Effects of predation and rabbit haemorrhagic disease on population dynamics of rabbits (Oryctolagus cuniculus) in North Canterbury, New Zealand

2002 ◽  
Vol 29 (6) ◽  
pp. 627 ◽  
Author(s):  
Ben Reddiex ◽  
Graham J. Hickling ◽  
Grant L. Norbury ◽  
Chris M. Frampton
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Breeding Season ◽  
Predator Control ◽  
Zealand Rabbit ◽  
Rabbit Haemorrhagic Disease ◽  
Low Levels ◽  
Haemorrhagic Disease ◽  
The Impact ◽  
Very High

The impact of predation and rabbit haemorrhagic disease (RHD) on population dynamics of rabbits, and the survival of juvenile rabbits, was investigated between July 1999 and March 2000 in North Canterbury, New Zealand. Rabbit abundance and pre- and post-emergent rabbit mortality were monitored on four sites, two of which were subject to predator control. RHD spread naturally through all sites from late November to early December. Rabbit densities declined on all sites, but after the RHD epidemic, declines were significantly greater where populations of predators had not been controlled. Survival of rabbit nestlings was lower where predators were not controlled. All post-emergent radio-collared rabbits died at sites where predators were not controlled, whereas 18% of those collared at sites where predators were controlled survived to maturity. In contrast to the results from previous studies, rabbits born at the start of the breeding season had very high rates of post-emergent mortality, as they appeared to be susceptible to the RHD virus later in the breeding season. The age at which juvenile rabbits become susceptible to RHD, the timing of RHD epidemics, and the abundance of predators are likely to be important in determining survival of juvenile rabbits. This study demonstrates that predation can reduce rabbit populations to low levels, but only in combination with other factors, in this case RHD.

Impact of rabbit haemorrhagic disease on introduced predators in the Flinders Ranges, South Australia

2002 ◽  
Vol 29 (6) ◽  
pp. 615 ◽  
Author(s):  
C. Holden ◽  
G. Mutze
Keyword(s):  
Population Dynamics ◽  
Physical Condition ◽  
South Australia ◽  
Feral Cats ◽  
Flinders Ranges ◽  
Introduced Predators ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease ◽  
The Impact

The impact of rabbit haemorrhagic disease (RHD) on the population dynamics and diet of foxes and feral cats was studied in the Flinders Ranges, South Australia. Populations of both foxes and cats decreased substantially some 6–10 months after the advent of RHD, when rabbit numbers were reduced by 85%. The diet of foxes changed as a result of reduced rabbit numbers, with much less rabbit and more invertebrates and carrion being eaten. The physical condition of foxes showed little change after RHD. The diet of cats did not change markedly, but their physical condition was substantially poorer than before RHD. Total predation on native fauna is considered to have decreased after RHD.

The reintroduction, and subsequent impact, of rabbit haemorrhagic disease virus in a population of wild rabbits in south-western Australia

2005 ◽  
Vol 32 (2) ◽  
pp. 139 ◽  
Author(s):  
John S. Bruce ◽  
Laurie E. Twigg
Keyword(s):  
Disease Virus ◽  
Western Australia ◽  
Morbidity Rate ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Rabbit Population ◽  
Rabbit Haemorrhagic Disease ◽  
Deliberate Release ◽  
Haemorrhagic Disease ◽  
The Impact ◽  
Variable Impact

The natural arrival of rabbit haemorrhagic disease virus (RHDV) in south-western Australia in September 1996 resulted in a reduction in rabbit numbers of ~65% (~90% morbidity, with ~72% mortality of infected rabbits). As no signs of the disease (clinical or serological) were seen over the next two years, and as rabbit numbers over the last 12-month monitoring period at the site were similar to those observed before the natural 1996 RHDV epizootic (i.e. pre-RHD), RHDV was deliberately reintroduced into this rabbit population in April 1999 (autumn). Seven RHDV-inoculated rabbits were released prior to the main breeding season when <3% of sampled rabbits (n = 118) were seropositive for RHDV antibodies. Following the deliberate release, the overall decline in rabbit numbers (68%) was comparable to that seen during the natural 1996 epizootic. However, on the basis of the observed changes in rabbit numbers, and in their serology, the impact of the deliberate RHDV release appeared to be more variable across the six trapping areas than was seen during the natural 1996 spring epizootic. The reductions in rabbit numbers on these areas 6–8 weeks after RHDV-release ranged from 55% to 90%. The serology of the surviving rabbits on the trapping areas was also variable over this period, with the proportion of seropositive rabbits ranging from 5% to 90%. Overall, only 15% of the surviving rabbit population showed evidence of recent challenge by RHDV, giving a morbidity rate of 73% 8 weeks after the release. However, over 90% of infected rabbits died. This provides further evidence that some rabbits remained un-challenged by RHDV for up to 8 weeks after its release. The variable impact of the April 1999 release may have been partially caused by the observed differences in abundance of insect vectors, and/or an apparent increase in the incidence of non-virulent RHDV in the months preceding the release.

scholarly journals Rabbit haemorrhagic disease: the new scourge of Oryctolagus cuniculus

