Eyes in the sky: conducting a population census from the air

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September is the time of year when managers of conservation areas take to the skies to conduct the annual aerial population census.

With the use of either a helicopter or small, fixed-wing aeroplane, the land is flown in East-West transects, 300m apart and all of the animals seen are counted. The aircraft usually contains the pilot and three passengers, or ‘spotters’. When an animal is encountered, the spotters will start counting the individuals in the group or herd. The data will include the herd composition; number of males, females, juveniles or unknowns. Generally, the information is given as a ratio of males: female: juveniles. One of the spotters will be in charge of operating a handheld logging device and record all sightings and group structure breakdown. At the moment of data entry, the current GPS location will also be taken.

Elephants viewed from the air


Although one can never expect to count all of the animals on the property with this method, the error remains the same year after year. The results give the reserve managers a wealth of knowledge as to what is happening on the property. Population trends can be seen over time and the survival success of each species can be ascertained. Additionally, it allows managers to see wildlife hot spots on the reserve. For the most part, these will already be known to the manager. They will correlate with resources such as water points, good grazing areas or areas with more palatable tree species.

Generally speaking, the results will be viewed alongside the annual ecological survey. The ecological report evaluates the habitat and vegetation. Areas of interest include; veld type, species composition, grass palatability, plant community and production potential. The ecological survey will suggest the carrying capacity for the reserve – the maximum number of animals that the veld can sustainably support.

A conservation management tool

The results from the aerial census combined with the ecological survey allow managers to make informed conservation decisions. Should the aerial census show game numbers above the carrying capacity of the property, the managers and stakeholders of the property can discuss the viability of removing animals and the best method of doing so. It is likely that the decisions will be species specific. The options will include formulating a hunting quota, mass culling or translocation. There are pros and cons to all the options but it will take another ten blog posts to discuss them in the depth that they deserve. Should game numbers appear lower than the carrying capacity, then re-stocking can be considered.

The aerial census is just another tool in a manager’s arsenal. The information assists them in making decisions that will ensure the sustainability and ecological balance of these delicate conservation areas.

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