Download CHANGES IN BEHAVIORAL PATTERNS TOWARDS HUMANS, OF

Changes in Behavioral Patterns Towards Humans of a Solitary,
Sociable Female Bottlenose Dolphin
Oz Goffman
Background
Dolphins are highly evolved marine mammals with a sophisticated social structure. The
interactions within a dolphin group are layered and nested. The hierarchal structure is
similar in its nature and complexity to those of chimpanzee and human societies. When
the dolphin group is permanent, with a consistent size and membership, the complexity
of its social structure may be studied and understood. It is known, however, for many
species of dolphins that the assemblage of the group is rather fluid, and may change by
splitting and merging, or when individuals move freely between groups.
One of the most significant examples of interspecies cooperation in nature is the joint
fishing by men and free-ranging common bottlenose dolphins Tursiops truncatus. This
phenomenon has been studied in modern times in Mauritania and Brazil. The
cooperative fishing which yields to both humans and dolphins a measure beyond what
could be acquired separately may be categorized as another predation method acquired
by this adaptable and versatile species. Although, in the above two locations, there is no
communication between specific members of the two species, the activity requires
timing and conscious collaboration that should not be underestimated.
In the last decades there has been an increase in the frequency of reports on solitary
dolphins that have established long-term daily social interactions with humans, as is the
focus of the current research. Previous research described these dolphins as living in
near-shore areas, and not necessarily as exceptional, old or handicapped animals.
While not a regular member of a dolphin group, a solitary dolphin may still maintain
interaction with conspecifics or with other species. There may be a variety of reasons
that cause an animal to become solitary, including dispersal/migration between
populations, predation pressure, prey scarcity and social constraints. Such dolphins are
usually not social at first, but later on they become increasingly accessible, and even
establish strong bonds with humans (Fig. 1). The accessibility develops gradually, as the
animal acclimates to human sociability and tolerates ever closer and lengthier
encounters that may culminate in physical contact, initiated either by swimmer or dolphin
(Fig. 2). Modern publicity, coupled with the fast and easy access to solitary social
dolphins by human tourists, even in remote locations, contribute to the widening
occurrence and growing scope of human-solitary dolphin interactions. Long-term
relations of free-ranging solitary social dolphins and humans are in most cases not
based on, or reinforced, by food reward.
Methods
The main subject of the current study was a female Indian Ocean bottlenose dolphin,
Tursiops aduncus, dubbed ‘Holly’. She arrived, of her own accord, at the age of 9, at the
beaches of Nuweiba in the Gulf of Aqaba, and began to swim and interact on a daily
basis with humans in the daytime. The dolphin occupied a very limited and highly
accessible home range, adjacent to the shore of the Bedouin village, Nuweiba M'zeina,
and had been documented over a period of 5.5 years, from 23rd June 1994 to 14th
November 1999. The database of the current investigation is made up of underwater
video recordings of Holly's interactions with human snorklers and divers, collected for 23 consecutive days each month and analyzed in the laboratory. For comparison and
generalization, underwater and surface video recordings of a mature solitary sociable
female common bottlenose dolphin (T. truncatus) were purchased and analyzed. This
social dolphin named ‘Pita’, spent 8 years in human company off the shore of Belize in
the 90s. Pita's data analyzed in the current study involved interactions from March to
July of 1994.
The analysis was performed using digital software, allowing precise documentation of
behavioral patterns and their duration. Since over time, the dolphin became a tourist
attraction and a financial resource managed by some of the villagers, there was no
possibility to experimentally control the numbers and the sex ratio of swimmers with the
dolphin. Published dolphin-dolphin and human-dolphin ethograms were used as a basis
for the ethogram developed in this investigation.
