Wildlife counts in Africa and elsewhere are often implemented using light aircraft with 'rear-seat-observer' (RSO) counting crews. Previous research has indicated that RSOs often fail to detect animals, and that population estimates are therefore biased. We conducted aerial wildlife surveys in Murchison Falls Protected Area, Uganda, in which we replaced RSOs with high-definition 'oblique camera count' (OCC) systems. The survey area comprises forests, woodlands and grasslands. Four counts were conducted in 2015-2016 using a systematic-reconnaissance-flight (SRF) strip-transect design. Camera inclination angles, focal lengths, altitude and frame interval were calibrated to provide imaged strips of known sample size on the left and right sides of the aircraft. Using digital cameras, 24 000 high-definition images were acquired for each count, which were visually interpreted by four airphoto interpreters. We used the standard Jolly II SRF analysis to derive population estimates. Our OCC estimates of the antelopeshartebeest, Uganda kob, waterbuck and oribiwere, respectively, 25%, 103%, 97% and 2100% higher than in the most recent RSO count conducted in 2014. The OCC surveys doubled the 2014 RSO estimate of 58 000 Uganda kob to over 118 000. Population size estimates of elephants and giraffes did not differ significantly. Although all four OCC buffalo estimates were higher than the RSO estimatesin one count by 60%these differences were not significant due to the clumped distribution and high variation in herd sizes, resulting in imprecise estimation by sampling. We conclude that RSO wildlife counts in Murchison have been effective in enumerating elephants and giraffe, but that many smaller species have not been well detected. We emphasize the importance of 60 years of RSO-based surveys across Africa, but suggest that new imaging technologies are embraced to improve accuracy.

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Abstract1. A 12-month-long survey (April 2013 to March 2014) for Nile crocodiles (Crocodylus niloticus) was conducted along a section of the Victoria Nile/Ramsar site of Murchison Falls National Park, in order to update the historic information on crocodile populations in the area, locating nesting areas, determining seasonality patterns and habitat use, and assess the current abundance and the population size trends since the 1960s. The methods employed included visual encounter surveys, transect counts and opportunistic methods, by using boats. 2. In general, there were diurnal and seasonal fluctuations in the number of crocodile sightings. The crocodile sightings peaked between the months of June and August, with the highest mean number of sightings encountered on any single day being 67 (in July 2013), and the second peak was between January and March with the highest mean of 118 recorded in January 2014. The second peak also coincided with the crocodile breeding season. This clearly shows that the distribution of the sub-population sampled followed a climatic regime. 3. Crocodiles were observed most frequently in water (37%). Grassy banks, islands, river mouths and sandy banks constituted about 47% of the habitats utilised by the crocodile population. Although basking was the most frequent type of activity performed by crocodiles (50%) over the entire survey period, their key activities varied significantly from month to month. Nesting was very visible during the last quarter of the year and the first quarter of the New Year. 4. There was a clear decline of the abundance of crocodiles in this population between 1960s and nowadays. This declining trend was obvious also taking into account the various survey methodologies employed over the decades.

Total Exploration and Production Uganda undertook a 3D seismic survey in Exploration Area 1/1A lying within the Murchison Falls National Park inhabited by many species of wildlife. During the seismic survey, an ecological avoidance program was applied to; i). Scout and map all sensitive features within the seismic footprint, ii). Avoid impacts on sensitive features and maintain their ecological integrity, iii). Proactively demonstrate sustainable oil & gas extraction in a sensitive ecosystem. A mitigation hierarchy of; Avoidance, Minimization, Restoration and Offsetting residual impacts was followed to limit ecological impacts. In this paper, we focus on Avoidance, presented as a model for future seismic or other intensive operations in similar sensitive ecosystems. This involved systematic surveys of predefined seismic lines for sensitive features, mapping locations of features, sensitizing Seismic crews, and on-ground supervision of Avoidance implementation. A total of 25,484 features such as; lekking grounds of ungulates, clay-licks and wallows were mapped along approximately 3300km in total of seismic lines surveyed. Out of 25,484 features mapped, 10,169 significant features were sorted, from which 678 features were sampled and revisited after seismic operations to assess compliance to Avoidance. Out of 678 features revisited, only one, a burrow was found to be impacted upon, having a tyre mark depression implying it was trampled by a vehicle. Three other burrows were found filled with soil, but with no indication of whether this was due to anthropogenic or natural occurrence. Five hundred and twenty features were found to have signs of animal activities such as; footmarks and physical presence of animals, including birds, indicating continued use of the features after seismic operations. The results indicate compliance by Seismic crews, suggesting that the Avoidance Mapping Procedure is an effective impact mitigation measure especially in such sensitive ecosystems. No such intensive seismic operation had been undertaken before in such a sensitive ecosystem. Some impact minimization measures used such as cable-less seismic data acquisition were implemented for the first time in Africa during these surveys. The Avoidance Mapping Procedure designed and applied was as well therefore the first of its kind, and provides an extensive knowledge, technicalities and experience in avoiding and minimizing impacts during seismic operations in such sensitive ecosystems.

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