Video technology takes biologists deeper into the secret world of animals.
Michael A. Greenwood, News Editor
When the finishing touches were put on the first Crittercam 20 years ago, the device more or less resembled a camera. It did take pictures, and it was attached successfully to a loggerhead sea turtle.
But those early models — 2 ft long, weighing 8 lb and able to capture only 1 h of video — are dinosaurs (maybe even predinosaurs) when compared with the latest generation of animal-borne cameras, which are increasingly compact and now are capable of providing hours of footage and audio, along with a host of other scientific data.
“It has evolved tremendously. The change is dramatic,” said Greg Marshall, who conceived of and built the first Crittercam in 1986. Today he works for the National Geographic Society in Washington and is refining further the now-trademarked device for still better performance. Other researchers, meanwhile, are developing their own camera systems for species such as crows and other wild birds, opening up new possibilities for wildlife research.
Figure 1. Shown is the first lioness to wear a Crittercam, seen shortly after deployment. Scientists have used the system to gather unique data on land animals such as lions, bears and eagles. Courtesy of National Geographic.
The Crittercam continues to pioneer animal-borne imaging, having captured a wealth of footage over two decades that has advanced research and delighted audiences. Providing intimate glimpses of nature from the perspective of animals as varied as a lioness (Figure 1) in Africa and a leopard seal (Figure 2) in Antarctica, it has been used to study more than 60 species. The device is strapped, stuck, collared or clipped to the animal, which carries the camera system into its home environment and provides images that in many cases never have been seen before. It offers an animal’s view of the world and allows researchers to witness natural behavior vicariously.
Figure 2. Tracey Rogers of the Australian Marine Mammal Research Centre gets a feel for her research subject, a leopard seal. Courtesy of National Geographic.
“It’s been an incredibly exciting time with some of the most charismatic and engaging animals on the planet,” Marshall said.
As the technology improves, National Geographic is poised to begin mass production of the camera (in the hundreds) to make it more available to researchers worldwide.
The Crittercam comes in two basic models, marine and terrestrial, each customized to meet the needs of specific animals and environmental conditions.
The digital marine camera is cylindrical, for ease of movement through the water. The Gen. 5.7 model, due for release in early 2008, has an outer diameter of 2.25 in. and is 10 in. long. It weighs 1.54 lb (though it is weightless in water) and can withstand depths up to 3280 ft. It features a 16-bit onboard central processing unit and is able to record more than 8 h of video. The redesigned camera will have 44 percent less drag in the water than its predecessor.
The terrestrial Crittercam, designed for large animals such as lions and bears, comes in a rectangular aluminum box that usually is attached to the animal with a collar. The camera measures 2.63 × 5.85 × 4.56 in. and weighs 3.5 lb. It is powered by a 16-V lithium battery that supplies up to 30 h of operation. With the use of an infrared headlight, it beams a real-time signal up to three miles in color or black and white and has a 92° field of view. A smaller system for animals such as house cats and birds also exists.
Marshall, meanwhile, is thinking of ways to improve the next generation of Crittercams. He wants to install a global positioning system on future models and, for the marine camera, to develop a component that measures salinity — all of this to gather even better, more complete biological information.
Angry blue sharks
Gregory B. Skomal will tell you that attaching a camera to an irritated shark, freshly plucked from the murky depths, is tricky.
One giant thrashed around so aggressively that it knocked off the camera and had to be released for its own safety, not to mention the crew’s well-being.
A second shark was secured successfully by Skomal and his team in 2006. They managed to clip the tube-shaped Crittercam to the dorsal fin and to release the 11-ft carnivore into the deep waters 20 miles off Maine’s coast.
The device functioned perfectly, allowing Skomal, a senior fisheries biologist for Massachusetts Marine Fisheries on Martha’s Vineyard, to capture nearly two hours of uninterrupted footage in the life of a blue shark (Prionace glauca). Skomal admits that the video probably will not win any film awards. It is not, as some might imagine, like a scene from Finding Nemo. There are no playful encounters with other ocean dwellers, any feedings or even any scenic underwater vistas.
“You’re basically going to look at nothing but blue water,” he said. “It’s probably one of the more boring ways to spend your time.”
