Updated: Aug 24, 2021
If duck species had a poster boy it would be the mallard duck. You know the one I'm referring to, the one with the green head, yes that one. Not is it only the most well known duck species, but it is also widespread across the world. I've been to many areas across the world and I think I've seen mallard ducks in most of the countries. They originate from Asia and Europe. Due to humans they have become an alien invasive species in many areas.
The male mallard duck has that classic green head while the female is a more drab brown colour.
An alien invasive species is a species of fauna or flora which has been moved purposefully or accidentally out of its geographic range and has now become a settled population which did not occur in that area prior to its arrival. The mallard duck (Anas platyrhynchos) is a waterfowl species which comes from the family Anatidae. This duck is found extensively around the world, originating from Eurasia, ranging from subarctic to subtropical areas. These ducks are now found in South Africa after having been introduced from these native areas. Many alien water bird species such as ducks and geese commonly hybridise with indigenous species like the yellow billed duck (Anas undulata). There are over 400 species of bird with stable alien populations around the world.
The distribution of mallard ducks in South Africa.
Hybridisation can lower diversity due to the breakdown of reproductive barriers, the coming together of formerly different evolutionary lineages, as well as extinction of populations and species. The most clearly seen path between human activities and extinction due to hybridisation are initiated by actively managed alien species which are intentionally released into indigenous habitat. Conservation managers understand this threat and have put measures into place to try and control these invasive birds, however the surrounding communities of these reserves see the ducks as aesthetically pleasing and are against the culling processes being carried out by the managers. Conflict between these two parties is an ongoing struggle
Why is it necessary to cull?
Alien invasive species have a range of effects including economic, social, health related and ecological. Diseases may be transferred to humans, domesticated and wild animals as well as plants. Once an alien invasive species has established itself, such as the mallard duck the damage to the indigenous biodiversity can be costly and strenuous to mitigate. Alien invasive birds can negatively impact indigenous species in a number of ways inter alia predation and competition over resources such as food, particularly interspecific competition that has an important role in shaping the communities. Interspecific competition can be split into exploitation competition and interference competition. Exploitation competition happens indirectly by the use of a scarce resource which then becomes unavailable for the indigenous species. Interference competition happens when individuals block access to scarce resources by direct negative interactions such as aggression.
Nesting areas are one of these limiting factors in population size and these areas can be used by many alien species. The impacts of exploitation competition may be important as some bird species may not breed in areas where nest sites are limited due to alien invasive bird species inhabiting all the accessible breeding areas. The link between anthropogenic activities and extinction risk originates as a result of actively managed individuals which are intentionally released into indigenous areas and then breed with indigenous species which causes hybridisation.
Hybridisation can be defined as breeding between genetically distinguishable populations and this can have many evolutionary outcomes. Hybridisation and introgression are well known threats that indigenous species face in their communities. The mallard duck (Anas platyrhynchos) is threatening indigenous bird species with extinction for example the yellow billed duck (Anas undulata) or may have already caused local extinctions in certain areas around the world. Invasive alien species along with their hybrids can assist as a bridge for gene flow between indigenous species. It has been found that hybrids have the full capacity to successfully reproduce. Invaders can also be vigorous and abundant spreading across a wide global range far beyond their first location of introduction. Hybridisation amongst invasive and indigenous species is expected to grow more problematic in the future. Increased trade internationally as well as climate change could grow the amount of alien invasive species and hybridisation. Increased growth of hybridisation between closely affiliated species could also decrease population viability by diluting particularly evolved gene complexities in which it destroys the genetic coherence. Human disturbed ecosystems are heterogeneous and unstable in ecological terms and thus enabling greater opportunity for hybrids to establish themselves.
Controversial strategies such as “shoot now and ask questions later” regularly remain the only practical plan, however while this eradication procedure has proven effective it is not usually implemented because of ethical concerns. Public support with regards to the general public and conservation managers is important for successful management of the mallard ducks (Anas platyrhynchos).