Aims
The main goal of the study was the analysis of long-term behavioral changes of a
female solitary social dolphin toward humans over a period of 5.5 years, which included
two gestation (Fig. 3) and calving cycles (both calves died at the age of 6 months). The
changes over time in the underwater behavioral patterns of Holly were examined in
relation to different human groups. The element of time was not analyzed in Pita’s data
because of the short documentation period. The current investigation also attempted to
reveal the effects and implications of long-term unsupervised swimming, based on interspecific interactions of a solitary dolphin with humans. Beside the basic scientific
interest, attention was paid to practical aspects that may contribute to the formulation of
’do‘ and ’don’t‘ rules, as part of an educational framework of regulations for potential
participants in encounters with free-ranging dolphins. The rules are devised such that a
full measure of the experience be enjoyed without posing a risk to either partner.
The main research questions were:
1. Are there specific behavioral patterns for dolphin-human interactions that are not part
of the documented dolphin-dolphin ethograms (behavioral vocabularies/lists) of groups
in the wild?
2. What was the long-term effect of the sociability period on the dolphin’s behavior?
For this aspect, temporal changes in different behavioral categories and behavioral
chains associated with human-dolphin interactions were investigated throughout the
study period. The changes were analyzed both as a function of time and of the stage in
the reproductive cycle: gestation, parental care and the recovery after calf death. The
behavioral categories (all referring to the dolphin) used in the investigation included:
Aggressive, Submissive, Abrupt (sudden activity), Sexual, Affiliative and Neutral
behaviors. The first five categories were adopted from Samuels and Spradlin's (Samuels
and Spradlin, 1995) study in the framework of the Swim with Dolphin (SWD) programs in
captivity conducted in four sites in the USA. The sixth category that describes spatial
proximity without a clear social context or directed behavior on the part of the human
that apparently did not affect the dolphin, was defined in the current research and
referred to as ’neutral‘ or ’indifferent‘. This category included behaviors that were
observed repeatedly in other dolphin-dolphin and dolphin-human studies, but had not
been previously addressed.
3. How do the following factors affect the frequency distribution of dolphin behavioral
categories?
A. Number of swimmers in the water.
B. Swimmers belonging to different groups, depending on gender and degree of
familiarity with the dolphin. The groups were divided to three levels of familiarity:
permanent ’school‘ or group members – adult male Bedouin termed ’trainers‘, in daily
contact with Holly, occasional but familiar ’school‘ members – other male Bedouin and
male and female Caucasians with repeated encounters over time, and male or female
tourist strangers with one-time or few encounters.
C. The presence in the water of the dolphin’s closest human companion, the trainer.
A special attribute considered in this context could qualitatively be described as
’jealousy‘, exhibited by Holly towards swimmers displaying familiarity with the trainers.
In this context, aspects studied in greater detail for A-C addressed the following
questions: Is there a qualitative and quantitative difference in the chance of eliciting
responses considered risky to the animal and/or swimmers, or in the nature of
behavioral chains leading to them? On the other hand, is there a qualitative and
quantitative difference in the chances for eliciting enjoyable, affiliative behaviors such as
rubbing, in the shared swimming?
4. Are there behavioral patterns reflecting the individual ’personalities‘ of Holly and Pita?
The basic assumption in this regard was that the majority of behaviors that the female
solitary social dolphin exhibits are universal, with some slight differences among
individuals.
Main findings and conclusions
1. It was found that the great majority of behavioral patterns exhibited by Holly were
identical to those previously described in dolphin-dolphin ethograms. In this respect it
would seem that solitary social dolphins on the whole exhibit their natural behavioral
repertoire while interacting with humans, and react with humans as if they were
members of a dolphin group. This is despite the great morphological and physiological
difference between the two species, a discrepancy that renders the dolphin physically
superior in the marine environment. A dolphin-human ethogram that includes a
collection of 16 cartoons portraying specific behavioral patterns selected out of a range
of dozens of inter-specific behaviors observed in the current study, was constructed.
The patterns fall into four behavioral aspects: soliciting contact, preventing swimmers
from cessation of contact and or leaving the scene (Fig. 4), aggressive behavior, and an
invitation to play.
