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Mangrove Finch: Chick Transfers

Anita Carrion (Charles Darwin Foundation) and Paula Castaño (Island Conservation) load mangrove finches into transport crates for their voyage to Isla Isabela.

Anita Carrion (Charles Darwin Foundation) and Paula Castaño (Island Conservation) load mangrove finches into transport crates for their voyage to Isla Isabela.

Be sure to read the previous post, Mangrove Finches: Hand-rearing Chicks.

Nearly 40 days after the first mangrove finch eggs and chicks were harvested from their nests at Playa Tortuga Negra, it was time to send them home. Ever since they had arrived at the Charles Darwin Research Station in the Galápagos as young chicks or embryos yet to hatch, we had spent all of our time hovering over them and attending to their every need with one goal in mind: to send healthy mangrove finches back to Isabela Island for release. It was an exciting and hectic time as we prepared to transfer the oldest chicks while the younger chicks were still being fed every hour!

Pre-release aviaries had been constructed in the mangrove at Playa Tortuga Negra by local builders and awaited the arrival of the seven oldest chicks that would make up the first release cohort. After the remaining eight were grown and feeding themselves, they would join the first cohort in the aviaries.

Members of the first cohort were fitted with a unique combination of color bands on their right leg for identification from a distance as well as a silver, numbered band on their left leg. A drop of blood was drawn from under the wing of each bird (just like pricking a finger) for DNA sexing. Transport crates were inspected by the Galápagos Biosecurity Agency to ensure that quarantine conditions would be maintained during the chicks’ transfer. The gear the field team would take with them was sprayed with insecticide and put into quarantine before it was allowed to leave for Isabela.

Mangrove finches relax in their transport crates aboard the Galápagos National Park boat "Guadalupe River."

Mangrove finches relax in their transport crates aboard the Galápagos National Park boat “Guadalupe River.”

The evening of our departure, we transferred the chicks from their fledging cages to mosquito-proof travel crates that we then covered with black sheets. Keeping the birds in the dark while traveling helps keep them calm as it simulates nighttime, when they are typically inactive. A small crowd of staff members from the research station and their children gathered outside of the lab to catch a glimpse of the chicks as we carried them to the truck that would take us to the dock. This group had supported us throughout the project, but due to the quarantine conditions in the lab, this was their only opportunity to see the chicks. The public turnout for the chick transfer was a touching reminder of the support we had received from so many to make the project a success. We loaded the chicks in their crates into a truck for the short ride from the lab to the dock where we took a small boat, or panga, to the Galápagos National Park boat Guadalupe River. The finches got their own bunk on the boat, and we were underway for Isabela.

We sailed overnight and awoke in the morning in the shadow of Volcan Darwin off the west coast of Isabela. After a rushed breakfast, we loaded the finches back into the panga and headed for the beach. The mangrove forest here is protected by a wide, black sand beach, but the porous lava bedrock lets the forest flood at high tide. Navigating the thick tangle of roots and branches is downright treacherous when the forest is flooded, so we were fortunate to land at low tide when the walk from the beach to the pre-release aviaries was relatively easy.

A wild mangrove finch visits the chicks in the pre-release aviary in the mangrove forest at Playa Tortuga Negra, Isla Isabela.

A wild mangrove finch visits the chicks in the pre-release aviary in the mangrove forest at Playa Tortuga Negra, Isla Isabela.

The first step toward getting the chicks used to their new surroundings was transferring them from their travel boxes into fledging cages identical to those they had lived in at the lab. These cages were hung inside one of the three large aviary chambers and allowed the chicks to have a look at their new home while still keeping them confined to a smaller space in case the novelty was too scary or overwhelming. They settled in quickly, and we spent the afternoon watching them while finishing up the fine details of the aviaries and filling in gaps.

Both of the local snake species had been spotted at the aviary site, and we hadn’t gone to all of the work raising these finches for them to be snake food! Rather than snakes, though, the chicks attracted the attention of two wild mangrove finches that came down to the aviary to check out the new arrivals! The wild visitors were the cherry on top of an exciting day that had gone almost precisely as planned. We bid the babies goodnight and went to set up our camp. I was only going to be at the field site for about a week, but the rest of the team would be there for two months, and there was a lot of food, water, and gear to be hauled and organized.

