Han DE VRIES;
Willem J. Netto;
Peter L.H. Hanegraaf
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MatMan is a program for performing a variety of ethological analyses of frequency (interaction) matrices and transition matrices. These analyses include linear hierarchy indices for dominance matrices (APPLEBY, 1983), reorganization of a dominance matrix such that the subjects are in rank order, matrix correlation methods such as Mantel's test (MANTEL, 1967) and rowwise matrix correlation (DE VRIES, 1993), methods based on information theory (STEINBERG, 1977), and the calculation of expected and residual values in transition matrices with defined or undefined diagonal. In addition, MatMan offers some useful options for manipulating matrices. Import of matrices from The Observer (NOLDUS, 1991) and SAS is, within certain limitations, possible. Export of matrices is possible to the programs CORAN (1985), Vegrow (FRESCO, 1989), NCSS (HINTZE, 1987), SAS and SPSSPC.
The predominant frequency, rate of clucking and intensity of the maternal cluck vocalization of the broody hen (Gallus gallus) are described. The frequency, rate of clucking, and level of intensity of the cluck vocalizations were altered independently of each other. Three-day-old chicks were given a simultaneous choice test between the normal and an altered cluck or between the two altered clucks in a 'T' shaped simultaneous choice test apparatus. No significant preferences were found when the frequency was increased or decreased by 25% (Experiment 1A) but the chicks significantly prefer the normal cluck over a cluck with a 33% increase in frequency. The preference for the normal cluck over the 33% decrease in frequency was nearly significant (Experiment 1B). Thus, there exists an optimal frequency range for the maternal cluck vocalization of the domestic hen. When the rate of clucking was increased or decreased by 25% the chicks preferred the higher rate of clucking in all conditions (Experiment 2). However, the highest rate of clucking used in this experiment was close to that of the normal cluck. When the intensity was increased or decreased by 100% no significant preferences were found in any choice test (Experiment 3). This contrasts with earlier findings possibly due to a methodological difference.
Fish shoals are usually seen as anonymous leaderless groups in which all individuals have the same influence on swimming velocity and direction. This hypothesis was tested by investigating swimming directions of shoals of roach (Rutilus rutilus) and three-spined stickleback (Gasterosteus aculeatus). In roach, the influence of front and rear fish on the shoal's swimming direction was compared by analysing video recordings. Front fish initiated new directions significantly more often and were followed by rear fish. In a second experiment two shoals of sticklebacks were released from two channels which were positioned at an angle relative to each other. The shoals usually appeared with a short time difference at the opening of the channels and then merged. Initially the two shoals faced in different directions based on the orientation of their respective channel and it was recorded which direction prevailed after the shoals had merged. The shoal that left the channel first, and therefore formed the front part of the merged shoal, clearly dominated the direction. Thus, both experiments gave evidence for front fish having a dominant influence on the direction of the shoal. In the context of sustained position preferences of individual fish, recently observed in roach, this suggests that fish shoals may have leaders over extended time periods.
Lekking males of the carpenter bee Xylocopa (Neoxylocopa) varipuncta compete for landmark territories, where they are occasionally visited by receptive females. In a study conducted over three flight seasons, less than 10% of marked males qualified as long-term residents (i.e. bees that held the same hovering station for 90 min or more on at least two afternoons). However, among the small minority of long-term residents were some bees that returned to the same landmark for up to 3 hr every afternoon for several weeks. These males defeated many intruders in aerial combat during each afternoon. The hypothesis that site-faithful males were individuals of unusual resource-holding power is not supported. Long-term residents were not larger on average than short-term territory holders. Moreover, the frequency of mating by long-term residents was very similar to that of males in the general population, suggesting that long-term residents did not hold territories that were exceptionally attractive to females. Thus, the basis for site fidelity in this species remains elusive. The rarity of site-faithful males in this species may be related to great daily fluctuations in the numbers of potentially receptive females visiting the landmark territories, which may make the timing of male mate-attracting behavior far more important than regularly returning to defend any one site.
In a laboratory experiment in I. baltica the precopulatory guarding was preceded by a period of struggles between the sexes as males continuously tried to initiate the precopulatory guarding and females resisted their guarding attempts. This struggling lasted for a few days, during which the females escaped from the males on the average 1.3 times per hour. While the females resisted, the males usually responded by kicking back. Once the precopula started, on the average 43 h before the completion of the female parturial ecdysis, the female resistance stopped. If the guarding male was replaced by another male, the female accepted the new male without resistance or resisted only weakly. Larger males were able to perform longer precopulas, and furthermore, when males were hunger stressed they performed shorter precopulas than control males. The female resistance and the existence of struggles imply a conflict between the sexes over whether or not to start the precopulatory phase. This conflict may occur either because of different optimum precopula duration of the sexes or because of the unwillingness of the females to pair with whatever male. By resisting, females may, at least to some extent, control the duration of the guarding, and the resistance may lead to selection among male candidates. Thus the female resistance, although for so far largely neglected, may have potential importance in the mate choice and sexual selection of aquatic crustaceans with precopulatory guarding.
