scholarly journals Fertility control to mitigate human–wildlife conflicts: a review

2014 ◽  
Vol 41 (1) ◽  
pp. 1 ◽  
Author(s):  
Giovanna Massei ◽  
Dave Cowan
Keyword(s):  
Population Growth ◽  
Wildlife Management ◽  
Population Level ◽  
Fertility Control ◽  
Public Consultation ◽  
Human Populations ◽  
Wildlife Diseases ◽  
Isolated Populations ◽  
Wild Mammals ◽  
Practical Applications

As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present review aimed at analysing trends in research on fertility control for wildlife, illustrating developments in fertility-control technologies and delivery methods of fertility-control agents, summarising the conclusions of empirical and theoretical studies of fertility control applied at the population level and offering criteria to guide decisions regarding the suitability of fertility control to mitigate human–wildlife conflicts. The review highlighted a growing interest in fertility control for wildlife, underpinned by increasing numbers of scientific studies. Most current practical applications of fertility control for wild mammals use injectable single-dose immunocontraceptive vaccines mainly aimed at sterilising females, although many of these vaccines are not yet commercially available. One oral avian contraceptive, nicarbazin, is commercially available in some countries. Potential new methods of remote contraceptive delivery include bacterial ghosts, virus-like particles and genetically modified transmissible and non-transmissible organisms, although none of these have yet progressed to field testing. In parallel, new species-specific delivery systems have been developed. The results of population-level studies of fertility control indicated that this approach may increase survival and affect social and spatial behaviour of treated animals, although the effects are species- and context-specific. The present studies suggested that a substantial initial effort is generally required to reduce population growth if fertility control is the sole wildlife management method. However, several empirical and field studies have demonstrated that fertility control, particularly of isolated populations, can be successfully used to limit population growth and reduce human–wildlife conflicts. In parallel, there is growing recognition of the possible synergy between fertility control and disease vaccination to optimise the maintenance of herd immunity in the management of wildlife diseases. The review provides a decision tree that can be used to determine whether fertility control should be employed to resolve specific human–wildlife conflicts. These criteria encompass public consultation, considerations about animal welfare and feasibility, evaluation of population responses, costs and sustainability.

Assessment of invasive rodent impacts on island avifauna: methods, limitations and the way forward

2015 ◽  
Vol 42 (2) ◽  
pp. 185 ◽  
Author(s):  
Lise Ruffino ◽  
Diane Zarzoso-Lacoste ◽  
Eric Vidal
Keyword(s):  
Population Growth ◽  
Population Level ◽  
Bird Conservation ◽  
Bird Population ◽  
Breeding Parameters ◽  
Population Growth Rates ◽  
Bird Populations ◽  
Field Evidence ◽  
Bird Breeding

Bird conservation is nowadays a strong driving force for prioritising rodent eradications, but robust quantitative estimates of impacts are needed to ensure cost-effectiveness of management operations. Here, we review the published literature to investigate on what methodological basis rodent effects on island bird communities have been evaluated for the past six decades. We then discuss the advantages and limitations of each category of methods for the detection and quantification of impacts, and end with some recommendations on how to strengthen current approaches and extend our knowledge on the mechanisms of impacts. Impact studies (152 studies considered) emphasised seabirds (67%), black rats (63%) and the Pacific Ocean (57%). Among the most commonly used methods to study rodent impacts on birds were the observation of dead eggs or empty nests while monitoring bird breeding success, and the analyses of rodent diets, which can both lead to misleading conclusions if the data are not supported by direct field evidence of rodent predation. Direct observations of rodent–bird interactions (19% of studies) are still poorly considered despite their potential to reveal cryptic behaviours and shed light on the mechanisms of impacts. Rodent effects on birds were most often measured as a change or difference in bird breeding parameters (74% of studies), while estimates of bird population growth rates (4%) are lacking. Based on the outcomes of this literature review, we highlight the need for collecting unbiased population-level estimates of rodent impacts, which are essential prerequisites for predicting bird population growth scenarios and prioritising their conservation needs. This could be achieved by a more systematic integration of long-term monitoring of bird populations into rodent management operations and modelling bird population dynamics. We also strongly recommend including various complementary methods in impact assessment strategies to unravel complex interactions between rodents and birds and avoid faulty evidence. Finally, more research should be devoted to a better understanding of the cases of non-impacts (i.e. long-term coexistence) and those impacts mediated by mechanisms other than predation and ecosystem-level processes.

scholarly journals Ecology of the Anthropocene signals hope for consciously managing the planetary ecosystem

2021 ◽  
Vol 118 (28) ◽  
pp. e2024150118
Author(s):  
Clarence Lehman ◽  
Shelby Loberg ◽  
Michael Wilson ◽  
Eville Gorham
Keyword(s):  
Population Growth ◽  
Cultural Evolution ◽  
Human Population ◽  
Human Populations ◽  
Present Moment ◽  
Minimal Set ◽  
The Past ◽  
Food Species ◽  
Large Predators ◽  
Population Numbers