Chick #1 forages in the pre-release aviary on Isla Isabela.

Chick #1 forages in the pre-release aviary on Isla Isabela.

The next morning we let the chicks out of the fledging cages to explore the full aviary. We had furnished their new home with rotten logs, strips of bark, and trays of leaf litter—all places that they would find food in the mangrove forest after their release. They set about busily exploring these new things. It was entertaining for the field crew to watch them interact and learn to navigate in the larger space and to see their foraging instincts kick in.

The next several days were mostly spent observing the chicks in the aviary, finishing the aviaries in preparation for the arrival of the second cohort of chicks, and watching wild mangrove finches at their nests. We even managed to trap and band one of the wild finches that kept coming around the aviaries to check out the chicks! The days were hot, and one afternoon as I was having a combination bath/swim in the ocean, a Park boat showed up out of the blue with instructions to take me to a cruise ship that would take me back to Puerto Ayora. I had to bid goodbye to the field crew, pack up my gear, and go with them right away because the ship was already underway, and we would have to catch it sailing down the coast of Isabela. It was an abrupt ending to a really special part of my Galápagos experience. I got to bring the first of our hand-raised mangrove finches back to their home forest and spend a week camping on a beautiful, remote beach flanked by volcanoes and surrounded by the spectacular wildlife of the Galápagos.

The first release cohort of hand-reared mangrove finch chicks gather together in the pre-release aviary.

The first release cohort of hand-reared mangrove finch chicks gather together in the pre-release aviary.

I arrived back in Puerto Ayora the following morning and was immediately back in preparation mode. It was nearly time for the second cohort of chicks to be transferred to the release site. We went through the entire process once more, and a week later, Michelle Smith with the Hawaii Endangered Bird Conservation Program and Anita Carrion of the Charles Darwin Foundation sailed for Playa Tortuga Negra with the second cohort of chicks.

With all of the chicks grown and moved back to Isabela, there was nothing left for me to do but clean and pack up the lab and wait to hear from the field team. I could do that from San Diego, so I headed home, excited by what we’d accomplished but still nervous about how the chicks would fare after their release.

Beau Parks is a senior keeper at the San Diego Zoo. Read his previous post, Mangrove Finch Eggs Hatch: A World First!


Harpy Eagle Chick: A Rough Patch

Harpy eagle chick at 65 days oldThe DNA sex results are in and the San Diego Zoo’s newest harpy eagle is a boy! (Read Beau’s previous blog, Harpy Eagle Chick Doubles Size.)

While male eagles are typically smaller than their female counterparts, as the holidays came and went this youngster was falling behind even the smallest healthy eaglets. The chick began to have trouble breathing, and a trip to the Zoo’s hospital was in order. With expert care from the veterinary staff, the eaglet was able to fight off a respiratory infection.

He wasn’t out of the woods yet, though, and shortly after returning from the hospital, he stopped eating entirely. For almost three weeks, committed care from vets and keepers kept the eagle afloat until he finally regained his appetite.

The chick is now back on track and, at over two months old, weighs in at nearly 6 pounds (2.7 kilograms), or almost 40 times his hatch weight! Each morning, after weighing, the eagle is carried outside in his nest tub and set in an outdoor pen. He is no longer being primarily hand fed but eats from a plate of chopped meat, which keepers set in his nest tub and replace throughout the day. The light gray feathers of his first-year plumage are opening up on his back and wings, and there’s sufficient strength in his legs now to stand for brief periods. Though he still won’t fledge for a few months, he’s beginning to flap his little wings, building up strength for when that day comes, and entertains himself by grabbing (or “footing”) the lining of his nest tub, practicing for even further down the road. Growing as fast as a baby eagle takes lots of energy though, and he still spends most of his day sleeping. At night, the tub with eaglet is brought inside where he is offered one last feeding before lights-out.

This past weekend, the chick hopped out of his nest tub for the first time. It’s just one small step toward fledging and an even smaller step toward independence. In the wild, young harpy eagles may stay around the nest for over a year! Even so, it’s an encouraging show of motivation from a chick that wouldn’t even feed itself three weeks ago.

Beau Parks is a keeper at the San Diego Zoo.

Read the Harpy Eagles blog.


