The dynamics of feral pig (Sus scrofa) populations in response to food supply

2019 ◽  
Vol 46 (3) ◽  
pp. 191 ◽  
Author(s):  
Matthew Gentle ◽  
Anthony Pople ◽  
Joseph C. Scanlan ◽  
John Carter
Keyword(s):  
Food Supply ◽  
Sus Scrofa ◽  
Predictor Variable ◽  
Numerical Response ◽  
Initial Population ◽  
Population Densities ◽  
Juvenile Mortality ◽  
Management Actions ◽  
Eastern Australia ◽  
Feral Pig

Context Feral pigs (Sus scrofa) are highly fecund, and populations can increase rapidly under favourable conditions. Population size can also fluctuate widely, driven largely by changes in juvenile mortality in response to food availability, but these relationships have only been explored on a limited number of sites and over short periods. Aims The present study aimed to investigate and quantify the numerical response of feral pig populations to changes in their food supply in north-eastern Australia. Methods Pig population densities were determined from aerial surveys conducted over a 21-year period on 10 regional blocks (~2000–6000 km2) throughout the Queensland rangelands. Densities were used to calculate annual exponential rates of increase (r), which were then corrected for anthropogenic mortality (baiting and commercial harvesting). Six proxy measures of annual food supply, including rainfall, pasture biomass and pasture growth (using the AussieGRASS model), were calculated for each survey block, and assessed as predictors of corrected r. The rates of increase predicted from the first half of the data series were then applied to initial population densities to estimate successive pig densities during the second period in each bioregion. Key results The most parsimonious model of the numerical response had parameters common to three bioregions, with rainfall in the 12 months between surveys being the best predictor variable. Modelled densities for each bioregion were a good fit to actual, observed densities. Relationships between r and each measure of food supply at the individual block level were inconsistent. Conclusions Using rainfall as a measure of food supply, the numerical response relationship provides a method for predicting the dynamics of feral pig populations at the bioregional scale. Predicting population dynamics at any one site using this relationship is less precise, suggesting that differences in landscape composition affect utilisation of resources supporting population growth. Implications The results from the present study could be used to predict feral pig population changes at the bioregional level, supplementing or reducing the need for more frequent, expensive population surveys. This improved ability to predict fluctuations in regional feral pig populations can help guide future management actions.

Invasive predators represent the greatest extinction threat to the endangered northern bettong (Bettongia tropica)

2018 ◽  
Vol 45 (3) ◽  
pp. 208 ◽  
Author(s):  
Tegan Whitehead ◽  
Karl Vernes ◽  
Miriam Goosem ◽  
Sandra E. Abell
Keyword(s):  
Climate Change ◽  
Synergistic Effects ◽  
Management Strategies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Active Management ◽  
Feral Cats ◽  
Juvenile Mortality ◽  
Management Actions ◽  
Eastern Australia

Context Identification of key threats to endangered species is vital for devising effective management strategies, but may be hindered when relevant data is limited. A population viability approach may overcome this problem. Aims We aimed to determine the population viability of endangered northern bettongs (Bettongia tropica) in north-eastern Australia. We also assessed the key threats to the population resilience and how the population viability responds to increases in mortality rates and changes in fire and drought frequency. Methods Using population viability analysis (PVA) we modelled survival probability of B. tropica populations under likely scenarios, including: (1) increased predation; (2) changes in drought and fire frequency predicted with anthropogenic climate change; and (3) synergistic effects of predation, fire and drought. Key results Population viability models suggest that populations are highly vulnerable to increases in predation by feral cats (Felis catus), and potentially red fox (Vulpes vulpes) should they colonise the area, as juvenile mortality is the main age class driving population viability. If B. tropica become more vulnerable to predators during post-fire vegetation recovery, more frequent fires could exacerbate effects of low-level cat predation. In contrast, it was predicted that populations would be resilient to the greater frequency of droughts expected as a result of climate change, with high probabilities of extinctions only predicted under the unprecedented and unlikely scenario of four drought years in 10. However, since drought and fire are interlinked, the impacts of predation could be more severe with climate change should predation and fire interact to increase B. tropica mortality risk. Conclusion Like other Potoroids, B. tropica appear highly vulnerable to predation by introduced mammalian predators such as feral cats. Implications Managers need information allowing them to recognise scenarios when populations are most vulnerable to potential threats, such as drought, fire and predation. PVA modelling can assess scenarios and allow pro-active management based on predicted responses rather than requiring collection of extensive field data before management actions. Our analysis suggests that assessing and controlling predator populations and thereby minimising predation, particularly of juveniles, should assist in maintaining stability of populations of the northern bettong.

