Introduction: the need for monitoring

There is danger that any conservation management plan will remain rigid and non-responsive to changes that occur to the species, population or environment being managed. It may thereby lose the initial perspective and focus as the operating environment diverges from the basis on which the plan was formulated. Changes in the species' conservation status or in its environment may result from management or from other, non-anticipated, factors. Ideally, management should be adaptive and either periodically or continuously dynamic in response to review as such changes occur. It follows that those changes must be detected and interpreted as reliably as possible to enable refinement of management, and curtailment of ineffective management components. As Hauser et al. (2006) noted, monitoring programmes are planned most commonly with the assumption that monitoring must be undertaken at fixed time intervals. For insects, these intervals are usually annual, to coincide with accessibility to a conspicuous life stage amenable to detection and counting. Often, these correspond to an intergenerational interval.

Monitoring is therefore sometimes defined as ‘intermittent or periodic surveillance’, and is the major means through which the success or failure of a conservation management programme can be assessed. It becomes particularly important when information is needed on short term effects of management, because correspondingly short term revision of that management may be critical if adverse effects are found. It also has many wider applications in revealing trends in abundance and distribution, some of which may trigger additional conservation interest or activity. Quantitative observations over time (so-called ‘longitudinal studies’) are often the only way in which the success or otherwise of management can be assessed.