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Sound Stationing: Using auditory cues with a visually impaired bottlenose (Tursiops truncatus)

By Melissa E. Berdine, Rachel E. Aizcorbe, Michael Hunt, & Billy Hurley — Marineland Dolphin Adventure

Originally published in Soundings Volume 38, Number 1 — First Quarter 2013


Nellie is a 59-year-old female Atlantic bottlenose dolphin (Tursiops truncatus). She was born to Happy (sire) and Susie (dam) at Marine Studios (later named Marineland Dolphin Adventure) on 27 February 1953. Nellie has spent her entire 59 years at Marineland, and is currently the oldest known dolphin at any zoo or aquarium location in the world.

In 2003, Nellie was diagnosed with the beginning stages of cataracts in both eyes. Over the next several years, progressive lenticular opacities occurred with gradual loss of visual acuity, and the animal training staff noticed Nellie missing and having difficulty discriminating between Sds. By 2009, Nellie’s vision had deteriorated to the point where she rarely emitted any behaviors on visual stimuli. If she did respond, the behavior was often incorrect. As her condition progressed, Nellie began showing other tell-tale indicators of blindness; stationing when not under stimulus control, drifting off to either side of her trainer, and continuing to remain at station after a session was ended. A-to-B behaviors were also challenging. Nellie appeared to become desensitized to hand taps on the surface of the water, as well as any redirection taps.

Training techniques used with marine mammals are generally designed to modify the behavior of sighted animals. Even non-visual conditioned stimuli and reinforcements are generally established using visual prompts. “As a result, it can be disconcerting to work with an animal that has suddenly lost its sight” (Streeter, 2005). Working with these impaired animals can prove tricky at times; hand signals cannot always be relied on, and training methods often must be modified to accommodate them (Hepting, 2006). With this in mind, a proactive behavior management plan was implemented to assist in non-visual communication with Nellie as her eyesight deteriorated. “Efforts to implement non-visual training techniques helps the animals reestablish their social status, relearn old behaviors, learn new behaviors, and have an opportunity to participate in the same programs available to sighted animals” (Streeter, 2005).

Photo 1

photo credit: Marineland Dolphin Adventure

Photo 2

Trainer with Nellie in water, clicking above the water
photo credit: Marineland Dolphin Adventure

Photo 3

Underwater pic of Nellie coming to clicker (clicker shown under water too)
photo credit: Marineland Dolphin Adventure

Video 1

Video 2

Video 3

Video 4

Video 5

Video 6

The process began with the transfer of visual Sds to tactile stimuli or a cue involving a directional splash in the water – essentially presenting the novel Sd immediately before the existing one. “Adjusting Sds enables us to continue to communicate with the animals despite vision loss or physical changes” (Burtis, Garver, Hoffman & Roberts, 2008). This was similar to techniques described by Mango, Laule, and Vitug (2009) when visual signals were converted to auditory and tactile cues with a 13-yearold South American sea lion (Otaria byronia).

First, we transferred Sds for less complex behaviors. For example, for a pectoral wave, a visual Sd (a wave of the hand) was paired with a tactile stimulus (a touch on her shoulder). The process was comparable to techniques described in Sayre and Wright’s article, “Disabled but Not Discounted: A Case Study of Two Tursiops truncatus,” in which tactile stimulation was introduced to evoke a pectoral presentation. Another example, to solicit vocalizations, a visual Sd (a shake of the pointer finger) was paired with a tactile stimulus (touch on her melon). In our experience with Nellie, her melon was an ideal area to transfer Sds onto because the information transmitted was clear and the contact with her was maintained(Dolphin Discovery, 2009). For A-to-B behaviors and pool shifting, a visual directional point was paired with a directional splash in the water and the B-point trainer tapped the surface to indicate Nellie’s destination.

A target pole was also utilized to aid Nellie in following her trainer around the habitat. As the target was touched to her rostrum, she oriented to whichever direction it lead her. This became a very effective way to maneuver Nellie during sessions and to aid in basic behavioral conditioning (Carollo et al., 2012).

Overcoming Challenges with Communication

By 2010, the conversion away from visual stimuli was complete. Despite the success with tactile signals within sessions, Nellie’s pre and post session behavior seemed to indicate she was unsure about when formal sessions were beginning and ending. Nellie also began to have challenges accurately performing A-to-B behaviors and being redirected successfully. To troubleshoot these challenges, we experimented with a variety of audible stimuli: snapping fingers underwater, fist popping hands underwater, and gently tapping the pool wall. This is similar to techniques utilized by Dolphin Quest Bermuda when they established alternative forms of communicating expectations using sound, tactile, and underwater Sds (Rice, Trainor, Hayward, & Campbell, 2006). Despite these efforts, Nellie continued to appear disoriented when starting sessions or while being redirected.

It became clear that we needed to fine-tune the methods by which we communicated the initiation and termination of formal sessions, redirected Nellie in the event of uncertainty, and provided consequences for undesirable behavior. By creating scenarios in which animals can succeed, we found an increase in
motivation and a decrease in frustration (Dolphin Discovery, 2009).

Start-of-Session Stimulus

When starting to focus the scope of this project, we utilized an extended duration whistle to indicate the start and the end of training sessions with Nellie exclusively. However, the use of the long whistle was replaced with a clicker to prevent generalization issues with animals involved in other sessions occurring in adjacent pools.

