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Patterns of locomotory activity were studied in adult triatomid bugs under various light-dark regimes by means of rocking acto graphs and suitable recording appartus. Under conditions of 12 hours of light, 12 hours of dark (LD 12:12) locomotor activity in Rhodnius prolixus, Triatoma infestans and Panstrongylus megistus was strictly nocturnal, with a pronounced peak occurring at the onset of darkness, In constant darkness (DD) and constant light (LL) the activity rhythm free-ran revealing its true circadian nature. In R. prolixus the period of the rhythm was shown to depend on the intensity of the light. When Rhodnius was exposed to LD cycles of various frequencies, the circadian rhythm became entrained only if the period of the LD regime lay between T = 18 and T = 32 hours. If the LD period was less than T = 18, the activity rhythm either free-ran (with an average period of about 27.5 hours) or attained a period of exactly 24 hours. When the change from light to darkness in LD 12:12 was advanced or delayed, Rhodnius re-entrained to the new LD regime, either immediately or after a few transient cycles, depending on the amount of phase change. Shifts in the phase of the freerunning rhythm were also produced by single pulses of light or darkness. The rhythm of Rhodnius also entrained after either the ocelli, the compound eyes or both had been occluded, indicating that extraocular photoreceptors may be involved. The pattern of oviposition in ~ prolixus, ~ megistus, T. infestans and T. phyllosoma shows a rhythm which is entrained by light-dark cycles with a 24-hour periodicity. In ~ megistus the circadian oviposition rhythm free-runs in DD. In LD cycles of T = 24 hours, a rhythm of ecdysis was observed whose timing was dependent on photoperiod. Ecdysis occurred before dawn when the photoperiod was short and after dawn when the days were long. Experiments indicated that, again, extraocular photoreceptors may be involved in entrainment. Continuous actograph records were obtained from individual desert scorpions Androctonous australis and Buthus occitanus and forest species Pandinus gregoryi and Hadogenese bicolour, under various lighting conditions. In LD 12:12 the desert scorpions were strongly nocturnal. Much of the activity of the forest species occurred in light. Detailed studies, however, revealed that these scorpions are nocturnal; the phase of their activity rhythm is set by the light-off signal. In both desert and forest species activity was circadian. In A. australis, activity could be entrained to LD 12:12 which was perceived by extraocular photorccptors in the mctasoma.

This project is a contribution towards the understanding of the mechanisms involved in the chemocommunication systems of large mammals. Data are included on the social behaviour and use of scent marking for the African lion <I>P. leo </I>as well as two other <I>Panthera </I>species namely the Siberian tiger, <I>P. tigris altaica, </I>and the leopard, <I>P. pardus. </I>The study was conducted in three Zoos or Safariparks in Denmark: København Zoo, Givskud Safaripark and Knuthenborg Safaripark. The project comprised behavioural observations of the undistributed social and marking patterns of the study groups. Particular attention was paid towards <I>Spraymarking, Scrape/urination </I>and normal <I>Urination </I>but <I>Clawing, Chinrubbing </I>and <I>Defaecation </I>were also recorded. Methods were developed which made it possible to collect samples of scent marks from the study animals. The scent samples collected were used in an experimental investigation in which the animals were presented with scent marks from foreign individuals of varying sex, age or reproductive status. In the final part of the study the scent mark samples collected were subjected to chemical analysis using the "Headspace" procedure on a combined Gas Chromatograph and Mass Spectrometer. The activity and social interactions of the animals, although under influence of the captive environment, were generally close to what one would expect to see for wild animals. Each animal showed a distinct activity pattern and social repertoire, but more general differences between the sex/age groups were also found. Males tended to stand more than females or cubs and show higher levels of <I>Investigation, </I>whereas females generally moved more than males. Cubs played more than the two adult groups. These trends were seen in all three species. Each animal had a distinct marking repertoire, but generally the male patterns were dominated by <I>Spraymarking </I>followed by <I>Scrape/urination, </I>whereas the female patterns were much more variable. Male lions had higher rates of <I>Spraymarking </I>and significantly higher rates of <I>Scrape/urination </I>than females. No significant difference was found between <I>Spraymarking </I>rates of male and female tiger, but both had significantly higher rates than castrated male tigers. The leopard male had higher rates of the two marking types than the female.

