Communication in coral reef fish: the role of ultraviolet colour patterns in damselfish territorial behaviour

Many coral reef fish possess ultraviolet (UV) colour patterns. The behavioural significance of these patterns is poorly understood and experiments on this issue have not been reported for free-living reef fish in their natural environment. The damselfish Pomacentrus amboinensis has UV facial patterns, and spectroradiometric ocular media measurements show that it has the potential for UV vision. To test the potential behavioural significance of the UV patterns, I studied the response of males, in natural territories on the reef and in aquaria, to two conspecific intruders, one presented in a UV-transmitting (UV+) container and the other in a UV-absorbing (UV-) one. Territory owners attacked intruders viewed through UV+ filters significantly more often and for longer than intruders viewed through the UV- filter. In general, the results of the field experiment confirmed those of the laboratory experiment. The results support the hypothesis that P. amboinensis males are sensitive to UV light and that reflectance patterns, which appear in high contrast only in UV, modulate the level of aggressive behaviour. A recent survey showed that many predatory fish may not have UV vision and the use of UV colours in select species of reef fish may therefore serve as a 'private communication channel'. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Cleaner fish, Labroides dimidiatus, diet preferences for different types of mucus and parasitic gnathiid isopods

Cleaner fish, Labroides dimidiatus, prefer the mucus of the parrotfish, Chlorurus sordidus, to parasitic gnathiid isopods, the main items in their diet, indicating a major conflict between clients and cleaners over what the latter should eat during interactions. We tested whether the conflict varied with client species (and the quality of its mucus) and with the presence of blood in the gnathfids. First, we offered cleaners the choice between mucus of the parrotfish and that of the snapper, Lutjanus fulviflamma. When offered equal amounts of mucus on Plexiglas plates, cleaners readily developed a significant preference for the parrotfish mucus. Reducing the amount of parrotfish mucus by 75% made the preference disappear. In a second test, we offered the cleaners gnathiids that were or were not engorged with client fish blood. Cleaners showed no significant preference for either food item. Our results suggest that the degree of conflict between cleaners and clients may vary between species, depending on whether the latter have a preferred mucus. In contrast, the cleaners' lack of preference for engorged gnathiids benefits clients because it means that cleaners do not hesitate to eat unengorged gnathiids before the gnathiids harm the fish by removing blood or by transmitting blood parasites. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Costs increase as ritualized fighting progresses within and between phases in the sierra dome spider, Neriene litigiosa

Magnitudes and patterns of energy expenditure in animal contests are seldom measured, but can be critical for predicting contest dynamics and understanding the evolution of ritualized fighting behaviour. In the sierra dome spider, males compete for sexual access to females and their webs. They show three distinct phases of fighting behaviour, escalating from ritualized noncontact display (phase 1) to cooperative wrestling (phase 2), and finally to unritualized, potentially fatal fighting (phase 3). Using CO2 respirometry, we estimated energetic costs of male-male combat in terms of mean and maximum metabolic rates and the rate of increase in energy expenditure. We also investigated the energetic consequences of age and body mass, and compared fighting metabolism to metabolism during courtship. All three phases involved mean energy expenditures well above resting metabolic rate (3.5 X, 7.4 X and 11.5 X). Both mean and maximum energy expenditure became substantially greater as fights escalated through successive phases. The rates of increase in energy use during phases 2 and 3 were much higher than in phase 1. In addition, age and body mass affected contest energetics. These results are consistent with a basic prediction of evolutionarily stable strategy contest models, that sequences of agonistic behaviours should be organized into phases of escalating energetic costs. Finally, higher energetic costs of escalated fighting compared to courtship provide a rationale for first-male sperm precedence in this spider species. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Temperature influences the coercive mating and swimming performance of male eastern mosquitofish