Harpy Eagle Chick Doubles Size

Harpy eagle chick, day 8Since hatching three weeks ago, the Zoo’s harpy eagle chick has grown from a helpless little ball of fluff to, well, a significantly larger ball of fluff. (Read Beau’s previous blog, Harpy Eagle Chick.) The chick doubled in size in just about a week and now (at almost three weeks) weighs nearly a pound.

At day 15Its little legs, barely wider than a toothpick at hatching, have grown wider than a Bic pen. They’re not even strong enough yet to support the rapidly growing chick, but as the talons grow in and begin to curve downward, the feet are becoming weak, miniature versions of the adult harpy eagle’s lethal killing tools. The adult harpy eagle’s foot can have a span as large as a man’s hand and is capable of exerting over 500 pounds (225 kilograms) per square inch of pressure. That’s more pressure than a gray wolf’s bite and about five times the grip of an average man’s hand!

A puppet in the shape of an adult harpy eagle feeds the chick on day 17. As the baby eagle has grown, its appetite has kept pace! The Avian Propagation Center’s (APC) animal food preparers are now providing skinned mice and rats that are minced into bite-sized pieces before being fed to the hungry chick. Yum! We supplement the chick’s meals with vitamin B and calcium and set them outside each day (weather permitting) to soak up vitamin D from the sunlight. The temperature in the eagle’s brooder is reduced little by little as the chick is able to better regulate its own body temperature. Soon the medium-white fluff ball will be moved out of the brooder’s confines and into a larger nest tub. There, as it gains strength, the eaglet will be able to stand up, stretch its wings and eventually “branch.” (To branch means to leave the nest and begin to climb out onto the surrounding branches.)

The chick's shellNobody knows yet if the eaglet is a boy or a girl. Adult female harpy eagles are significantly larger than their male counterparts, but the only way to definitively sex a baby is with a DNA test. Fortunately, such a test can be performed without laying a finger on the eaglet. As the chick developed inside the egg, blood vessels also formed on the inner surface of the shell. That vascular tissue was left over after hatching and the broken eggshell has been sent off to a lab where technicians will be able to recover enough DNA from the tissue to determine the chick’s sex.

Beau Parks is a keeper at the San Diego Zoo.


Harpy Eagle Chick

On Monday, December 1, the San Diego Zoo welcomed its newest addition, a baby harpy eagle Harpia harpyja, the 14th hatched at the Zoo since 1994.

The Zoo’s pair of adult harpy eagles laid a single egg in their exhibit on October 10. Ten days later, the egg was pulled and set in an incubator, where its development could be carefully watched by the keepers at the Avian Propagation Center (APC). We weighed the egg daily to make sure that it was losing the right amount of water as the chick developed inside. We also monitored the progression of the embryo using a technique called “candling.”

When a bright light is shone through an egg, it allows the keepers to see what’s happening on the inside and keep an eye on the chick’s development throughout its incubation.

After 51 days in the egg, the chick began its escape the night of November 30, and after a long day of determined pecking, finally broke free at 7:15 the following evening. The new chick, wet and exhausted, weighed in at 2.58 ounces or 73.15 grams (or about half as much as a baseball). It was a humble beginning for one of the world’s largest eagle species. Female harpy eagles (the larger sex) can grow to be 20 pounds (9 kilograms); in the wild, they use their powerful feet and needle-sharp talons to snatch their prey from tree branches in the Central and South American rain forests. All of that seemed a little ambitious at that moment, though, as the freshly-hatched chick curled up to sleep off a long day’s work.

The following morning, we moved the chick into its new home in the APC’s “Brooder Room.” A brooder is a warm, humid box that mimics the environment under a parent bird. It is important that the chick never become imprinted on its human surrogates, so this particular brooder is covered with a towel, set behind a curtain, and continuously serenaded by a CD of soothing rain forest sounds to drown out the keepers’ voices. When it comes time to feed the baby, we put a sheet (or “ghost”) over our head and use a harpy eagle puppet to deliver the food.

The chick finally woke up and took its first small meal of diced pinkie mice at 4 p.m., 21 hours after hatching. It was the beginning of a gluttony that will turn this 73-ounce puffball into the most powerful avian predator on Earth!

Be sure to check back for regular updates.

Beau Parks is a keeper at the San Diego Zoo.

Read another blog about the San Diego Zoo’s harpy eagles