1997 ◽  
Vol 31 (1) ◽  
pp. 33-44 ◽  
Author(s):  
David Chasey
Keyword(s):  
Incubation Period ◽  
Oryctolagus Cuniculus ◽  
Accidental Release ◽  
Domestic Rabbit ◽  
Rabbit Haemorrhagic Disease ◽  
Subsequent Exposure ◽  
Haemorrhagic Disease ◽  
Very High ◽  
Infectious Condition ◽  
Important Disease

A new, widespread and important disease of rabbits, rabbit haemorrhagic disease (RHD), is concisely reviewed and discussed. RHD is an acute, infectious condition of adult rabbits and morbidity and mortality, after a relatively short incubation period, can be very high. The disease appears typically as a necrotizing hepatitis with associated haemorrhaging, and death occurs as a result of generalized organ dysfunction. RHD is caused by a calicivirus, antigenically related to a similar virus found in brown hares but distinct from other known caliciviruses, and is spread to susceptible rabbits by a number of routes and vectors. The disease is easily identified and can be effectively controlled in commercial and domestic rabbit populations by slaughter and vaccination regimes. The occurrence of pre-existing cross-reacting antibody in a proportion of rabbits unchallenged by the disease implies the presence of non-pathogenic strains of the virus. This antibody protects against disease on subsequent exposure to RHD. Uniquely, pre-existing antibody does not occur in rabbits in Australia where, after accidental release, the virus is currently spreading rapidly.

Corrigendum to: The impact of rabbit haemorrhagic disease on wild rabbit (Oryctolagus cuniculus) populations in Queensland

2004 ◽  
Vol 31 (6) ◽  
pp. 651
Author(s):  
G. Story ◽  
J. Scanlan ◽  
R. Palmer ◽  
D. Berman
Keyword(s):  
Biological Control Agent ◽  
South Australia ◽  
Control Agent ◽  
Wild Rabbit ◽  
Isolated Populations ◽  
Rabbit Haemorrhagic Disease ◽  
Northern Edge ◽  
The Mean ◽  
Haemorrhagic Disease ◽  
The Impact

Rabbit haemorrhagic disease virus (RHDV) escaped from quarantine facilities on Wardang Island in September 1995 and spread through South Australia to Queensland by December 1995. To determine the impact of this biological control agent on wild rabbit populations in Queensland, shot sample and spotlight count data were collected at six sites. RHDV spread across Queensland from the south-west to the east at a rate of at least 91 km month–1 between October 1995 and October 1996. The initial impact on rabbit density appeared highly variable, with an increase of 81% (255 ± 79 (s.e.) to 385 ± 73 rabbits km–2) at one site and a decrease of 83% (129 ± 27 to 22 ± 18 rabbits km–2) at another during the first outbreak. However, after 30 months of RHDV activity, counts were at least 90% below counts conducted before RHDV arrived. Using a population model to account for environmental conditions, the mean suppression of rabbit density caused by rabbit haemorrhagic disease (RHD) was estimated to be 74% (ranging from 43% to 94% between sites). No outbreaks were observed when the density of susceptible rabbits was lower than 12 km–2. Where rabbit density remains low for long periods RHDV may not persist. This is perhaps most likely to occur in the isolated populations towards the northern edge of the range of rabbits in Australia. RHDV may have to be reintroduced into these populations. Further south in areas more suitable for rabbits, RHDV is more likely to persist, resulting in a high density of immune rabbits. In such areas conventional control techniques may be more important to enhance the influence of RHD.

Multiple warren use by subadult wild rabbits, Oryctolagus cuniculus, and its implications for disease transmission

2017 ◽  
Vol 44 (7) ◽  
pp. 582 ◽  
Author(s):  
Scott Jennings ◽  
Gregory Mutze
Keyword(s):  
Population Density ◽  
Breeding Season ◽  
Disease Transmission ◽  
Critical Role ◽  
Late Summer ◽  
Adult Size ◽  
Contact Rates ◽  
Rabbit Haemorrhagic Disease ◽  
European Rabbits ◽  
Haemorrhagic Disease

Context Contact rates are a key determinant of disease transmission. Territorial behaviour has generally been considered to limit contact between European rabbits occupying different warrens, particularly during the breeding season. Aims We investigated warren use by subadult rabbits during a period of low population density to determine their potential role in transmission of rabbit haemorrhagic disease and myxomatosis. Methods Subadult rabbits were radio-collared in late summer and relocated twice-weekly for 25 weeks, during which time they grew to adult size and breeding commenced. Key results Rabbits of both sexes used an average of four warrens each on a regular basis, even after older rabbits had commenced breeding. Warrens used by individual rabbits formed a continuously overlapping, irregular array. Subadult rabbits did not belong to separate social groups that utilised separate groups of warrens. Conclusions Subadult or young adult rabbits did not display the same territorial warren fidelity that had been previously described for rabbits. They have potential to carry pathogens between warrens at a landscape scale. Implications Movement of subadult rabbits between warrens is therefore likely to play a critical role in disease transmission, particularly when population density is low. This may help to explain the prevalent seasonality of RHD epizootics in spring when first-born litters of each breeding season typically reach that size.