Although the functional consequences of temperature variation have been examined for a wide range of whole-animal performance traits, the implications of thermal variation for reproductive behaviour or performance are poorly known. I examined the acute effects of temperature on the mating behaviour and swimming performance of male eastern mosquitofish, Gambusia holbrooki, which rely on a coercive strategy to obtain matings and are routinely exposed to wide daily temperature fluctuations. Males showed reproductive behaviours across the entire test temperature range of 14-38 degrees C, representing one of the widest reproductively active temperature ranges for any ectotherm. Both the time spent in pursuit of females and the total number of mating attempts increased with temperature to a plateau that started at approximately 22-26 degrees C. However, males maintained a constant level of copulations at 18-34 degrees C, the temperature range they routinely experience in southeast Queensland. In contrast, maximum swimming performance and approach speeds during copulations were highly thermally dependent across this temperature range. Thus, acute temperature variation has important fitness implications for male G. holbrooki, but mating performance was significantly limited only at extreme temperatures. (c) 2005 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Costs of learning: the dynamics of mixed-prey exploitation by silver perch, Bidyanus bidyanus (Mitchell, 1838)

Although generalist predators have been reported to forage less efficiently than specialists, there is little information on the extent to which learning can improve the efficiency of mixed-prey foraging. Repeated exposure of silver perch to mixed prey (pelagic Artemia and benthic Chironomus larvae) led to substantial fluctuations in reward rate over relatively long (20-day) timescales. When perch that were familiar with a single prey type were offered two prey types simultaneously, the rate at which they captured both familiar and unfamiliar prey dropped progressively over succeeding trials. This result was not predicted by simple learning paradigms, but could be explained in terms of an interaction between learning and attention. Between-trial patterns in overall intake were complex and differed between the two prey types, but were unaffected by previous prey specialization. However, patterns of prey priority (i.e. the prey type that was preferred at the start of a trial) did vary with previous prey training. All groups of fish converged on the most profitable prey type (chironomids), but this process took 15-20 trials. In contrast, fish offered a single prey type reached asymptotic intake rates within five trials and retained high capture abilities for at least 5 weeks. Learning and memory allow fish to maximize foraging efficiency on patches of a single prey type. However, when foragers are faced with mixed prey populations, cognitive constraints associated with divided attention may impair efficiency, and this impairment can be exacerbated by experience. (c) 2005 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Factors affecting the vigilance and flight behaviour of impalas

This study investigated the influences of various natural and anthropogenic factors on the vigilance and flight behaviour of impalas in the Save Valley Conservancy, Zimbabwe, using multivariate statistical techniques. The factor that most significantly affected the proportions of time that individuals spent being vigilant and their rates of vigilance was the position of a focal animal in the group; impalas on the periphery of a group were more vigilant than central impalas. Both measures of vigilance were also negatively related to group size. Males spent more total time being vigilant but females raised their heads more often. Impalas spent more time being vigilant in the late afternoon than in the early morning, when greater than ten metres from cover, and when predators had been nearby within the previous six hours. Impalas spent more time vigilant at the property where more impalas were hunted, possibly reflecting the differences in the intensity of hunting by humans on the two properties. Flight distances at the approach of humans were significantly greater at one property than the other, and were also greater for small groups. Further research into the effects of hunting by humans on animals' antipredator behaviours would provide valuable insights for wildlife managers.

Developmental vitamin D (DVD) deficiency in the rat alters adult behaviour independently of HPA function

Developmental vitamin D deficiency (DVD) has been shown to alter the orderly pattern of brain development. Even though the period of vitamin D deficiency is restricted to gestation this is sufficient to induce behavioural abnormalities in the adult offspring consistent with those seen in many animal models of schizophrenia. Given that some of these behavioural alterations could also be an indirect result of either impaired maternal hypothalamic pituitary axis (HPA) function (which in turn could influence maternal care) or the result of a permanent alteration in HPA function in the adult offspring we have examined HPA status in both maternal animals and adult offspring. In this study we have established that HPA function is normal in the maternally vitamin D deficient rat. We replicate the behavioural phenotype of hyperlocomotion whilst establishing that HPA function is also unchanged in the adult mate offspring. We conclude that the behavioural alterations induced by DVD deficiency are due to some adverse event in brain development rather than via an alteration in stress response. (c) 2006 Elsevier Ltd. All rights reserved.