Human populations have grown to such an extent that our species has become a dominant force on the planet, prompting geologists to begin applying the term Anthropocene to recognize the present moment. Many approaches seek to explain the past and future of human population growth, in the form of narratives and models. Some of the most influential models have parameters that cannot be precisely known but are estimated by expert opinion. Here we apply a unified model of ecology to provide a macroscale summary of the net effects of many microscale processes, using a minimal set of parameters that can be known. Our models match estimates of historic and prehistoric global human population numbers and provide predictions that correspond to some of the more complicated current models. In addition to fitting the data well they reveal that, amidst enormous complexity in our human and prehuman past, three key ecological discontinuities have occurred in turn: 1) becoming dominant competitors of large predators rather than their prey, 2) becoming mutualists with food species rather than acting as predators upon them, and 3) changing from a regime of uncontrolled population growth to one of controlled fertility instead. All three processes have been interlinked with cultural evolution and all three ushered in developments of the Anthropocene. Understanding the trajectories that have delivered us to this stage can help guide prudent paths into the future.

scholarly journals Epidemiological trends in digestive cancers compared to trends in alcohol consumption. Facts from Romania: correlation or coincidence?

2018 ◽  
Vol 91 (4) ◽  
pp. 376-386
Author(s):  
Simona Valean ◽  
Romeo Chira ◽  
Dan Dumitrascu
Keyword(s):  
Alcohol Consumption ◽  
Population Level ◽  
Epidemiological Data ◽  
Epidemiological Studies ◽  
Incidence Rates ◽  
Human Populations ◽  
Causative Relationship ◽  
Consumption Data ◽  
Digestive Cancers ◽  
Epidemiological Trends

Cancer has emerged as the leading cause of death in human populations, according to recent estimations. Epidemiological studies emphasized the role of life style and of environmental factors in promoting the risk for digestive cancers. The contribution of alcohol was highly suspected. Even for digestive cancers with dominant infection etiology, like liver cancer and gastric cancer, the contribution of alcohol should be assessed. At population level there is therefore a need to compare trends in epidemiological data of gastrointestinal cancers and data on alcohol consumption, in order to extrapolate any causative relationship. The purpose of this review was to analyze the time trend of digestive cancers in Romania, in terms of mortality rates (between 1955-2012), and incidence rates (between 2008-2012), in males and females, and to analyze the alcohol consumption data, aiming to find out if there is any association.

scholarly journals The shape of density dependence and the relationship between population growth, intraspecific competition and equilibrium population density

2018 ◽  
Author(s):  
Emanuel A. Fronhofer ◽  
Lynn Govaert ◽  
Mary I. O’Connor ◽  
Sebastian J. Schreiber ◽  
Florian Altermatt
Keyword(s):  
Population Growth ◽  
Growth Models ◽  
Population Level ◽  
Logistic Growth ◽  
Population Densities ◽  
Density Regulation ◽  
Logistic Growth Model ◽  
Regulation Functions ◽  
Consumer Resource ◽  
Population Growth Models

AbstractThe logistic growth model is one of the most frequently used formalizations of density dependence affecting population growth, persistence and evolution. Ecological and evolutionary theory and applications to understand population change over time often include this model. However, the assumptions and limitations of this popular model are often not well appreciated.Here, we briefly review past use of the logistic growth model and highlight limitations by deriving population growth models from underlying consumer-resource dynamics. We show that the logistic equation likely is not applicable to many biological systems. Rather, density-regulation functions are usually non-linear and may exhibit convex or both concave and convex curvatures depending on the biology of resources and consumers. In simple cases, the dynamics can be fully described by the continuous-time Beverton-Holt model. More complex consumer dynamics show similarities to a Maynard Smith-Slatkin model.Importantly, we show how population-level parameters, such as intrinsic rates of increase and equilibrium population densities are not independent, as often assumed. Rather, they are functions of the same underlying parameters. The commonly assumed positive relationship between equilibrium population density and competitive ability is typically invalid. As a solution, we propose simple and general relationships between intrinsic rates of increase and equilibrium population densities that capture the essence of different consumer-resource systems.Relating population level models to underlying mechanisms allows us to discuss applications to evolutionary outcomes and how these models depend on environmental conditions, like temperature via metabolic scaling. Finally, we use time-series from microbial food chains to fit population growth models and validate theoretical predictions.Our results show that density-regulation functions need to be chosen carefully as their shapes will depend on the study system’s biology. Importantly, we provide a mechanistic understanding of relationships between model parameters, which has implications for theory and for formulating biologically sound and empirically testable predictions.

