Aerial Survey of Elephants and other Large Herbivores in Gonarezhou National Park (Zimbabwe) and some adjacent areas: 2016 K.M. Dunham & H.F. van der Westhuizen October 2016 Aerial Survey of Elephants and other Large Herbivores in Gonarezhou National Park (Zimbabwe) and some adjacent areas: 2016 K.M. Dunham & H.F. van der Westhuizen October 2016 Frankfurt Zoological Society Gonarezhou Conservation Project Gonarezhou National Park, Chiredzi, Zimbabwe This survey was conducted jointly by the Parks & Wildlife Management Authority and Frankfurt Zoological Society. The views expressed in this report are those of the authors and do not necessarily represent those of Frankfurt Zoological Society, or the Parks & Wildlife Management Authority. Suggested Citation: Dunham, K.M. & van der Westhuizen, H.F. (2016). Aerial Survey of Elephants and other Large Herbivores in Gonarezhou National Park (Zimbabwe) and some adjacent areas: 2016. Frankfurt Zoological Society, Gonarezhou Conservation Project, Gonarezhou National Park, Chiredzi, Zimbabwe. Aerial Survey of Elephants and other Herbivores in Gonarezhou NP (Zimbabwe) & surrounds: 2016 Summary Elephants and other large herbivores, wild and domestic, in Gonarezhou National Park, Malapati Safari Area and Mahenye and Naivasha communal lands in south-eastern Zimbabwe were surveyed from the air during September 2016. The survey area lies within the Great Limpopo Transfrontier Conservation Area. A fixed-wing aircraft was used to conduct a sample survey, flying transects over the area. The area surveyed totalled 5633 km2 and was divided into 10 strata. By design, sampling intensity varied between strata and ranged from 13 to 22 %. Sampling intensity averaged 21.5 % in Gonarezhou NP and 20.7 % in the entire survey area. The principal objective of the survey was to provide relatively precise and accurate estimates of the number of elephants in the survey area as a whole, using a technique that could be executed within a reasonable time and at a reasonable cost. Secondary objectives included provision of population estimates for other large herbivores, determination of the spatial distributions of elephants and other large herbivores; and estimation of the number and spatial distribution of elephant carcasses. The methods used were suitable for meeting the survey objectives, repeatable and technically robust. Some large herbivores are not easily seen from the air and their numbers were undoubtedly underestimated. Nonetheless, population estimates are given for these species, because the estimates provide useful indices of abundance with measures of precision and can be used to determine spatial distribution, as well as temporal trends in population number. No corrections have been applied to any of the estimates to compensate for any undercounting or missed animals. The estimated population numbers of the principal large herbivores in Gonarezhou NP were: elephant 10715 (upper and lower 95% confidence limits ± 17.5 %); impala 7421 (± 27.3 %); buffalo 4797 (± 50.7 %), kudu 1789 (± 27.6 %); zebra 1830 (± 26.2 %); wildebeest 929 (± 43.4 %); giraffe 446 (± 36.8 %); eland 241 (± 81.6 %); nyala 187 (± 47.1 %); waterbuck 326 (± 60.3 %); cattle 1346 (± 45.9 %); and sheep and goats 1246 (± 65.7 %). Most domestic animals were in the Chitsa area in the north of the park, but others were seen in the very south of the park, and near the international border with Mozambique, close to the Chefu River. There were estimated to be 704 elephant carcasses in the entire survey area and 656 in Gonarezhou NP. The all-carcass ‘ratio’ (i.e. the ‘ratio’ for elephant carcasses of all age categories) was 6.0 % in the survey area as a whole and 5.8 % in Gonarezhou NP. If it is assumed that all unidentified carcasses were elephant carcasses, the all-carcass ratio increases to 9.1 % for the entire survey area and 8.5 % for Gonarezhou NP. The 1+2 carcass ‘ratio’ [based on fresh (age category 1) and recent (age category 2) carcasses of elephants] was to 0.30 % for the entire survey area and 0.26 % for Gonarezhou NP. The 2016 estimate of 10715 elephants in Gonarezhou NP is only slightly below the peak estimate of 11120 elephants during 2014, which was the highest estimate of the number of elephants in this park since sample surveys began there during 1975. i Aerial Survey of Elephants and other Herbivores in Gonarezhou NP (Zimbabwe) & surrounds: 2016 Table of Contents Summary .................................................................................................................................................. i List of Tables ........................................................................................................................................... iii List of Maps ............................................................................................................................................. iii List of Figures .......................................................................................................................................... iv Introduction .............................................................................................................................................. 1 Survey Area ............................................................................................................................................. 2 Methods ................................................................................................................................................... 3 Survey Design ..................................................................................................................................... 3 Flight Procedures ................................................................................................................................. 3 Strip Width and Calibration .................................................................................................................. 4 Observations ........................................................................................................................................ 5 Cameras .............................................................................................................................................. 5 Data Analysis ....................................................................................................................................... 6 Entire survey area and land units within it ....................................................................................... 7 Elephant carcasses ......................................................................................................................... 7 Search Effort ........................................................................................................................................ 8 Results ..................................................................................................................................................... 9 Search Effort ........................................................................................................................................ 9 Animal Numbers .................................................................................................................................. 9 Elephant Carcasses ........................................................................................................................... 10 Animal Distributions ........................................................................................................................... 10 Human Activities ................................................................................................................................ 10 Comparison of Observers .................................................................................................................. 10 Trends in Animal Numbers in Gonarezhou NP ..................................................................................... 13 Discussion ............................................................................................................................................. 24 Elephants ........................................................................................................................................... 24 Elephant Carcasses ........................................................................................................................... 24 Other Large Herbivores ..................................................................................................................... 24 Encroachment on the Parks and Wild Life Estate ............................................................................. 24 Acknowledgements ................................................................................................................................ 25 References ............................................................................................................................................ 25 Appendix 1. Calibration of strip width .................................................................................................... 60 Appendix 2. Survey flight summary ....................................................................................................... 62 Appendix 3. Transect start and end points, and lengths ....................................................................... 63 Appendix 4. Transect summaries of sightings ......................................................................................