Results (mg kg⁻¹).

*<p>Rf = Raphia farinifera, Fu = Funtumia elastic, Cp = Cleistopholis patens, Abo = Astonia boonei, Zgo = Zanha golungensis, Fe = Ficus exasperate, Fv = Ficus varifolia, Fm = Ficus mucuso, Cm = Celtis mildbraedii, Mi = Mangifera indica, Bp = Broussonettia papyrifera, La = Lantana sp., Be = Beoquartiodendron oblanceolatum.</p>**<p>wadge (see text).</p

Mann-Whitney U-test results: raphia samples (without wadge sample) vs all other samples.

<p>Mann-Whitney U-test results: raphia samples (without wadge sample) vs all other samples.</p

Means and (ranges) (solid samples in mg/kg, water samples in ppm) for groups of samples.

<p>Key: <i>Na</i> = sodium, <i>K</i> = potassium, <i>P</i> = phosphorus, <i>Ca</i> = calcium, <i>Fe</i> = iron, <i>Mn</i> = manganese, <i>Al</i> = aluminium, <i>Cu = copper</i>, <i>Mg</i> = magnesium. Asterisks indicate that data were not obtained.</p><p>Means and (ranges) (solid samples in mg/kg, water samples in ppm) for groups of samples.</p

Subadult male chimpanzee Frank approaching clay hole (Photo: A. Schel).

<p>Subadult male chimpanzee Frank approaching clay hole (Photo: A. Schel).</p

Results of laboratory analysis (mg/kg for solid samples or ppm for water samples).

<p>Key: <i>Na</i> = sodium, <i>K</i> = potassium, <i>P</i> = phosphorus, <i>Ca</i> = calcium, <i>Fe</i> = iron, <i>Mn</i> = manganese, <i>Al</i> = aluminium, <i>Cu = copper</i>, <i>Mg</i> = magnesium, <i>Cl = chloride</i></p><p>Asterisks indicate that data were not obtained.</p><p>Results of laboratory analysis (mg/kg for solid samples or ppm for water samples).</p

Adult female Nambi (L) using a leaf-sponge at waterhole, watched by 10-yr old juvenile Karo (R) (Photo: C. Hobaiter).

<p>Adult female Nambi (L) using a leaf-sponge at waterhole, watched by 10-yr old juvenile Karo (R) (Photo: C. Hobaiter).</p

Frequency of <i>Raphia farinifera</i> (RF), <i>Cleistopholis patens</i> (CP) and clay, 1991–2014 (Qualitative data).

<p>Frequency of <i>Raphia farinifera</i> (RF), <i>Cleistopholis patens</i> (CP) and clay, 1991–2014 (Qualitative data).</p