Abstract: Staddon and Higa's (1999) trace-strength theory of timing and memory for event duration can account for pigeons' bias to “choose short” when retention intervals are introduced and to “choose long” when, following training with a fixed retention interval, retention intervals are shortened. However, it does not account for the failure of pigeons to choose short when the intertrial interval is distinct from the retention interval. That finding suggests that stimulus generalization (or ambiguity) between the intertrial interval and the retention interval may result in an effect that has been attributed to memory loss. Such artifacts must be eliminated before a theory of memory for event duration can be adequately tested.

Abstract: Socio-ecological explanations for intra- and interspecific variation in the social and spatial organization of animals predominate in the scientific literature. The socio-ecological model, developed first for the Bovidae and Cervidae, is commonly applied more widely to other groups including the Equidae. Intraspecific comparisons are particularly valuable because they allow the role of environment and demography on social and spatial organization to be understood while controlling for phylogeny or morphology which confound interspecific comparisons. Feral horse (Equus caballus Linnaeus 1758) populations with different demography inhabit a range of environments throughout the world. I use 56 reports to obtain 23 measures or characteristics of the behaviour and the social and spatial organization of 19 feral horse populations in which the environment, demography, management, research effort and sample size are also described. Comparison shows that different populations had remarkably similar social and spatial organization and that group sizes and composition, and home range sizes varied as much within as between populations. I assess the few exceptions to uniformity and conclude that they are due to the attributes of the studies themselves, particularly to poor definition of terms and inadequate empiricism, rather than to the environment or demography per se. Interspecific comparisons show that equid species adhere to their different social and spatial organizations despite similarities in their environments and even when species are sympatric. Furthermore, equid male territoriality has been ill-defined in previous studies, observations presented as evidence of territoriality are also found in non-territorial equids, and populations of supposedly territorial species demonstrate female defence polygyny. Thus, territoriality may not be a useful categorization in the Equidae. Moreover, although equid socio-ecologists have relied on the socio-ecological model derived from the extremely diverse Bovidae and Cervidae for explanations of variation in equine society, the homomorphic, but large and polygynous, and monogeneric Equidae do not support previous socio-ecological explanations for relationships between body size, mating system and sexual dimorphism in ungulates. Consequently, in spite of the efforts of numerous authors during the past two decades, functional explanations of apparent differences in feral horse and equid social and spatial organization and behaviour based on assumptions of their current utility in the environmental or demographic context remain unconvincing. Nevertheless, differences in social cohesion between species that are insensitive to intra- and interspecific variation in habitat and predation pressure warrant explanation. Thus, I propose alternative avenues of inquiry including testing for species-specific differences in inter-individual aggression and investigating the role of phylogenetic constraints in equine society. The Equidae are evidence of the relative importance of phylogeny and biological structure, and unimportance of the present-day environment, in animal behaviour and social and spatial organization.

Abstract: Research on melioidosis and its pathogen has been ongoing in China for more than two decades. It has been demonstrated that the natural foci are located predominantly in Hainan, Guangdong and Guangxi province, where there is a good correlation between soil isolation and the serum prevalence of antibodies to Burkholderia pseudomallei. The cases of melioidosis reported up to now are concentrated in the Hainan and Zhanjiang peninsula. Investigations on serotype, virulence, ecology, antibiotic susceptibility, whole cell analysis by gas chromatography, and genetics have led to a new understanding of the pathology of the disease. Immunological cross reactions between Burkholderia mallei and B. pseudomallei and the difference between melioidosis and glanders in horses is discussed.

Abstract: Humans are consciously aware of some memories and can make verbal reports about these memories. Other memories cannot be brought to consciousness, even though they influence behavior. This conspicuous difference in access to memories is central in taxonomies of human memory systems but has been difficult to document in animal studies, suggesting that some forms of memory may be unique to humans. Here I show that rhesus macaque monkeys can report the presence or absence of memory. Although it is probably impossible to document subjective, conscious properties of memory in nonverbal animals, this result objectively demonstrates an important functional parallel with human conscious memory. Animals able to discern the presence and absence of memory should improve accuracy if allowed to decline memory tests when they have forgotten, and should decline tests most frequently when memory is attenuated experimentally. One of two monkeys examined unequivocally met these criteria under all test conditions, whereas the second monkey met them in all but one case. Probe tests were used to rule out “cueing” by a wide variety of environmental and behavioral stimuli, leaving detection of the absence of memory per se as the most likely mechanism underlying the monkeys' abilities to selectively decline memory tests when they had forgotten.