26Crop losses from elephants are one of the primary obstacles to the coexistence of 27 elephants and people and one of the contributing causes to elephant population 28 decline. Understanding if some individuals in an elephant population are more likely 29 to forage on crops, and the temporal patterns of elephant visits to farms, is key to 30 mitigating the negative impacts of elephants on farmers. We used camera traps as a 31 novel technique to study elephant crop foraging behaviour in farmland adjacent to 32 the Udzungwa Mountains National Park in southern Tanzania from October 2010 to 33 August 2014. Camera traps placed on elephant trails into farmland captured 34 elephants on 336 occasions over the four-year study period. We successfully 35 identified individual elephants from camera trap images for 126 of these occasions. 36All individuals detected on the camera traps were independent males, and we 37 identified 48 unique bulls aged between 10 and 29 years. Two-thirds of the bulls 38 identified were detected only once by camera traps over the study period, a pattern 39 that also held during the last year of study when camera trapping effort was 40 continuous. Our findings are consistent with previous studies that found that adult 41 males are more likely to adopt high-risk feeding behaviours such as crop foraging, 42 though young males dispersing from maternal family units also consume crops in 43 Udzungwa. Our study found a large number of occasional crop-users (32 of the 48 44 bulls identified) and a smaller number of repeat crop-users (16 out of 48), suggesting 45 that lethal elimination of crop-using elephants is unlikely to be an effective long-term 46 strategy for reducing crop losses from elephants. 47 48

No abstract

51Detecting and monitoring illegal harvesting pressure on wild populations is 52 challenging due to the cryptic nature of poaching activities. Although change in 53 population age structure has been suggested as an indicator of harvesting pressure, 54 few studies have tested its validity when based on short-term field surveys. Using data 55 from rapid demographic assessment surveys carried out in 2009 at six sites in 56Tanzania, we examined whether African elephant populations experiencing 57 contrasting levels of poaching pressure showed significant differences in their age 58 structure, operational sex ratio (i.e. adult males to adult females), dependent 59 individual to adult female ratio at the group level, and proportion of tuskless 60 individuals. We also compared similar metrics between the population sampled in 61Ruaha National Park in 2009 and again in 2015 following a suspected increase in 62 poaching. Elephant populations experiencing medium and high levels of poaching in 63 2009 were characterised by fewer calves and old individuals, a reduced number of 64 adult males relative to adult females, and a lower ratio of calves to adult females 65 within groups. We also found a higher proportion of tuskless individuals in poached 66 populations (> 6 %). Changes in age structure in the Ruaha population between 2009-67 15 were similar to those observed across sites in 2009. Our findings are consistent 68 with previous work documenting how the loss of older individualstargeted for their 69 larger tusksdecreases recruitment and survival of elephant calves. Illegal killing for 70 ivory is a huge threat to the survival of African elephants. In this context, the present 71 study contributes towards validating the use of age structure as an indicator of 72 poaching pressure in elephant populations, but also in other wildlife populations 73where illegal offtake is targeted at specific age classes. 74 75 KEYWORDS: age structure, operational sex ratio, rapid demographic assessment, 76Ruaha National Park, Tanzania, tusklessness. 77 78