various parts are presented in tabular form. A Graaffian follicle of 5-6 mm diameter is present in one ovary at oestrus. At this stage there is mitotic proliferation in the uterine epithelia and cornified cells are found in the epithelia of the posterior parts of the vaginal complex. Mitotic proliferation continues in the uterine epithelia after oestrus. During the luteal phase a corpus luteum of 6-8 rnm diameter is present, the uterine glands are well developed with high columnar epithelium and basally situated nuclei, and mitoses do not occur in the uterine epithelia. Regression of the hteal phase is followed by pro-oestrus in both pregnant and non-pregnant females.

Breeding in wild populations of the Red Kangaroo, Megaleia rufa

The study was based on the examination of 3342 kangaroos collected at' three sites in inland New South Wales and Queensland, that were chosen to give a series of different environments. Some female red kangaroos in the wild reached sexual maturity before they were 18 months old, but most did not do so until they were about 30 months old. There were considerable differences in the age at which sexual maturity was reached according to the aridity of the region. Male red kangaroos in the wild reached sexual maturity at 28-39 months of age but this age also might have been modified by the environment from time to time and fxom place to place. Of the 2528 mature females examined 78.7% had pouch young and 21.5% of the females with pouch young also had a young-at-foot. There was some intrauterine mortality but the principal mortality occurred at the end of pouch life, from 196 days of age onwards and among the young-at-foot. The mortality was greatest in the area of drought where 83 % failed to reach maturity. The red kangaroo bred continuously throughout the year and it is concluded that mortality of pouch young, probably induced by failure of lactation, consequent on the mother's reduced food supply, was an important factor in the regulation of numbers.

Oestrus in the lactating red kangaroo.

The reproductive condition of 18 female red kangaroos, Megaleia rufa (Desmarest), collected in central Australia and found to be suckling sizeable pouch young (average age about 54 days), is described. They were either approaching, undergoing, or had just undergone oestrus. None had a mature corpus luteum of lactation in either ovary. No similar case was found in many hundreds of females suckling sizeable pouch young which had a mature corpus luteum of lactation in one of their ovaries. It is concluded that the presence of a functional corpus luteum of lactation or of pregnancy in the ovary may be the only inhibitor of ovulation in the mature Megaleia, provided that environmental conditions are suitable. Some kangaroos during severe drought miss the customary oestrus following birth of a young because the pregnant females do not undergo the reproductive changes necessary for it. Despite this disruption of the reproductive cycle the young are born and suckled normally, but the females cannot, therefore, have a corpus luteum of lactation. The 18 females described in this paper must have belonged to this class of animals during the drought, their condition having been brought on presumably by poor nutrition. The unusual features of reproduction in Megaleia are hard to reconcile with the assumptions that pregnancy in marsupials depends on the hormones of the normal oestrous cycle, and that reproduction in marsupials is controlled by the same kinds of hormones found in eutherian mammals; doubt is, therefore, thrown on the validity of these assumptions. Megaleia has a remarkable ability to care for its young during severe drought, and a method of overcoming the effects of the drought on its reproductive cycle when the drought breaks, with the result that the production of young is not impaired. Both these features must aid the chance of the species to survive in the arid parts of Australia.

Growth of the pouch young, tooth eruption and age determination in the Red Kangaroo, Megaleia rufa

Growth of pouch young, molar eruption sequence, and molar progression were studied in a colony of red kangaroos in captivity in order to find criteria by which age could be determined. Methods of measuring young, and methods of examining teeth in the living animal are described. Serial nleasurements of head, ear, arm, hind foot, leg, and tail lengths together with body weights were taken of pouch young of known age and the results are shown as regressions against age. The method was tested by comparing actual ages of a series of pouch young of known age, which were not used when constructing the growth curves, against their ages as calculated from the growth curves. The highest percentage error (about 17 %) occurred in the estimated ages of young less than 20 days old although the actual error was only 3 days. In older young the error in. ages estimated from the growth curves was rarely greater than 5 % and usually much less. There were no differences between growth rates of males and females until they were more than one year old: The ages at which pouch, scrotum, and body hairs appeared, at which eyes and lips opened, and at which other anatomical features appeared are shown. The teeth of semi-adult and adult animals were examined regularly and the molar eruption stage noted. The results were compared with the ages of the animals. Although there was considerable variation in the time of eruption of the individual teeth it is considered that the method offers a practical means of aging kangaroos from the end of pouch life to the time of complete eruption of the last molar at the age of at least 6 years. During the periodical dental examinations the forward movement of the molars relative to the descending process of the zygoma was also noted. Correlation between molar position and age appeared to be less accurate than eruption sequence but after the eruption of the last molar it is probably the only method available for aging except a method based on tooth wear. Unfortunately, the forward movement of the molar row in the jaw slows down with advancing age. In spite of the shortcomings of molar eruption and progression as indices of age the methods based on them are the only obvious practical ones. They are of great value in field ecological studies and it is expected that continuing observations will lead to more precise correlations.

COXIELLA BURNETI IN KANGAROOS AND KANGAROO TICKS IN WESTERN QUEENSLAND

SUMMARYComplement‐fixing antibodies to Coxiella burneti were present in 23 p.c. of kangaroos collected in western Queensland, and agglutinins in 15 p.c. Red kangaroos, Megaleia rufa, showed a higher incidence of complement‐fixing antibodies (33 p.c.) than grey kangaroos, Macropus major (12 p.c.). In three areas, the incidence of complement‐fixing antibody in M. rufa was between 46 and 54 p.c.C. burneti was isolated in mice from the blood of one Macropus major.Thirteen isolations were made from nearly 3,000 ornate kangaroo ticks, Amblyomma triguttatum, collected from kangaroos, goats and sheep. The titre of infectivity of infected ticks for mice was usually in the range 10−6 to 10−9.Infection of kangaroos and A. triguttatum was found over a considerable area, between 24 and 28° S. and 144 and 149° E., in western Queensland.It thus seems probable that a natural kangaroo‐tick cycle exists. The three‐host life cycle and wide host range of this tick would allow it to spread infection to domestic animals as well as kangaroos. Infestation of sheep would bring infected ticks into contact also with workers in the sheep‐shearing industry, and was probably responsible for recent outbreaks of Q fever among them.