Distribution, Prevalence, and Epidemiology of Bovine Tuberculosis in Brushtail Possums, Trichosurus-Vulpecula, in the Hohonu Range, New-Zealand

1988 ◽  
Vol 15 (6) ◽  
pp. 651 ◽  
Author(s):  
JD Coleman
Keyword(s):  
Body Weight ◽  
Lymph Node ◽  
New Zealand ◽  
Disease Transmission ◽  
Bovine Tuberculosis ◽  
Infected Animal ◽  
Disease Prevalence ◽  
Trichosurus Vulpecula ◽  
Wide Range ◽  
Autumn And Winter

Over a 12-month period, 1467 brushtail possums were trapped and then killed or were poisoned along sampling lines on pasture-forest margins and in nearby forest. An additional 334 possums were shot on adjacent farm land. All possums were necropsied, and 141 had macroscopic lesions typical of bovine tuberculosis. Infected possums occurred most commonly in small foci of 2-5 individuals along pasture-forest margins; the furthest from pasture that an infected animal was taken was 4050 m. Lesions occurred in possums of all ages in both sexes, but disease prevalence was highest in immature males and during autumn and winter. Infected possums bred as successfully as non-infected individuals, but were of lighter body weight. Macroscopic lesions occurred in a wide range of visceral and lymph node sites. Lesions were most common in the lungs and axillary nodes, and occasionally formed open sinuses from which infected possums could shed M. bovis readily, and thus were likely to be highly infective. Evidence suggested that disease transmission occurs most frequently on pasture-forest margins, where possum numbers are greatest and possum and cattle mix most freely.

Impact of bovine tuberculosis on a population of brushtail possums (Trichosurus vulpecula Kerr) in the Orongorongo Valley, New Zealand

2004 ◽  
Vol 31 (4) ◽  
pp. 389 ◽  
Author(s):  
A. Arthur ◽  
D. Ramsey ◽  
M. Efford
Keyword(s):  
Overall Survival ◽  
New Zealand ◽  
Population Density ◽  
Bovine Tuberculosis ◽  
Local Population ◽  
Trichosurus Vulpecula ◽  
Considerable Uncertainty ◽  
Highly Sensitive ◽  
Competing Models ◽  
The Impact

Brushtail possums are the main wildlife vectors of bovine tuberculosis (Tb) in New Zealand. Possum–Tb models form the basis of possum control aimed at eradicating the disease, and yet competing models show different behaviour, and are highly sensitive to parameters about which there is considerable uncertainty. One area of great uncertainty is the impact of the disease on possum populations. We investigated the impact of Tb on a local population of brushtail possums in the Orongorongo Valley, Wellington. Bovine Tb was first detected in 1997 at one site within an intensively studied population, but has not been detected in another intensively studied population 3 km away since the early 1980s. Using a Before-After-Control-Impact (BACI) analysis, detection of Tb coincided with a 42% (95% CI = 23–56%) reduction in the odds of apparent yearly survival of a possum >17 months of age, i.e. a decrease in yearly survival from 0.85 to 0.77 in 'good' years, and a decrease from 0.71 to 0.60 in 'bad' years. This suggests that Tb had a significant impact on overall survival. However, there was no impact on local population density in September each year due to compensatory recruitment.

scholarly journals Geographic distribution of restriction types ofMycobacterium bovisisolates from brush-tailed possums (Trichosurus vulpecula) in New Zealand

1986 ◽  
Vol 96 (3) ◽  
pp. 431-438 ◽  
Author(s):  
D. M. Collins ◽  
G. W. De Lisle ◽  
D. M. Gabric
Keyword(s):  
New Zealand ◽  
High Resolution ◽  
Mycobacterium Bovis ◽  
Bovine Tuberculosis ◽  
Restriction Enzymes ◽  
Restriction Endonuclease Analysis ◽  
Trichosurus Vulpecula ◽  
Typing System ◽  
Dna Restriction ◽  
Endonuclease Analysis