But to the biologist’s eye, the footage supplies information that is all but impossible to gather otherwise. Besides images, the latest-generation Crittercam provides a host of other valuable data, including depth, temperature, acceleration and magnetic direction. A software package reconstructs a three-dimensional map of the shark’s aquatic meanderings.
“It gives you an animal’s view of the world,” Skomal said. “It’s just an incredible interface.”
Figure 3. Gregory Skomal takes a blood sample from a gray reef shark about 800 miles south of the Hawaiian Islands to assess and quantify the level of stress experienced by the shark as a result of the capture method. Courtesy of Massachusetts Marine Fisheries.
He is using the Crittercam as part of a study on what happens to game fish after they experience the jolt of being caught and released. He wants to know whether these fish live or die and what humans can do to lessen the stress. He is working on a series of species-specific recommendations.
In the case of the blue shark, Skomal observed the test subject dive deep, move toward the surface, and then repeat the cycle again and again. In short, the animal did what blue sharks are known to do. The stress of the recent capture appeared to be minimal.
Separate research with gray reef sharks (Carcharhinus amblyrhynchos) was conducted in the Pacific Ocean in 2003 (Figures 3 and 4). One of the captured sharks received an eye injury as it was being reeled in. When the shark was released with a camera on its fin, Skomal witnessed the animal settle on the ocean’s bottom and then roll over. This was unnatural behavior, which Skomal attributed to the injury. The gray reef shark eventually rose from the ocean floor and appeared to swim away normally. A different type of hook might have prevented the injury, Skomal said.
Figure 4. A gray reef shark with a Crittercam attached to its dorsal fin shortly before being released. Courtesy of Massachusetts Marine Fisheries.
When it comes to retrieving the camera, perseverance and a bit of luck are involved. A hydrophone placed in the water helps the scientists in the boat above track the movements of the test subject below. A mechanism on the camera allows it to be released electronically at a preprogrammed time, usually when the camera’s memory is full. If everything goes right, the camera floats to the surface, and a radio signal leads researchers to it.
Exactly where do you fasten a video camera to a bird?
The head won’t work; neither will the wings or the feet.
Researchers led by Christian Rutz from the University of Oxford in the UK, attached a specially made camera to one of the few places remaining in avian anatomy: under the rear tail feathers. The setup allows the lens to protrude delicately between the feathers and provides a worm’s-eye view of the bird’s underbelly and, more importantly, its beak (Figure 5). This view allows Rutz and his team to see what his subjects — New Caledonian crows (Corvus moneduloides) — eat, how they forage for food and what tools they use. The crow species is one of the most prolific tool users in the avian world, but because of the birds’ shyness and their inaccessible habitat, this activity usually is difficult to record.
Figure 5. Schematic showing the position and viewing angle of a miniaturized video camera (red) on a crow. The main body of the unit (batteries, 2.4-GHz video transmitter, voltage regulator, timer chip and VHF radio tag) is taped to the upper side of two inner tail feathers. The camera lens, at the bent distal end, is protruding through the feathers, peeking forward through the subject’s legs. This design produces a “crow’s-eye view” of the environment, does not interfere with locomotion and ensures safe shedding of the tag with natural molt. Courtesy of Jolyon Troscianko.
Rutz is using the camera — which was developed separately from the Crittercam and is not affiliated with National Geographic — to study the crows on the small island of New Caledonia in the South Pacific, from which the birds’ name is taken.
Camera for the birds
The tail-mounted camera represents the first time, Rutz said, that wild, free-roaming flying birds have been outfitted with such a device.
“This new technology has the potential to revolutionize the way ornithologists study wild birds. Our cameras can record bird behavior in its full ecological, physiological and social context and in locations and circumstances where conventional observation techniques fail.”
Rutz’s camera is very small (4.5 × 2.0 × 1.3 cm) and light (~14.54 g) so that birds, even the medium-size crows, can move and fly unhindered (Figure 6). The camera is held in place with two thin pieces of adhesive tape attached to tail feathers to ensure that it will fall off by natural molt, by which time the filming is completed.
Figure 6. Shown is a video camera unit for mounting on a wild New Caledonian crow. The device contains two independent transmitters: (1) a conventional VHF radio tag (with a long, thin antenna) that transmits permanently for about three weeks, enabling positional tracking of the animal and possible recovery of a shed camera tag; and (2) a 2.4-GHz transmitter (with a short, thick antenna) that broadcasts a color video signal with sound for up to 70 min, once it has been activated by a timer chip that delays transmission for a specified habituation period. Courtesy of Lucas A. Bluff.
