I had this lousy picture in my slide collection for two years before I obtained the Field Guide to the Reptiles of East Africa by Spawls, et al. By checking into every green snake that lives in the area, I've convinced myself that this was a boomslang. Boomslangs have a distinctive egg-shaped head and very clear scale lines, both visible in this picture. They are also fairly common and extremely good climbers. The few other solid green snakes in the area looked enough different that I'm satisfied with this identification.
Boomslangs are members of the Colubridae family, which was historically thought to consist only of harmless snakes. However, in 1957 prominent herpetologist Karl Schmidt died from the bite of a boomslang, and Colubridae lost its innocent reputation.
- Branch, B. 1998. Field Guide to Snakes and Other Reptiles of Southern Africa, third revised edition
- Spawls, S. 2017. A Guide to Amphibians and Reptiles of the Maasai Mara
- Spawls, S., Howell, K., Hinkel, H., Menegon, M. 2018. A Field Guide to East African Reptiles, 2nd edition