We introduced the clicker sound by pairing it with an extended whistle when initiating and terminating sessions. Use of the whistle was quickly faded. We approximated the start of each session with three clicks below the surface of the water, leaving our hands in the water to provide a destination on which to echolocate. When correctly oriented towards the destination, a whistle bridge was utilized to reinforce Nellie’s response to the clicker cue. Nellie quickly responded to any click below the water, which effectively became a form of recall. A recall is a trained behavior. You give the signal (whatever you have chosen), the animal returns to station (is recalled), and the animal is then reinforced like any other behavior (Ramirez, 1990).

Use of Redirection Click

We found value in utilizing the clicker as an audible directional cue. If Nellie did not approach the correct station at the beginning of session, appeared disoriented, or was drifting from station the trainer could offer one additional underwater click as a prompt to provide clarity and direction. If Nellie reoriented toward the correct station, no further clicks are offered; instead, the whistle bridge is used to indicate a correct response.

This worked initially, but Nellie started deviating from the correct approach to her control trainer and would refuse the redirection click to station. To troubleshoot this and to prevent Nellie from becoming desensitized to numerous redirection clicks, a contingency was implemented which allowed for a maximum of two opportunities for a redirection click before terminating a session.

As Nellie’s reinforcement history grew with following basic audible prompts, we employed its use as a B-point location in other areas of the pool. Nellie learned that a directional underwater hand sweep from the A-point trainer was followed by an underwater click prompt from the B-point trainer. This process is utilized when shifting Nellie between pools; the B-point trainer simply clicks once in the destination habitat.

End-of-Session Stimulus

Marineland’s training program does not employ a formal end-ofsession stimulus. However, we decided to make an exception for Nellie in reaction to her continuing to station after a session ended. The end-ofsession stimulus is three clicks above the water. If a session is terminated because of refusal to respond to a start of session stimulus, redirection click, or if Nellie stations at an incorrect control point, the control trainer (without moving their position) offers three above-water clicks.


Many species of animals must deal with failing vision as they age. This is no reason to give up on the relationship already established with these animals. New relationships are formed and new training begins even when an animal is blind from the start. “Often it is an animal with a disability or medical concern that can benefit most from a good training program” (Ramirez, 1999).

Since the initiation of this proactive behavior management plan, Nellie’s behavior has proven to be consistent and reliable. Providing framework for sessions and clear redirection has allowed Nellie to safely continue to participate in guest interaction programs and make history each day she is with us. Working with animals like Nellie lends us the opportunity to learn about age-related issues as they get older. We are able to track their daily age-related changes through our husbandry interactions.

Older animals also afford the opportunity to conduct research about the species in its senescence. For example, Marineland funded and conducted a hearing threshold study exploring the Auditory Brainstem Response (ABR). This is a non-discriminatory method used to measure hearing abilities. It established hearing thresholds on the Marineland dolphins, ranging in age from 3.5 years to 52 years (Nellie’s age at time of study). This allowed for comparison to wild dolphins and select populations in human care. These studies are made possible through our preventative healthcare and animal training techniques combined with the incredible relationships we develop with each animal. It is important to remember that visually-impaired animals of all ages are still active learners. “While it may take a little more time and effort to engage these animals, the results are well worth it” (Hepting, 2006).


The authors wish to thank our fellow Marineland Dolphin Adventure animal trainers for coordinating as a team to implement Nellie’s clicker training plan. In addition, we wish to acknowledge Kevin Roberts, Curator of Animal Care, for offering perspective on Nellie’s medical and behavioral history.


Burtis, K., Garver, A., Hoffman, B., & Roberts, D. (2008). Modifying husbandry and behavioral approaches to benefit our geriatric marine mammals. Soundings, 33(4), 17.
Carollo, H., Rael, T., Paschke, J., Coan, M., Whelan, K., & Levine, R. (2012). Adventures in training a naïve, blind sea lion. Soundings, 37(2), 20-21.
Dolphin Discovery (2009). Trainers’ Forum. Soundings, 34(1), 27.
Hepting, D. (2006) The blind leading the blind: engaging visually impaired animals in Enrichment. Soundings. 31(3), 28-29.
Magno, C., Laule, G., & Vitug, J. (2009). I can’t see clearly now! Training show and husbandry behaviors with a visually imparied South American sea lion (Otaria byronia) [Abstract]. Proceedings of the 37th Annual Conference of the International Marine Animal Trainers’ Association, 37, 21.
Ramirez, K. (1990). Training a blind California sea lion basic behaviors. Soundings, 15(4), 21.
Ramirez, K. (1999). Animal training: successful animal management through positive reinforcement. Chicago: Shedd Aquarium.
Rice, K., Trainor, C., Hayward, R., & Campbell, M. (2006). Preventative measures for behavioral management and training of a visually impaired Atlantic bottlenose dolphin (Tursiops truncatus) in an interactive environment [Abstract]. Proceedings of the 34th Annual Conference of the International Marine Animal Trainers’ Association, 34, 24.
Sayre, S, & Wright, M. (2008) Disabled but not discounted: a case study of two Tursiops truncatus [Abstract]. Proceedings of the 36th Annual Conference of the International
Marine Animal Trainers’ Association, 36, 17.
Streeter, K. (2005). Now you see me, now you don’t [Abstract]. Proceedings of the 33rd Annual Conference of the International Marine Animal Trainers’ Association, 33, 31.