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 overall difference in the delay times of male and female Infanticide is one aspect of the study of 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 , especially This result confirms that subjects waited significantly species such as ground squirrels () 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 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). . J. ., 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). McLean (1978; not cited regulation of density in Uinta ground squirrels by Sherman) reported one instance of an adult male (Citellus armatus). M. S. thesis, Utah State Univer- killing a yearling. sity. S. beecheyi: Linsdale (1946, page 342) noted that Linsdale, J. M. 1946. The California . several unexplained disappearances of recently emerged Berkeley: University of California Press. juveniles could be due to intraspecific mortality, but McLean, I. G. 1978. Plugging of nest burrows by female emphasized that he neither observed killing nor had any Spermophilus columbianus. & Mammal., 59, conclusive evidence for its occurrence. One dead wounded 437-439. young, probably a preweaned animal judging from its McLean, I. G. 1979. Paternal behaviour and intraspecific weight and stomach contents, was found by a burrow, killing by the Arctic ground squirrel. Am. ZooL, but Linsdale (1946, page 357) did not indicate how or by 19, 936. whom the injury may have been inflicted. S. franklinii: Sowls (1948, page 125) gave a second- McLean, I. G. 1981. Social ecology of the Arctic ground hand report of a single instance of cannibalism in the squirrel Spermophilus parryii. Ph. D. thesis, field; an adult was seen eating a young animal. No University of Alberta. information was provided as to the age of the young or Michener, G. R. 1973a. Field observations on the social how it might have died. relationships between adult female and juvenile S. richardsonii: Quanstrom (1968, page 51) noted, as Richardson's ground squirrels. Can. Y. Zool., has Michener (1973a; not cited by Sherman), that females 51, 33-38. identify and chase emerged juveniles that are not their Michener, G. R. 1973b. Intraspecific aggression and own. Quanstrom (1968, also 1971, page 650; not cited by social organization in ground squirrels. J. Mammal., Sherman) once observed an adult female injure a juvenile 54, 1001-1003. that intruded into her territory. Michener (1973b) found Quanstrom, W. R. 1968. Some aspects of the ethoecology no injured juveniles during a 3-year study. Neither of Richardson's ground squirrel in eastern North Quanstrom nor Michener reported intraspecific killing of Dakota. P h . D . thesis, University of Oklahoma. either pre- or postweaned young in natural contexts. Quanstrom, W. R. 1971. Behaviour of Richardson's Sherman (1981) grouped 17 North American species of ground squirrel Spermophilus richardsonii richard- Spermophilus into three classes: six for which no appro- sonii. Anim. Behav., 19, 646-652. priate field data regarding infanticide are available, three Sherman, P. W. 1981. Reproductive competition and in which infanticide has not been seen during two or more infanticide in Belding's ground squirrels and other field studies, and eight in which infanticide has been animals. In: Natural Selection and Social Behavior observed in free-living populations. From the literature (Ed. by R. D. Alexander & D. W. Tinkle), pp. cited by Sherman, I conclude that intraspecific killing in 311-331. New York: Chiton Press. field situations involving either preweaned or recently Sowls, L. K. 1948. The Franklin ground squirrel, Citellus emerged young has been witnessed in two species (S. franklinii (Sabine), and its relationship to nesting beldingi and S. parryii) and is suggested by circumstantial ducks. J. Mammal., 29, 113-137. 938 A N I M A L , B E H A V I O U R , 3 0 , 3

Steiner, A. L. 1970. l~tude descriptive de quelques activit6s hypothesized (Sherman 1981, page 327): 'The likelihood et comportements de base de Spermophilus that neonatal young may sometimes be killed in S. eolumbiamts eolumbianus (Ord). II. Vie de groupe. riehardsonii is seemingly increased by Miehener's report Rev. Comp. Anhn., 4, 23-42. (1973c) that, in the laboratory, six of seven virgin females Steiner, A. L. 1972. Mortality resulting from intraspecific and one of six nonlactating adults attacked or killed fighting in some ground squirrel populations. conspeeific juveniles presented to them'. Y. MammaL, 53, 601-603. For Columbian ground squirrels, Steiner (1972, page 601) witnessed: 'many chases of and serious attacks (Received 19 October 1981; revised29 December 1981; on immature individuals by a d u l t s . . , a m o n g . . . MS. number: AS-160) Spermophilus eolumbianus... (see Steiner, 1970a, 1970b)'. In his 1970 papers, published in French, Steiner referred Infanticide in Ground Squirrels to the young he watched as 'les juv6niles'. A translational I concluded nay report on infanticide in Belding's ground misunderstanding ensued: various subsequent authors, squirrels (Spermophilus beldingi: Sherman 1981) with the beginning with Miehener (1973b, page 1001), cited suggestion that infanticidal behaviour may be widespread Steiner for observations of attacks on juveniles resulting in this genus (also Hoogland 1979, page 27). Recently