Wendi Fellner - Synchrony poster at SMM '99

Synchrony between a Mother-Calf Pair of Bottlenose Dolphins (Tursiops truncatus)

Wendi Fellner and Gordon B. Bauer

New College of the University of South Florida

Poster session presented at the 13th Biennial Conference of the Biology of Marine Mammals, Wailea, HI. December, 1999.

Abstract --- Introduction --- Methods --- Results --- Discussion --- References

Abstract

Synchronous behavior is a commonly observed characteristic of adult dolphin groups, but the development of synchronous processes in dolphins has not been described previously. Behavioral synchrony occurs within a broad range of species under a variety of contexts. Some proposed functions of synchrony include energy conservation, predator avoidance, social learning, and the facilitation of the exchange of social signals. In humans, synchronous behavior correlates with efficient communication and also having developed a sense of self. Through microanalysis of videotapes, this study systematically examined specific synchronized body positions of a bottlenose dolphin and her calf over the first 4 weeks of the calf's life. It was found that the mother-calf pair spent 98% of their time swimming in synchrony, were in direct contact with each other 82% of the time, and were most commonly observed in echelon position (90% of the time). When compared to earlier recordings of the mother and her two, adult, female tankmates before the calf’s birth, preliminary analysis indicated that the calf swam synchronously 3 times as often and was in direct contact 13 times as often as when the adults swam with the mother. Swimming in echelon position occurred equally often in both groups. The commencement of nursing was associated with several changes in the mother-calf swimming style, which may indicate that the calf had rapidly learned to maintain synchrony, a behavior that was reinforced with milk. This would be an indication that the calf is developing the skills necessary to maintain synchronous behavior in adult groups.

Introduction

Synchronous behavior has been mentioned frequently in the literature (e.g., Johnson & Norris, 1994; McBride & Hebb, 1948), but no quantitative studies have been reported.
Fish and birds may school and flock for energy conservation and predator avoidance (Cutts & Speakman, 1994; Pitcher & Parrish, 1993)
In humans, synchrony facilitates communication (Bernieri, Reznick & Rosenthal, 1988) and in parent-infant pairs is correlated with a secure attachment style (Crandell, Fitzgerald, & Whipple, 1997)
Dolphin synchrony appears ubiquitous – traveling, feeding, socializing, playing, herding

Methods

Subjects included 4 bottlenose dolphins (Tursiops truncatus): a newborn calf, her primiparous mother, and two other adult females
950 minutes of videotape were microanalyzed in which the calf aged from birth to 4 weeks
Characteristics studied were overall proportion of time spent synchronously, duration of bouts, which dolphin initiated and terminated each bout, position (infant, echelon, and follow-the-leader), proximity (touching, near, intermediate, and far), and suckling behavior
In addition, 130 minutes of preliminary data were analyzed on the synchronous relationships between the 3 adult females 1 month prior to the calf's birth

Results

Synchrony occurred immediately at a high rate between the mother and calf, subsuming 98% of the calf's time
Durations of synchronous bouts increased from 1:40 min to 2:57 min, and the number of breaks in synchrony decreased from 2.0 to 0.7 per five-minute sample

The calf spent nearly all of her time swimming synchronously with her mother.

All synchronous interactions with other dolphins included the mother.

Calf-initiated bouts of synchrony increased from 0% to 50%. Mother-initiated bouts decreased from 80% to 0%. Bouts where both came together increased from 20% to 50%.
Calf-terminated bouts of synchrony increased from 50% to 100%. Mother-terminated bouts decreased from 50% to 0%.

The calf began sharing responsibility for maintaining synchrony during the 3rd week.

Initially, the mother initiated most bouts of synchrony and the calf initiated none. In 20% of the bouts, both dolphins changed their behavior to come together. Terminations were evenly split between mother and calf. Most instances of termination by the mother represented situations in which she broke off in order to intervene between the calf and an obstacle. By the 2nd week, intervention was no longer necessary. During the 3rd week, the calf began reinitiating bouts of synchrony after a break 50% of the time. By the 4th week, all bouts were either initiated by the calf alone or by both the mother and calf simultaneously.

The echelon position was the most frequent among every pair
The calf was often in direct contact with her mother (82.3%), but was mostly commonly in near proximity to the other two females. No dolphin was observed swimming synchronously at far proximity

The calf swam primarily in echelon position and in direct contact with her mother.

Swimming in echelon position was the predominant position for every pair studied, including between Mother and Other #1 (89.4%) and between Mother and Other #2 (90.3%) before the calf's birth. A dramatic difference was seen between pairs, however, in the amount of time spent in contact with each other. The mother-calf pair were touching 82.3% of the time while synchronous as opposed to 0.9% and 0.2% with Other #1 and Other #2. While synchronous, the non-parental pairs were most frequently found near the calf, but only slightly less often at an intermediate distance. The five most frequent body part combinations in contact calf-to-mother were: trunk-to-trunk (80.8%), pec fin-to-trunk (8.9%), rostrum-to-trunk (7.7% -- generally indicated suckling), trunk-to-pec fin (1.6%), and trunk-to-rostrum (1.0%).

