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936 A N I M A L B E H A V I O U R , 3 0 , 3 Unknown to the subject, this interaction was observed manner. This lack of awareness is possible because through a two,way mirror, and a hidden observer recorded of the display's subtlety. As is often the case under natural .the amount of time that elapsed between when the sub- conditions, our experimenter tongue-showed by allowing ject first turned and glimpsed the experimenter and the only the tip of his tongue to be visible. Under naturalcon- time when he first made a vigorous attempt to gain the ditions, also, the tongue-show is not frequently noticed: experimenter's attention. This hidden observer was if it were, then persons would be more cognizant of it as situated so that he could not see the experimenter's facial a display. Our study confirms, then, that the tongue-show expression. is a display that is consciously overlooked but which Half of the subjects (12 male, 13 female) saw the experi- is effective nevertheless. menter displaying a neutral, attentive expression when KIM GALE DOLGIN* they turned in their seats; the others were confronted JOHN SABINI with the experimenter displaying a tongue-show. The presence of the tongue was the only aspect of the facial Department of Psychology, expression allowed to vary. We demonstrated the display University of Pennsylvania, to W. J. Smith, and he confirmed that it was being per- 19104. formed correctly and in an appropriate context. Selec- Philadelphia, Pa. tion of the facial expression followed a randomized pat- *Present address: Institute of Child Development, tern, so that the hidden observer was never aware of University of Minnesota, Minneapolis, MN, 55455. which facial display the experimenter was presenting. The mean hesitation for a subject who saw the neutral Reference attentive expression was 7.72 s (SD = 5.45 s); the mean delay for subjects who saw a tongue-show was 19.93 s Smith, W. J., Chase, J. and Lieblich, A. 1974. Tongue- (so = 25.65 s). As a conservative measure, M a n n - Showing: a facial display of humans and other Whitney U-analyses w e r e performed: several of the primate species.' Semiotica, 11, 201-246. subjects who observed tongue-shows waited for atypically long periods before making an interruption attempt (Received 19 October 1981; revised 1 April 1982; (over 2 min, in the case of one subject). Since this test MS. number AS-159) uses only the ranks of the time lags, these few extreme cases could not unduly skew its results. There was no Infantidde in Ground Squirrels overall difference in the delay times of male and female Infanticide is one aspect of the study of animal behaviour subjects (z = 0.36, NS), SO the subjects were pooled for recently invigorated by applying concepts of natural the critical analysis. When the delay time of subjects selection to account for its origin and maintenance who had seen the neutral expression were compared with (Blaffer Hrdy 1979; Sherman 1981). Acquiring empirical the delays of subjects who had seen a tongue-show, a data on the frequency of infanticide and on the identities z-score of 1.872 was obtained (P < 0.05, one-tailed test). of perpetrators is difficult for most mammals, especially This result confirms that subjects waited significantly species such as ground squirrels (Spermophilus) that longer before interrupting the experimenter when he was sequester their preweaned young in a refuge. Instances of tongue-showing. infanticide among Belding's ground squirrels (S. beldlngi) Once the subject had interrupted, the study was over were witnessed in the field by Sherman (1981) who found and he or she was informed of the experiment's real that, in the population he studied, above-ground killing purpose. Subjects were then asked to reproduce the facial of preweaned young by conspecifics occurred in each of expression that they observed: none reproduced a tongue- 4 years and involved the loss of at least 8 ~ of the estimated show. Instead, all displayed neutral, attentive expressions. infant population. In considering whether infanticide, When the subjects who had witnessed the tongue-show which he defined as 'the killing of conspecific young', had it demonstrated for them, most denied having noticed occurs in natural contexts in other species of ground the display. When questioned further, many said that the squirrels, Sherman noted that infanticide has been re- experimenter looked as if he did not wish to be inter- ported for the eight species of Spermophilus he listed under rupted, and that they were conscious of a reluctance to 'Infanticide Observed' (Sherman 1981, Table 19-6). disturb him. None of the subjects who had seen the Inspection of the original references reveals that for neutral expression mentioned such a compunction to only two species has killing of young been witnessed in hesitate. When asked, no subject reported finding either the field. the situation or facial expression strange or incongruous. The purpose of