How much land is needed for feral pig hunting in Hawai‘i?

2014 ◽  
Vol 20 (1) ◽  
pp. 54 ◽  
Author(s):  
Steven C Hess ◽  
James D Jocobi
Keyword(s):  
Sus Scrofa ◽  
Minimum Amount ◽  
Land Area ◽  
Feral Pigs ◽  
The Public ◽  
Management Actions ◽  
In The Wild ◽  
Pig Meat ◽  
Sustained Yield ◽  
Feral Pig

Hunting is often considered to be incompatible with conservation of native biota and watershed functions in Hawai‘i. Management actions for conservation generally exclude large non-native mammals from natural areas, thereby reducing the amount of land area available for hunting activities and the maintenance of sustainable game populations. An approach which may be useful in addressing the necessary minimum amount of land area allocated for hunting in Hawai‘i is to determine the amount of land area necessary for sustaining populations of hunted animals to meet current levels harvested by the public. We ask: What is the total amount of land necessary to provide sustained-yield hunting of game meat for food at the current harvest level on Hawai‘i Island if only feral pigs (Sus scrofa) were to be harvested? We used a simplistic analysis to estimate that 1 317.6 km2–1 651.4 km2 would be necessary to produce 187 333.6 kg of feral pig meat annually based on the range of dressed weight per whole pig, the proportion of a pig population that can be sustainably removed annually, and the density of pig populations in the wild. This amount of area comprises 12.6–15.8% of the total land area of Hawai‘i Island, but more likely represents 27.6–43.5% of areas that may be compatible with sustained-yield hunting.

Commentary: Not All Vulture Feeding Stations Are Supplementary—Proposed Terminology for Carcass Provisioning with Reference to Management Goals and Food Sources

2021 ◽  
Author(s):  
Olivier Duriez ◽  
Jovan Andevski ◽  
Christopher G. R. Bowden ◽  
Alvaro Camiña-Cardenal ◽  
Hans Frey ◽  
...  
Keyword(s):  
Food Supply ◽  
Ex Situ ◽  
Food Sources ◽  
Management Actions ◽  
Carcass Disposal ◽  
Feeding Station ◽  
Vulture Conservation ◽  
Key Aspects ◽  
Conservation And Management

ABSTRACT Although vulture feeding stations are a widely used tool for vulture conservation in many regions worldwide, there has been some confusion about their functions and this is reflected in the range of terminology used. The origin of food supply at provisioning sites (both for in situ and ex situ situations) and the goals of feeding station managers (ranging from purely conservation of vultures to the necessity for carcass disposal) are two key aspects that are often neglected. We review the definitions and nomenclature for the provision of predictable anthropogenic food for vultures and vultures' role in sanitation in the landscape. We propose that “supplementary feeding stations for vultures” (SFSV) defines a particular case and this term should only be applied when a station has vulture conservation goals and a food supply coming from outside of the landscape (ex situ). We introduce the term “recycling station with vultures” (RSV) for cases when the goal is the elimination of carcasses and the food is sourced in situ (natural, NRSV) or ex situ (supplementary food, SRSV). This clarification of goals and terminology for feeding stations worldwide could have important consequences for the understanding and assessment of vulture conservation and management actions, among researchers and conservationists and also importantly among stakeholders and wider society.

Estimation of partial resistance in potato genotypes against Meloidogyne chitwoodi

Nematology ◽  
2011 ◽  
Vol 13 (4) ◽  
pp. 477-489 ◽  
Author(s):  
Thomas Been ◽  
Corrie Schomaker ◽  
Patrick Norshie
Keyword(s):  
Partial Resistance ◽  
Damage Threshold ◽  
Internal Quality ◽  
Yield Reduction ◽  
Initial Population ◽  
Multiplication Rate ◽  
Population Densities ◽  
Meloidogyne Chitwoodi ◽  
Industrial Processing ◽  
Final Population