Detailed studies of energy/nutrient acquisition and food selection have been completed for both African apes and orangutans in mast-fruiting dipterocarp forests, but, to date, no studies of this type have been completed on orangutans in non-masting forests, which experience more muted fluctuations in fruit availability. Such studies may be instructive in understanding whether the observations on orangutans in masting habitats are specific to orangutans, or specific only to orangutans in masting habitats. To investigate this, orangutan diet composition, energy intake, food selection and behaviour were studied in relation to orangutan fruit/flower availability, and chemical and non-chemical food properties, in the Sabangau peat-swamp forest, Central Kalimantan from July 2005-June2007. All data were collected using standard methods, and comparisons made with published data on orangutans in mast-fruiting habitats and on African apes. Orangutan fruit availability in Sabangau was lower and less variable than in the masting forests of Gunung Palung National Park, West Kalimantan. Daily energy intake was below requirements in most months, and similar to periods of very low food availability between mast-fruiting events in Gunung Palung. Mechanisms through which orangutans may have survived this prolonged energetic shortfall are suggested. In addition, unlike in Gunung Palung, where energy intake and fruit availability are tightly linked in both sexes, the only age-sex class in which energy intake in Sabangau was related to fruit availability was flanged males. Although selection of preferred vs. fall-back food types in Sabangau appears to be governed at least partially by the expected rate of energy returns, fruit and flower selectivity rank appears better explained by food quality: the best multivariate model of adult female fruit selectivity rank contained only protein/fibre ratio, and bivariate correlations between fruit-pulp selectivity rank and protein/fibre ratio were also significant for flanged males. Furthermore, adult female and flanged male fruit selectivity rank was negatively affected by fibre, weight or energy intake in at least one bivariate analysis. This is suggested to represent selection against ingestion of large amounts of relatively indigestible fibre, and implies that maximising dietary quality, rather than energy intake, as has been suggested in masting forests in Borneo, may be the optimal feeding strategy for orangutans in habitats where fruit quality is relatively poor and/or fruit availability is relatively consistent. Finally, compared to orangutans in Bornean masting forests, Sabangau orangutans exhibit a relative lack of modifications in nonfeeding behaviours in response to reductions in preferred food availability. These results suggest that, compared to masting forests in Borneo, lower mean quality and quantity of fruit, and lower variability in these parameters, in the Sabangau peat swamps leads to important differences in feeding behaviour between these habitat types. When compared to data on orangutans in other sites and African great apes, these observations are compatible with a graded-response hypothesis, in which the less predictable the availability of high-energy fruit in a site: (1) the stronger the relationship between fruit availability, fruit consumption and energy intake, (2) the more food is selected based on energy content, and (3) the stronger the influence of fluctuations in fruit availability on behaviour and, ultimately, probably also female reproduction. The implications of these findings are discussed.

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Life history theory seeks to explain how comparative developmental and maturational parameters vary between species and how such differences affect survival and reproductive success. In primates, the immature period is found to be longer than in other relatively sized mammals, delaying sexual maturation but being essential for brain growth and social development. Compared to adulthood, the primate immature period remains understudied, limiting our understanding of how delayed maturation contributes towards species fitness. This thesis investigates social development of western gorillas (Gorilla gorilla gorilla), who have a relatively prolonged period of immaturity, and focuses on the pre-reproductive period from weaning until sexual maturity. Behavioural data were collected from 13 male (3-11 years) and 9 female (3-8 years) non-reproductive individual (NRI) western gorillas, housed in 5 family groups in European zoos. Data from a further 9 male and 7 female NRIs housed in 3 peer groups in sanctuaries were collected for comparison. A combination of continuous focal sampling, as well as scan, all occurrence and ad libitum sampling was used; 1300 hours of data were collected over 180 days. Within the thesis, a quantitative method to categorise gorillas into a life-stage was designed, which demonstrated distinct behavioural disparities between immature life-stages and between the sexes, highlighting the problems of life stage categories that are based only on dtatic age classes. A study of social relationship development followed, finding that spatially, NRIs became increasingly peripheralised from the group core with age. Socially, younger NRIs invested in prominent maternal and conspecific relationships, whereas older NRls did not. Relatedness affected sociality, with full siblings being more interactive than paternal half siblings are. An investigation of alloparenting showed that both male and female NRIs displayed this behaviour, with females continuing infant interactions until adulthood. It was postulated that gorilla alloparental behaviour is driven by the NRI and supports the 'learning to parent' hypothesis. Social play behaviour was also examined and found to be most common between similar-sized peers, with males generally being the preferred play partner. Disparate-sized play partners were more likely to be full siblings than paternal half siblings were. Younger NRIs were found to engage in more predictable play sequences whilst older NRIs engaged in play that was more sporadic. Support for the 'neural' hypothesis of social play was found, with social play having delayed benefits for the individual, although the immediate benefits of play were not dismissed. Finally, family-raised NRI behaviour was compared to peer-raised NRI behaviour. Behavioural trajectories and spatial orientation were comparable between rearing groups. Peer-groups thus enabled the development of species-specific behaviour, although atypical behaviours also developed. In conclusion, the success of novel methods to understand behaviour in the pre-reproductive period and its function in gorilla life history has been demonstrated.

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