this note is to re-examine the evidence, The conclusion that can be drawn from these data is primarily from the sources cited by Sherman, for infanti- that the tongue-show is an effective human non-verbal cide in Spermophilus. For clarity, and because the dis- display: it succeeded in getting observers to delay dis- tinction may be important in interpreting the significance turbing the displayer, even under conditions in which of intraspecific killing, I distinguish preweaned young interruption was necessary. Although subjects were (infants still in the natal burrow) from postweaned shown only one form of the display (tongue-show ac- young (juveniles that have commenced above-ground companied by gaze aversion) this style is not atypical; activity but are less than 1 year old). In accordance with the display was presented in an appropriate context of Sherman's definition, I herein consider the killing of concentration, and it was contrasted with a neutral expres- either infants or juveniles as infanticide. sion which was also accompanied by gaze aversion. S. beldingi: During his 4-year study, Sherman (1981, Although we cannot rule out the possibility that in other Fig. 19-1) witnessed the deaths of 26 preweaned young contexts the display might have been interpreted differ- that were brought above ground and then killed by con- ently, in this situation the tongue-show conveyed the specifics other than the mother. Killings ceased when displayer's unwillingness to interact. Of particular interest animals were 27-29 days old and were capable of fleeing is the fact that subjects were unaware of the source or defending themselves from attackers. Sherman (1981, of their reluctance. This is in accord with intuition and page 314) attributed a loss to infanticide only if he ob- helps confirm that the display was performed in a natural served above ground killing. SHORT COMMUNICATIONS 937 S. parryii (S. undulatus): Although he did not report evidence for two others (S. armatus and S. townsendii). deaths of preweaned young, Steiner (1972, page 601) did These witnessed and inferred instances of infanticide find wounded and dead juveniles which, with his obser- indicate the necessity of being alert to the phenomenon vations of adult males attacking recently emerged juveniles, when studying free-living populations of Spermophilus. suggested that males sometimes killed postweaned young. However, from the information currently available, it This was subsequently confirmed via direct observation would be premature to conclude that infanticide is of by McLean (1979), who witnessed four killings (details common or widespread occurrence within this genus. in McLean 1981). McLean additionally reported killing I thank J. O. Murie and M. A. Harris, University of of preweaned young after observing that three females, Alberta, for many valuable discussions and comments. whose nest burrows had been entered by adult males, L. S. Davis, University of Alberta and Z. T. Halpin, brought dead infants to the surface, ceased lactating, or University of Missouri-St.Louis, encouraged my interest weaned atypically small litters. in this topic. Conversation with P. W. Sherman, Cornell S. townsendii: On about 20 occasions during a 4-year University, helped to clarify my ideas. study, Alcorn (1940, page 166) found freshly injured and dead preweaned young beside burrow entrances. Several GAIL R. MICHENER times he saw adults consuming neonates that he suspected had been killed by conspecifics, but no killings were Department of Biological Sciences, witnessed. University of Lethbridge, S. armatus: Burns (1968, page 10) excavated a burrow Lethbridge, Alberta, Canada T1K 3M4. that had been visited by a neighbouring female during the resident's absence and found five dead young (age not given), all with recently inflicted bites. The dead References animals were estimated to be less than 3 weeks old (Balph, Alcorn, J. R. 1940. Life history notes on the Piute ground personal communication). squirrel. J. Mammal., 21, 160-170. S. cohtmbianus: Steiner (1970, 1972) did not mention killing of preweaned young, and his field observations Betts, B. J. 1976. Behaviour in a population of Columbian ceased before juveniles commenced above-ground activity. ground squirrels, Spermophilus columbianas col- He did observe adult males persistently chasing yearlings, umbianus. Anita. Behav., 24, 652-680. typically a sexually immature cohort in this species and Blaffer Hrdy, S. 1979. Infanticide among animals: a referred to as 'les juveniles' by Steiner (1970, page 37). review, classification, and examination of the Betts (1976, page 665; not cited by Sherman) also obser- implications for the reproductive strategies of ved violent fights and chases between adults and immatures females. Ethol. Sociobiol., 1, 13-40. (less than 2 years old), but he rarely saw injuries and never Burns, R. J. 1968. The role of agonistic behavior in observed mortality (page 666).

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