- Adaptive management - Monitoring -

Adaptive management

It has been emphasised throughout this study that the population dynamics of hippo are most unusual and the population response to management interventions is difficult to predict. What has been put forward as the expected population dynamics of hippo in response to various management treatments should be seen as hypotheses in an adaptive management system (Holling 1976). Indeed, the proposed 'project' which involves harvesting, sport hunting and problem animal control should be seen as an active adaptive management research opportunity.

Under Passive Adaptive Management ("cautious fiddling") the effort is varied narrowly around some point for fear that any major change will result in system collapse. The result is that the optimum operating point is seldom detected. Under Active Adaptive Management the effort is deliberately varied over a period of time so that the population characteristic (or response to the harvest) can be defined. This may have considerable relevance to the hippo 'project'.

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Monitoring

To understand the population dynamics of the Caprivi hippo several key parameters need to be monitored:

Population numbers: Once population harvesting starts, an aerial survey such as that done last year by Stander (2004) should be carried out annually. To make comparisons from one year to the next it is worth maintaining the same strata and counting blocks. The ecological objective of this management plan is to create the conditions for the hippo population to increase and such surveys will be needed to establish whether this is happening.

This should be supplemented with local level counts on the ground (or in the water) in all the conservancies. Hippo are one of the few species whose numbers can be reasonably measured by direct observation. If conservancies are to be seen to be genuinely managing their wildlife then this sort of inventory is necessary and it should not be confused with Event Book monitoring. It requires one or two individuals to spend long hours with binoculars getting to know exactly what hippo are in their areas. The numbers to keep track of are fairly low: Salambala - 1; Kwandu - 8; Mashi - 18; Mayuni - 42; Kasika and Impalila -30). This data is useful also for 'ground-truthing' aerial surveys.

This intensive ground observation is also an excellent method of monitoring illegal hunting. Apart from the likelihood of actually seeing illegal hunters, the disappearance of known animals from local populations is a good indicator that illegal hunting is taking place.

Ages of all hippo killed: All lower jaws from hippo killed or dying naturally should be collected, clearly tagged: Each lower mandible should carry a label giving date of death, locality and category of death (e.g. natural mortality, hunting trophy, problem animal or animal harvested). The jaws should be transported to a central place where one person can determine the ages of the animals. Over several years an age structure for the population can be built up and, in conjunction with the population model of this study, a great deal can be inferred about the population dynamics.

This is also the most reliable method for adjusting quotas of trophy animals: the hypothesis put forward in this study is that a half-percent quota will result in a few males living beyond 30 years of age. If this is not the case, then the quota should be reduced: alternatively, if most trophies are over 30 years of age, quotas can be increased. These data also allow some inference about the age-specific natural mortality for the older males.

Reproductive data: For all females killed under a harvesting programme, it is worth recording whether or not they are pregnant or lactating in order to establish both fecundity and age at first conception for the population since these reproductive parameters are variable in the literature..