SUMMARYDNA restriction endonuclease analysis was used for intra-specific typing ofMycobacterium bovisisolates from 83 brush-tailed possums (Trichosurus vulpecula) obtained between 1982 and 1984 from the three major regions in New Zealand with endemic bovine tuberculosis. All the isolates were found to be genetically very similar. Differentiation of the isolates into 33 restriction types was achieved by using high-resolution electrophoresis and the combined results from separate digestions with the restriction enzymesBstEII,PvuII andBclI. The typing system was entirely reproducible. Isolates of the same type were usually found in adjacent localities and were always limited to one of the three major regions. In some cases, isolates of the same type were found in both 1982 and 1984. The phenotypic significance of the small genetic differences identified between different isolates is unknown. The typing system will be useful for monitoring the transmission ofM. bovisto other species and the future spread of differentM. bovistypes through possum populations.

Restricting the movements of brushtail possums (Trichosurus vulpecula) on farmland with electric fencing

1992 ◽  
Vol 19 (1) ◽  
pp. 47 ◽  
Author(s):  
PE Cown ◽  
DS Rhodes
Keyword(s):  
New Zealand ◽  
Bovine Tuberculosis ◽  
Trichosurus Vulpecula ◽  
Electric Fence ◽  
Electric Fencing

A trial was conducted to test whether an electric fence would limit local movements of brushtail possums (Trichosurus vulpecula) on farmland in the central North I. of New Zealand. If effective, such a system could be used to reduce possum and cattle interactions and the spread of bovine tuberculosis. A 3-km-long, 9-strand electric fence was erected from ridge to ridge across a valley catchment of about 160 ha. Possums were live-trapped and released at bush patches within the study area and in open areas immediately adjacent to the electric fence. Only about 30% of possums caught at local bush patches were ever retrapped at the fence, and most were caught only once at the fence. About a third of possums caught at the fence were trapped at least once on both sides of the fence. The electric fence reduced possum movements through the fenced area by about 60-80%. Most possums trapped at the fence had come from bush patches within 200 m of the fence. When the fence was switched off, possum captures on the outside increased rapidly. The effectiveness of the fence was reduced because of frequent voltage reduction by earthing from a wide variety of causes, and because possums learned to move around the ends of the fence and the fences along the farm roads. Improvements to fence design are discussed.

A live-trapping of Australian brush-tailed possums, Trichosurus vulpecula (Kerr), in the Orongorongo Valley, Wellington, New Zealand

1973 ◽  
Vol 21 (1) ◽  
pp. 75 ◽  
Author(s):  
MC Crawley
Keyword(s):  
New Zealand ◽  
Home Ranges ◽  
Trichosurus Vulpecula ◽  
Adult Males ◽  
Adult Females ◽  
Capture Site ◽  
Live Trapping ◽  
Indigenous Forest ◽  
Autumn And Winter ◽  
Initial Capture

A live-trapping study of a population of Australian brush-tailed possums, Trichosurus vulpecula (Kerr), in indigenous forest of the Orongorongo Valley, Wellington, N.Z., was carried out from March 1966 to November 1968. In 14 ha of podocarp-mixed broadleaf forest, 301 possums (150; 151) were individually marked and repeatedly captured in a series of trapping periods. The population comprised residents and transients of both sexes with sub- adults forming the bulk of the latter, particularly in spring. The estimated population density varied from 10.6 per ha in November 1966 to 6.4 per ha in August 1968. There was one well-defined season of births each autumn and a few births in winter. On average, 73% (67-92%) of mature females produced pouch young each year. Females resident throughout the study had the highest breeding success (79%). Achievement of sexual maturity was delayed; no females bred until they were 2 yr old, and some not even at 3 yr. Losses occurred at all stages of the life history and averaged 62% between the pouch young and subadult stages; thus only 28 subadults per 100 females were recruited. Adult losses averaged 26% per annum. Adult males (mean weight 2.46 kg) were heavier than adult females (2.33 kg). Weights varied seasonally, with males heaviest in summer and lightest in spring, and females heaviest in winter and lightest in summer. Possums of both sexes were rather sedentary, with males (95% of captures within 115 m of the initial capture site) being less so than females (95 % of captures within 90 m of the initial capture site). More than half of the captures (55% for males, 62% for females) were made within 30 m of the site of initial capture. Males moved farther in autumn and summer than in other seasons, while females did so in autumn and winter. Subadults were apparently more sedentary than adults. Home ranges of adult males (mean 0.81 ha) were significantly larger than those of adult females (0.46 ha). Considerable overlapping of the ranges of both sexes occurred, and territorial behaviour was not conspicuous. The dispersion of the population remained the same throughout the study although the component individuals changed. The results of the present study are compared with those of similar studies in New Zealand and Australia, and the dynamics of the Orongorongo Valley possum population are discussed with reference to variable rates of reproduction and mortality.

