Stéphan G. Reebs

University of Moncton · Faculté des Sciences

In many fish species, some individuals arediurnal while others are nocturnal. Sometimes,the same individual can be diurnal at first andthen switch to nocturnalism, or vice-versa.This review examines the factors that areassociated with such plasticity. It covers thebreakdown of activity rhythms during migration,spawning, and the parental phase; reve...

The goal of this study was to determine whether fish can learn to forage in different places at different times of the day, each place being associated with a specific time. Groups of eight golden shiners (Notemigonus crysoleucas) were kept in aquaria equipped with automatic feeders that dropped food on one side in the morning and on the other side...

The goal of this study was to provide an example of nonsocial and nonphotic entrainment in Syrian hamsters, together with a corresponding phase response curve (PRC). Fourteen male hamsters were given 2-hr bouts of induced activity (mostly wheel running) at 23.83-hr intervals in constant darkness (DD). The activity onsets of 10 hamsters entrained to...

There is no information on whether the daily foraging movements of fish shoals are the result of chance, the collective will of all shoalmates, or the leadership of a few individuals. This study tested the latter possibility. Shoals of 12 golden shiners, Notemigonus crysoleucas, were trained to expect food around midday in one of the brightly lit c...

The present study investigated the preference of male and female Syrian hamsters, Mesocricetus auratus, for different types of running wheels. Hamsters were placed individually in sets of multiple cages linked by tunnels, each cage with a different running wheel. The number of wheel revolutions in each cage was tallied daily over 40 days. The hamst...

The preference of Syrian hamsters (Mesocricetus auratus) for different in-cage shelters was tested. First, 15 males and 15 females were made to choose between a cage with a shelter and one without. Different shelters were tested consecutively: short (10-cm) or medium (15-cm) pipes made of black acrylonitrile butadiene styrene (ABS), 7.6 cm in diame...

This study tested whether Syrian hamsters (Mesocricetus auratus) have an aversion to old bedding (up to 14 days) by offering them the option to nest in a new cage. A secondary goal was to assess the relative value of shelters by testing whether the tendency to nest in the new cage was reduced when a shelter was present in the old cage. Individual h...

Syrian hamsters (Mesocricetus auratus) run extensively in exercise wheels. This running may cause paw lesions. Three treatments of these wounds (topical application of vitamin E, wheel blocking, and a combination of both) were compared using both sexes. A pretreatment period with or without wheels lasted 15 days and the ensuing treatment period las...

This commentary discusses the idea that leader and follower roles can be exchanged between individuals of a same group. Training individuals to obtain food in different places at different daily times can provide an experimental paradigm for the study of this temporal skill pool hypothesis.

The present study investigated the effects of bedding material (pine shavings versus beta chip) and running wheel surfaces (standard metal bars versus metal bars covered with a plastic mesh) on the occurrence of wounds on the paws of male and female Syrian (golden) hamsters, Mesocricetus auratus. Four groups of 10 males and 10 females were each ass...

This study aimed to determine whether Syrian (golden) hamsters, Mesocricetus auratus, prefer certain bedding materials and whether bedding material can affect paw condition, body weight gain and wheel-running activity. In a first experiment, 26 male hamsters had access to two connected cages, each cage containing a different bedding material (eithe...

Shoals of golden shiners (Notemigonus crysoleucas) often swim along the perimeter of their large indoor tank at dawn and dusk, and can also be trained to anticipate food arrival by swimming directly towards the food source at midday. In this study all golden shiners in six shoals of 8-12 fish were individually marked with a visible implant elastome...

Circadian rhythms play a critical role in fish development and daily activities. Although a major circadian "master" clock, like the SCN of mammals, has not yet been identified in fish, indirect evidence suggests that a light-entrainable oscillator is present in fish brain. Furthermore, the structural and functional design of fish circadian systems...

Institutional animal care committees may one day require for the welfare of captive hamsters more floor space and the introduction of tunnels and toys. As hamsters are popular animal subjects in chronobiological research, and as clock phase is usually measured through running wheel activity, it is important to determine what effect cage enrichment...

