Coming down from the trees: is terrestrial activity in Bornean orangutans natural or disturbance driven?

Ancrenaz, M.
Sollmann, R
Meijaard, E.
Hearn, A.J
Ross, J
Samejima, H
Loken, B
Cheyne, S.M
Stark, D.J
Gardner, P.C
Goossens, B
Mohamed, A
Bohm, T
Matsuda, I
Nakabayasi, M
Lee, S.K
Bernard, H
Brodie, J
Wich, S.
Fredriksson, G.M
Hanya, G
Harrison, M.E
Kanamori, T
Kretzschmar, P
Macdonald, D. W
Riger, P
Spehar, S
Ambu, L.N
Wilting, A.