Hystrix Africaeaustralis Research Articles

Demography of a Cape porcupine, Hystrix africaeaustralis, population

The Cape porcupine is a large (12.0 kg), nocturnal hystricomorph rodent and widely distributed throughout southern Africa. The present paper examines age‐specific survival, mortality and fecundity rates in a population, evaluates the roles of possible density‐dependent changes of population parameters in the regulation of porcupine numbers, and describes the life history strategy of the species. The study is based on data sets obtained from animals collected during 1977/78 and during 1981/82. Changes in demographic characteristics are ascribed to an artificial reduction in density, resulting in the relaxation of social factors inhibiting reproduction in young adults.

Pre‐ and postnatal growth of the Cape porcupine Hystrix africaeaustratis

Pre‐ and postnatal growth of the Cape porcupine Hystrix africaeaustralis is evaluated by means of the Huggett & Widdas equation, a modification thereof, and the von Bertalanffy equation. Specific foetal growth velocity for the Cape porcupine is higher than that recorded for most other hystricomorph rodents, but similar to that recorded for large‐bodied rodents of the same group. Relatively high foetal growth velocity in porcupines is ascribed to their relatively short gestation period, the latter being longer than expected for mammals of equal size, but shorter than expected for a hystricomorph rodent.Postnatal growth is nearly linear up to the age of 20 weeks and asymptotic body weight is attained at an age of 52 weeks, this coinciding with the observed age at sexual maturity. Growth rates of males and females are similar. Their high rate of postnatal growth and development results in an extended reproductive period, thereby enhancing individual reproductive values by counteracting the effects of seasonal breeding and small litter size.

Reproductive biology of the male Cape porcupine, Hystrix africaeaustralis.

The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8-18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23-30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.

Functional anatomy of the ovaries of pregnant and lactating Cape porcupines, Hystrix africaeaustralis.

The constituent cell types of the ovary of the porcupine were similar to those of New World hystricomorph rodents and accessory corpora lutea and luteal bodies were formed through the luteinization of the membrana granulosa or theca interna of antral follicles. All luteal bodies were histologically similar. The total volume of luteal tissue per female was not affected by fetal age and was unrelated to circulating concentrations of maternal plasma progesterone. Maternal plasma progesterone concentrations were correlated with fetal age. Follicular activity occurred throughout pregnancy but was not affected by fetal age or related to circulating values of oestradiol-17 beta. The formation of accessory corpora lutea during pregnancy is regarded as important in supplementing progesterone during pregnancy.

Osteophagia in the Cape porcupineHystrix africaeaustralis

Two groups of porcupines (Hystrix africaeaustralis) were maintained for a period of 23 weeks on a diet containing high levels of Ca2* and PO4. Parallel to this another two groups were maintained on a diet containing low levels of these minerals. All groups were provided with defatted bovine bones during weeks 18 to 23 of the experiment. Plasma Ca2+ and P04 levels were determined at intervals throughout the experiment. The amount of osteophagia that occurred was determined by weighing the bones at two-weekly intervals. No significant differences in the plasma Ca2+ and P04 levels of the porcupines on the high diet and those on the low diet were detected. Osteophagia by porcupines on the low diet was twice that of porcupines on the high diet.

Sexual behavior of the female porcupine Hystrix africaeaustralis

Porcupines are sexually active throughout the estrous cycle, and sexual behavior is not affected by the reproductive status and hormonal milieu of females. Increased female-male interactions during estrus are the only indications of behavioral changes during estrus. The lack of aggression shown by females to known males as opposed to aggression shown to strange males, the greater interest shown by males toward certain females, and the superior breeding success of these females suggest a pair-bonding mating system. Limited changes in female receptivity throughout the cycle might be of importance in maintaining the pair-bond.

Circulating progesterone and oestradiol-17 beta concentrations in cyclic Cape porcupines, Hystrix africaeaustralis.

The general pattern of steroid secretion during the 30-day oestrous cycle of the Cape porcupine is that of a surge (25-176 pg/ml) in oestradiol-17 beta secretion at the time of perforation of the vaginal closure membrane, followed by an increase in progesterone concentrations, the latter attaining peak values (mean 5.9 +/- 2.1 ng/ml) 8-19 days (13.8 +/- 2.8 days) after vaginal opening. Copulation occurred after the oestradiol-17 beta surge and the length of the luteal phase of the cycle varied from 21 to 35 days (29.3 +/- 4.7 days), this representing 93% of the length of the cycle. Perforation of the vaginal closure membrane was not always accompanied by an increase in oestradiol-17 beta levels and some instances (19%) of vaginal opening were not followed by an increase in progesterone secretion. The hormonal characteristics of the oestrous cycle of females housed with vasectomized males were similar to those of females housed with intact males.

