Abstract: Herding behavior in ungulates is executed mainly by males. There are several forms of herding: guarding a single estrous female; rounding up a bunch of females during the rutting season; territorial herding by which a male keeps females inside his territory; herding of a moving, permanent, harem group; social herding in which group members of both sexes are herded by one dominant male. When put into this sequence, a phenotypical trend is illustrated, leading from an intimate connection of herding with mating behavior toward an increasing independence from sexual behavior and culminating in a complete socialization of herding. Aspects and problems of herding behavior are the recognition of, and the animal's respect for, partners in gregarious species; the animal “taking offense” at activities of others which deviate from its own activity; the active coordination and synchronization of group activities; the use of, and the effects of, threat, dominance and courtship displays in herding; the possibility of substitution among expressive displays in relation to partners of different sex; the communicative function of the animal's orientation relative to the partner; social hierarchy and leadership in a group; the possibility of interspecific herding, particularly in man-animal relationships, which is closely linked to the process of domestication.

Abstract: Several species use the number of young produced as public information (PI) to assess breeding site quality. PI is inaccessible for synchronously breeding birds because nests are empty by the time the young can collect this information. We investigate if location cues are the next best source of inadvertent social information (ISI) used by young prospectors during breeding site choice. We experimentally deployed ISI as decoys and song playbacks of breeding males in suitable and sub-optimal habitats during pre- and post-breeding periods, and monitored territory establishment during the subsequent breeding season for a social, bobolink (Dolichonyx oryzivorus), and a more solitary species, Nelson's sharp-tailed sparrow (Ammodramus nelsoni). The sparrows did not respond to treatments, but bobolinks responded strongly to post-breeding location cues, irrespective of habitat quality. The following year, 17/20 sub-optimal plots to which bobolink males were recruited were defended for at least two weeks, indicating that song heard the previous year could exert a “carry-over attraction” effect on conspecifics the following year. Sixteen recruited males were natal dispersers, as expected when animals have little opportunity to directly sample their natal habitat quality. We suggest that differences in breeding synchronicity may induce an equivalent clinal distribution of ISI use.

Abstract: We compared the size of skeletal and ornamental traits, and asymmetries in bilateral skeletal traits, between victims of cannibalism, cannibals and bystanders within small groups of caged female White Leghorns at the time of cannibalistic attacks (i.e. injurious pecks resulting in bleeding). We hypothesised that victims of cannibalism have discernible morphological traits that predispose them to cannibalistic attack. We predicted that victims would have smaller skeletal traits (body length, ulna length, metatarsus length and width, toe length), lower body weight, poorer body condition, smaller combs and more asymmetrical bilateral skeletal traits than their flock mates. Contrary to our prediction, victims of cannibalistic attacks to the head/neck area (N=23) tended to have larger combs than their flock mates (Wilcoxon matched-pairs signed-ranks test, S=59, P=0.037, NS after sequential Bonferroni adjustment). Their cannibals were more asymmetrical than non-cannibalistic bystanders (metatarsus length, S=48, P=0.011 and composite asymmetry, S=62.5, P=0.002, significant after sequential Bonferroni adjustment). In agreement with our prediction, victims of cannibalistic attacks to other body parts (N=27), including the back, wings, rump, tail, cloaca, abdomen and toes, were more asymmetrical (composite asymmetry, S=78, P=0.022, significant after sequential Bonferroni adjustment) and tended to have lower body weights (S=79.5, P=0.029, NS after sequential Bonferroni adjustment) than their flock mates. Their cannibals did not differ in skeletal or ornamental traits from the non-participating bystanders. The results suggest that large combs either elicit attacks to the head and neck area or increase vulnerability to injury during such attacks. Attacks to other body parts appear to be directed towards birds with signs of weakness relative to their flock mates. In these attacks, there were no distinguishing features separating cannibals from bystanders, suggesting that the bystanders could all be potential cannibals.

Abstract: Social group size has been shown to correlate with neocortex size in primates. Here we use comparative analyses to show that social group size is independently correlated with the size of non-V1 neocortical areas, but not with other more proximate components of the visual system or with brain systems associated with emotional cueing (e.g. the amygdala). We argue that visual brain components serve as a social information 'input device' for socio-visual stimuli such as facial expressions, bodily gestures and visual status markers, while the non-visual neocortex serves as a 'processing device' whereby these social cues are encoded, interpreted and associated with stored information. However, the second appears to have greater overall importance because the size of the V1 visual area appears to reach an asymptotic size beyond which visual acuity and pattern recognition may not improve significantly. This is especially true of the great ape clade (including humans), that is known to use more sophisticated social cognitive strategies.