Nav: Home

Radio-tracking dolphins reveals intimate details about their behavior

February 21, 2019

Using telemetry units in hospitals to monitor patient health is standard practice. Now, a similar approach is proving to be invaluable for dolphins, too. Researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute, Hubbs-SeaWorld Research Institute and collaborators have conducted the most extensive radio-tracking effort of bottlenose dolphins in the Indian River Lagoon (IRL) using radio-telemetry.

Findings from their study reveal new and surprising information about how they use their habitats, how they spend their time, and how they interact with their own species.

A population of bottlenose dolphins (Tursiops truncatus) consider the IRL along the Atlantic Coast of Florida their "home sweet home." Yet, little is known about their short-term movements, association patterns, activities, and habitat use -- factors that are critical to understanding and managing animal populations. Moreover, these long-lived, top-level predators are impacted by ecological changes following large-scale environmental shifts including seagrass loss, fish kills and algal blooms.

Although IRL bottlenose dolphins have routinely been monitored via photo-identification surveys, this method only provides an intermittent evaluation. Radio-telemetry - on the other hand - enabled the researchers to consistently observe, track and monitor the dolphins in close proximity over time.

The study, recently published in the journal Aquatic Mammals, emphasizes the value of radio-telemetry as an important method to evaluate seasonal ranging patterns and provides essential baseline data on habitat preferences.

For the study, Greg O'Corry-Crowe, Ph.D., co-author and a research professor at FAU's Harbor Branch, Wendy Noke Durden, M.S., lead author and a research scientist at Hubbs-SeaWorld Research Institute, and collaborators, selected and fitted nine IRL bottlenose dolphins with radio tags in June 2007 and June 2010. Eight were male, one was female, and all of the animals were adult except for one juvenile.

They conducted radio-tracking by boat, with assistance from a Cessna 172 aircraft, and visually located and followed each animal several times per week. Over the course of 122 hours of observation, they compiled a total of 1,390 scan samples.

Results of the study show that these tagged dolphins spent most of their time traveling (53 percent), followed by milling together in groups (27 percent), foraging (17 percent), and socializing (2.3 percent). They also spent a surprising amount of their time on their own for such a famously social animal. The juvenile dolphin spent the most time alone, documented at 72 percent in 2007 and decreasing to 36 percent in 2010.

"The fact that these dolphins seem to have a lot of alone time adds a new dimension to our understanding of the sociality of the Indian River Lagoon dolphins," said O'Corry-Crowe. "It also was fascinating to find that many dolphins have brief encounters with many other dolphins. The tracking approach is really adding a whole new dimension to how we view and ultimately conserve this species."

The researchers found that some dolphins also formed longer associations. Adult males often pair up, but they also found one pair in the company of a female. According to the researchers, it appears that they primarily hang out to forage and eat rather than reproduce.

"Like other social mammal species, bottlenose dolphins exhibit a 'fission-fusion' social association where they hang out in a group or split up during the day. These associations can change frequently in composition and size or remain stable over the years. For example, male bottlenose dolphins have been known to form male-male alliances that last for years," said Noke Durden. "Our study reveals how dynamic the fission-fusion aspect of dolphin societies can be over short temporal periods, with tagged dolphins having brief associations with a large number of marked and many other unmarked individual dolphins."

Other findings show that only the social interactions and play activity varied by age class, with the juvenile animal spending more time socializing and playing with foreign objects like mangrove seeds and seagrass. The juvenile dolphin's activities changed over time, increasing in time spent traveling and decreasing in time spent milling with other dolphins as it approached reproductive maturity.

Habitat-use patterns varied among the individual dolphins, however, the tagged dolphins predominantly used shallow to mid-depth water. They also foraged and played more in shallow waters compared to other depths. The fewest observations occurred in deep water. Social behavior, however, did not occur significantly more at any of the four water depths categories in the study.

One concern of the researchers is the fact that bottlenose dolphins and other animals consider the lagoon their permanent home, given the recent environmental changes in the IRL.

"Our finding that shallow water habitats are used extensively by Indian River Lagoon bottlenose dolphins, particularly for foraging, indicates that these habitats are likely critical to their health and fitness. Ecosystem changes in the lagoon could significantly impact them," said O'Corry-Crowe.

Likewise, one animal only ranged approximately eight miles over 97 days, while on average dolphins ranged 17 miles during the course of the study.

"Given recent ecosystem changes in the IRL, fixed habitat utilization is concerning as animals inhabiting areas undergoing significant ecological pressures will need to adapt and or modify ranging patterns or inevitably suffer decreased fitness," said Noke Durden.
-end-
Collaborators of the study, "Small-Scale Movement Patterns, Activity Budgets, and Association Patterns of Radio-Tagged Indian River Lagoon Bottlenose Dolphins (Tursiops truncates)," are University of Central Florida; Seven Degrees of Mapping, LLC; Bayside Hospital for Animals; Georgia Aquarium; and Protect Wild Dolphins Alliance.

This research is supported by proceeds from the Protect Wild Dolphins and Discover Florida's Oceans specialty license plates; Hubbs-SeaWorld Research Institute; and by the SeaWorld and Busch Gardens Conservation Fund.

