Figure 1.
Schematic layout of the bonobo facility at Twycross Zoo, including location of playback equipment and artificial food sites.
Table 1.
Composition of the two bonobo subgroups at Twycross Zoo (UK) in April 2009.
Figure 2.
Box plots indicating foraging responses of bonobos (N = 4) following playbacks of food-associated calls given to high value (kiwi) or low value (apple) foods.
(a) Site of first entry expressed as a median proportion of the individual's median choices per condition; (b) median number of visits per trial; (c) median time spent foraging following playback (s). Box plots illustrate medians, inter-quartile ranges, and highest and lowest values, excluding outliers.
Figure 3.
Scatter plot showing the relationship between the food type encountered (highly preferred = kiwi, less preferred = apple) and the cumulative value of the stimuli sequence.
Calls were assigned a cardinal score based on how frequently they were produced in response to high vs. low value food (e.g. barks were six times more frequent to high than low preference foods, so that: B = 6.00, P = 1.86, PY = 0.52, Y = 0.12). The relationship between foraging responses and stimuli scores are indicated in table 3.
Table 2.
Relative frequency of food-related call types within natural call sequences given to high and low-value foods by bonobos at Twycross Zoo and the corresponding playback stimuli.
Table 3.
Composition of different call stimuli and resulting behavioural responses in receivers.
Figure 4.
Spectrographic illustrations of two playback stimuli.
(a) High value sequence originally given to kiwi consisting of bark/peep/bark/peep and (b) low value sequence originally given to apple consisting of peep-yelp/peep-yelp/yelp/yelp. Recordings of the corresponding call sequences are available as audio S1 and audio S2.