Biotech prospects for the control of introduced mammals in Australia

2001 ◽  
Vol 13 (8) ◽  
pp. 705 ◽  
Author(s):  
Robert F. Seamark
Keyword(s):  
Genetically Modified Organisms ◽  
Significant Risk ◽  
Fertility Control ◽  
Emerging Diseases ◽  
Research Centre ◽  
Cooperative Research ◽  
Wildlife Diseases ◽  
Continental Scale ◽  
Immune Resistance ◽  
Livestock Health

More than twenty exotic vertebrate species are now listed as pests in Australia. Collectively, these pests have a huge economic and environmental impact and pose a major threat to Australia’s ecosystems and unique biodiversity. Management of such pests on a continental scale is a major challenge. Recent advances in biotechnology suggest alternatives to the lethal diseases normally sought for use as biological control agents. One proposal, being investigated in the Pest Animal Control Cooperative Research Centre, Canberra, is the use of biotechnology to develop a new generation of agents that act through controlling reproduction to prevent the build up of pest populations. The core concept is fertility control through immunocontraceptive vaccines delivered by viruses that specifically infect the target pest population. Proof of this exciting concept has been obtained for the mouse and, very recently, the rabbit, and a candidate vaccine vector identified for the fox, portending better control of a trio of Australia’s most pervasive pests. Other advances in biotechnology suggest ways to negate the build up of both innate and acquired immune resistance in target pest populations that normally act to limit the efficacy and effective life of biocontrol agents in the field. Prospects for extending the use of virally vectored vaccines to the field management of wildlife diseases are also identified. Targets for such vaccines include a growing suite of emerging diseases, hosted by Australia’s wildlife, which pose a threat to human and livestock health. Numerous technical challenges remain to be addressed before any of these new agents are ready for use in the field. However, the major risk to their development is now no longer viewed as being technical, but the failure to gain public acceptance for their use in the field. This already significant risk is exasperated by the present heightened level of public concern about all introductions of genetically modified organisms.

scholarly journals Fertility Control for Wildlife Management The Brushtail Possum in New Zealand

2006 ◽  
Vol 22 ◽  
Author(s):  
Phil Cowan ◽  
Janine Duckworth ◽  
Xianlan Cui ◽  
Frank Molinia ◽  
Werner Lubitz ◽  
...  
Keyword(s):  
New Zealand ◽  
Wildlife Management ◽  
Fertility Control ◽  
Brushtail Possum

scholarly journals Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

2018 ◽  
Vol 285 (1871) ◽  
pp. 20172443 ◽  
Author(s):  
Richard B. Sherley ◽  
Barbara J. Barham ◽  
Peter J. Barham ◽  
Kate J. Campbell ◽  
Robert J. M. Crawford ◽  
...  
Keyword(s):  
South Africa ◽  
Bayesian Inference ◽  
Population Growth ◽  
Prey Availability ◽  
Population Level ◽  
Marine Ecosystems ◽  
Forage Fish ◽  
Chick Survival ◽  
Marine Predator ◽  
Management Interventions

Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time–area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator—we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers.

No evidence for Galapagos Plasmodium lineage arriving via Humboldt Current seabirds.

2014 ◽  
Vol 20 (1) ◽  
pp. 37 ◽  
Author(s):  
Iris I Levin ◽  
Michael J Adkesson ◽  
Maranda Evans ◽  
Cindee K Rettke ◽  
Patricia G Parker
Keyword(s):  
South American ◽  
Wildlife Diseases ◽  
Isolated Populations ◽  
Humboldt Current ◽  
Island Populations ◽  
Negative Results ◽  
Contact Rates ◽  
Haemosporidian Parasites ◽  
Genus Plasmodium ◽  
Current Flows

Avian malaria, caused by parasites in the genus Plasmodium, has recently been detected in the endangered Galapagos penguin (Spheniscus mendiculus). Understanding possible routes of parasite and pathogen introduction is important for management of small and isolated populations, because island populations can be at higher risk of adverse effects due to lower immunity. One possible means of introduction could be through contact with pelagic birds from coastal South America. In order to better understand the origins of Plasmodium in Galapagos penguins, we used a PCR protocol to test for haemosporidian parasites in Humboldt penguins (Spheniscus humboldti), the sister species of Galapagos penguins, and two other Humboldt Current endemics, the guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian pelican (Pelecanus thagus). None of these seabirds, all sampled at Punta San Juan, Peru, tested positive for haemosporidian parasites. Although the strong Humboldt Current flows from Antarctica up the South American coast and towards Galapagos at the equator, contact rates between these Humboldt endemics and Galapagos birds might still be rare. Despite negative results, this information is important for furthering our knowledge of Plasmodium in Galapagos and in our efforts to effectively manage wildlife diseases.

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