AbstractThree new potato genotypes, designated AR 04-4107, AR 04-4096 and AR 04-4098, with resistance towards Meloidogyne chitwoodi, and the susceptible cv. Désirée were grown at a range of population densities of M. chitwoodi in a climate-controlled glasshouse in order to establish the presence and degree of partial resistance. Tuber parts of about 12 g were planted at densities (Pi) of 0, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 and 256 second-stage juveniles (J2) (g dry soil)−1. The plants were allowed to grow for a period of 105 days. Tomato cv. Moneymaker was included and inoculated at Pi = 2 J2 (g soil)−1 to verify the quality of the inoculum by measuring the multiplication rate. Plant height was measured weekly over 11 weeks. At harvest, fresh shoot, root and tuber weights, and number of tubers were measured to express yield. Final population densities (Pf) were calculated as the total number of nematodes found in soil and roots. Tubers were scored for visible symptoms and a root-knot index was calculated. The relation between pre-plant population densities (Pi) and nematode densities at harvest (Pf) was fitted using R. The multiplication rate a of M. chitwoodi on AR 04-4107, AR 04-4096, AR 04-4098 and cv. Désirée was 0.55, 0.27, 0.91 and 32, respectively. Partial resistance rsa of AR 04-4107, AR 04-4096 and AR 04-4098 was 1.7%, 0.8% and 2.8%, respectively. Partial resistance expressed as rsM was 0.2%, 0.2% and 0.1%, respectively. It can be concluded that AR 04-4107, AR 04-4096 and AR 04-4098 are strongly partially resistant to M. chitwoodi. Also, the population dynamics curves run almost parallel between both the tested genotypes and the reference cultivar, indicating that a simple and cheap partial resistance test is feasible. When tuber yields were fitted to the Seinhorst model for yield reduction, cv. Désirée showed a minimum yield (m) of 0.86, while all three resistant genotypes suffered no yields losses at all (m = 1), which indicates that the observed resistance was associated with tolerance. As a result of the remarkably high partial resistance, quality damage was low compared with cv. Désirée. The root-knot index, which takes into account internal quality damage of the potato tuber, was below 10 for all genotypes with partial resistance, the lower damage threshold used for industrial processing of consumption potatoes. Visible symptoms on the tuber skin were absent up to densities of 32 J2 (g soil)−1 for genotypes AR 04-4098 and AR 04-4096 and 2 J2 (g soil)−1 for AR 04-4107, and significantly reduced at higher densities when compared with the susceptible cv. Désirée. However, when tuber peels were investigated, egg masses were detected in tubers at almost all initial population densities.

Digging in: a review of the ecology and management of a threatened reptile with a small disjunct distribution – the heath skink, Liopholis multiscutata, in Victoria, south-eastern Australia

2019 ◽  
Vol 25 (3) ◽  
pp. 222 ◽  
Author(s):  
Geoff W. Brown ◽  
Peter Robertson ◽  
Ben G. Fanson
Keyword(s):  
General Trend ◽  
Disjunct Distribution ◽  
Population Status ◽  
Management Actions ◽  
Eastern Australia ◽  
Disjunct Populations ◽  
History Of ◽  
Available Information ◽  
Management Priorities ◽  
Ongoing Monitoring

The central issue for species that are highly localised habitat specialists and occur in relatively small numbers is vulnerability to extinction processes. The heath skink, Liopholis multiscutata, is considered Critically Endangered in Victoria, in part because it is restricted to essentially four small and highly disjunct populations in semiarid mallee dunefields. It provides an example of a rare and cryptic species that is especially vulnerable to decline and consequently provides management challenges. Here, we crystallise available information on the ecology and life history of this threatened lizard, and review monitoring data to evaluate population status, primary threats and management imperatives. There has been a substantial decrease across the known range of the lizard in Victoria, most likely due to predation and fire. Recent monitoring of the four potentially viable populations revealed a general trend of decline. Recommendations for research and management priorities for the lizard in Victoria are provided; generally, these include further exploration of the lizard’s phylogeny and ecology, and ongoing monitoring of the trajectory of the lizard’s population status, threats to the lizard’s persistence and the effectiveness of management actions employed to ameliorate extinction threats.