in injuries or deaths (e.g. Betts 1976, page 666; McLean Michener (1982)chaUenged nay proposal. Accepting 1978, page 438; Sherman 1981, page 326). In a recent as evidence only above-ground slayings, she judged that clarification, Steiner (personal communication) confirmed infantidde is known only in Belding's and Arctic ground that he saw adults inflict severe wounds on 1-year-olds squirrels (S. parryii: McLean 1979, 1981). I adopted a but that he did not study adult-juvenile interactions. less restrictive approach in my summary of a diverse, In light of these considerations, the 'Infanticide Obser- largely anecdotal literature than I had in my own data ved' sub-heading of my Table 19-6 (Sherman 1981) may because in ground squirrels, attacks on immatures and have been too direct. Nonetheless the frequency with deaths from resulting wounds may often occur in sub- which S. beldingi attack and kill nonkin pups and the terranean nests. To avoid dismissing any possible cases similarities between infanticidal behaviours I observed of infanticide, I cited reports of infants or juveniles being and the anecdotal reports quoted here suggest to me 'injured or killed' when authors implicated conspeeifics as that (page 311): 'Infanticide...particularly among the assailants. ground squirrels.., may be a more important mortality For example, consider Burns's summary (1968, page source and a more widespread form of reproductive com- 10) of the demise of a Uinta ground squirrel litter petition than is currently recognized'. (S. armatus): 'Five dead juveniles were found in the nest I thank R. D. Alexander, J. L. Hoogland, F. A. Pitelka, of a yearling female (820) soon after she was accidentally and C. K. Sherman for commenting on the manuscript, killed. A neighboring adult female (24) was seen entering and A. L. Steiner and G. R. Michener for discussions. and leaving 820's bttrrow. The burrow was excavated a Note added in proof: D. Balfour (University of few hours later and each young had fresh puncture wounds Guelph) has recently informed me that during her 1977 on its head and neck, apparently inflicted by the incisors field study of S. eolumbianus she witnessed infanticide: of another ground squirrel'. And, Alcom's description an adult female killed a neighbour's juvenile offspring. (1940, page 166) of juvenile deaths in Townsend's ground PAUL W. SHERMAN squirrels (S. townsendii): 'On a score of occasions Neurobiology and Behavior, . . . I found small squirrels.., partly eaten and still Cornell University, Ithaca, N. Y., 14850, U. S. A. squirming, lying at the entrance of a burrow . . . . On several other occasions I saw adult squirrels eating young. References In each instance evidence pointed to an adult of Alcorn, J. R. 1940. Life history notes on the Piute ground their own kind as responsible for the killing. The young squirrel. J. Mammal., 21, 160-170. squirrels eaten were only a few days old; their eyes were Betts, B. J. 1976. Behaviour in a population of Columbian not open yet'. ground squirrels, Spermophilus columbianus eolumb- For California ground squirrels (S. beecheyi), Linsdale ianus. Anita. Behav., 24, 652-680. (1946, page 343) reported that: 'On June 9 (a) mate was Burns, R. J. 1968. The role of agonistic behavior in seen to enter the burrow containing young, lZaint sounds, regulation of density in Uinta ground squirrels possibly of scuffling, were heard within the burrow. The (Citellus armatus). Unpublished MS. thesis, young one missing afterwards was last trapped on June Utah State University, Logan. 8 and thus might have been killed on this occasion'. Hoogland, J. L. 1979. Aggression, ectoparasitism, and This led me to suggest that infanticide 'probably' oc- other possible costs of (Sciuridae, curs, because Linsdale 'Observed unexplained disap- Cynomys spp.) coloniality. Behaviour, 69, 1-35. pearances of young and attributed them to intraspecific Linsdale, J. M. 1946. The California Ground Squirrel. killing' (Table 19-6 in Sherman 1981). For Franklin's Berkeley: University of California Press. ground squirrels (S. franklinii), Sowls (1948, page 125) Mclean, I. G. 1978. Plugging of nest burrows by female noted that a captive adult ate a young conspeeific that Spermophilus eolumbianus. J. Mammal., 59, escaped into its enclosure and that (in the field) 'On 437439. July 18, 1938, Albert Hochbaum found an old squirrel McLean, I. G. 1979. Paternal behavior and intraspecific devouring a freshly killed young one'. killing by the Arctic ground squirrel. Am. Zool., Quanstrom (1968, page 51) witnessed an adult female 19, 936. Richardson's ground squirrel (S. richard~onii) attack and McLean, I. G. 1981. Social ecology of the Arctic ground wound a juvenile. Although Michener (1973a, 1973b) did squirrel Spermophilusparryii. Unpublished. Ph.D. not find injured or dead young in the field, her laboratory thesis, University of Alberta, Edmonton. pup-retrieval experiments (1973c) showed that lactating Michener, G. R. 1972. Social relationships between adult females carry infants into their nests while (as in free-living and young in Richardson's ground squirrel S. beldingi) non-reproductive females and 1-year-old Spermophilusrichardsoniiriehardsonii. Unpublished males (Micheuer 1972, page 57) often eat them. Thus I Ph.D. thesis, University of Saskatchewan, Regina.