2. A significant long-term change was detected in the nature of the dolphins’ behavior
that was expressed as a rise in the relative frequency of aggressive behavior and a
decline in submissive and abrupt behaviors. The reproductive stage also significantly
affected the frequency distribution of the behavioral categories. Holly exhibited extreme
aggressive and submissive behaviors in the gestation periods. She was less tolerant to
touch while gestating and even less so when accompanied by her calf. While parental
care was taking place, she exhibited more 'neutral' behavior. In view of the changes in
selected affiliative behaviors observed in the study, it is deemed inadvisable to initiate
physical contact with a gestating dolphin or a mother-calf pair during the calf’s first year
of life.
3a. Examination of the effect of the number of swimmers on the dolphin’s interactions
revealed that she showed a preference for a variety of affiliative behaviors, including
contact and play, when the swimmers' group was small (<5). A rise in aggression level
was detected in the presence of a larger number of swimmers (>5). Since unsolicited
touch or attempt to touch were the main reasons for aggression on part of the dolphin,
and since the average number of swimmers (and touch attempts) increased over time, it
was concluded that the latter fact was the main reason for Holly's increased aggression
over time.
3b. The dolphin showed an overall significant preference to interact with members of the
’trainers’ group, both regarding the number of events and the cumulative interaction
time. Gender also significantly affected her behavior (all gender-based analyses
excluded the trainers group, being all males). There was a significant difference in favor
of males, in the frequency of abrupt, affiliative and sexual behaviors. No difference was
detected between males or females in the mean duration of the behavioral event
directed at the swimmer. It is possible that the preference for the male gender stems
from a higher number of male swimmers with a high familiarity level (all-male trainers
and twice the number of male occasional pod members to females of this class).
3c. In marked difference to findings in SWD programs, the presence of the trainer
resulted in an increase in behaviors considered dangerous to swimmers – aggressive,
abrupt and sexual. ’Jealous‘ expressions by Holly were mostly expressed by
interposition between a trainer and a strange adjacent (often female) swimmer.
4. Some degree of similarity was found between the two animals studied, yet, at the
same time, each exhibited her own social preferences. Holly preferred to interact with
the ’trainers’ and then with female ’occasional group members‘, while ’Pita‘ preferred
prolonged swimming with strange females and males. This difference in preferences
could have stemmed from the fact that Pita was only accessible by boat and did not
have prolonged daily contact with a tight group. A common denominator was found in
the overall frequency of aggressive behavior that was similar and low (~3%). Most
aggressive acts of both animals (other than towards the trainers) involved strangers,
independently of their gender. It is possible that these one-time swimmers were not
informed about the appropriate behavior around the animals and/or did not recognize
pre-aggression warning signs shown by the animals.
In line with the substantial increase in the popularity of human interactions with freeranging dolphins/cetaceans over the last decades, so have the dangers associated with
such joint swims. By the end of the study period, Holly expressed a marked wariness of
human companionship. As time progressed, she rejected more and more attempts to
pet or chase her, and signaled that the interactions had come to be of a forced nature by
pre-aggression warnings to swimmers from all categories without preference.
From the birth of the 3rd female calf, until her premature death at the age of 18, Holly
altered her social patterns. She widened her home range and drastically reduced the
amount of time spent in human company and her tolerance of human touch. She also
initiated prolonged group interactions with her calf and 2-3 conspecific males. It is
possible that her withdrawal from human company was part of an attempt to improve her
maternal skills and success.
Following the findings of the study, instructions on the behavior of human swimmers
with solitary social dolphins are suggested, including those related to joint swimming
with mother-calf pairs. These instructions restrict the number of swimmers, clarify
situations that allow physical contact, indicate parts of the body that are permitted or
prohibited to touch, and refer to activities that solicit affiliative behavior versus those that
may result in aggressive behavior as well as warning signs of such situations.
Implementing these suggestions can increase the enjoyment and reduce the risks of
unsupervised swimming with solitary dolphins.
Supervisors: Prof. E. Spanier, Dr. D. Kerem and Prof. Y. Terkel
Reference: Samuels, A. and Spradlin, S. 1995. Quantitative behavioral study of
bottlenose dolphins in swim with dolphin programs in the United States. Marine Mammal
Science 114: 520-544.