A hybrid duck from a mallard and yellow billed duck
In the 18th and 19th centuries, European colonialists founded novel socio-ecological systems with species from their homes translocated to capture cultural and sentimental features that reminded colonists of their old homes they left behind. Human-human conflicts exist in line with humans preferring to conserve as a result of their values. Disagreements over these values can be very personal. Most importantly, finding the extent of the conflict and its effect. Researchers define stakeholders as individuals, groups and organisations that are affected by or can affect those parts of the phenomenon. The stakeholders are split into two separate groups. The first group of stakeholders are mostly the conservationists, researchers and environmentalists whose actions are determined by research data and literature. The second group of stakeholders are the surrounding communities who view the ducks as aesthetically pleasing, as well as seeing the removal or culling of the ducks as inhumane, cruel and unnecessary.
Given the interaction of multiple viewpoints by a variety of stakeholders concerning these social and ecological aspects of species, invasion biology is overwhelmed with problematic situations as well as head on public opposition. This may be seen by others as having valuable ecosystem services, cultural benefits or having intrinsic worth. This results in social conflict which can thus impede planned control measures. It demonstrates a hands-on approach to enable public support in order for management to implement successful control projects. Aspects normally taken as being negative from an environmental point of view may be seen as positive for other social organisations. This means that a wide range of ecological, economic, and sociological impacts should be addressed when an invasion problem is being assessed. Social science research indicates that people’s attitudes and behaviour towards nature and its resource management, such as invasive alien species and their control, are influenced by psychological, cultural and evolutionary factors).
Culling of alien invasive species in order to protect biodiversity brings up complicated ethical dilemmas. Prioritising certain species for conservation over the worth of single animals is mainly used to justify culls. However this logic is questioned when culls fail to have a favourable impact on the species that need protecting. Other problems include the misuse of conservation funds on ineffective culls and risks to animal welfare due to possible inhumane control techniques.
Conflict between animal rights groups and government agencies have been raised in the management of large or charismatic animals such as deer (Cervus elaphus). Most deer species in Britain are able to move across the countryside and therefore landowners have different views regarding conflicting ways to manage them. Deer (Cervus elaphus) have many values to the communities such as hunting, venison production and tourism activities however they negatively impact the farming sector. Collaborative management has been found to be the best strategy used for this situation. In areas where this strategy has not been implemented conflict still occurs. Like the deer (Cervus elaphus), the mallard duck (Anas platyrhynchos) debate originates from a simple value disagreement based on the intrinsic worth of the animal, regardless of where it is from or what its impacts are. Scientists and managers need to make more of an effort with communicating to stakeholders, however this may not be so simple. The reason being that even if they understand the scientific evidence, they may still disagree about the best strategy being put forward. If stakeholders are satisfied with the management policies put forward by management they will prioritise and care for wildlife. However if the policies are unacceptable to stakeholders they will be less likely to engage in nature conservation programmes. Extreme outcomes may result in individuals actively opposing conservation with negative behaviours towards animals.
Local communities can have strong opinions and beliefs about animals and culling.
Research shows that conflicts with escalated decision-making strategies were done without participation and transparency which led to local communities mistrusting government agencies. These confrontations arose as a result of different evaluations of possible hazards and thus a lack of confidence becoming a driving factor.
Democracy in conservation management is becoming more critically acknowledged so as to minimise conflict and enable successful conservation outcomes. Acquiring a broad range of stakeholder views is important because if a stakeholder is left out, whether large or minor, it causes further issues and prolongs the strategies planned to control the alien invasive species. Disparity in stakeholder viewpoints could increase unsustainable wildlife implementation methods. Another aspect to determine is the variation in tolerance. Human versus wildlife conflict literature show that stakeholders vary widely in their attitudes and tolerance towards animals, for instance some stakeholders remove animal species regardless of not encountering any issues, while others with issues will not remove the animals. An example of tolerance was seen in research done in 2016 at Zandvlei Nature Reserve whereby mallard ducks (Anas platyrhynchos) were tolerated more than Egyptian geese (Alopochen aegyptiaca) which is an indigenous species in the area. Other stakeholders will administer mitigation procedures to inhibit or reduce damage while others may not, therefore find the stakeholders tolerance level may be critically important. Studies have also found that when participants were aware of control projects, their attitudes and level of support increased in regard to the control of that certain species.
