Abstract: The nature of spatial information used for memorizing and recalling places is largely unclear. Earlier studies tested integration of geometric and feature information mostly during reorientation in artificial environments without including time as a memory-critical component. Here, we tested a harbour seal in a delayed matching-to-sample task (DMTS) in a familiar environment under two spatial multiple-choice conditions. The feature condition consisted of a DMTS task with four comparison stimuli presented on fixed positions in a classic matching apparatus and was designed to make stimulus features the most prominent information. The landscape condition consisted of a DMTS task in a familiar environment with four places marked by comparison stimuli and allowed the use of all available spatial information including geometrical and feature information. The seal's performance was impaired by delays of 3, 6, 9 or 12 s only in the feature condition; a delay of 12 s resulted in chance level performance. Replacing the comparison stimuli at the apparatus with identical spheres resulted in impaired performance. Performance in the landscape condition was impaired neither by delays nor by replacing comparison stimuli with spheres. Landscape information obviously was encoded redundantly and could be recalled more reliably and longer than feature information, which reveals feature information to be a less valuable type of spatial information for memorizing and recalling places.

Abstract: Three experiments were conducted to test whether a pair of tufted capuchin monkeys (Cebus apella) could generalize their ability to exchange tokens and tool objects with a human experimenter to similar exchanges with a conspecific partner. Monkeys were tested in side-by-side enclosures, one enclosure containing a tool-use apparatus and one or more token(s), and the other enclosure containing one or more tool object(s). The monkeys willingly transferred tokens and tools to a conspecific with little practice. Following a small amount of training, we also found that the monkeys would select situation-appropriate tokens to exchange for specific tools, but did not select appropriate tool objects in response to another monkey's token transfers. Implications regarding role reversal are discussed.

Abstract: Tool use is rare amongst rodents and has never been recorded in connection with agonistic displays. We witnessed a behaviour, stick display (StD), involving tool use in free-living Eurasian beavers (Castor fiber) that we conclude is a display behaviour. Two beavers were the main performers of the signal that was observed in at least six beavers from three families. Beavers reacted to displays by increased evasive and agonistic behaviours compared with their usual behavioural patterns when at territory borders. The behaviour was almost exclusively seen between rivals at territory borders. We suggest that the display is used in agonistic encounters, mainly in a territorial context.

Abstract: Here we compare the performance of 2-year-old human children with that of adult rhesus macaques on a cognitive imitation task. The task was to respond, in a particular order, to arbitrary sets of photographs that were presented simultaneously on a touch sensitive video monitor. Because the spatial position of list items was varied from trial to trial, subjects could not learn this task as a series of specific motor responses. On some lists, subjects with no knowledge of the ordinal position of the items were given the opportunity to learn the order of those items by observing an expert model. Children, like monkeys, learned new lists more rapidly in a social condition where they had the opportunity to observe an experienced model perform the list in question, than under a baseline condition in which they had to learn new lists entirely by trial and error. No differences were observed between the accuracy of each species' responses to individual items or in the frequencies with which they made different types of errors. These results provide clear evidence that monkeys and humans share the ability to imitate novel cognitive rules (cognitive imitation).

Abstract: To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for black rhinoceroses (Diceros bicornis), we investigated the apparent absorption (aA) of macro- and microminerals in eight black rhinoceroses from three zoological institutions in a total of 32 feeding trials with total faecal collection, with additional data from three unpublished studies (18 feeding trials). Feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Mn, Cu, Zn and Co. The resulting aA coefficients, and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content [per 100 g dry matter (DM)], were compared with data for domestic horses. Rhinoceroses had significantly higher aA coefficients for Ca and Mg (because of a higher calculated 'true' absorption), and lower ones for Na and K (because of calculated higher endogenous faecal losses). High absorption efficiency for divalent cations is hypothesized to be an adaptation to a natural diet of particularly high Ca:P ratio (approximately 14:1); an effective removal of Ca from the ingesta guarantees sufficient P availability at the fermentation site in the hindgut. Higher faecal losses of Na and K are hypothesized to be linked to a higher faecal bulk per DM intake in black rhinoceroses as compared with horses because of a generally lower digestive efficiency. There were no relevant differences in the absorption patterns of microminerals. In particular, there were no discernable differences in Fe absorption within the rhinoceroses for diets with and without tannin supplementation. Several of the zoo diets assessed in this study were deficient in Cu, Mn or Zn, and most contained excessive levels of Fe when compared with horse requirements. The findings of this study indicate that differences in mineral absorption between occur even between species of similar digestive anatomy; that in particular, Ca absorption might vary between hindgut fermenters with Ca:P ratio in their natural diet; that Na might be a particularly limiting factor in the ecology of free-ranging rhinoceroses; that moderate doses of tannins do not seem to markedly influence mineral absorption; and that diets for captive animals should contain adequate, but not excessive mineral levels.