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Table 1 Processing steps of food items: the most frequent combinations of the different processing steps, as well as descriptions of the corresponding food items with local and scientific names of example species (T = Tuanan, S = Suaq)

From: Development of foraging skills in two orangutan populations: needing to learn or needing to grow?

Nr Processing steps Food item types Examples
0 Pick Fruits and flowers where everything is eaten Lunuk (Ficus sp.; T), Tapuhut Putih (Syzigium sp.; T), Nyatoh Puntik (Palaquium pseudorostrum; T), Resak Ubar (Brackenridgea palustris Bartell; S), Tapis Batu (Garcinia sp.; S)
1 a) Pick, bite off a) Fruits and flowers where a small outer part is bitten off after picking, discarded, and the remaining parts are eaten a) Medang Baru (Litsea gracilipes Hook f.; S), Nyatoh undus buah merah (Palaquium ridleyi; T), Katiau (Madhuca motleyana; T), Mangkinang Blawau (Elaeocarpus sp.; T)
b) Pick, drop b) Fruits and flowers where only the sap is ingested and all other parts are discarded after chewing b) Rewui (Microcos sp.; T), Piais (Nephelium mangayi; T), Tampang (Artocarpus dadak; T)
2 a) Pick, peel, spit out a) Fruits where the pulp is eaten while the skin and the seed are discarded a) Puwin (Sandoricum beccarianum Baill.; S), Papung (Sandoricum borneense; T)
b) Pick, bite in half, scrape flesh out b) Hard-shell fruits where pulp and seeds are eaten but the empty pod is discarded b)Malaka (Tetramerista glabra; S), Lewang (Pouteria cf malaccensis; T)
c) Pick, turn repeatedly in mouth, drop seed and skin layers c) Fruits with edible flesh tightly attached to an inedible seed and thin skin c) Enyak Beruk (Syzygium sp.; T), Nyatoh undus buah besar (Palaquium cochlearifolium; T), Tantimun unripe (Tetrameristra glabra; T)
d) Pick, pop pod open, extract seed d) Fruit pods with an edible seed enclosed d) Ubar (Horsfieldia crassifolia; S), Akar Kamunda (Leucomphalos callicarpus; T)
3 a) Pick, bite in half, scrape flesh out, spit out a) Hard shell fruits where the pulp and seeds are eaten but the empty pod and seeds are discarded a) Malaka unripe (Tetramerista glabra; S), Karandau Putih (Blumeodendron kurzii; T), Tutup Kabali (Diospyros pseudo-malabarica; T)
b) Pick, peel, bite away flesh, remove skin around seed b) Fruits where the skin around the seed is eaten after removing the inedible skin and flesh b) Manga Hutan (Mangifera gracilipes Hook f.; S)
c) Pick, pop pod open, extract seed, pop seed open c) Fruit pods with a seed enclosed; only the internal part of the seed is eaten while the rest is discarded c) Sepang (Sterculia sp.; S)
d) Collect substrate, scratch or bite open, suck d) Insects embedded in wood or other substrate d) Ants (Formicidae; T + S), Termites (Isoptera; T + S)
  e) Bite piece of bark loose, rip or strip it off, scrape inner bark off e) Inner bark (i.e. i.e., cambium/phloem) e) Maruang (Myristica lowiana; T), Pantung (Dyera lowii; T), Resak Payo (Dialium patens Backer.; S)
4 a) Pick, bite tip off, pull string off of pod to open it, turn pod open, extract seed a) Bean-like fruits with inedible skin but edible seeds a) Basong (Alstonia spatulata BI.; S)
b) Pick, pop pod open, extract seed, pop seed open, extract and spit out skin around seed b) Fruit pods with a seed enclosed; only the internal part of the seed is eaten while the inedible seed skin is discarded b) Sepang unripe (Sterculia sp.; S)
  c) Break dead twig off, examine, bite appart, suck c) Ants hidden in hollow twigs c) Ants (Formicidae; S)
5 a + b) Break stick off, peel (optional), chew (optional), insert into tree hole/ nest extract insects or insect product, collect from tool tip Tool use: a) tree hole b) insect nests a) Sweat bees (Stingless bees: Halictidae spp.; S) b) Ants (Formicidae; S), Termites (Isoptera; S), Bees (Apidae spp.; S)
c) Break fruit off, break stick off, peel (optional), chew (optional), insert into tree fruit, extract seed, collect from tool tip, spit out seed skin c) fruits c) Cemenang (Neesia aquatica; S)