Approaches such as meetings led by a mediator may be beneficial. The formation of guidelines and activities enhance listening and achieve success while addressing small conflicts before handling larger ones. Although it takes more time and resources it provides stakeholders with more knowledge as well as allowing them to participate in management options and decision making. This will result in more public participation and interest, which will see the outcome of long term goals of nature conservation realised, however correct scientific and technical data are needed in order for it to work efficiently.
Continue the culling of the mallard duck (Anas platyrhynchos) until it has been eradicated, ensuring stakeholders are aware of the correct methods being performed. The mallard ducks (Anas platyrhynchos) are lured with bread which is moistened with water and mixed with a sedative called Alpha - chloralose. A hunting permit is acquired before each operation from Cape Nature. The SPCA would monitor the process to assist in compliance with the animal anti-cruelty act which ensures minimal stress. Other stakeholders on site for example, land owners, Media liaison personnel, and project manager with city veterinarians. Although the mallard duck (Anas platyrhynchos) is an alien species the public has become attached to them and thinks of them as domesticated. Education in this regard must be introduced to reinforce the harmfulness of the mallard ducks (Anas platyrhynchos) being an alien invasive species. People at all levels such as ministers in parliament need to alter their behaviour with regards to the laws they draw up.
Environmental education is an important tool with which to change behaviour by attempting to teach children and adults how to learn about their environment and what harms it in order to make intelligent and informed decisions and how they can take care of it, by developing new attitudes and motivations.
A contraceptive called Nicarbazin was developed in the 1950s for broiler chickens (Gallua gallus) and has been tested on mallard ducks (Anas platyrhynchos) as a possible technique for decreasing alien invasive waterfowl, in particular urban ducks and geese. It was discovered that mallard ducks (Anas platyrhynchos) and Canada goose responded well to the absorption of the drug and thus may prove to decrease the mallard duck (Anas platyrhynchos) population in the Western Cape. This could be used as an effective management tool if administered correctly and in the right dosage. However more research is needed into Nicarbazin and its effects on the mallard duck (Anas platyrhynchos) population in the Western Cape as this study was compiled in the United States of America.
Open meetings to take place with managers of reserves and stakeholders along with interested and affected parties regarding culling techniques with full disclosure of when, where and how the operation will take place. Stakeholders can share their opinions about the methods and what their attitudes towards them are. Managers could also reinforce the knowledge regarding the harmful effects that are caused by these alien birds. In doing this the stakeholders could trust managers more and not inhibit conservation efforts. From the viewpoint of social science biodiversity conflict management is connected to stakeholder participation. Good advertising and accessibility to meetings are important. A separate meeting can be held after culling and managers could explain the success or failure of the operation as well as what will be done about the mallard duck (Anas platyrhynchos) control in the future.
An alternative solution in accordance with the culling of the mallard duck (Anas platyrhynchos) is to supply the dead bird carcasses to the local disadvantaged communities. South African households have a strong reliance to wild harvested products as it has been found that 80% of these communities use wildly harvested products in a legal manner. These products include fuelwood, herbs and other food items. Many of these communities are in close proximity to the Table Mountain National Park and 23 city managed nature reserves. Informal houses are expanding on the edges of Cape Town. On average households consist of four individuals and there is an amount of 54% unemployment in the Khayalitsha settlement alone. The level of education in these communities consists of 58% of adults educated below matric level and added to this only 8.5% are educated to grade five.