A framework for the study of genetic variation in migratory behaviour

Evolutionary change results from selection acting on genetic variation. For migration to be successful, many different aspects of an animal's physiology and behaviour need to function in a co-coordinated way. Changes in one migratory trait are therefore likely to be accompanied by changes in other migratory and life-history traits. At present, we have some knowledge of the pressures that operate at the various stages of migration, but we know very little about the extent of genetic variation in various aspects of the migratory syndrome. As a consequence, our ability to predict which species is capable of what kind of evolutionary change, and at which rate, is limited. Here, we review how our evolutionary understanding of migration may benefit from taking a quantitative-genetic approach and present a framework for studying the causes of phenotypic variation. We review past research, that has mainly studied single migratory traits in captive birds, and discuss how this work could be extended to study genetic variation in the wild and to account for genetic correlations and correlated selection. In the future, reaction-norm approaches may become very important, as they allow the study of genetic and environmental effects on phenotypic expression within a single framework, as well as of their interactions. We advocate making more use of repeated measurements on single individuals to study the causes of among-individual variation in the wild, as they are easier to obtain than data on relatives and can provide valuable information for identifying and selecting traits. This approach will be particularly informative if it involves systematic testing of individuals under different environmental conditions. We propose extending this research agenda by using optimality models to predict levels of variation and covariation among traits and constraints. This may help us to select traits in which we might expect genetic variation, and to identify the most informative environmental axes. We also recommend an expansion of the passerine model, as this model does not apply to birds, like geese, where cultural transmission of spatio-temporal information is an important determinant of migration patterns and their variation.

Development of an animal repellent - selection, efficacy and presentation

Under some circumstances it may be desirable to repel herbivorous pests (e. g. goats and wallabies) from plants (e. g. horticultural or forestry seedlings) rather than to kill them. These circumstances may include using these animals as a resource at a later time, and there may also be welfare, public perception or legislative issues where repelling animals from particular plants or area is preferable to killing them. The first experiment tested the efficacy of 5 different materials (tiger fecal extract, maggot brew-the liquid exudate from a flyblown goat, capsaicin, dog urine, and burnt goat hair, skin and carcass+fat) to repel groups of goats in a feedlot pen from 1 trough of feed when another trough of feed was available to them to eat. Each repellent was tested on 5 groups of mixed age female goats for periods of 3 days. All 5 groups were exposed to the 5 repellents. Both tiger fecal extract and maggot brew reduced intake of feed from the 'protected' feed trough and significantly (P < 0.05) delayed 'normal' feeding behaviour by more than 5 h from that trough. The repellents became less effective with repeated use even with different groups of goats. The reduction in effectiveness was indicated by higher intakes of feed and earlier feeding from the protected trough. This habituation to the repellents, where the effectiveness is reduced with repeated exposure, is of concern. In the second experiment, we selected the most effective repellent (tiger fecal extract) and tested its efficacy under similar conditions, after the repellent had been mixed with a carrier (bentonite) in an endeavour to increase the duration of its effectiveness. This repellent was significantly more effective in repelling groups of 3 goats in a feedlot pen from 1 trough of feed for 3 days, when another trough of feed was available to them to eat.

Swimming behaviour and post-swimming activity in Vitamin D receptor knockout mice

Animal experiments have shown that Vitamin D plays a role in both brain development and adult brain function. The adult Vitamin D receptor null mutant mouse (VDR -/-) is reported to be less active and more anxious than wild-type litter mate controls and to have poor swimming ability. However, an anxious behavioural phenotype is inferred from differences in locomotor behaviour. This is a general problem in behavioural phenotyping where a neurological phenotype is inferred from changes in locomotion which will be affected by non-neurological factors, such as muscle fatigue. In this study of VDR -/-, we conducted a detailed examination of one form of motor behaviour, swimming, compared to wildtype littermate controls. Swimming was assessed using a forced swim test, a laneway swimming test and a watermaze test using a visible platform. Post-swimming activity was assessed by comparing grooming and rearing behaviour before, and 5 min after, the forced swimming test. We replicated previous findings in which VDR -/- mice demonstrate more sinking episodes than wildtype controls in the forced swim test but they were similar to controls in the time taken to swim a 1 m laneway, and in the time taken to reach a visible platform in the watermaze. Thus, the VDR -/- mice were able to swim but were not able to float. Grooming and rearing behaviour of the VDR -/- mice was similar to wildtype controls before the forced swim but the VDR -/- were much less active after the swim compared with wildtype mice which displayed high levels of grooming and rearing. We conclude that VDR -/- mice have muscular and motor impairments that do not affect their ability to swim but significantly alters the ability to float as well as their post-swimming activity. Differences in muscle strength may confound tests of activity that are used to infer an anxious phenotype. (c) 2005 Elsevier Inc. All rights reserved.