SMALL MAMMALS OF THE MITCHELL PLATEAU REGION, KIMBERLEY, WESTERN-AUSTRALIA

This paper presents the background for a series on the biology of small mammals in the Mitchell Plateau region, an area characterised by a wet-dry tropical climate. From June 1981 to December 1982, 19 species of small terrestrial mammals were captured at Mitchell Plateau. Of 17 species captured on eight mark-release grids, 13 clustered into four significant groups which reflected the major habitats of the region: (1) Sminthopsis virginiae, Leggadina sp. and Pseudomys nanus in riparian and plateau escarpment sites; (2) Phascogale tapoatafa, Trichosurus arnhemensis and Pseudomys laborifex in plateau open forest; (3) Conilurus penicillatus and Mesembriomys macrurus in open woodland and coastal mosaics; (4) the commoner species Dasyurus hallucatus, Isoodon macrourus, Melomys sp. cf. burtoni, Zyzomys argurus and S. woodwardi in an array of habitats. Rattus tunneyi, Pseudantechinus sp., Wyulda squamicaudata and Planigale maculata did not cluster significantly with other species. Two species, Pseudomys delicatulus and Mesembriomys gouldii, were represented by single specimens captured outside the capture-mark-release grids, in sandstone and plateau woodland respectively. Open forests, particularly on the lateritic plateau surfaces, had the richest and most diverse mammal assemblage over the entire study period. The vine thickets and sandstone contained relatively stable populations of fewer species, and several habitats had seasonally variable populations and species

The biology of the northern brown bandicoot, Isoodon macrourus (Marsupialia: Peramelidae) at Mitchell Plateau, Western Australia

Breeding, population dynamics and seasonal changes in physical and physiological parameters were examined in Isoodon macrourus at the Mitchell Plateau between September 1981 and November 1982. Females gave birth to litters of 2.5 ± 1.0 (16) young between September and April. They produced up to three litters in a breeding season with an average interval between successive litters of 89.5 (51-108) days. Adult testosterone levels and scrota1 size began to increase in July and peaked in September 1982. The overall ratio of adult males to adult females was 1:0.54; it was 1:0.80 for pouch young. Females were more frequently trapped on sequential trips than were males. Density on the grids increased towards the end of the dry season (July and September 1982)-mostly as a result of increased numbers of females. Adult males and females moving onto the grids during the dry season tended to select different habitats. Adult males moved significantly more in the wet season (September 1981, January and April) than they did in the dry season (July and September 1982); they also moved significantly more than adult females in the wet season. Seasonal variations were recorded for most physical and physiological parameters. During the wet period from September 1981 to January 1982, body weight, haemoglobin, haematocrit and total plasma albumin declined, while total white blood cells and proportion of lymphocytes to granular leucocytes rose. This indicated that this period was one of change in condition for this species. Compared to adult females, adult males were larger and heavier, had higher values of haematocrit and lymphocytes, and lower values of granular leucocytes, free steroids, CBGBd and albumin bound corticosteroid. There was considerable between-year variability in condition of individuals and both sexes differed significantly in September 1981 and 1982 in their weight, haematocrit, total white blood cells, granular leucocytes, MCBC and testosterone. Individuals at disparate localities at the Mitchell Plateau showed similar seasonal physiological and physical responses, except for one grid where they were heavier.C. Kemper, D. J. Kitchener, W. F. Humphreys, R. A. How, L. H. Schmitt and A. Bradle

ECOLOGY AND PHYSIOLOGY OF THE NORTHERN QUOLL, DASYURUS-HALLUCATUS (MARSUPIALIA, DASYURIDAE), AT MITCHELL PLATEAU, KIMBERLEY, WESTERN-AUSTRALIA

Breeding, population dynamics and seasonal changes in physical and physiological parameters were examined in the northern quoll (Dasyurus hallucatus) at Mitchell Plateau, Western Australia, between September 1981 and November 1982. Females gave birth to a single litter of young in July or August. Births were earlier on near‐coastal sites than on inland sites. Litter size was greater on inland sites and litter size differed between years. By September all females were either carrying pouch young or were lactating. Lactation ceased by April. Testosterone levels in males peaked in July. There were significantly more male than female pouch young. However, in only one grid was the adult sex ratio different from parity, with an excess of females in September 1981 and 1982. Embryonic mortality was > 53% but loss of pouch young was small. Although males and females moved similar distances between successive recaptures, the extent of movement varied seasonally, being greatest in September. Males were generally larger and heavier than females. Seasonal variations were recorded for most physical and physiological parameters. The most pronounced changes occurred towards the end of the dry season (July to September) for both males and females. Over this period there was a significant decline in weight (males), haematocrit (males), plasma albumin (males) and leucocytes (both males and females) and significant elevations in values of haemoglobin and both free and protein‐bound Cortisol in both males and females. Few males survived the post‐mating period from July to September. They appeared to decline in condition over this period more markedly than females: they lost more weight, their haematocrit and plasma albumin values declined to a greater extent, and they were more heavily infected with lice (Boopia uncinata). Males with lower testosterone and higher free and protein‐bound Cortisol had increased prospects of surviving the breeding season, which suggests that it is the dominant males that are less likely to survive the breeding season. Individuals in the three major populations at Mitchell Plateau differed greatly in their physiological values. The high‐density population in a sandstone area had intermediate levels of free Cortisol and higher haematocrit values than both the other populations, and higher levels of haemoglobin than the population on laterite substratum