Life cycle and damage of the root-knot nematode Meloidogyne minor on potato, Solanum tuberosum

Nematology ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Wim M.L. Wesemael ◽  
Lirette M. Taning ◽  
Nicole Viaene ◽  
Maurice Moens
Keyword(s):  
Life Cycle ◽  
The Netherlands ◽  
Second Generation ◽  
The United States ◽  
Initial Population ◽  
Base Temperature ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Damage Development

Meloidogyne minor is a root-knot nematode reported in Belgium, Ireland, The Netherlands, Portugal, United Kingdom, Chile and the United States. It is found in sport fields and golf courses where it causes the yellow patch disease. However, M. minor has also been detected in potato fields in The Netherlands and the UK and may pose a threat for potato cultivation. Therefore, the life cycle and damage of M. minor on potato cv. Bintje were examined under controlled conditions. To assess its life cycle, young potato plants were inoculated with freshly hatched second-stage juveniles (J2). The developmental stages of M. minor were recorded at weekly intervals after inoculation until second generation J2 were detected. One week after inoculation, only vermiform juveniles were found in the roots. All juveniles were swollen after 3 weeks and the first adult females were observed. Egg masses were seen after 6 weeks together with second generation J2. The number of degree days for M. minor to complete its life cycle was calculated using a base temperature of 5°C (DD5); between 606 and 727 DD5 were needed to complete the life cycle. Damage development of M. minor on potato was examined in a pot experiment with different inoculation densities. Symptoms (galling on the tubers) were similar to those caused by M. chitwoodi and M. fallax. At initial population densities () of 10 J2 (100 cm3 soil)−1 and more, tubers showed galls. Severely damaged potato tubers were observed at (100 cm3 soil)−1 and a damage threshold of 41 J2 (100 cm3 soil)−1 was calculated. An in vitro test showed that five, commonly grown, potato cultivars were good hosts for M. minor. Based on our results, M. minor is able to develop on potato and cause severe damage at low initial population densities. Therefore, further spread of this nematode in agricultural fields should be avoided.

Effects of Feral Pig (Sus scrofa) Exclusion on Enterococci in Runoff from the Forested Headwaters of a Hawaiian Watershed

2011 ◽  
Vol 221 (1-4) ◽  
pp. 313-326 ◽  
Author(s):  
Dashiell O. Dunkell ◽  
Gregory L. Bruland ◽  
Carl I. Evensen ◽  
Mark J. Walker
Keyword(s):  
Sus Scrofa ◽  
Feral Pig

scholarly journals Utilization of Sugarcane Habitat by Feral Pig (Sus scrofa) in Northern Tropical Queensland: Evidence from the Stable Isotope Composition of Hair

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e43538 ◽  
Author(s):  
Christopher M. Wurster ◽  
Jack Robertson ◽  
David A. Westcott ◽  
Bart Dryden ◽  
Antoine Zazzo ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Sus Scrofa ◽  
Isotope Composition ◽  
Stable Isotope Composition ◽  
Feral Pig

Habitat use and movements of Australian grayling (Prototroctes maraena) in a Victorian coastal stream

2018 ◽  
Vol 69 (8) ◽  
pp. 1259 ◽  
Author(s):  
D. R. Dawson ◽  
W. M. Koster
Keyword(s):  
Habitat Use ◽  
Conservation Management ◽  
Radio Telemetry ◽  
Management Strategies ◽  
Movement Ecology ◽  
Ecological Requirements ◽  
Management Actions ◽  
Eastern Australia ◽  
The World ◽  
Australian Grayling

Riverine fishes are among the most imperilled fauna in the world; however, for many species, there is little or no understanding of their ecological requirements. The Australian grayling (Prototroctes maraena) is a small diadromous fish endemic to rivers in south-eastern Australia that has declined considerably in range and abundance and is listed as threatened nationally. To improve understanding of the species’ movement ecology and to inform the development of conservation management actions, we examined the day-to-day movements and habitat use of Australian grayling (n=7) over 8 weeks by using radio-telemetry. Tagged individuals of Australian grayling typically occupied restricted (i.e. tens to hundreds of metres) reaches of stream, and were mostly located in moderate- to fast-flowing habitats (i.e. glide or run), although, at night, use of slower-flowing habitats (i.e. pools) increased. They also undertook longer-distance downstream movements during a period of increased streamflow. Incorporation of such information into management strategies has the potential to improve our capacity to maintain or re-instate the conditions required to conserve and restore Australian grayling populations.

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