At present the active ingredient for euthanasia is phenobarbital, a schedule two drug, along with another drug called CO2, which is toxic to humans. A new drug which is human friendly could be investigated and implemented into the culling process of the mallard ducks (Anas platyrhynchos). The dead birds’ bodies could then be taken to a disadvantaged community as a food source. There are 198 fauna species harvested for communities including water birds. However the sustainability of this practice is questionable due to it being a short term plan and once all the mallard ducks (Anas platyrhynchos) and their hybrids have been culled the communities will continue to expect this resource which is not sustainable. This may lead to poaching of indigenous ducks. In spite of national and international contributions, wildlife poisoning is reportedly increasing even where policing is well resourced for example in some countries in America and Europe and in southern African countries such as Zimbabwe and South Africa.
There are many options in which local communities and conservationists can compromise for the benefit of both parties.
To date no conservation conflict has been successfully resolved completely, however varying degrees of success have been accomplished in minimising their detrimental effects. Humans have disrupted plant and animal ecosystems by introducing exotic species from all over the world. Some species are unable to cope in the new conditions and die whereas others, for example the Port Jackson (Acacia saligna) and the mallard duck (Anas platyrhynchos) have overcome the barriers and thrive as well as outcompeting the indigenous wildlife.
Educating the public looks only at potential differences in knowledge. Information programmes are unlikely to change people’s perceptions or beliefs “one person’s pest is often another person’s livelihood or joy”, according to. It was found that the participants saw the conservationists as xenophobic for rejecting and trying to eliminate the invasive alien species. If people’s views continue along these lines it could be detrimental to nature reserves and the indigenous species found within them. When conflicts are handled in the wrong way they can become the reason for continued public frustration and this will in turn mean that the agency responsible will lose credibility and detract from the goal at hand. Managers are finding that mutual resolution of conflict can prove beneficial.
Ultimately conflict is a growing reality due to the increasing human population. It can be seen that the majority of scenarios hold a variety of different aspects that have been used in making confrontation between managers and stakeholders a complex issue to rectify. Consequently, being aware of suitable factors in any specific situation will aid conservationists to establish multifaceted and culturally appropriate mitigation programmes. Conservation will succeed in conflict management strategies if they have defined goals, adhere to the values of their stakeholders as well as having transparent cooperation with them. Academics and policy makers need to examine evidence and trade-offs in negotiating a path in which all concerned accept and agree to. Along with this, monitoring and evaluation in management strategies are important in order to improve negative results and assist adapting to change.
At its core conflict management is about gathering stakeholders face to face to discuss and debate possible solutions. The capacity for conservation and livelihoods to live harmoniously depends on the readiness of stakeholders to recognise issues as shared ones and to consider them collaboratively. One aspect that arises continuously in the literature is the need for transparency among all parties concerned. This is in relation to stakeholder’s position and goals as well as the goals and values of the interested academics. It is important that stakeholders are able to contribute and discuss issues on an equal platform and in so doing this will benefit conservation in the long-term goals for management. Adaptive management approaches need to factor in direct involvement with the general public where the ducks are found, with regards to research development and management strategies. Stakeholders should, on the grounds of ethical principle have a direct say in the management approaches which affect their lives and surroundings. Academics and managers will have to walk a thin line between convincing the general public on scientifically based assessments while being conscious of recognizing and respecting the values and interests of the general public. Better connections are needed between natural and social sciences so that a firmer understanding about human-wildlife and human-human conflict can be grasped. Without sound understanding, successful management will continue to be a problem. These programmes are becoming increasingly important due to the high speed of urbanisation, biodiversity loss and global change.
Austin, Z., Smart, J.C.R., Yearley, S., Irvine, R.J. & White, P.C.L. 2010. 'Identifying Conflicts and Opportunities for Collaboration in the Management of a Wildlife Resource: A Mixed-Methods Approach'. Wildlife Research, (37): 647-657.
