Human handling might interfere with conspecific recognition in the european rabbit (Oryctolagus cuniculus).

Handled rabbit pups react with decreased fear to a human at weaning. We hypothesized that pups learn species-specific features of their handler. Experiment 1 showed that handled animals' reactions were similar to both a human and their mother. Experiment 2 showed that pups reacted similarly to their mother and other adult rabbits. In Experiment 3, we used nonhandled control pups, and pups in the experimental groups were stimulated either by a human, a cat, or both. Only human-handled animals showed high affinity to approach a human at weaning. Similarly, only rabbit pups exposed to a cat did not show fear reaction towards a cat. Nonhandled controls avoided both the cat and the human, and rabbits stimulated by both species did not avoid any of them at weaning. We demonstrated that handling affected the behavior of weanling rabbits in a selective manner, as they only approached those objects frequently to which they had been exposed to.

Regular handling early in the nursing period eliminates fear responses toward human beings in wild and domestic rabbits.

The effect of early handling has been of special interest as there is accumulating evidence that the experimenter might be considered as a predator by the animals, resulting in an undesirable level of fear in experimental studies. The aims of the present study were (a) a systematic investigation of the effect of regular daily handling on the fear reaction toward human beings both in domestic and in wild type rabbits, (b) to measure the long-term consequences of the handling, (c) to investigate whether the effective handling is linked to the nursing period, and (d) to see whether the effectivity of handling is confined to a sensitive period in the rabbit. We found that both domestic and wild rabbits are sensitive to human handling, especially when it is performed near the time of nursing. There was a sensitive period, the 1st week postpartum, in the effectiveness of handling. The animals handled in the sensitive period readily and repeatedly approached the observer, indicating the lack of fear. The effect of handling seemed long- lasting as handled females raised to adulthood were superior to nonhandled individuals in their breeding performance. These results indicate that reduced fear of humans can be achieved via handling and this might be a prerequisite for studying the unbiased behavior of animals via direct observation.

The effect of early handling is dependent upon the state of the rabbit (Oryctolagus cuniculus) pups around nursing.

We investigated the behavior toward humans in 4-week-old pups and adult rabbits handled daily at different times around the nursing visits during their 1st week of life. The timing of handling significantly influenced its efficiency in altering the subsequent behavior of rabbits. Animals handled around nursing readily approached a human hand when tested at weaning. Other pups, handled either 6, 12, or 18 hr after nursing, avoided the human hand. Our results show that there is a narrow sensitive period for successful stimulation, because only those rabbits that were handled within the interval starting 15 min before and ending 30 min after nursing became tame. The effect of early handling proved to be long-lasting because nonhandled rabbits tested as adults were afraid of humans and showed behavioral elements of avoidance, while the handled ones behaved fearlessly in the open field. The effect of handling proved to be specific toward humans because both handled and nonhandled animals showed avoidance toward a stuffed fox.

Transmission of food preference in the rabbit: the means of information transfer.

Rabbit pups raised by mothers fed different diets during pregnancy and lactation show a clear preference for the diet of their mother at weaning. By supplementing does' lab chow diet with aromatic juniper berries, the present study aimed to investigate the relative importance of 1) fecal pellets deposited by the mother in the nest, 2) prenatal experience in utero, and 3) contact with the mother during nursing in determining pups' later food preference. The three means of transmission were found to be equally effective. Thus, pups from normally fed does raised with fecal pellets from juniper-fed mothers, pups from juniper-fed mothers cross-fostered to normally fed does immediately after birth, and pups of normally fed mothers nursed by juniper-fed does all showed as strong a preference for juniper as pups raised by juniper-fed mothers exclusively. Such apparent redundancy may not only help insure that less aromatic substances or substances transmitted differentially by these routes are learned, but also that pups can acquire a preference for a variety of foods eaten by their mother at different times.

A pharmacological discrimination of two behavioral forms of the paradise fish (Macropodus opercularis).

Intracranial injections of 5 micrograms/fish (equivalent to 2 nmol/g) of the dopamine agonist Apomorphine into the paradise fish brain considerably decrease the occurrence of escape behavior with a parallel increase of time spent in swimming. All other elements of the behavioral repertoire are unaffected. The simultaneous administration of 0.5 micrograms/fish (equivalent to 0.15 nmol/g) of the dopamine antagonist Pimozide abolishes this effect. In a second experiment a dose dependent decrease in escape behavior was obtained with a parallel increase of swimming. On the bases of these pharmacological data it is concluded that the escape and the swimming reactions are truly independent units but their regulation might be closely related.

Variable learning performance: the levels of behaviour organization.

Our experiments were focused on some special aspects of learning in the paradise fish. Passive avoidance conditioning method was used with different success depending on the complexity of the learning tasks. In the case of simple behavioural elements various "constrains" on avoidance learning were found. In a small, covered place the fish were ready to perform freezing reaction and mild punishment increased the frequency and duration of the freezing bouts very substantially. However, it was very difficult to enhance the frequency of freezing by punishment in a tank with transparent walls, where the main response to punishment was escape. The most easily learned tasks were the complex ones which had several different solutions. The fish learned to avoid either side of an aquarium very easily because they could use various behavioural elements to solve the problem. These findings could be interpreted within the framework of different organizational levels of behaviour.

Behavioural elements of the paradise fish (Macropodus opercularis). II. A functional analysis.

The effects of various environmental influences, such as presence of a living predator, dominant conspecific or frightening artificial stimulus, on particular behavioural elements of the paradise fish (Macropodus opercularis) were studied. It has been found that certain sets of the elements are manifested as organizational complexes which characterize a certain mood or form of defensive behaviour. The compound elements of these complexes seemed to be partly interchangeable, partly under environmental control. The main behavioural complexes of the paradise fish were the Territorial complex characterizing the peaceful, home-living animal, Emotionality complex appearing in case of immediate and past danger, Active and Passive defense complexes which represent alternatives in defense, depending on particular stimulus settings. Some supporting evidence for these behavioural complexes are presented and discussed.

Behavioural elements of the paradise fish (Macropodus opercularis). I. Regularities of defensive behaviour.

Elements of behaviour were described for the paradise fish on the basis of the topography, location and orientation of the animal observed in various seminatural and laboratory environments. Correlations and repeatability of the parameters of observation were analyzed. Environmental influences, such as periods of the day, housing, feeding, raising conditions, presence of various frightening stimuli and species, and strain differences, were studied. Several functional connections were found among the behavioural elements.