The device contains two independent transmitters. One is a VHF radio tag that transmits continuously for nearly three weeks and allows the bird to be tracked and the camera to be retrieved after it has been shed. The second is a 2.4-GHz transmitter that broadcasts a color video signal with sound for nearly 70 min. It is activated by a timer chip that delays transmission for up to 48 h to allow the subject to become comfortable with the apparatus. Live footage is captured on mini digital videotapes with Canon digital video camcorders that provide image resolution of 720 × 480 pixels at a rate of 29.97 fps. The signal is picked up with a custom-built receiver.
Rutz and his team were able to record 7.5 h of footage from 12 subjects. They observed crows handle or eat snails, lizards, small invertebrates, berries, pieces of fruit and three unidentified objects.
Perhaps of even greater interest, the tail camera captured the crows using a variety of tools to assist in their foraging. One crow used at least three tools as a probe during a 45-min hunt for food. The team observed the crow travel more than 100 m with a tool, put it aside to use its beak and then pick up the same tool for continued use. Based on these observations, Rutz believes that crows may keep a particularly effective tool for future use. The research was published in the Nov. 2 issue of Science.
The tail-mounted camera also recorded the crows using a foraging instrument that appeared to be a grasslike stem, an object that had not been documented before as being part of the bird’s tool repertoire. Rutz said that the footage already has changed the understanding of the bird’s foraging ecology. He and his team plan to deploy many more cameras in the future.
When Marshall traveled to Alaska several years ago, he wanted to try the Crittercam on a wild bear, but he needed someone familiar with the powerful, elusive mammals. He found that person in LaVern Beier.
Beier is a wildlife biologist for Alaska’s Department of Fish and Game and has studied the state’s wild coastal brown and black bears for more than three decades, foot-snaring, helicopter-capturing and radio-collaring hundreds during that time for research purposes. It turned out to be a fruitful collaboration.
Beier and Marshall eventually collared a female brown bear cub (Ursus arctos), a close cousin of the grizzly, with a specially designed Crittercam (Figure 7) and captured footage so compelling that National Geographic made it into a documentary film, Bear Island, which aired on PBS TV in June 2007. Although the Crittercam had been used on dozens of species of marine life, it still was relatively unproved with land animals as recently as several years ago.
Figure 7. Greg Marshall (left) and LaVern Beier (right) with a sedated bear cub that was captured and outfitted with a Crittercam on Alaska’s Chichagof Island before being released. Courtesy of LaVern Beier.
The trapped bear weighed about 175 lb, but the researchers had no idea whether it belonged to a family or was on its own. They went ahead and strapped the Crittercam around the animal’s neck and hoped for the best. When it was turned on an hour later, they were delighted with the real-time images being transmitted onto their small portable screen. The bear had rejoined its mother and two siblings, providing a portrait of an ursine reunion.
The researchers intermittently turned on the camera (to stretch out the batteries over several days) and watched the four bears ramble through the rugged wilderness of Chichagof Island, about 40 miles west of Juneau. They saw the cub nibble berries, eat what appeared to be a toad and fish for salmon in a stream. The camera captured the cub and its family bedding down in the forest and vocalizing sounds between them.
“The picture and sound quality ranged from very good to snow,” Beier said. At one point, the researchers thought that the camera had gone dead. All they could see was blackness, but they still could hear the rhythm of the cub’s breathing. They surmised that the lens had been wedged in the dirt as the bear rested on top of it.
The camera lens eventually did fog up, and the team decided to hit the button to release electronically the expensive device. It fell to the ground and emitted a VHF signal that allowed Beier to locate it quickly.
Beier hasn’t used the Crittercam since. One problem with studying bears is that it is difficult to draw conclusions about their behavior based on the actions of one, or even a few. “They are very much individuals, like people,” he said.
That is not to say that such cameras cannot provide useful information on bears. Beier thinks that they could be used in the future to study bears’ den site selection, den emergence, the decision making of nuisance bears and the use of travel corridors.
The camera also has value as an educational tool and as entertainment.
“It really draws in advocates for your animal species,” he said. “Everybody gets a kick out of seeing life from their point of view because it’s so different and unique.”