Context-dependent visual preferences in starlings and blue tits: mate choice and light environment

There is considerable interest in the role that ultraviolet (UV) cues play in the foraging and mate choice decisions of birds. However, with the exception of the zebra finch, Taeniopygia guttata, it is not yet clear whether ultraviolet preferences are context specific, or whether birds show a general preference for full-avian-spectrum environments 320-700 nm) irrespective of the activity in which they are engaged. We investigated whether European starlings, Sturnus vulgaris, and blue tits, Parus caeruleus, show general (nonresource based) or context-specific preferences for full-spectrum environments. We found that neither species showed a general preference for UV-present (UV+) over UV-deficient (UV-) environments, when those environments contained no resources (experiment 1). Furthermore, neither species showed a UV+ preference when cages contained food, water and perches (starlings; experiment 2) or food, perches and heterospecifics (blue tits; Hunt et al. 1999. Animal Behaviour, 58, 809-815). However, both species did show highly significant preferences for UV+ conditions when viewing potential mates. Such experiments are necessary before one can conclude that particular wavebands have specific relevance to mate choice. In fact, our results suggest that the importance of particular wavelength compositions do indeed vary with behavioural context. (C) 2002 The Association for the Study of Animal Behaviour.

The role of ultraviolet-A reflectance and ultraviolet-A-induced fluorescence in budgerigar mate choice

Many parrots have plumage that either reflects strongly in the ultraviolet-A (UVA) waveband, between 315-400 nm, or exhibits UVA-induced fluorescence. Previous experimental work on budgerigars (Melopsittacus undulatus) suggests that UVA reflectance plays a role in mate choice, as in other diurnal birds, but evidence for fluorescent cues playing a role is unconvincing. Here we report two experiments on budgerigars, designed to determine whether fluorescent cues play a role in signalling when UVA reflectances are absent, an approach which separates removal of UVA reflectance from removal of fluorescence. First, we determined whether the choices of different females are correlated under these treatment conditions. Secondly, we investigated female preferences for fluorescing and non-fluorescing males when UVA reflections are absent, to determine whether the yellow emissions of fluorescence are playing a role in mate choice. Results from experiment 1 do not suggest that females agree on which males are attractive when UVA reflectances are absent, with only half of the subjects choosing the same male. Neither did different females make the same choices in experiment 2. This lack of agreement provides further evidence that UVA reflectances from males play an important role in female choice in this species. Experiment 2 provides no evidence to suggest that UVA-induced fluorescence plays a role in mate choice. Overall, our study supports previous findings showing that UVA reflectance plays a role in sexual signalling in this species, but provides no evidence to suggest the same for fluorescence when UVA reflectances are absent.

Developmental stress and female mate choice behaviour in the zebra finch

The potential effects of early environmental conditions on adult female mate choice have been largely neglected in studies of sexual selection. Our study tested whether developmental stress affects the mate choice behaviour of female zebra finches, Taeniopygia guttata, when choosing between potential mates. In an experiment manipulating developmental condition, female zebra finches were raised under nutritional stress or control conditions. In adulthood, female preferences were assessed using extensive four-stimulus mate choice trials. Nutritional stress affected growth rates during the period of stress, with experimentally stressed females lighter than controls. During mate choice trials stressed females were almost three times less active than controls and made fewer sampling visits to the stimulus males, although we found no evidence of a direct effect of developmental experience on which males were preferred. Thus, developmental experience had a clear effect on behavioural patterns in a mate choice context. To test whether this effect is specific to a mate choice context, we also investigated the effect of developmental stress on female activity rates in three social contexts: isolation, contact with a conspecific male (a potential mate) and contact with a conspecific female. Here, female activity did not differ between the experimental treatments in any of the social situations. Overall, our findings suggest that environmental conditions during early development can have long-term context-dependent consequences for adult female mate choice behaviour, mediated by changes in activity rates.

Sex differences in insect immune function : a consequence of diet choice?

