Hawaiian Petrel Chicks Thrive Under A Caretaker's Watchful Eye
Seabird fans might well think Robby Kohley has the best job in the world. As an avian ecologist and aviculturist at Pacific Rim Conservation, Kohley oversees the care, feeding, and release of endangered Hawaiian Petrel chicks that were translocated earlier this month from their mountain burrows to a new home within a predator-proof enclosure at Kilauea Point National Wildlife Refuge. As of today, four of the 10 chicks had fledged.
Kohley is no stranger to rare Hawaiian birds. He has hand-raised Laysan Albatrosses and Hawaiian Crows for conservation, and was part of the team that in 2011 and 2012 successfully translocated the Nihoa Millerbird to Hawai'i's Laysan Island.
“Each species presents its own unique challenges that keep me humble in my attempt to replicate what nature does easily,” Kohley says. “I must admit that I think about the chicks constantly! I am very conscious that they are completely dependent on me until they fledge, and I have no desire to let them down.”
The stakes are high: The young Hawaiian Petrels in Kohley's care will be the founders of the only fully protected colony of federally listed seabirds anywhere in the Hawaiian Islands. Scientists hope the chicks imprint on their new, predator-free home and return there in a few years to raise their own young. Kohley took a few minutes away from the round-the-clock care of the petrel chicks to talk about his unique job.
Q: Tell us about these chicks. What are they like?
A: Each seabird species I have worked with seems to have a slightly different disposition. The Hawaiian Petrel chicks are adorable and very feisty for their size. They seem to be more high-strung than other seabird species I have worked with. And I can confirm that their bills are very sharp!
One of the unique challenges of caring for the petrels is that they are out of sight, hidden away in their burrows. Also, adult Hawaiian Petrels only visit land at night, so that's when the chicks are most active.Because they spend most of their time in their burrows, I am not able to observe their “normal behavior.” I have to rely on the short glimpses I get while feeding and handling them and what I can see from cameras that capture their movements at night.
Q: Can you describe the protected area within the refuge?
A: The area within the predator-proof fence encompasses seven acres on a section of the refuge not open to the public. The fence keeps out all predators, including cats, dogs, pigs, rats, and even mice. It has a beautiful view of the ocean, with a gradual slope toward the ocean cliffs below.The sloping terrain and its orientation to the trade winds gives the fledging petrels a straight shot to the ocean.
Q: What is a typical day for you?
A: Taking care of the Hawaiian Petrel chicks is an all-day job! Although I put a lot of emphasis on the actual feeding and handling of the birds, in reality those tasks are only a small part of the job. The majority of my time is spent on research, diet preparation, data, and cleaning. Everything has to be clean and sterile. I clean so much that I often joke about being a “bird janitor.”
Every day, I feed the chicks a slurry of fish and squid that, without proper care, could become a perfect medium for growing bacteria. We never want this to happen, because bacteria could make the chicks ill or cause a lethal infection. So, every day we clean all equipment that comes in contact with the chicks and their food. We make fresh food every day and pay careful attention to its quality and temperature. Any food that reaches room temperature for too long must be thrown out.
Q: Do you work alone to take care of the birds, or with others?
A: This project is the result of the hard work of so many people. But as it relates to the day-to-day care of the chicks, I prefer to work with just one assistant, Marilou Knight. This consistency allows us to work quickly and efficiently, keep the stress on the chicks to a minimum, and quickly notice if an individual chick's behavior has changed.
Behavior can be important in determining a bird's health and proximity to fledging. Each chick has a slightly different temperament: Chick No. 9, for instance, is extremely feisty and scorns all aspects of our presence. So if No. 9 was to one day be mellow, I would be very concerned.
Q: What do the young Hawaiian Petrels eat? How much, and how often?
A: At this stage in the birds' development, the parents would be covering huge distances at sea to find enough food to feed their chicks. As a result of these long forays for food, the chicks sometimes go many days between meals. However, to be sure the chicks are receiving quality meals that they will metabolize quickly, I feed them every day.
