Surveys in 1982 in these two parks were conducted using narrower strip widths at high intensities and carcass and live elephant numbers were used to calculate the carcass ratio without applying correction factors. Iain Douglas-Hamilton and A. Burrill recommend that strips of less than 200 m wide are used for carcass counts from aerial surveys. Visibility of carcasses is greatly affected by the state of the vegetation, particularly grass height. Surveys which seek to count carcasses should therefore be conducted in the dry season when grass is short or burnt. Carcass is now a skeleton, with clean white bones and in wet areas no skin.
Skeletons are difficult to see from the air.
Carcass breakdown depends greatly on local conditions and can vary tremendously from year to year. Local conditions greatly affect the results of aerial surveys for elephants and carcasses. In particular, there is a great difference between wet and dry seasons in savannah habitats. Aerial surveys have to be carried out in the dry season. In hot seasons elephants will seek out shade earlier in the morning and remain in it for longer in the afternoon, thus reducing the amount of time that they are easily visible.