Time–place learning, or the ability to learn to be in different places at different times of day, is already known to occur in response to daily spatio-temporal patterns of food availability. However, the ability to learn daily patterns of predation risk and move between areas at the right time of day in order to avoid predation has never been test...

In shoals of uniformly-sized golden shiners (Notemigonus crysoleucas), a minority of individuals who know when and where food is available can lead their naïve shoalmates to food. The present study investigated whether such leadership still takes place when leaders and followers are of different body size. Shoals of either 3 small and 9 large shine...

This study tested whether light pulses with a dusklike offset or a dawnlike onset caused phase shifts of different sizes in the circadian wheel-running activity of Syrian hamsters, Mesocricetus auratus. Six experiments were conducted, each with 30 hamsters; the hamsters received first one type of pulse and then the other type a few weeks later, all...

Shoals of four golden shiners, Notemigonus crysoleucas, were fed daily at a fixed time, which could be the beginning, middle, or end of a 12-h artificial day, or beginning, middle, or end of a 12-h artificial night, depending on the shoal. Almost all shoals showed food-anticipatory activity (FAA), that is, a gradual increase in locomotor activity n...

This study provides evidence that a circadian light-entrainable oscillator is at least partially involved in the timing of food-anticipatory activity (FAA) in a fish, the golden shiner, Notemigonus crysoleucas. Shoals of four golden shiners were fed for 11-20 days at a fixed daily time (either early night, midnight, late night, early day, midday, o...

For 12 days, captive groups each containing four golden shiners (Notemigonus crysoleucas) were fed by automatic feeders at two diametrically opposed daily times. These two times could be midday and midnight, late day and late night, or early day and early night. As measured by interruptions of an infrared beam underneath the feeder, golden shiners...

In response to a light pulse, hamsters normally generate phase advances that are positively correlated with the length of their circadian period (tau). To determine whether this is a general property of the phase-shifting oscillator, the present study looked for a correlation between tau and phase-advance size not only for photic but also for nonph...

The goal of this study was to test whether food-anticipatory activity, which is more subtle than feeding activity, can be used as a cue for local enhancement by fish. Golden shiners, Notemigonus crysoleucas, were offered a choice between spending time near a shoal of conspecifics normally fed at that time of day or a shoal normally fed at another t...

When an animal has a choice of joining one group over another, its decision may depend on its relative vulnerabilities to predation and starvation. For example, a well-fed animal may choose a large group of individuals with body size matching its own because this gives good protection against predators, but a hungry animal may prefer smaller groups...

Traps were set in Catamaran Brook and the Little Southwest Miramichi River, New Brunswick, to determine the diel activity pattern of threespine stickleback Gasterosteus aculeatus, juvenile white sucker Catostomus commersoni, blacknose dace Rhinichthys atratulus, and lake chub Couesius plumbeus. All fish except lake chubs were diurnal, although stri...

This study investigated the ability of nest-guarding convict cichlid (Cichlasoma mgrofasciatum) females to recognize their own mate and to defend their brood effectively against strangers at night. Cichlids in the laboratory bred in nesting boxes made of plexiglas. At the fry stage, various conspecific males were introduced, at night, into the nest...

In most biparental, substrate-brooding species of cichlid fishes, female and male roles differ. Females are usually more involved in direct care of the young while males spend more time away patrolling the territory. This study tested the flexibility of these sex roles with removal experiments in the convict cichlid, Cichlasoma nigrofasciatum. When...

This study examined whether a nonphotic factor, scheduled daily exercise, could cause aftereffects on the free-running circadian period of Syrian hamsters. Groups of hamsters were kept under a cycle of 14-h light:10-h dark with access to their running wheel for only 3 h a day. Depending on the group, this 3-h period coincided with early day, midday...

From November 1992 to February 1993, observations were made during 30 departures and 30 arrivals at a Mourning Dove (Zenaida macroura) roost in Moncton, New Brunswick, Canada. Our objective was to identify the effect of cold on the timing of roosting flights in this species, a recent addition to the local wintering fauna. The effect of other enviro...