The amount of food is based on each bird's body weight and age. We blend a combination of fish, squid, Pedialyte, and vitamin supplements into a smooth slurry, and regularly adjust the proportion of protein to fluids and vitamins according to the chicks' needs.
Q: Caretakers for Whooping Crane chicks famously wear hooded costumes meant to mimic the appearance of adult birds to prevent the chicks from imprinting on humans. Do you have to worry about that? What precautions do you take?
A: The Hawaiian Petrel chicks are wild animals, and the feeding and handling can be a very stressful time for them. The biggest precaution we take is to do all that we can to minimize our contact with them and get them back in their burrows as quickly as possible.
Imprinting in captive propagation can be a concern for some species when you raise them from eggs with little or no parental care. Because even the youngest chicks in the translocation cohort were at least half-raised by their parents, imprinting is not a huge concern. In fact, the chicks are very aware that they are Hawaiian Petrels and we are not!
Q: What kind of data do you keep on the chicks, and what do you learn from it?
A: During the hand-rearing process, we collect very specific data every day, including weight, wing length, and how much the bird ate. The data tell us a lot, but most importantly they provide a glimpse into the health and growth of the chick. We depend on these data to calculate whether we are feeding each chick enough, whether it is developing normally, and how close it is to fledging.
Q: The chicks vary slightly in age. Does this change the way you take care of each individual bird?
A: The translocated Hawaiian Petrels do vary widely in age, from approximately 60 days to 100 days old at the time of the translocation. Fledging typically occurs around 120 days. So the different ages of the translocated chicks mean that each bird has slightly different needs.
Younger chicks, for example, need to be fed more than older chicks that are closer to fledging. As a chick approaches fledging, it can be a balancing act. We want them light and hungry enough to fly away, but with enough fat reserves to carry them over until they find that first meal.
Q: Do you have to worry about the chicks fledging too soon? Are there any signals when a bird is ready to fledge?
A: A chick fledging too soon is a concern. We resolve this by blocking the exit to each burrow until we know a chick's wing-length-to-body-weight ratio is such that it could safely fly away. When the chicks have reached that point, we open up the burrows to allow the chicks to come out at night and exercise their wings.
With their burrows open, the chicks will often come out many nights to exercise before fledging. We leave the burrows open until the chicks decide to fly away on their own. The closer the chicks get to fledging, the more restless they become, and often they will refuse food.
Q: What is the most rewarding part of the job?
A: When the chicks fledge! Although, after all the hard work, this part has turned out to be a bit anticlimactic. We show up one morning and they are just gone, having fledged under the cover of darkness. When I check the trail cameras the next morning and see pictures of a chick's first flight, I feel proud.
But for the chicks, their journey is just beginning. In the coming days and months, they must learn how to find food and navigate the perils of the open ocean on their own. They won't return to land to breed for five to six years!
The true reward will be when the birds return to breed inside the safety of the predator-proof fence. But for that, we have to wait.
Editor's note: The translocation effort was led on the ground by Pacific Rim Conservation; Kaua‘i Endangered Seabird Recovery Project, a Hawai‘i Department of Land and Natural Resources' Division of Forestry and Wildlife (DOFAW) project administered by Pacific Cooperative Studies Unit, University of Hawaii; the U.S. Fish and Wildlife Service, Kilauea Point National Wildlife Refuge; and ABC. Kaua‘i Island Utility Cooperative and DOFAW supported predator control within Hono O Na Pali Natural Area Reserve. The National Tropical Botanical Garden provided important assistance with vegetation restoration at the translocation site. The National Fish and Wildlife Foundation provided critical funding support.
Robby Kohley joined Pacific Rim Conservation in 2015. He has extensive experience in avian ecology and aviculture, having worked as the Research Coordinator and Facility Manager for the San Diego Zoo's Hawai'i Endangered Bird Conservation Program; the State of Hawaii on the Maui and Kauai Forest Bird Recovery Projects; the Institute for Wildlife Studies; and the Alaska Maritime National Wildlife Refuge.