Habitat management is the manipulation of habitats to provide suitable conditions for species of interest, or in some cases to reduce the number of species considered as pests. Habitat management is most commonly used to:
• provide suitable conditions for species where these are no longer created by natural processes;
• maintain characteristic assemblages of species, where persistence of the assemblage is dependent on continuation or re-instatement of particular land-management;
• maximize the harvestable surplus of game species (Chapter 13).
Most habitat management involves preventing or reversing the direction of vegetation succession. In some cases it is also used to create suitable vegetation structure, increase food availability, and provide suitable nesting areas for birds.
The successional stage of an area, and hence its suitability for a given species, is influenced by processes such as grazing by large herbivores and disturbance by fire, floods, and storms. In many remaining fragments of semi-natural habitat, the key natural processes influencing succession either no longer operate, or if they do, they operate at an inappropriate scale or frequency to maintain suitable conditions for the species of interest. The absence of suitable natural processes is most acute in small and isolated patches of habitat. For example, small patches of semi-natural habitat are rarely grazed by large wild herbivores, let alone by their full complement of native species. Large-scale disturbances caused by fire or flood are largely prevented as a matter of policy. If they do occur, they are likely to affect the whole of the remaining small fragment of habitat, and so make it temporarily unsuitable for most of its associated species. If the fragment of habitat is isolated from sources of re-colonization, the less mobile species lost because of the disturbance are unlikely to re-colonize. In these situations, habitat management can be used to mimic the effects of these natural processes in a controlled manner to maintain a continuity of suitable conditions for desired species.
The main way of manipulating succession and creating suitable vegetation structure in terrestrial systems is by removing vegetation, either by cutting, grazing/browsing, burning, or herbicide use. Succession in wetlands can also be manipulated by controlling water levels and, in some cases, nutrient inputs.
When considering habitat management, it is useful to distinguish between phases of management aimed at restoring suitable conditions (restorative management) and those aimed at maintaining them (maintenance management). Wholesale habitat creation on land of little or no conservation value, such as arable land, usually involves increasing the rate of succession by optimizing conditions for the establishment and growth of desired vegetation, and in some cases also introducing seeds and plants. Techniques for habitat creation are outside the scope of this chapter.
Habitat management for birds has only been widely used in more intensively managed regions, such as Europe and parts of North America. Most of this chapter is therefore based on experience and research from these areas, although the principles involved are applicable elsewhere. An understanding of the general principles and effects of habitat management is fundamental to good site management, but the specific aims and details of any management should always be decided on a site by site basis. Habitats have been excluded where management is rarely, if ever, driven by the specific requirements of birds, such as deserts, mountain tops, sea cliffs, marine habitats, and rivers.
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