The importance of brood size, offspring age, and male size for parental care behaviour was studied in the common goby, Pomatoschistus microps. In field observations, the aggression of nest guarding males was measured as attacks towards a finger when disturbing the nest. Attacking males had larger and more developed clutches compared to non-attacking males, but did not differ in body size. In another set of observations nest guarding males were exposed to a predator (eelpout, Zoarces viviparus) and subsequently chased away from their nests. Time away from the nest decreased significantly with egg developmental stage, i.e. with the time the male had spent guarding a particular brood. However, no correlations with male body length or numbers of eggs in the nest were found. We conclude that male common gobies evaluate future reproductive success by using brood age and brood size as cues for making decisions about risk-taking and aggressive behaviour during parental care.
This study reinvestigates the effects of primary imprinting of chicks with either a naturalistic stimulus or an artificial object on subsequent imprinting with artificial objects. Initial experience with a live chick (group C) or a yellow cylinder (group Y) had differential effects on the development of a secondary filial attachment in chicks. In chicks of both groups, growth of attachment to the novel imprinting object manifested itself rather abruptly, but the change in response to the novel object occurred later in C- than in Y-chicks. There was no difference between the groups in the outcome of secondary imprinting: chicks in groups C and Y eventually became equally strongly attached to their novel imprinting stimulus, and when exposed to a third object, chicks in both groups imprinted equally well on this object. Thus, (1) initial imprinting on a naturalistic stimulus postponed, but did not block secondary imprinting on an artificial object, and (2) within the lengths of exposure used, the capacity to form new filial attachments was not limited, contrary to the prediction of the competitive exclusion model for imprinting. Secondary imprinting was delayed for a longer time when chicks were exposed to the novel imprinting stimulus in an unfamiliar environment. This indicates that induction of fear in chicks interfered with the occurrence of secondary imprinting. This effect may havc contributed to the difference between groups C and Y in the length of delay of secondary imprinting. Possibly, separation from the first stimulus and exposure to the second stimulus was more fearful to C-chicks than to Y-chicks. Introduction Imprinting was originally described by LORENZ (1935, 1937) as an irreversible process. This does not necessarily mean that a young animal cannot form secondary filial attachments after having been imprinted on a
Five experiments were conducted to investigate the effect of novelty on visually-mediated taste-avoidance learning in domestic chicks. In experiments l a and b, chicks were reared with either uncoloured or blue fluid in their home cages, and then required to discriminate between blue and uncoloured fluids that were either palatable or unpalatable (quinine-adulterated). For some chicks the distasteful fluid was novel in appearance, for others it was familiar. In both experiments chicks readily discriminated between a novel unpalatable fluid and a familiar palatable one, but failed to discriminate between a familiar unpalatable fluid and a novel palatable one. This failure to discriminate resulted from avoidance of the palatable fluid. In neither experiment did novelty enhance the rate of avoidance learning. Experiment 2 tested more directly the effect of novelty on speed of avoidance learning. Chicks were reared on either red or blue palatable fluid, then tested with either red or blue distasteful fluid. Avoidance learning was more rapid when the distasteful fluid was novel in colour, in both red-reared and blue-reared chicks. Experiment 3 investigated the inability of chicks to discriminate between a familiar unpalatable fluid and a novel palatable one, demonstrated in experiment 1. Chicks were required to discriminate between different-coloured palatable and unpalatable fluids when both were familiar in appearance (experiment 3a) or when both were novel (experiment 3b). Discrimination occurred in the first case but not in the second. In addition, avoidance learning was slower when both unpalatable fluids were familiar. I conclude that (a) novelty faciliates visually-mediated taste-avoidance learning in chicks and (b) the failure of chicks to discriminate a novel palatable fluid from a familiar unpalatable one depends on the relative novelty of the palatable fluid and not on the relative familiarity of the unpalatable one. The results are discussed in the context of warning coloration and are explained in terms of an interaction between unlearned and learned avoidance tendencies.
The concept of dominance has contributed greatly to our understanding of social structure in animals. Over the past three decades, however, a variety of concepts and definitions of dominance have been introduced, leading to an ongoing debate about the usefulness and meaning of the concept. Criticisms aimed at one definition of dominance do not necessarilly apply to other definitions. Existing definitions can be structural or functional, refer to roles or to agonistic behaviour, regard dominance as a property of individuals or as an attribute of dyadic encounters, concentrate on aggression or on the lack of it, and be based either on theoretical constructs or on observable behaviour. Thirteen definitions of dominance are reviewed, and their usefulness assessed with respect to their descriptive value. The predictive and explanatory values of definitions are specific to the questions asked in each particular study and are not considered as criteria to judge the usefulness of the dominance concept. By virtue of its high descriptive value, the original definition of dominance by SCHJELDERUPP-EBBE (1922, Z.Psychol. 88: 226-252) emerged as the basis to formulate a structural definition with wide applicability and which reflects the essence of the concept: Dominance is an attribute of the pattern of repeated, agonistic interactions between two individuals, characterized by a consistent outcome in favour of the same dyad member and a default yielding response of its opponent rather than escalation. The status of the consistent winner is dominant and that of the loser subordinate. Dominance status refers to dyads while dominance rank, high or low, refers to the position in a hierarchy and, thus, depends on group composition. Dominance is a relative measure and not an absolute property of individuals. The discussion includes reference to the heritability of dominance, application of dominance to groups rather than individuals, and the role of individual recognition and memory during agonistic encounters.