About Harbor Branch Oceanographic Institute:

Founded in 1971, Harbor Branch Oceanographic Institute at Florida Atlantic University is a research community of marine scientists, engineers, educators and other professionals focused on Ocean Science for a Better World. The institute drives innovation in ocean engineering, at-sea operations, drug discovery and biotechnology from the oceans, coastal ecology and conservation, marine mammal research and conservation, aquaculture, ocean observing systems and marine education. For more information, visit http://www.fau.edu/hboi.

About Florida Atlantic University:

Florida Atlantic University, established in 1961, officially opened its doors in 1964 as the fifth public university in Florida. Today, the University, with an annual economic impact of $6.3 billion, serves more than 30,000 undergraduate and graduate students at sites throughout its six-county service region in southeast Florida. FAU's world-class teaching and research faculty serves students through 10 colleges: the Dorothy F. Schmidt College of Arts and Letters, the College of Business, the College for Design and Social Inquiry, the College of Education, the College of Engineering and Computer Science, the Graduate College, the Harriet L. Wilkes Honors College, the Charles E. Schmidt College of Medicine, the Christine E. Lynn College of Nursing and the Charles E. Schmidt College of Science. FAU is ranked as a High Research Activity institution by the Carnegie Foundation for the Advancement of Teaching. The University is placing special focus on the rapid development of critical areas that form the basis of its strategic plan: Healthy aging, biotech, coastal and marine issues, neuroscience, regenerative medicine, informatics, lifespan and the environment. These areas provide opportunities for faculty and students to build upon FAU's existing strengths in research and scholarship. For more information, visit fau.edu.

About Hubbs-SeaWorld Research Institute:

Hubbs-SeaWorld Research Institute was founded in 1963 to conduct research in the tradition of world-renowned scientists Dr. Carl L. and Laura C. Hubbs. Since the beginning, the Institute's scientists have been dedicated to addressing the complex conservation challenges facing our oceans and coasts. Institute scientists seek effective solutions that protect and conserve marine animals and habitats while balancing the needs of humans and their reliance on marine resources. In 2013, HSWRI celebrated 50 years of its mission "to return to the sea some measure of the benefits derived from it." Additional information about the Institute can be found at http://www.hswri.org.

As an autonomous nonprofit organization, Hubbs-SeaWorld Research Institute is dependent upon the benevolence of individuals and businesses to grow and sustain our primary mission programs at the highest levels possible. Donation opportunities can be found at https://donate.hswri.org/annualcampaign.

Florida Atlantic University

Related Dolphins Articles:

Exeter researchers help protect Peru's river dolphins
River dolphins and Amazonian manatees in Peru will benefit from new protection thanks to a plan developed with help from the University of Exeter.
New study defines the environment as an influencer of immune system responses in dolphins
Two populations of wild dolphins living off the coast of Florida and South Carolina are experiencing more chronically activated immune systems than dolphins living in controlled environments, raising concerns of researchers about overall ocean health, and the long-term health of bottlenose dolphins.
Immature spinner dolphin calf SCUBA tanks spell disaster in tuna fisheries
Dolphins that live in the deep ocean have well developed oxygen storage, but now it turns out that spinner dolphin calves do not develop their SCUBA capacity any faster than coastal species, despite their deep diving lifestyle.
The latest HKU study clarifies how many dolphins there are in Hong Kong waters
The latest study by researchers at the University of Hong Kong (HKU) delivered the first-ever comprehensive population assessment of the Chinese white dolphins that inhabit Hong Kong waters, and what they found differs from the common public belief.
Crocodiles and dolphins evolved similar skulls to catch the same prey: Study finds
A new study involving biologists from Monash University Australia has found that despite their very different ancestors, dolphins and crocodiles evolved similarly shaped skulls to feed on similar prey.
Cutting-edge cameras reveal the secret life of dolphins
A world-first study testing new underwater cameras on wild dolphins has given researchers the best view yet into their hidden marine world.
Dolphins following shrimp trawlers cluster in social groups
Bottlenose dolphins near Savannah, Georgia are split into social groups according to whether or not they forage behind commercial shrimp trawlers, according to a study published Feb.
Scientists studying dolphins find Bay of Bengal a realm of evolutionary change
Marine scientists have discovered that two species of dolphin in the waters off Bangladesh are genetically distinct from those in other regions of the Indian and western Pacific Oceans, a finding that supports a growing body of evidence that the Bay of Bengal harbors conditions that drive the evolution of new life forms, according to a new study by the American Museum of Natural History(AMNH), WCS (Wildlife Conservation Society), and the cE3c -- Centre for Ecology, Evolution and Environmental Changes (Universidade de Lisboa).
Researchers probing the beneficial secrets in dolphins' proteins
Why reinvent the wheel when nature has the answer? That's what researcher Michael Janech, Ph.D. of the Medical University of South Carolina, has found to be true, drawing from the field of biomimicry where researchers look to nature for creative solutions to human problems.
Former pesticide ingredient found in dolphins, birds and fish
A family of common industrial compounds called perfluoroalkyl substances, which are best known for making carpets stain resistant and cookware non-stick, has been under scrutiny for potentially causing health problems.

Related Dolphins Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".