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What is Conservation Success?

We hear the term ‘conservation success story’ quite often in the media, but how do we actually define conservation success? This is an important topic within conservation, as funding is not an infinite resource, therefore it’s important to know which conservation methods are more likely to yield successful results. It’s also important to be able to determine the ‘end point’ of a project, to know when the conservation target no longer needs direct (or indirect) conservation action. Multiple frameworks have been created to try and define the criteria needed to determine the success of a conservation project.

Biological factors

Traditionally, conservation success was measured on biological factors such as population growth, biodiversity, and total area of conservation. However, this criteria ignores the impact of threats such as persecution, habitat loss, pollution, and socio-political pressures, therefore not taking into account the stability of the species. For example, red kites (Milvus milvus) are often considered a conservation success, due to the population increase from their near extinction in the 1870s. Their range expansion and the successful breeding between wild and released birds are also toted. However, the populations in both England and Scotland are slow-growing and slow to expand, leading to high densities of birds within small areas, often centred around the release sites. This slowed population growth is mainly attributed to the continued threat presence from illegal killings. Therefore, although the population size is growing, the conservation is not fully successful as, if the conservation actions were withdrawn, and without further intervention, these populations may not prove to be sustainable.


There has been a shift, primarily led by the International Union for Conservation of Nature (IUCN), to widen the scope of conservation from preventing the extinction of a single species to restoring that species as a functioning part of its ecosystem. This is usually measured as successful when the species has a viable, healthy population that is found across its former range, with the ecosystem interactions restored. However, there are many limitations to this approach. Firstly, it is far easier said than done, as often much of the former range has undergone land-use change, often through urbanisation or agricultural expansion, and is thus no longer suitable for the species. Therefore, would that mean that a species that now occupies the same size range as it historically did, but not one across the same area as it historically was, would not be considered a conservation success story?

Additionally, restoring ecosystem interactions is another huge task, as more often than not, it’s not just one species within the ecosystem that is missing or in need of conservation. In the UK, our apex predators are missing; therefore many of our ecosystems are not fully functioning. Would this mean that the current conservation of beavers (Castor fiber) within the UK couldn’t be considered successful until if we reintroduce their predators, lynx (Lynx lynx) and wolves (Canis lupus lupus)?

Conservation dependence

In many cases, species are dependant upon the conservation efforts they receive, as, without them, they would become extinct. They are not a fully restored, functional part of the ecosystem, as they require human intervention or management. In the absence of natural predators in many countries where the Eurasian beaver has been introduced, the population is controlled through shooting. If this conservation intervention were removed, the only limits to beaver populations would most likely be food supply, accidental death (such as from cars), and infectious diseases. This could lead to rapid growth and the eventual collapse of not only the beaver populations but also the ecosystem they are a part of, especially given their status as ecosystem engineers and a keystone species. Therefore, even though many of the populations are healthy and viable, and even if all threats such as persecution were removed, the conservation could still not be considered a success, as the beaver still relies on the intervention of humans to remain a stable population.

Big success vs little success

Many of the criteria currently being proposed requires big conservation action, usually through the coordination of multiple projects over years or even decades. Even then, success, as it’s being proposed, may not be possible, due to the irreversible impacts humans have had on the ecosystem. Parts of the ecosystem have gone extinct and replacing them with species that could play a similar role is not always possible or even feasible. Land-use change has caused many habitats to be altered or lost, and with an ever-growing population, it is not possible to remove urban or agricultural areas. Climate change has made conditions no longer suitable for species to be reintroduced or have their habitats and population expanded. The eradication of invasive is an expensive endeavour and often not achievable. But does this mean that conservation can never be successful?

Increasing the population of a species on the brink of extinction is an achievement. Expanding the range of a rare, severely restricted species is an achievement. Establishing a breeding population of a species previously lost is an achievement. These may not indicate the overall conservation success of the species but does indicate the success of a conservation project. Yes, it is important to remove threats, create viable, stable populations, and return species to their previous ranges to restore ecosystem interactions, but not every project will be able to achieve these. Therefore, conservation success should be considered in stages, by measuring the progress that is made towards clear goals set out by the projects. Conservation should be considered in three stages, immediate action (i.e. viability of reintroduction or breeding programs, assessment of and action against threats, halting population decline), the reestablishment of previous population levels over previous ranges (where possible), and the stabilisation of the population within its ecosystem, without the continued management from humans.


Gruber, J., Mbatu, R., Johns, R., and Dixon, B., 2017. Measuring conservation success beyond the traditional biological criteria: the case of conservation projects in Costa Rica, Mekong Valley, and Cameroon. Natural Resources Forum, 42(1), pp. 19-31

Nolet, B., and Rosell, F., 1998. Comeback of the beaver Castor fiber: An overview of old and new conservation problems. Biological conservation, 83(2), pp. 165-173

Salafsky, N., Margoluis, R., Redford, K., and Robinson, J., 2002. Improving the Practice of Conservation: a Conceptual Framework and Research Agenda for Conservation Science. Conservation Biology, 16(6), pp. 1469-1479

Smart, J., Amar, A., Sim, I., et al., 2010. Illegal killing slows population recovery of a re-introduced raptor of high conservation concern – The red kite Milvus milvus. Biological Conservation, 143(5), pp. 1278-1286

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