Males often have reduced immune function compared to females but the proximate mechanisms underlying this taxonomically widespread pattern are unclear. Because immune function is resource-dependent and sexes may have different nutritional requirements, we hypothesized that sexual dimorphism in immune function may arise from differential nutrient intake (acquisition hypothesis). To test this hypothesis, we examined patterns of phenoloxidase (PO) activity in relation to nutrient consumption in Queensland fruit flies (Q-flies). In the first experiment, flies were allowed to choose their preferred nutrient intake. Compared with males, female Q-flies had higher PO activity, consumed more calories, and preferred a higher protein:carbohydrate (P:C) diet, suggesting that differential acquisition could explain sex differences. In the second experiment, we restricted flies to one of 12 diets varying in protein and carbohydrate concentrations and mapped PO activity for each sex onto a nutritional landscape. Counter to our hypothesis, females had higher PO activity than males at any given level of nutrient intake. Both carbohydrate and protein intake affected PO activity in females but only protein affected PO activity in males. Our results indicate that sex differences in Q-fly immune function are not solely explained by sex differences in nutrient intake, although nutrition does contribute to the magnitude of these sex differences.

Applying choice based conjoint measurement to forcast demand for a new restaurant category

This paper examines the use of Choice Based Conjointexperimentation for forecasting demand for a new restaurant category.The results of the forecasting experiment are compared to demand forexisting restaurant categories to determine whether the choice experimentreplicates actual category shares in the sampled region. The analysisshows that Choice Based Conjoint experiments are able to predictcategory shares for existing restaurant categories. It is then shown howthe approach may be used to estimate demand for a new category.

Oxytocin enhances the appropriate use of human social cues by the domestic dog (Canis familiaris) in an object choice task

It has been postulated that the neuropeptide, oxytocin, is involved in human-dog bonding. This may explain why dogs, compared to wolves, are such good performers on object choice tasks, which test their ability to attend to, and use, human social cues in order to find hidden food treats. The objective of this study was to investigate the effect of intranasal oxytocin administration, which is known to increase social cognition in humans, on domestic dogs' ability to perform such a task. We hypothesised that dogs would perform better on the task after an intranasal treatment of oxytocin. Sixty-two (31 males and 31 females) pet dogs completed the experiment over two different testing sessions, 5-15 days apart. Intranasal oxytocin or a saline control was administered 45 min before each session. All dogs received both treatments in a pseudo-randomised, counterbalanced order. Data were collected as scores out of ten for each of the four blocks of trials in each session. Two blocks of trials were conducted using a momentary distal pointing cue and two using a gazing cue, given by the experimenter. Oxytocin enhanced performance using momentary distal pointing cues, and this enhanced level of performance was maintained over 5-15 days time in the absence of oxytocin. Oxytocin also decreased aversion to gazing cues, in that performance was below chance levels after saline administration but at chance levels after oxytocin administration.

Street characteristics preferred for transportation walking among older adults: a choice-based conjoint analysis with manipulated photographs

BACKGROUND: Knowledge about the relationships between micro-scale environmental factors and older adults' walking for transport is limited and inconsistent. This is probably due to methodological limitations, such as absence of an accurate neighborhood definition, lack of environmental heterogeneity, environmental co-variation, and recall bias. Furthermore, most previous studies are observational in nature. We aimed to address these limitations by investigating the effects of manipulating photographs on micro-scale environmental factors on the appeal of a street for older adults' transportation walking. Secondly, we used latent class analysis to examine whether subgroups could be identified that have different environmental preferences for transportation walking. Thirdly, we investigated whether these subgroups differed in socio-demographic, functional and psychosocial characteristics, current level of walking and environmental perceptions of their own street.

METHODS: Data were collected among 1131 Flemish older adults through an online (n = 940) or an interview version of the questionnaire (n = 191). This questionnaire included a choice-based conjoint exercise with manipulated photographs of a street. These manipulated photographs originated from one panoramic photograph of an existing street that was manipulated on nine environmental attributes. Participants chose which of two presented streets they would prefer to walk for transport.

RESULTS: In the total sample, sidewalk evenness had by far the greatest appeal for transportation walking. The other environmental attributes were less important. Four subgroups that differed in their environmental preferences for transportation walking were identified. In the two largest subgroups (representing 86% of the sample) sidewalk evenness was the most important environmental attribute. In the two smaller subgroups (each comprising 7% of the sample), traffic volume and speed limit were the most important environmental attributes for one, and the presence of vegetation and a bench were the most important environmental attributes for the other. This latter subgroup included a higher percentage of service flat residents than the other subgroups.

CONCLUSIONS: Our results suggest that the provision of even sidewalks should be considered a priority when developing environmental interventions aiming to stimulate older adults' transportation walking. Natural experiments are needed to confirm whether our findings can be translated to real environments and actual transportation walking behavior.