Two lines of female farm mink were selected among the offspring of 495 mothers kept under conventional farm conditions. A low-stereotyping line (n=146) arose from 75 non-stereotyping females and a high-stereotyping line (n=150) was established from the 75 most stereotyping females. In two successive generations, the incidence of stereotypies was four times higher in the offspring of high-stereotyping females than in those of non-stereotyping females indicating a genetic transmission of the trait. Stereotypies were associated with higher fertility as revealed by fewer barren females, increased litter size, and lower mortality among the pups. Stereotyping females had lower body weight than non-stereotypers, and the association between stereotypies and fertility could exclusively be explained by reducing effects of stereotypies on body weight.

In a 2×2 factorial experiment, the effects of gestation and farrowing housing on (1) periparturient behaviour and circulating prolactin, prostaglandin F2α (PGF2α) and oxytocin in gilts with access to peat, straw and branches, and (2) correlational relationships between the periparturient behaviour and hormones were studied. The treatments consisted of housing in stalls or pens from mating to day 110 of gestation followed by farrowing crates or pens until after parturition. Landrace×Yorkshire gilts were observed from video recordings (n=25) from 20h prepartum and blood sampled via jugular catheters (n=16) from 24h prepartum until 2h after the birth of the first piglet.

In Lorenz's 'psychohydraulic model', behaviour is regulated by performance: the motivation to perform a behaviour builds up with time and can be reduced only by performance itself. However, a convincing example of Lorenzian regulation has been lacking. We studied dustbathing in featherless and feathered chicks, Gallus gallus domesticus, the latter trained to dustbathe on glass with sand underneath. In both cases the function, that is, plumage cleaning, was eliminated. In both featherless and feathered chicks dustbathing increased with time since the last performance as found in normal dustbathing, and there was a compensatory adjustment when the amount of previous dustbathing was artificially reduced. We suggest that the amount of dustbathing performed at any one time may be controlled by the cooperative action of a deprivation or timer mechanism and a counter mechanism. The timer mechanism responds to the time since the last performance, whereas the counter mechanism records the number of elements during that last dustbathing. Alternatively, there may be a single mechanism that continually records the deficit in the amount of dustbathing performed. Lorenz's model may be valid not only for dustbathing in fowl but also for other comfort behaviours. Our results suggest the existence of behavioural needs that can be satisfied only by performance. Copyright 1999 The Association for the Study of Animal Behaviour.

Studies on domestic chicks have indicated that preferences for dustbathing substrates are related to early pecking experience before full dustbathing behaviour has appeared. In this study we investigated if this was also the case in game pheasant (Phasianus colchicus), a close relative of fowl. Pheasant chicks were kept as pairs in wire floored cages and given either 2 min or 5 min pecking experience by simultaneous presentation of pear and sand on days 2-11. On days 13 and 14 they were tested for dustbathing performance during 30 min simultaneous presentation of sand, peat and feed. Chicks on the 5 min treatment had a higher pecking rate (P < 0.01) and therefore gained more experience with the pecking substrates than chicks on the 2 min treatment. Furthermore, chicks on the 5 min pecking treatment dustbathed more in the substrates than those on the 2 min treatment (P < 0.05). Generally, chicks preferred to peck at peat rather than at sand (P < 0.02) and they also preferred to dustbathe in peat (P < 0.03).In the 2 min group dustbathing in the substrates and early overall pecking rate on days 2-11 at the substrates were positively correlated, with a strongly increased correlation coefficient by day 8. In the 5 min group the correlations between pecking at either sand or peat and dustbathing in sand peaked on day 4. During the dustbathing tests three chicks that had no or very little experience of pecking the substrates preferred to dustbathe in food. We suggest that like domestic chicks game pheasant chicks imprint on dustbathing substrates by pecking at them during the first days of life.