Aspects of the ecology and the behaviour of the Leopard <i>Panthera pardus </i>in the Kalahari desert

Tracking in sand revealed data on hunting and kill rates, range, movements, activity, cover and water use, reproduction and interactions with other carnivores, by the leopard Panthera pardus in the Kalahari Gemsbok National Park. For leopards in the interior, 812,5 km of tracks were followed for 54 days, and 205,1 km for 15 days for females with cubs. In the Nossob riverbed 30,2 km of tracks were folowed in eight days. Medium-sized mammals featured prominently in the diet of all leopards, with prey used influenced by habitat type. Leopards in the interior moved greater distances than those in the Nossob riverbed. Leopards rested frequently at the onset and end of activity and used dense vegetation and aardvark Orycteropus afer and porcupine Hystrix africaeaustralis burrows as daytime cover. Leopards are independent of water, and females apparently have no definite breeding season. Lions Panthera leo dominate leopards, but the outcome of leopard/spotted hyaena Crocuta crocuta encounters depend on the size of the leopard and the number of hyaenas in the pack. Leopards in the Kalahari Desert are opportunists which occupy this harsh envi- ronment successfully.

Adaptations in three species of large mammals (Antidorcas marsupialis, Hystrix africaeaustralis, Hyaena brunnea)to arid environments

Adaptations in the springbok Antidorcas marsupialis, porcupine Hystrix africaeaustralis and brown hyaena Hyaena brunnea to arid environments are discussed. Springbok evolved in the arid west of southern Africa. The proximate factor triggering the onset of oestrus is improved nutrition following rainfall and adaptations have evolved to ensure the success of year-round opportunistic breeding. The porcupine can also breed throughout the year but in the Karoo with its dry cold winters, young are only born in warmer wetter months. Following a gestation period of 93 days and lactation anoestrus lasting 120 days, the female porcupine has evolved a special adaptation whereby she will only conceive during the third to seventh oestrous cycle following the end of lactation. This period may be shortened or lengthened thereby enabling her to adjust to climatic conditions in an unpredictable arid environment. The brown hyaena is well adapted to living along the Namib coastal region where severe extremes in temperature occur and bitterly cold south-west winds sweep along the coastal strip. Long hair and pilo-erection probably assist brown hyaenas in adjusting to these adverse climatic conditions. The spotted hyaena, Crocuta crocuta, does not occur along the coast. Morphological differences between the two species are considered in the light of climatic differences between the coastal and interior desert regions.

Two new parsitic mites (Acarina) from the South African porcupine.

Three new parasitic mites—a fur mite, a mange mite, and a nasal mite—were recovered recently on dissolving the head of a specimen of Hystrix africaeaustralis Peters, the South African porcupine, in a solution of potassium hydroxide. The fur mite is being studied by Dr R. F. Lawrence of the Natal Museum. The other two species, the mange mite, belonging to the genus Psorergates Tyrrell, and the nasal mite, belonging to the genus Rhinophaga Fain, are described below.

Notice of the Gypsum of Plaister Cove in the Strait of Canseau

The Strait of Canseau is a narrow passage fourteen miles in length, separating Nova Scotia proper from Cape Breton Island. On the Nova Scotia side it affords an imperfect section of carboniferous strata, interrupted near the middle of the Strait by a mass of reddish syenite and disturbed slates, forming the promontory of Cape Porcupine, which is the abrupt termination of a hilly range extending far into Nova Scotia. On the Cape Breton side, the section exhibits carboniferous rocks; and nearly opposite Cape Porcupine is the small indentation, whose name of Plaister Cove is derived from the mass of gypsum to which the following remarks refer. The gypsum of Plaister Cove, like other large masses of that rock occurring in this province, belongs to the lower part of the carboniferous system, and is associated with limestone and marls. The structure and accompaniments of the bed are, however, more perfectly exposed than in most of the larger masses of gypsum which I have examined. For this reason I shall endeavour, with the aid of the accompanying section fig. 1, and specimens, to give a somewhat detailed view of the appearances presented at this place, with the object of recording facts which may be useful in explaining the origin of the great beds of gypsum. (1). At McMillan's Point, about three-quarters of a mile north of the Cove, are thick beds of grey conglomerate, in a vertical position. These beds form the base of the carboniferous system in this district; and, at