The natural history of Salmonellae in mammals of the tropical Kimberley region, Western Australia

Screening for salmonellae was conducted on five occasions within a year on mammals from many different habitats in the Mitchell Plateau area of the tropical Kimberley Division of Western Australia. Some data were obtained from reptiles. Forty-two Salmonella serotypes, two Edwardsiella and one Arizona strain were isolated. Marsupials harbour significantly more (1.6 times) Salmonella serotypes than eutherians. Eleven Salmonella serotypes and one Arizona strain were isolated from reptiles. All Salmonella strains were common to the mammalian species. Varanid lizards showed higher prevalence of salmonellae than other reptilian families. Top carnivores (reptile and marsupial) show relatively high numbers of Salmonella serotypes and prevalence levels. Four mammalian species showed marked seasonal variation in the prevalence of salmonellae and three species in the number of serotypes isolated. Pooled mammalian community data for individual survey sites showed similar seasonal variation which reflected the pattern seen in the predominant host species on the site. Significant seasonal variation in the prevalence of salmonella was concurrent in three of the host species showing maximum prevalence in the wet season (January-summer) followed by a declining prevalence to the end of the dry season (October). Prevalence in the fourth species was also high in January, but continued to increase after the wet season (April) before decreasing as the dry season progressed (July and October). Dendrograms of association showed that the salmonella 'community' does not associate according to any systematic category of the hosts and no evidence of such communities was found using other criteria, such as site or coastal vs inland locations. No evidence was found for host or site specificity of given serotypes. Multiple serotype infections by salmonella were common, with up to three present in mammals and reptiles, and they occurred at random. When hosts in coastal habitats were compared with those in inland sites higher, lower or no difference was found in the prevalence of salmonella, depending upon which host was considered. Sites with similar mammals and vegetation sometimes showed marked differences in salmonella prevalence at a given time. Generally a given Salmonella serotype was lost from the host within ≃ 3 months. Surveys for salmonellae should be designed to include a range of species, replicated vegetation types and, especially, be repeated in several seasons. Edwardsiella tarda was isolated twice from a carnivorous marsupial

Long-term trends and a risk analysis of cetacean entanglements and bycatch in fisheries gear in Australian waters

Assessments of fisheries interactions with non-target species are crucial for quantifying anthropogenic threatening processes and informing management action. We perform the first multi-jurisdictional analysis of spatial and temporal trends, data gaps and risk assessment of cetacean interactions with fisheries gear for the entire Australian Exclusive Economic Zone. Bycatch and entanglement records dating from 1887 to 2016 were collected from across Australia (n=1987). Since 2000 there has been a substantial increase in reported bycatch and entanglements and this is likely the result of improved monitoring or recording by some jurisdictions and fisheries as well as changing fishing effort, combined with continuing recovery of baleen whale populations after cessation of commercial whaling. A minimum of 27 cetacean species were recorded entangled, with over 30% of records involving interactions with threatened, vulnerable or endangered species. Three times the number of dolphins and toothed whales were recorded entangled compared to baleen whales. Inshore dolphins were assessed as most vulnerable to population decline as a result of entanglements, though humpback whales, common bottlenose dolphins, and short-beaked common dolphins were the most frequently caught. Only one-quarter of animals were reported to have survived entanglement, either through intervention or self-release from fishing gear. Spatial mapping of the records highlighted entanglement hotspots along the east and west coast of the continent, regions where high human population density, high fishing effort, and high density of migrating humpback whales all occur, augmented by high captures of dolphins in shark control gear along the east coast. Areas of few entanglements were more remote, highlighting substantial bias in entanglement reporting. Our gap analysis identified discrepancies in data quality and recording consistency both within and between jurisdictions. Disparities in the types of fisheries data provided for the analysis by different state agencies limited our ability to compile bycatch data in a representative and systematic way. This research highlights the need for improved standardised data recording and reporting by all agencies, and compulsory sharing of detailed fisheries interaction and effort data, as this would increase the value of entanglement and bycatch data as a conservation and management tool