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.

scholarly journals Bioacoustic monitoring of New Zealand avifauna before and after aerial 1080 operations

2021 ◽  
Author(s):  
◽  
Roald Egbert Harro Bomans
Keyword(s):  
New Zealand ◽  
Bird Species ◽  
Conservation Practice ◽  
Significant Difference ◽  
Mammalian Predators ◽  
Before And After ◽  
Scale Population ◽  
The Creation ◽  
Negative Impacts ◽  
Native Birds

<p>Introduced mammalian predators, namely possums, stoats and rats, are the leading cause of decline in native avifauna in New Zealand. The control of these species is essential to the persistence of native birds. A major component of mammal control in New Zealand is carried out through the aerial distribution of the toxin sodium monofluoroacetate (otherwise known as 1080). The use of this toxin, however, is subject to significant public debate. Many opponents of its use claim that forests will ‘fall silent’ following aerial operations, and that this is evidence of negative impacts on native bird communities. With the continued and likely increased use of this poison, monitoring the outcomes of such pest control operations is necessary to both address these concerns and inform conservation practice. The recent growth in autonomous recording units (ARUs) provides novel opportunities to conduct monitoring using bioacoustics. This thesis used bioacoustic techniques to monitor native bird species over three independent aerial 1080 operations in the Aorangi and Rimutaka Ranges of New Zealand.  In Chapter 2, diurnal bird species were monitored for 10-12 weeks over two independent operations in treatment and non-treatment areas. At the community level, relative to non-treatment areas, the amount of birdsong recorded did not decrease significantly in treatment areas across either of the operations monitored. At the species level, one species, the introduced chaffinch (Fringilla coelebs), showed a significant decline in the prevalence of its calls in the treatment areas relative to non-treatment areas. This was observed over one of the two operations monitored. Collectively, these results suggest that diurnal native avifaunal communities do not ‘fall silent’ following aerial 1080 operations.  The quantity of data produced by ARUs can demand labour-intensive manual analysis. Extracting data from recordings using automated detectors is a potential solution to this issue. The creation of such detectors, however, can be subjective, iterative, and time-consuming. In Chapter 3, a process for developing a parsimonious, template-based detector in an efficient, objective manner was developed. Applied to the creation of a detector for morepork (Ninox novaeseelandiae) calls, the method was highly successful as a directed means to achieve parsimony. An initial pool of 187 potential templates was reduced to 42 candidate templates. These were further refined to a 10-template detector capable of making 98.89% of the detections possible with all 42 templates in approximately a quarter of the processing time for the dataset tested. The detector developed had a high precision (0.939) and moderate sensitivity (0.399) with novel recordings, developed for the minimisation of false-positive errors in unsupervised monitoring of broad-scale population trends.  In Chapter 4, this detector was applied to the short-term 10-12 week monitoring of morepork in treatment and non-treatment areas around three independent aerial 1080 operations; and to longer-term four year monitoring in two study areas, one receiving no 1080 treatment, and one receiving two 1080 treatments throughout monitoring. Morepork showed no significant difference in trends of calling prevalence across the three independent operations monitored. Longer-term, a significant quadratic effect of time since 1080 treatment was found, with calling prevalences predicted to increase for 3.5 years following treatment. Collectively, these results suggest a positive effect of aerial 1080 treatment on morepork populations in the lower North Island, and build on the small amount of existing literature regarding the short- and long-term response of this species to aerial 1080 operations.</p>

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 Assessing bird predation on New Zealand’s lizard fauna using lizard-mimicking replicas

2021 ◽  
Author(s):  
◽  
Brittany Florence-Bennett
Keyword(s):  
New Zealand ◽  
Predation Risk ◽  
Bird Species ◽  
Canopy Cover ◽  
Daily Rainfall ◽  
Small Range ◽  
Lizard Species ◽  
Avian Predation ◽  
Top Predators ◽  
Mammalian Predators

<p>Wildlife management is fraught with challenges due to the complexities of community ecology. Interventions aimed at restoring ecosystems, or managing species, can have unintended negative outcomes for target species. The effect of avian predation on native lizard fauna in New Zealand is not clearly understood, despite birds being regarded as top predators within mammal-free ecosystems. At least thirty-one species of bird have been recorded preying on native lizards, but few studies have directly addressed avian predation on lizards, with the majority of evidence sourced from published anecdotes. New Zealand’s herpetofauna are already vulnerable due to range contractions resulting from mammalian predation and habitat loss, with 87% of New Zealand lizard species considered ‘At Risk’ or ‘Threatened’. Understanding the risks posed to lizards will help to inform successful management of vulnerable populations.  I used lizard-mimicking replicas to identify and assess predation rates exerted by bird species on lizard populations within the Wellington region of New Zealand. I examined the use of lizard replicas as a tool to quantify predation by examining how birds interacted with replicas and comparing attack rates with novel items simultaneously placed in the field. I determined which bird species were preying on replicas, the extent of such predation, and whether site vegetation or daily weather influenced the probability of avian attack on replicas. Although attack frequency did not differ between novel items and lizard replicas, birds exhibited a realistic predatory response by preferentially attacking the head of lizard replicas. Interactions by birds with lizard-mimicking replicas cannot be confirmed as true predation attempts, but lizard replicas can nevertheless be used to quantify predation pressures exerted on lizard populations by opportunistic bird species.   Seven ground-foraging bird species were found to attack lizard replicas. Two species, the pūkeko (Porphyrio melanotus melanotus) and southern black-backed gull (Larus dominicanus dominicanus), were identified as high impact species. The average predation risk experienced by lizard replicas varied greatly across environments, with 0 – 25% of replicas attacked daily at sites. Canopy cover and daily rainfall were not significant predictors, but potentially decreased the likelihood of replica attack. Predation risk varied for lizard replicas as a result of differing assemblages of bird predators at sites, and the presence and foraging behaviour of specific predatory birds.   Predation by birds is likely to be an issue where predation pressure is high, or lizard populations are small, range restricted, or recovering from the presence of mammalian predators. When managing vulnerable lizard populations, managers should take into account the threats posed by avian predators so that lizard communities can recover successfully following the same trajectory as native birds.</p>