A new trap-catch index of patchiness in animal distribution

2004 ◽  
Vol 31 (4) ◽  
pp. 433 ◽  
Author(s):  
J. A. Brown ◽  
R. J. McAuliffe ◽  
G. J. Hickling
Keyword(s):  
New Zealand ◽  
Species Distribution ◽  
Bovine Tuberculosis ◽  
Trichosurus Vulpecula ◽  
Trap Catch ◽  
Animal Distribution ◽  
Wildlife Species ◽  
Wildlife Populations ◽  
Catch Rates ◽  
Index Of Abundance

Researchers and managers commonly use catch rates on trap-transects as an index of abundance for trappable wildlife species. We describe a method whereby the data collected from such surveys can be further analysed to obtain information on the patchiness of the trapped species' distribution on those transects. For certain applications, such as the management of wildlife disease, the index is likely to have significant advantages over traditional indices of spatial aggregation. One such situation is the management of brushtail possums (Trichosurus vulpecula) in New Zealand to inhibit the spread of bovine tuberculosis within their populations. Trap-catch data from a possum survey are used to illustrate the proposed method, and the potential for application of such monitoring to wildlife populations is discussed.

Investigating brushtail possum (Trichosurus vulpecula) home-range size determinants in a New Zealand native forest

2017 ◽  
Vol 44 (4) ◽  
pp. 316 ◽  
Author(s):  
K. S. Richardson ◽  
C. Rouco ◽  
C. Jewell ◽  
N. P. French ◽  
B. M. Buddle ◽  
...  
Keyword(s):  
New Zealand ◽  
Population Density ◽  
Home Range ◽  
Disease Transmission ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Native Forest ◽  
Trichosurus Vulpecula ◽  
Age And Sex

Context The Australian brushtail possums (Trichosurus vulpecula) introduction to New Zealand has exacted a heavy toll on native biodiversity and presented the country with its greatest wildlife reservoir host for bovine tuberculosis (TB). Management efforts to control both possums and TB have been ongoing for decades, and the biology of possums has been studied extensively in Australia and New Zealand over the past 50 years; however, we still do not have a clear understanding of its home-range dynamics. Aims To investigate determinants of home range size by using a uniquely large dataset in the Orongorongo Valley, a highly monitored research area in New Zealand and compare our findings with those of other studies. Methods Possum density was estimated, for subpopulations on four 13-ha cage-trap grids, by the spatially explicit capture–mark–recapture analysis of trapping data from 10 consecutive months. Home ranges were estimated from trap locations using a 100% minimum convex polygon (MCP) method for 348 individuals and analysed with respect to grid, age and sex. Key results Mean (standard error) possum density, estimated as 4.87 (0.19), 6.92 (0.29), 4.08 (0.21) and 4.20 (0.19) ha–1 for the four grids, was significantly negatively correlated with mean MCP home-range size. Grid, age, and the interaction of age and sex were significantly related to home-range size. Older possums had larger home ranges than did younger possums. When ‘juvenile cohort’ and ‘adult cohort’ data were analysed separately, to investigate the significant interaction, males in the ‘adult cohort’ had significantly larger home ranges than did females, with the grid effect still being apparent, whereas neither sex nor grid effects were significant for the ‘juvenile cohort’. Conclusions Our findings indicate that, in addition to density, age and sex are likely to be consistent determinants of possum home-range size, but their influences may be masked in some studies by the complexity of wild-population dynamics. Implications Our findings have strong implications regarding both disease transmission among possums and possum management. The fact that adult males occupy larger home ranges and the understanding that possum home range increases as population density decreases are an indication that males may be the primary drivers of disease transmission in possum populations. The understanding that possum home range increases as population density decreases could be a direct reflection of the ability of TB to persist in the wild that counteracts current management procedures. If individuals, and particularly males, infected with TB can withstand control measures, their ensuing home-range expansion will result in possible bacteria spread in both the expanded area of habitation and new individuals becoming subjected to infection (both immigrant possums and other control survivors). Therefore, managers should consider potential approaches for luring possum males in control operations.