Blackburn, T.M., Pysek, P., Bacher, S., Carlton, J.T., Duncan, R.P., Jarosik, V., Wilson, J.R.U. & Richardson, D.M. 2011. A proposed unified framework for biological invasions. Trends in Ecology and Evolution, 26(7): 333–339.
Bremner, A. & Park, K. 2007. Public attitudes to the management of invasive non-native species in Scotland. Biological Conservation, 139(4): 306 – 314.
Charter, M., Izhaki, I., Ben-Mocha, Y. & Kark, S. 2016. Nest-site competition between invasive and native cavity nesting birds and its implication for conservation. Journal of Environmental Management, (181): 129–134.
Dickman, A.J. & Hazzah, L. 2016. Money, Myths and Man-Eaters: Complexities of Human – Wildlife Conflict. Problematic Wildlife. Angelici F.M. Switzerland: Springer International Publishing Service, 339–356.
Doherty, T.S., Ritchie, E.G. 2016. Stop Jumping the Gun: A Call for Evidence-Based Invasive Predator Management. Conservation Letters, (10): 15–22.
Estevez, R.A., Anderson, C.B., Cristobal Pizarro, J. & Burgman, M.A. 2014. Clarifying values, risk perceptions, and attitudes to resolve or avoid social conflicts in invasive species management. Conservation Biology, 29(1): 19–30.
Evans, J.M., Wilkie, A.C. & Burkhardt, J. 2008. Adaptive Management of Non-native Species: Moving Beyond the “Either-Or” Through Experimental Pluralism. Journal of Agriculture and Environmental Ethics, (28): 521–539.
Fischer, A., Selge, S., Van Der Wal. R. & Larson, B.M.H. 2014. The Public and Professionals Reason Similarly about the Management of Non-Native Invasive Species: A Quantitative Investigation of the Relationship between Beliefs and Attitudes. PLoS ONE, 9(8): 1–10.
Frantz, C.M. & Mayer, F.S. 2014. The importance of connection to nature in assessing environmental education programs. Studies in Educational Evaluation, (41): 85–89.
Kansky, R., Kidd, M. & Knight, A.T. 2016. A wildlife tolerance model and case study for understanding human wildlife conflicts. Biological Conservation, (201): 137–145.
Kumschick, S., Blackburn, T.M. & Richardson, D.M. 2016. Managing alien bird species: Time to move beyond “100 of the Worst” lists? Bird Conservation International, 26(2): 154 -163.
Liu, S., Walshe, T., Long, G. & Cook, D. 2012. Evaluation of Potential Responses to Invasive Non-Native Species with Structured Decision Making. Conservation Biology, 26(3): 539–546.
Lute, M.L., Navarrete, C.D., Nelson, M.P. & Gore, M.L. 2016. Moral dimensions of human – wildlife conflict. Conservation Biology, 30(6): 1200–1211.
Messmer, T.A. 2009. Human-wildlife conflicts: emerging challenges and opportunities. Human–Wildlife Conflicts, 3(1): 10 –17.
Muboko,N., Gandiwa, E., Muposhi, V. & Tarakini, T. 2015. Illegal hunting and protected areas: Tourist perceptions on wild animal poisoning in Hwange National Park, Zimbabwe. Tourism Management, 52: 170-172.
Olszanska, A., Solarz, W. & Najberek, K. 2016. To kill or not to kill — Practitioners’ opinions on invasive alien species management as a step towards enhancing control of biological invasions. Environmental Science & Policy, 58: 107–116.
Petersen, L.M., Moll, E.J., Collins, R. & Hockings, M.T. 2012. Development of a Compendium of Local, Wild-Harvested Species Used in the Informal Economy Trade, Cape Town, South Africa. Ecology and Society, 17(2): 1-16.
Pluess, T., Jarosik, V., Pysek, P., Cannon, R., Pergl, J., Breukers, A. & Bacher, S. 2012. Which Factors Affect the Success or Failure of Eradication Campaigns against Alien Species? PLoS ONE, 7(10): 1- 11.