Introduced species in New Zealand ? Their impacts on a biodiversity hotspot

2010 ◽  
Vol 16 (4) ◽  
pp. 230 ◽  
Author(s):  
Mark N. H. Seabrook-Davision ◽  
Dianne H. Brunton
Keyword(s):  
New Zealand ◽  
Introduced Species ◽  
New Caledonia ◽  
Biodiversity Hotspot ◽  
Rapid Expansion ◽  
Brushtail Possum ◽  
Mammal Species ◽  
Mustela Nivalis ◽  
Mammalian Predators ◽  
Mustela Furo

The issue of naturalization of introduced species to New Zealand was raised in an article in Nature (Ritchie 1922a Thompson 1922) 88 years ago. Here, we take the opportunity to assess the impacts of introduced species to the islands of New Zealand, one of the only entire countries, such as Madagascar, Japan, Philippines and New Caledonia to be described as a biodiversity hotspot (Reid 1998; Abbitt et al. 2000; Smith et al. 2001; Mittermeier et al. 2004). Between 1769 and 1919, 1170 species were recorded as being introduced to New Zealand (Thompson 1922) (Table 1). Ritchie (1922) reviewed the publication of Thompson?s inventory and warned against the introduction of exotic species without proper planning and assessment of the impacts on the existing biota. The warning was given because of New Zealand?s biodiversity had evolved in the absence of mammalian predators. Many bird, reptile and invertebrate species had limited defences against mammal species such as rats Rattus spp, mustelids (Stoat Mustela erminea, Ferret Mustela furo and Weasel Mustela nivalis vulgari), Brushtail Possum Trichosurus vulpectula and Cat Felis cattus. At the beginning of the 20th century, most of New Zealand?s large land vertebrates were extinct or threatened with extinction. The rapid expansion of mustelids, rats and Cat had caused considerable contractions in the distribution of large ground birds such as Kakapo Strigops habroptilus, South Island Takahe Porphyrio mantelli hochstetteri and species of waterfowl.

Short-term ecological effects of rabbit haemorrhagic disease in the short-tussock grasslands of the South Island, New Zealand

2002 ◽  
Vol 29 (6) ◽  
pp. 599 ◽  
Author(s):  
Grant Norbury ◽  
Richard Heyward ◽  
John Parkes
Keyword(s):  
New Zealand ◽  
Native Species ◽  
Production Management ◽  
Grazing Pressure ◽  
Short Term ◽  
Grazing Impacts ◽  
Increased Risk ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease ◽  
Native Birds

Rabbit haemorrhagic disease (RHD) has reduced populations of rabbits (Oryctolagus cuniculus) across most rabbit-prone short-tussock grasslands of New Zealand, at scales rarely seen there before. Flow-on effects to other parts of these ecosystems will be inevitable. We report evidence for increases in pasture biomass, increases in abundance of other exotic herbivores, declines in abundance of rabbit-specialist predators, and short-term increases in predation rates of some native birds by these predators. At one site in Central Otago, RHD reduced an index of rabbit abundance by 88%, and an index of their grazing impacts by 77%. Recovered biomass consisted mostly of fast-growing exotic pasture species of moderate palatability to livestock. Spotlight counts and hunters' returns suggest increases in possum (Trichosurus vulpecula) and hare (Lepus europeaus) abundance, but their grazing pressure is unlikely to replace that originally imposed by rabbits. The apparent increase in possum numbers poses an increased risk from the spread and maintenance of bovine tuberculosis (Tb), although this risk may be offset by declines in the counts of ferrets (Mustela furo), which also carry Tb. Declines in predator numbers (including feral cats, Felis catus) may also, in the longer term, benefit some native fauna that are secondary prey of these predators. There is evidence for increased predation of some native birds' eggs since RHD arrived. It is not possible at this stage to generalise the effects of RHD-induced declines in rabbit abundance on New Zealand ecosystems. Effects are highly variable, and their implications for pastoral production, management of bovine Tb, and conservation of native species are likely to vary locally according to the suite of plant and animal species originally present.

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