Environmental and behavioral cues are useful sources of information that allow group foraging individuals to improve their foraging success. Few studies to date, however, have examined how varying degrees of environmental unpredictability may affect when and how individuals use the social information they obtain in foraging groups. In this experiment, European starlings (Sturnus vulgaris) were tested to determine in which type of environment, predictable or unpredictable, social information would be the most valuable. Subjects were placed under one of four conditions: an unpredictable environment with either (1) an informing demonstrator bird or (2) an uninforming demonstrator; or a predictable environment with either (3) an informing demonstrator or (4) an uninforming demonstrator. Environmental predictability was manipulated by altering the meaning of available color cues. Subjects in the unpredictable environment that had an informing demonstrator performed significantly better than subjects in an unpredictable environment with an uninforming demonstrator, although only on the second day of testing. Subjects in both the predictable conditions performed similarly to each other. The results suggest that social information is more valuable to individuals in an unpredictable environment than it is in a predictable environment; however, there appears to be a time lag in the ability of the birds to recognize the value of this information.

Olfactory enrichment, like odor cues, can positively affect behavior, reproductive success, and stress physiology in zoo-housed species. Our goal was to determine if odor cues were enriching to the African wild dog (AWD; Lycaon pictus), a species with a complex social structure and a highly developed sense of smell. Our objectives were to: (1) examine changes in activity levels and stress hormone physiology in response to fecal odor cues from natural competitor and natural/unnatural prey species; and (2) determine whether these odor cues could function as effective enrichment for zoo-housed AWDs. Over a 6-month period, fecal samples were collected from two males (AWD 1: dominant, AWD 2: subordinate), fecal glucocorticoid metabolites (FGMs) were validated using an ACTH-challenge, and hormones were analyzed for FGMs by enzyme immunoassay. Behavioral observations were conducted using scan-sampling, and contact and proximity were recorded. AWDs were presented with three fecal odor cues: LION (competitor), CATTLE (unnatural prey), and GAZELLE (natural prey). Only the GAZELLE cue elicited an increase in activity (10.6%) in both individuals and increased positive social behaviors with higher frequencies of affiliative, submissive, and dominant behavior. AWD 1 demonstrated lower (P < 0.05) FGMs than AWD 2 both before and after all odor cues, and FGMs decreased (P = 0.08) in AWD 2 after all cues. We conclude that exposure to natural prey odor cues may be used as effective enrichment for AWDs, and that changes in stress hormone physiology in response to odor cues may be dependent on social rank in this species.

Only one of the 15 species of monogamous hylobatids, the siamang (Symphalangus syndactylus), demonstrates direct paternal care in the form of infant-carrying, providing a unique model for examining hormonal correlates of paternal care differences between siamangs and gibbons. We used behavioral data and fecal hormone analysis to investigate (1) differences in monthly percent father-infant proximity in relation to monthly fecal androgen metabolite concentrations from infant birth to the late postpartum period between siamangs and gibbons, (2) the pattern of change in fecal androgen and fecal estrogen metabolite concentrations during the 8-week peripartum period between siamangs and gibbons, and (3) the change in mean fecal glucocorticoid metabolite concentrations at 1-month postpartum from individual baseline between siamangs and gibbons. Father-infant proximity increased as androgen concentrations decreased over the postpartum period in siamangs but not in gibbons. Androgen concentrations increased around birth in siamangs during the 8-week peripartum period, but exhibited a decreasing trend around birth in gibbons. Estrogen concentrations increased from pre- to postpartum in siamangs during the 8-week peripartum period, but exhibited a decreasing trend from pre- to postpartum in gibbons. The difference in mean glucocorticoid metabolite concentrations from baseline was greater in siamangs than gibbons. Our data suggest a relationship between specific steroid hormone patterns and differences in paternal care among the hylobatids, warranting further investigation of such proximate mechanisms.