Redpath, S.M., Young, J., Evely, A., Adams, W.M., Sutherland, W.J., Whitehouse, A., Amar, A., Lambert, R.A., Linnell, J.D.C., Watt, A. & Gutierrez, R.J. 2013. Understanding and managing conservation conflicts. Trends in Ecology and Evolution, 28(2): 1-8.
Reed, M.S., Graves, A., Dandy, N., Posthumus, H., Hubacek, K., Morris, J. Prell, C., Quinn, C.H. & Stringer, L.C. 2009. Who’s in and why? A typology of stakeholder analysis methods for natural resource management. Journal of Environmental Management, (90): 1933-1949.
Roy, S., Ridley, R., Sandon, J., Allan, J.R., Robertson, P.A. & Baxter, A. 2016. Adapting strategies to maintain efficiency during a cull of yellow-legged gulls. Human Wildlife - Interactions, 10(1): 83–90.
Selge, S., Fischer, A., Van Der Wal, R. 2011. Public and professional views on invasive non-native species – A qualitative social scientific investigation. Biological Conservation, 9(14): 1-9.
Shine, R. & Doody, J.S. 2010. Invasive species control: understanding conflicts between researchers and the general community. Frontiers in Ecology and Environment, 9(7): 400-406.
Simberloff, D., Martin, J., Genovesi, P., Maris, V., Wardle, D.A., Aronson, J., Courchamp, F., Galil, B., Garcia-Berthou, E., Pascal, M., Pysek, P., Sousa, R., Tabacchi, E. & Vila, M. 2014. Impacts of biological invasions: What’s what and the way forward. Trends in Ecology and Evolution, 8(1): 58-66.
Sokół, R., Raś-Noryńska, M., Gesek, M., Murawska, D., Hanzal, V. & Janiszewski, P. 2016.The parasites of the mallard duck (Anas platyrhynchos) as an indicator of health status and quality of the environment. Annals of Parasitology, 62(4): 351–353.
Spear, D., Foxcroft, L.C., Bezuidenhout, H. & McGeoch, M.A. 2012. Human population density explains alien species richness in protected areas. Biological Conservation, 159: 137–147.
Stafford, L. 2010. Mallard Strategy for South Africa. Cape Town.
Todesco, M., Pascual, M.A., Owens, G.L., Ostevik, K.L., Moyers, B.T., Hubner, S., Heredia, S.M., Hahn, M.A., Caseys, C., Bock, D.G. & Rieseberg, L.H. 2016. Hybridization and extinction. Evolutionary Applications, 9(7): 1-17.
Van De Crommenacker, J., Bourgeois, Y.X.C., Warren, B.H., Jackson, H., Dogley. F., Groombridge, J. & Bunbury, N. 2015. Using molecular tools to guide management of invasive species: assessing the genetic impact of a recently introduced island bird population. Biodiversity research, (8): 1–14.
Van Rensburg, B.J., Peacock, D.S. & Robertson, M.P. 2009. Biotic homogenization and alien bird species along an urban gradient in South Africa. Landscape and Urban Planning. Pretoria: Elsevier. 1-9.
White, R.M., Fischer, A., Marshall, K., Travis, J.M.J., Webb, T.J., di Falco, S., Redpath, S.M. & Van Der Wal, R. 2008. Developing an integrated conceptual framework to understand biodiversity conflicts. Land use Policy, 26: 242–253.
Yoder, C.A., Miller, L.A. & Bynum, K.S. 2005. Comparison of Nicarbazin Absorption in Chickens, Mallards, and Canada Geese. Poultry Science, 84:1491–1494.
Acknowledgements to Mfundo Tafeni, Project manager of Invasive Species in the Environmental Management Department. City of Cape Town. Stephanie De Villiers, Veterinarian at Department of Agriculture, Forestry and Fisheries.