Every day at dusk, many parental cichlids 'retrieve' their fry: they take wandering fry into their mouth and spit them into a previously dug pit. The present study investigated the relative importance of illumination changes and endogenous clock mechanisms in the daily timing of fry-retrieving behaviour in convict cichlids, Cichlasoma nigrofasciatu...

This paper presents a test of time-place learning in fish. Convict cichlids, Cichlasoma nigrofasciatum, were offered food several times a day for 10–30 consecutive days. A signal was given 1 min before each food presentation. If the food was always delivered in the same corner of the aquarium, the fish spent 66% of their time in that corner after t...

Visual cues are important for egg care in fish. Recent observations of nocturnal egg care suggest, however, that such cues are not essential. To determine what external stimuli allow fish to find and fan eggs in the absence of visual cues, the nocturnal behaviour of parental convict cichlids was measured after experimental brood substitutions. Pare...

Sleep is a behaviour pattern that can be observed in most animals, yet its adaptive significance is still a matter of debate. One view, developed and championed by Meddis (1975, 1977), is that sleep acts as an immobiliser. By forcing an animal to find a safe shelter and remain immobile in it during an ecologically unprofitable part of the solar day...

Breeding pairs of convict cichlids, Cichlasoma nigrofasciatum, and rainbow cichlids, Herotilapia multispinosa, were observed at night with an infrared visionscope to determine the extent of nocturnal egg care. In both species, females fanned eggs at night. The position of the female while fanning differed between day and night; the female's snout w...

In birds, as in other animals, the mechanism for photoperiodic time measurement is based on circadian rhythmicity. In models of this mechanism, the entrainment of circadian rhythms is a key feature. One can therefore ask whether any synchronizing agent (zeitgeber) that can entrain circadian rhythms could also induce photoperiodic responses. We addr...

Cycles of presence/absence of social factors can sometimes entrain the circadian activity rhythms of diurnal animals kept under constant light. This might represent a special case of photic entrainment; social factors might awaken the subjects and make them see the light at times when they are normally unaware of it because of sleep. The present st...

Pulses of darkness can phase-shift the circadian activity rhythms of hamsters, Mesocricetus auratus, kept in constant light. Dark pulses under these conditions alter photic input to the circadian system, but they also commonly trigger wheel-running activity. This paper investigates the contribution of running activity to the phase-shifting effects...

Bouts of induced wheel-running, 3 h long, accelerate the rate of re-entrainment of hamsters' activity rhythms to light-dark (LD) cycles that have been phase-advanced by 8 h (Mrosovsky and Salmon 1987). The bouts of running are given early in the first night of the new LD cycle, and by the second night the phase advance in activity onset already ave...

This paper reviews the discovery and characterization of a behavioural system for entrainment of circadian rhythms. This behavioural system depends on non-photic inputs but interacts with the light-entrainment system. Non-photic stimuli can be powerful quantitatively: behavioural events can shift rhythms by several hours. Non-photic entrainment off...

Animals breeding only once late in life should spend most of the time during their one reproductive season attempting to reproduce. Contrary to this prediction, we found that the individuals of three species of sticklebacks (Pisces: Gasterosteidae) spent very short periods of time on their breeding ground. Tidal flooding of the site controlled patt...

On 102 occasions from September 1984 to April 1985, the time of morning departure and evening arrival of a population of black-billed magpies (Pica pica) was recorded at a winter roost near Edmonton, central Alberta. The goal was to determine whether an effect of cold on daily roosting time could be observed and distinguished from that of other env...

The loss of eggs from clutches deposited in simulated and natural nests of spruce grouse was investigated during the spring of 1983 in lodgepole pine forests of southwestern Alberta. Two-thirds of all clutches, both in simulated and natural nests, were partially or completely lost. Density of simulated nests had no impact on proportional loss. Evid...

Observations of male three-spined stickleback (Gasterosteus aculeatus L.) parental care were made in a salt-marsh tide pool at 3-h intervals over 24-h cycles, to determine if male behavior varied in association with diel changes in water temperature and dissolved oxygen concentration. An analysis of egg metabolism in situ revealed positive correlat...