Table 1. Summary of aerial count survey methodology (* denotes lack of georeferenced data).
| Aerial count year |
Month |
Type of platform | Type of count | Strip width (m) | % of Rift Valley sampled | % of GNP sampled |
|---|---|---|---|---|---|---|
| 1968 late dry season * | November | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1969 wet season * | February | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1969 late dry season | October | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1970 wet season | January | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1971 wet season * | March | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1972 late dry season | October | Fixed-wing | Full count | 1,000 | 100.0 | 64.7 |
| 1994 late dry season | June | Fixed-wing | Sample count | 255 | 4.2 | 2.9 |
| 1997 late dry season | October | Fixed-wing | Sample count | 255 | 6.5 | 5.2 |
| 2000 late dry season | October | Helicopter | Sample count | 500 | 13.6 | 11.6 |
| 2001 late dry season | November | Helicopter | Sample count | 500 | 24.8 | 24.4 |
| 2002 late dry season | November | Helicopter | Sample count | 500 | 21.4 | 14.6 |
| 2004 late dry season | October | Fixed-wing | Sample count | 303 | 9.9 | 9.6 |
| 2007 late dry season | November | Helicopter | Sample count | 500 | 24.7 | 21.9 |
| 2010 late dry season | November | Helicopter | Sample count | 500 | 24.7 | 22.5 |
| 2012 early dry season | May | Helicopter | Sample count | 500 | 25.8 | 23.8 |
| 2014 late dry season | October | Helicopter | Full count | 500 | 71.8 | 49.9 |
| 2016 late dry season | October | Helicopter | Full count with additional sample lines outside of Rift Valley |
500 | 73.0 | 53.9 |
| 2018 late dry season | October | Helicopter | Full count with additional sample lines outside of Rift Valley |
500 | 74.2 | 58.9 |