Richard H. Porter

Does the newborn baby find the nipple by smell

We studied the involvement of naturally occurring odours in guiding the baby to the nipple. One breast of each participating mother was washed immediately after delivery. The newborn infant was placed prone between the breasts. Of 30 infants, 22 spontaneously selected the unwashed breast. The washing procedure had no effect on breast temperature. We concluded that the infants responded to olfactory differences between the washed and unwashed breasts.

Olfactory cues mediate food selection by young chicks.

An illness-induced aversion paradigm was used to assess the possible influence of olfactory cues on food selection by young chicks. At 2-3 days posthatching, chicks were exposed briefly to food scented with a novel odor (orange) followed by an injection of LiCl or saline. LiCl-injected chicks subsequently displayed stronger avoidance of orange-scented food than did the controls. Chicks in a second experiment were preexposed to novel-scented food, then either injected with LiCl or not injected. The LiCl chicks, but not the controls, later avoided food associated with the preexposure odor (relative to food treated with an unfamiliar odorant). Two- to three-day-old chicks are capable of associating specific food odors with negative consequences and modify their feeding behavior as a function of such experience.

Influence of a conspecific agemate on distress bleating by lambs

Abstract Lambs typically display behavioral and physiological indicants of distress when they are removed from their mother. In the present experiment, we assessed the effects of the presence of agemate conspecifics on the rate of distress bleating by 3-week-old lambs immediately following maternal separation. When removed from their mother and tested in isolation, lambs emitted more distress bleats than they did when paired with a social partner—either their twin ( P P P

Preliminary evidence of a sensitive period for olfactory learning by human newborns.

Aim: To test the hypothesis that a brief window of time immediately after delivery may be a particularly sensitive period for olfactory learning by human neonates.

The biological significance of skin-to-skin contact and maternal odours

Infant‐mother bodily contact is believed to be the species‐typical pattern of immediate postpartum child care. Mothers and newborns engage in mutually beneficial interactions. Maternal odours stimulate breastfeeding activity and are implicated in individual recognition.

Social discrimination in lambs: persistence and scope

Abstract Social recognition among familiar unrelated lambs was assessed in a series of tests. Lambs and their mothers were housed together in small groups for 1 week (Original groups; O) then reorganized into new groupings (Recent-groups; R) for the remainder of the experiment. During test series 1, lambs that were paired with a familiar O-group partner, from which they had been separated for 5 days, emitted fewer distress bleats than did those tested with an unfamiliar partner. This same effect was not evident when the test was repeated several hours later, indicating that the animals had become habituated to the testing procedures. Two days later, when given the choice between an O- versus a R-partner (test series 2), lambs did not display a preference for either of the stimulus lambs. However, in an additional two-choice test (test series 3) the subject lambs responded discriminatively to a recent familiar partner that was simultaneously present with an unfamiliar lamb. Overall, the results suggest that lambs are capable of developing discriminative relationships with age-mates from different sub-groups, and that such social discrimination persists over a separation period lasting at least several days. It is not clear whether lambs recognize several individual conspecifics per se or discriminate between members of higher order social categories (e.g. familiar versus unfamiliar individuals). Proximal and distal social discrimination may be mediated by different combinations of sensory modalities.

Twin/non-twin discrimination by lambs : An investigation of salient stimulus characteristics

A series of experiments was conducted to elucidate the stimuli that mediate twin/non-twin discrimination among 2-3 week old lambs. After being separated from their mother, lambs emitted more distress bleats when tested in isolation than when penned with their familiar twin, but separated from that lamb by a barrier of evenly spaced wood bars. A similar, albeit weaker effect was found for paired vs isolated non-twins. Twins separated by the barrier bleated less than did the non-twins in this condition. In contrast, bleat rates did not differ when subject lambs were tested in the presence of their twin vs a non-twin on the opposite side of a solid opaque barrier. Intact lambs in a final experiment bleated less when tested with their tranquillized twin vs a tranquillized non-twin agemate. The tranquillized stimulus lambs displayed atypical behavior patterns, including suppression of bleats and reduced activity levels. These data indicate that full bodily contact, vocalizations or normal behavioral patterns are not necessary for lambs to be recognized by their twin. Rather, twin/non-twin discrimination (and the effect of a twin on the rate of distress bleating) appears to depend upon visual, and possibly olfactory cues.

An experimental study of social attraction and spacing between the sexes in sheep

SUMMARY Most ungulates are gregarious species and outside the mating season are typically observed in single-sex groups. However little is known about the mechanisms underlying social segregation between sexes. We investigated the effect of conspecific attraction on individual spacing between unrestrained merino sheep Ovis aries and confined conspecifics. We considered differences between males and females and whether attractiveness of the confined conspecifics depends on their sex. A series of binary choice experiments was conducted in a large outdoor arena, located in pastures. One or two stimulus animals were placed in small individual cages (1.5 m×1 m) on opposite sides of the arena. Sheep were tested with one fixed peer of the same or opposite sex vs an empty cage, and with two fixed peers of either the same sex as themselves, or one male and one female. Sheep in a control condition were exposed to two empty cages. In all of the test conditions, confined sheep were highly attractive. Males were more attracted by single stimulus peers of the same than the opposite sex, whereas females did not display such a preference. Sheep confronted with two restrained conspecifics tended to remain between the stimuli. This also occurred when the stimuli were of opposite sex, although the males tended to be located nearer the same-sex peer. Our findings can explain the strong aggregative behaviour of merino sheep, but also the social segregation previously observed in a mixed-sex group through higher attraction for same-sex than opposite-sex peers in males.

Discriminative responsiveness by lambs to visual images of conspecifics

A series of experiments was conducted to assess whether lambs are discriminatively responsive to visual images of conspecifics. Lambs (3-4-week-old) consistently responded with more interest and less avoidance when exposed to a life-like image of an unfamiliar lamb, a ewe or the silhouette of a ewe, than to a meaningless mosaic of the same conspecific stimulus. In each instance, lambs preferentially sniffed the head region of the conspecific image. Slides of a ewe and a dog likewise elicited differential responses by lambs, but there were no clear differences in their attraction to, or avoidance of these two categories of stimuli. In contrast, adult ewes responded more negatively to the dog image than to the ewe slide. Overall, lambs appeared to respond to conspecific images as social stimuli, however, social discrimination by visual cues alone may improve with age and experience.

Establishment of maternal bonding and its mediation by vaginocervical stimulation in goats.

To investigate the establishment of offspring recognition in mother goats, 11 females were subjected to two successive 5-min tests with their own kid and an alien, 2 h 30 min postpartum. All mothers accepted their own kid, while nine rejected the alien. This suggests that in goats, 2.5 h are sufficient for the development of an exclusive bond with the kid. We also studied the role of physiological factors mediating maternal bonding in this species. Eight of the nine goats that rejected alien kids were, therefore, submitted to 5 min of vaginocervical stimulation (VCS) immediately following the selectivity tests. Of these eight goats, five changed their behavior after VCS and accepted the alien kid (0/8 before VCS vs. 5/8 after VCS, p = 0.031). Thus, VCS appears to reduce rejection behavior towards alien kids while resulting in a significant increase in their rate of acceptance. Underlying physiological mechanisms by which VCS may act are discussed.