Some 65 percent of forest elephants were killed in Central Africa between 2002 and 2013.
The new data from the field in Central Africa revealed elephants were being poached for their ivory, at a shocking nine percent per year.
The data marks an update to an earlier paper in the online journal PLOS ONE on the status of forest elephants across Central Africa, published by the same scientists.
Many organisations collaborated in the study, which covered 80 sites, in five countries, over the 12 years of data collection.
The earlier paper, published in 2013, already had shown a decline of 62 percent of the population between 2002 and 2011.
The update, released at the United for Wildlife symposium in London, was made by adding new data from 2012 and 2013 and using the same analysis methods as before.
The results show that the relatively small nation of Gabon has the majority (almost 60 percent) of the remaining forest elephants.
Historically, the enormous Democratic Republic of Congo (DRC) would have held the largest number of forest elephants.