Den Sites of Possums, Trichosurus-Vulpecula, and Frequency of Use in Mixed Hardwood Forest in Westland, New-Zealand

1987 ◽  
Vol 14 (3) ◽  
pp. 285 ◽  
Author(s):  
WQ Green ◽  
JD Coleman
Keyword(s):  
New Zealand ◽  
Bovine Tuberculosis ◽  
Ground Level ◽  
Root Systems ◽  
Hardwood Forest ◽  
Trichosurus Vulpecula ◽  
Frequency Of Use ◽  
Below Ground ◽  
Males And Females

Forty-seven common brushtail possums, Trichosurus vulpecula, were radiotracked to 282 dens on 546 occasions. Just over half of all dens were in living trees; the remainder were evenly distributed between dead standing stems (including short stumps) and logs, with a few (3%) in banks and rock fissures. Of all the den entrances, 73% were at, or below, ground level amongst root systems or in logs. Although dead standing stems (over 25 cm d.b.h.) made up only 4% of standing stems in forest below 500 m altitude, they contained 41% of the dens. Each possum probably used between 10 and 15 dens each year. There were no differences in den choice and frequency of use between mature males and females. Den choice by matures and immatures was similar, but mature possums used dens in 'dead' sites more than did immatures. The implications of dens in the transmission of bovine tuberculosis are discussed.

Reduced spillover transmission ofMycobacterium bovisto feral pigs (Sus scofa) following population control of brushtail possums (Trichosurus vulpecula)

2011 ◽  
Vol 140 (6) ◽  
pp. 1036-1047 ◽  
Author(s):  
G. NUGENT ◽  
J. WHITFORD ◽  
I. J. YOCKNEY ◽  
M. L. CROSS
Keyword(s):  
New Zealand ◽  
Disease Transmission ◽  
Population Control ◽  
Mammalian Species ◽  
Oral Route ◽  
Poison Control ◽  
Brushtail Possum ◽  
Infection Prevalence ◽  
Trichosurus Vulpecula ◽  
Feral Pigs

SUMMARYIn New Zealand, bovine tuberculosis (bTB) is present in domestic cattle and deer herds primarily as the result of on-going disease transmission from the primary wildlife host, the brushtail possum (Trichosurus vulpecula). However, bTB is also present in other introduced free-ranging mammalian species. Between 1996 and 2007, we conducted a series of studies to determine whether poison control of possum populations would have any effect on the prevalence ofMycobacterium bovisinfection in sympatric feral pigs (Sus scrofa). We compared trends in the prevalence of bTB infection in feral pigs in six study areas: possum numbers were reduced in three areas, but not in the other three, effectively providing a thrice-replicated before-after-control-intervention design. Before possum control, the overall prevalence of culture-confirmedM. bovisinfection in feral pigs was 16·7–94·4%, depending on area. Infection prevalence varied little between genders but did vary with age, increasing during the first 2–3 years of life but then declining in older pigs. In the areas in which possum control was applied,M. bovisprevalence in feral pigs fell to near zero within 2–3 years, provided control was applied successfully at the whole-landscape scale. In contrast, prevalence changed much less or not at all in the areas with no possum control. We conclude that feral pigs in New Zealand acquireM. bovisinfection mainly by inter-species transmission from possums, but then rarely pass the disease on to other pigs and are end hosts. This is in contrast to the purported role of pigs as bTB maintenance hosts in other countries, and we suggest the difference in host status may reflect differences in the relative importance of the oral route of infection in different environments. Despite harbouringM. bovisinfection for a number of years, pigs in New Zealand do not sustain bTB independently, but are good sentinels for disease prevalence in possum populations.

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