Crop loss to foraging elephants is one of the most significant causes of conflict between people and elephants in areas where wild elephants share resources with people. Effective solutions to reduce the effects of human–elephant conflict on local livelihoods are thus essential to foster coexistence between elephants and people. We assessed the effectiveness of chilli-briquettes (bricks made of dry chilli, elephant dung and water) in altering elephants use of space in the eastern Okavango Panhandle, Botswana. We burned > 600 briquettes during the night over a 2-month period to test five treatments: frequent burning of (1) chilli and (2) chilli-free briquettes, occasional burning of (3) chilli and (4) chilli-free briquettes, and (5) a control treatment. Using camera traps and footprint surveys we assessed the number of elephants that used experimental sites, and the times at which they did so. We found elephants changed their movement behaviour from predominantly nocturnal to diurnal in areas where chilli-briquettes were burned throughout the night; however, there was no difference in the mean numbers of individuals between treatments with and without chillies. In other words, chilli-briquettes had a repellent but not a deterrent effect on elephants, keeping them away only at times when chilli-briquettes were smouldering. Based on these findings we recommend the use of chilli-briquettes as a method to deter elephants in the short term. In the long term, chilli-briquettes should be applied in combination with other larger-scale mitigation approaches, such as land management and cooperative community-based tools.

Crop losses to foraging elephants are one of the primary obstacles to the coexistence of elephants and people. Understanding whether some individuals in a population are more likely to forage on crops, and the temporal patterns of elephant visits to farms, is key to mitigating the negative impacts of elephants on farmers’ livelihoods. We used camera traps to study the crop foraging behaviour of African elephants Loxodonta africana in farmland adjacent to the Udzungwa Mountains National Park in southern Tanzania during October 2010–August 2014. Camera traps placed on elephant trails into farmland detected elephants on 336 occasions during the study period. We identified individual elephants for 126 camera-trap detections. All were independent males, and we identified 48 unique bulls aged 10–29 years. Two-thirds of the bulls identified were detected only once by camera traps during the study period. Our findings are consistent with previous studies that found that adult males are more likely to adopt high-risk feeding behaviours such as crop foraging, although young males dispersing from maternal family units also consume crops in Udzungwa. We found a large number of occasional crop-users (32 of the 48 bulls identified) and a smaller number of repeat crop-users (16 of 48), suggesting that lethal control of crop-using elephants is unlikely to be an effective long-term strategy for reducing crop losses to elephants.

This study demonstrates a highly sensitive humidity sensor based on treated multiwalled carbon nanotube (tr-MWCNT) and hydroxyethyl cellulose (HEC) composite films. Tr-MWCNTs are obtained by mixed acid treatment to enhance their hydrophilicity and improve their dispersion in distilled water. Compared to tr-MWCNT/silicone rubber (SR) composite film, the humidity sensitivity of tr-MWCNT/HEC film is much higher than tr-MWCNT/SR film with the same film thickness. The humidity sensing mechanisms of tr-MWCNT/HEC composites are explained by electron donation model and swelling mechanism. Speaking and blowing experiments were also carried out and the results show that tr-MWCNT/HEC composite film is sensitive to both speaking and blowing; furthermore, it can distinguish the small humidity level difference between speaking and blowing. Other sensing characteristics, including response and recovery time, stability, and temperature effect, are also investigated. The high humidity sensitivity of tr-MWCNT/HEC composite film indicates that it can be an excellent humidity sensitive material.