Many reef fish have strong microhabitat preferences when they settle to the juvenile population, and choices at this time may influence fish survival. This is exemplified in anemonefishes (Family: Pomacentridae) that exhibit obligate symbiotic relationships with a restricted range of sea anemone species. This study examined how juvenile anemonefish Amphiprion melanopus select their host, and whether recognition and selection are mediated by an imprinting-like mechanism. Specifically, we experimentally examined the host-selection made by A. melanopus that had been reared under constant conditions, but whose embryos had received 1 of 3 treatments: (1) in contact with a known natural host sea anemone, Entacmaea quadricolor; (2) in contact with the sea anemone Heteractis malu, which is not a host for A. melanopus in nature, but is a host for anemonefish of other species; and (3) without a sea anemone (or chemical cues released from sea anemones) at any life stage. Our study shows that olfaction, not vision, is used by juvenile A. melanopus to recognize host anemones. Furthermore, the choice of a settlement site for juvenile A. melanopus is strongly influenced by events that occur early in development, prior to the dispersal of larvae from their natal site. We suggest that juvenile A. melanopus possess an innate preference for E. quadricolor, a preference that is enhanced by imprinting. Interestingly, it was not possible to imprint A. melanopus larvae to the non-host sea anemone H. malu, which suggests that anemonefish host-imprinting may be rather restricted.

The use of statistics that assume independence between observations may not be an adequate tool in the analysis of how prey fish co-ordinate their swimming when inspecting piscine predators. This is mainly caused by the fact that continuity is an inevitable feature of locomotion. Thus, if one takes observations at close intervals, the assumption of independence will probably be violated, while observations taken too far apart may lose significant information of what goes on in between. In this paper we present one way of dealing with these problems and demonstrate what may come out when applied to empirical data of predator inspection in fish. The method models measurements taken at equispaced points in time as dynamic systems of simultaneous stochastic difference equations, and may well be applied in general to auto- and cross-correlated data. A full account of statistical procedures and how to estimate the order of difference presented in an appendix. Swimming trajectories, represented as successive distances to predators at intervals of 2 s, were obtained from paired male guppies inspecting piscine predators. Dynamic models of swimming were then estimated and used for quantifying causes of locomotion that relates to inertia of own swimming, to motion of co-inspectors, and to independent causes generated elsewhere. The derived models complied with second order systems in 9 out of the 10 fish that were investigated. Feed-back relations within co-inspectors varied between pairs, but none of the fish moved independently of its partner. All models may be interpreted in terms of interacting attracting/repelling 'forces' between each prey fish and the predator. The way swimming by a particular fish affected co-inspectors was further analysed. Mean properties of this influence revealed that even when partners lagged behind inspecting individuals, they mostly behaved so as to make the leading fish approach the predators even further. This finding suggests other behavioural strategies to be involved than those assumed previously, and one alternative is discussed.

Two experiments were conducted to examine the effects of repeated immobilisations and food restriction on normal activity and stereotypies in low and high stereotyping female ranch mink. Repeated immobilisations had immediate inhibitory effects on normal activity and stereotypies in both groups, whereas food restriction had the opposite immediate effects. Subsequent to both immobilisations and food restriction, stereotypies were increased, whereas normal activities returned to pre-experimental levels. Repeated immobilisations were followed by increases in cortisol levels in both low and high stereotyping females. High stereotyping females had lower baseline cortisol levels than low stereotypers but tended to show higher cortisol responses to immobilisations. These results indicate that stressful experiences may affect stereotypies, but that the direction of the changes depends on type of stressor as well as the duration of exposure to the stressor. It is moreover suggested that stereotypies can be emancipated.

AbstractForaging, agonistic, and sexual behaviour in heterosexual groups of Poecilia velifera were examined during conditions of captivity. Social organization was found to resemble what was previously found in other poeciliids, hierarchies being established within each sex. Males showed considerably more aggressive activities than females, and alpha males tended to dominate all individuals.Aggressiveness is the only measure where dominating individuals exceed submissives. Levels of aggressiveness higher than a specific value may have negative influences in gaining access to resources: Those individuals with highest or lowest scores for aggressive behaviour were low scoring with respect to sexual and foraging behaviour.Attempts were made to separate factors determining aggressiveness in competition for food and mates by observing in periods with and without food being presented. Only beta individuals changed levels significantly: females decreased both chasing and biting during non‐feeding periods, whereas males only decreased biting.Sexual behaviour in terms of butting tended to decrease in alpha and increase in omega males during non‐feeding periods, whereas beta males in the same periods showed significantly decreased levels of both butting and gonopodial thrusting.