Diet of mammalian predators in braided river beds in the central South Island, New Zealand

2004 ◽  
Vol 31 (6) ◽  
pp. 631 ◽  
Author(s):  
Elaine C. Murphy ◽  
Rachel J. Keedwell ◽  
Kerry P. Brown ◽  
Ian Westbrooke
Keyword(s):  
New Zealand ◽  
Bird Species ◽  
Gut Contents ◽  
Frequency Of Occurrence ◽  
Braided River ◽  
Braided Rivers ◽  
Rabbit Haemorrhagic Disease ◽  
Mammalian Predators ◽  
Mustela Furo ◽  
Haemorrhagic Disease

In New Zealand, five of the six endemic bird species that breed primarily in South Island braided river beds are classed as threatened. A major cause of decline for these species is predation by introduced mammals, and predator-trapping programs are undertaken in the braided rivers of the Mackenzie Basin to protect them. Trapping programs carried out between September 1997 and April 2001 provided the opportunity to investigate predator diet from the gut contents of 375 cats (Felis catus), 371 ferrets (Mustela furo) and 86 stoats (Mustela erminea). As a percentage frequency of occurrence of the main prey items, cat diet consisted of lagomorphs (present in 70% of guts), birds (in 47%), lizards (30%) and invertebrates (36%). Ferret diet consisted of lagomorphs (69%) and birds (28%). Stoat diet consisted of lagomorphs (50%), birds (51%), lizards (21%) and invertebrates (23%). The frequency of occurrence of birds in all three predators was higher in the spring/summer of 1997 – immediately after rabbit haemorrhagic disease (RHD) was introduced – than in any other previous diet study on these braided rivers. This suggests that RHD did lead to increased predation pressure on birds, at least in the short term.

Seropositivity to rabbit haemorrhagic disease virus in non-target mammals during periods of viral activity in a population of wild rabbits in New Zealand

2006 ◽  
Vol 33 (4) ◽  
pp. 305 ◽  
Author(s):  
J. Henning ◽  
P. R. Davies ◽  
J. Meers
Keyword(s):  
New Zealand ◽  
Disease Virus ◽  
Small Sample ◽  
European Rabbit ◽  
Wild Rabbit ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Target Species ◽  
Rabbit Population ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease

As part of a longitudinal study of the epidemiology of rabbit haemorrhagic disease virus (RHDV) in New Zealand, serum samples were obtained from trapped feral animals that may have consumed European rabbit (Oryctolagus cuniculus) carcasses (non-target species). During a 21-month period when RHDV infection was monitored in a defined wild rabbit population, 16 feral house cats (Felis catus), 11 stoats (Mustela erminea), four ferrets (Mustela furo) and 126 hedgehogs (Erinaceus europaeus) were incidentally captured in the rabbit traps. The proportions of samples that were seropositive to RHDV were 38% for cats, 18% for stoats, 25% for ferrets and 4% for hedgehogs. Seropositive non-target species were trapped in April 2000, in the absence of an overt epidemic of rabbit haemorrhagic disease (RHD) in the rabbit population, but evidence of recent infection in rabbits was shown. Seropositive non-target species were found up to 2.5 months before and 1 month after this RHDV activity in wild rabbits was detected. Seropositive predators were also trapped on the site between 1 and 4.5 months after a dramatic RHD epidemic in February 2001. This study has shown that high antibody titres can be found in non-target species when there is no overt evidence of RHDV infection in the rabbit population, although a temporal relationship could not be assessed statistically owning to the small sample sizes. Predators and scavengers might be able to contribute to localised spread of RHDV through their movements.

scholarly journals The current status of Argentine stem weevil (Listronotus bonariensis) as a pest in the North Island of New Zealand

2011 ◽  
Vol 64 ◽  
pp. 55-62 ◽  
Author(s):  
A.J. Popay ◽  
M.R. McNeill ◽  
S.L. Goldson ◽  
C.M. Ferguson
Keyword(s):  
New Zealand ◽  
Perennial Ryegrass ◽  
Italian Ryegrass ◽  
Current Status ◽  
The North ◽  
Listronotus Bonariensis ◽  
Low Levels ◽  
The Impact ◽  
Microctonus Hyperodae ◽  
Behavioural Adaptations

Recent sampling in Waikato and Taranaki shows that Argentine stem weevil (Listronotus bonariensis) can still cause major damage to susceptible ryegrass pastures despite the introduction of the parasitoid Microctonus hyperodae in 1991 Percentage of tillers with L bonariensis larval damage in diploid and tetraploid perennial ryegrass and Italian ryegrass in January and February were between 11 and 68 High egg numbers were noted on occasion Although there is evidence that M hyperodae reduces host populations parasitism levels vary considerably between years in Canterbury and are low in Otago and Southland where high populations of L bonariensis have recently been recorded Factors that may be lessening the impact of M hyperodae are considered These include asynchronous generations of the parasitoid and its host host behavioural adaptations compensatory oviposition and inhibition of flight in parasitised individuals leading to low levels of parasitism in new pastures

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