Interactions became calmer and the calf was allowed to swim on either side of the mother once suckling became a routine behavior
The calf's pattern of synchrony with Others reflected the mother's pre-birth pattern with them. Preliminary data indicated that before the birth of the calf, the mother swam most frequently with Other #1 and rarely with Other #2. This relationship was not disturbed by the arrival of the calf.

Milk as a possible reinforcer for synchronous swimming.

During the first 15 hours, the calf was not observed suckling. This period was characterized by a high degree of stereotypic synchronous swimming regulated primarily by the mother. Each time the calf broke synchrony, the mother responded rapidly and quickly regained control (M = 5 sec). The calf was not allowed to swim on the outside of the mother's circular path (presumably in order to protect it from colliding with a wall), and travel was almost exclusively in the mother's preferred counterclockwise direction. Once nursing was established, a brief period of increased chaotic behavior ensued. Asynchrony increased from 3% to 11%, and clockwise swimming increased from <1% to 2%. At this point, the mother suddenly allowed the calf to swim on the outside of her path. Instead of continually bursting ahead in a random direction whenever possible as before, the calf generally followed the mother. Once suckling behavior became more routine, the calf rarely attempted to break synchrony.

Discussion

The mother and calf swam together synchronously from the first hour of the calf's life. Initially, the calf appeared to take a passive role in synchronous swimming as the mother continually herded the calf to the inside of her circular path. Constant circular swimming was generally effective at restraining the calf. Each time the calf was able to stray, the mother immediately regained control of the calf's movements by bursting ahead and turning into her path so she was "scooped" back into position. Drastic changes were observed after the calf began nursing, including the calf taking a more active role in maintaining synchrony. The abrupt changes in asynchrony and swimming path that centered around the onset of nursing are intriguing. Future studies could document whether these changes typically occur at the onset of suckling behavior or whether this is a time-dependent phenomenon. If nursing is responsible for the changes, it is likely that milk acts as a reinforcer for maintaining synchrony.

Although synchrony was apparent immediately, differences in the amount of synchrony and bodily contact were seen between the synchronous behavior of the calf and that of adults. Solo swimming by the calf was generally wobbly in appearance throughout the first 3 weeks. Continuous contact by the mother may have aided the calf in learning how to better control her swimming movements.

Finally, synchrony may have an important link with the dolphin's imitation abilities. Bottlenose dolphins sometimes overlap behaviors temporally while imitating rather than performing them sequentially (Tayler & Saayman, 1973). A tendency to move in synchrony could be an effective foundation for the development of imitation.

References

Bernieri, F.J., Reznick, S., & Rosenthal, R. (1988). Synchrony, pseudosynchrony, and dissynchrony: Measuring the entrainment process in mother-infant interactions. Journal of Personality and Social Psychology, 54, 243-253.

Crandell, L.E., Fitzgerald, H.E., & Whipple, E.E. (1997). Dyadic synchrony in parent-child interactions: A link with maternal representations of attachment relationships. Infant Mental Health Journal, 18, 247-264.

Cutts, C.J. & Speakman, J.R. (1994). Energy savings in formation flight of pink-footed geese. Journal of Experimental Biology, 189, 251-261.

Johnson, C.M., & Norris, K.S. (1994). Social Behavior, In K.S. Norris, B. Würsig, R.S. Wells, & M. Würsig (Eds.), The Hawaiian Spinner Dolphin Berkeley (pp. 243-286). CA: University of California Press.

McBride, A.F., & Hebb, D.O. (1948). Behavior of the captive bottle-nose dolphin, Tursiops truncatus. Journal of Comparative and Physiological Psychology, 41, 111-123.

Pitcher, T.J. & Parrish, J.K. (1993). Functions of shoaling behaviour in teleosts. In T.J. Pitcher (Ed.), Behaviour of teleost fishes (pp. 363-439). New York: Chapman and Hall.

Tayler, C.K., & Saayman, G.S. (1973). Imitative behavior by Indian Ocean bottlenose dolphins (Tursiops aduncus) in captivity. Behaviour, 44 (3-4), 277-298.

Acknowledgments

We would like to gratefully acknowledge the support of the staff, management, and interns of Disney's EPCOT: The Living Seas, and the invaluable assistance of Cristal Ange, Debi Colbert, Pete Fellner, and Heidi Harley. This research was generously supported by grants from the New College Alumnae/i Association, the New College Foundation, and the Walt Disney Company.