Mangrove Finch: Nest Rescues Begin with Flying Start

An evening cruise through the Galápagos Islands is always an exciting prospect, but this voyage was even more exciting than usual: we were about to embark on bold new steps to prevent the extinction of the mangrove finch (see post Giving the Mangrove Finch a Headstart to Recovery)! I contemplated what we would be attempting over the next few days and in the weeks to come.

Playa Tortuga Negra; with the mangrove forest adjoining the beach, camp in the foreground and the island of Fernandina in the distance. Photo credit: Swen Lorenz,  Charles Darwin Foundation

Playa Tortuga Negra; with the mangrove forest adjoining the beach, camp in the foreground and the island of Fernandina in the distance. Photo credit: Swen Lorenz, Charles Darwin Foundation

The next morning, I arrived at Playa Tortuga Negra, a beach far up on the west coast of Isabela. Neighboring the beach are two tiny patches of mangrove forest, the only remaining habitat for the mangrove finch Camarhynchus heliobates, which has the notable distinction of having the most limited distribution of any songbird on the planet. The plan was to collect eggs from the nests of wild mangrove finches and transport them to the project’s newly created bird-rearing facility at the Charles Darwin Research Station. Throughout the journey we would be keeping the developing embryos alive and healthy by transporting them in a portable incubator. Isabela is the large, seahorse-shaped island that effectively divides the archipelago in two, formed by the merger of six volcanoes, five of which are still active. The Research Station lies on the southern coast of the island of Santa Cruz, approximately 80 miles (130 kilometers) away.

The Charles Darwin Foundation’s Franny Cunninghame collects the eggs from the first nest.

The Charles Darwin Foundation’s Franny Cunninghame collects the eggs from the first nest.

For the previous 10 days, while Anita Carrion and I had been working on the bird-rearing facility, Franny Cunninghame, the Foundation’s mangrove finch project leader, and her team had been camped out on the beach. Every day, they surveyed the mangrove forest, keeping a keen eye out for nest-building behavior and evidence of mangrove finch females incubating their eggs. When they found a nest, they erected a complex rigging of ropes in the tree limbs, which would provide access to the nests on collection day. This was no mean task, thanks to the positioning of the nests, sometimes at the ends of precarious branches more than 40 feet above the ground.

I had hitched a boat ride to Playa Tortuga Negra with a BBC crew filming our work as part of a documentary on the changing face of Galápagos. Once we had unloaded gear, Franny briefed the camera crew on the best possible locations to take footage of the finch nests, and off they went to hoist ropes into the canopy. Together with the rest of the team, we then walked and talked through the whole process of nest collection, from removal of the nests from the trees to having the eggs safely in the portable incubator. Even then, the lives of the embryos would be dependent upon the car batteries that powered the incubator throughout their journey. It was then that I was also reminded of the demanding field conditions. We were up to our waists in the muddy, tidal waters, scaling mangrove roots, only to emerge into the brutal sun that caused the sand to scorch the soles of feet in seconds. No wonder the Galápagos had presented humans such a challenge to colonize.

The first mangrove finch nest is lowered safely out of the tree.

The first mangrove finch nest is lowered safely out of the tree.

February 2, 2014, was the day of the first nest collections. The field team had located 6 nests worthy of collection, but, sadly, 2 had failed in the previous 48 hours, apparently due to predation. However, four nests still looked promising. Communication with the outside world was limited, and although we had received confirmation via the crackly satellite phone that the helicopter would be arriving to transport the eggs, we were all anxious about whether it would arrive on time, if at all. We then tested and gathered our equipment and set off into the mangrove.

The first nest collection didn’t exactly go according to plan. Based on the behavior of the female finch coming and going from the nest, Franny suspected that the eggs may have already hatched. Collecting chicks was not part of our original plan, but we were faced with the alternative of leaving the chicks in the nest, almost certainly to die at the hands of the parasitic Philornis fly larvae that are known to have a devastating impact on mangrove finch chick survival. Fortunately, we were prepared for this eventuality; I had brought hand-rearing equipment, and we had set the moth trap overnight, providing us with a good supply of moth guts for chick food.

The contents of the first three nests are in the portable incubator and almost ready for the helicopter flight: 2 chicks and 7 eggs.

The contents of the first three nests are in the portable incubator and almost ready for the helicopter flight: 2 chicks and 7 eggs.

Displaying a great deal of arboreal talent, Franny climbed the tree, carefully removed the nest from the branches, and lowered it out of the tree in a container on a rope. As we opened up the dome-shaped nest at the base of the tree, sure enough, we found two tiny, newly hatched chicks. I transferred these into a cotton wool-lined nest cup within a thermos, and we carefully navigated the lattice of mangrove roots, passing the chicks hand-to-hand over the particularly tricky obstacles and then along the beach to our base camp. At the base camp, the chicks were transferred to the portable incubator, which was set at the appropriate temperature.

From that point on, I manned the camp, waiting for the remaining nest collections to arrive while carefully monitoring the temperature of the incubator. Every hour or so, I fed the chicks with moth guts. At this point, I noticed that there appeared to be gray spots in the tiny chicks’ nostrils and ears. Could this be evidence that the chicks were already infested with Philornis larvae? The larger of these two chicks, estimated to be only one or two days old, was weak, and the inside of its mouth appeared a pale orange color instead of a healthy, rich pink. Had the Philornis larvae already started sucking blood from the chick, causing it to be anemic?

The eggs are now safely in the incubator at the Charles Darwin Research Station.

The eggs are now safely in the incubator at the Charles Darwin Research Station.

Meanwhile, the field team tackled the other three nests. Nest #2 contained 4 eggs, each one particularly small. Nest #3 contained 3 eggs; by candling them using a flashlight in the shade, it appeared that they were approximately halfway through development. Nest #4 held 1 chick, which we judged to be 2 days old, plus 1 unhatched egg whose contents appeared to be decomposing. All in all, it was as good a harvest as we could have hoped for.

Mid-morning, the Galápagos National Park helicopter arrived right on time, bringing the director of the park, Arturo Izurieta, and a small team to give their support to the nest-collection effort. Once the team had emerged from the forest, we took time for a quick debrief and a final check on the contents of the incubator. We loaded the incubator and its battery into the helicopter’s front seat. Throughout the journey, I held the incubator aloft in my arms to provide some shock absorbance to the shakes and motion of the helicopter.

As we approached the port of Villamil, we landed on the deck of the National Park’s boat to refuel, a maneuver that added extra excitement to an already nerve-wracking journey. Having taken off again, we crossed the straits toward Santa Cruz.

Our teammate, Beau Parks, had been waiting patiently at the Research Station. As soon as the eggs arrived in the propagation room, they were placed in the incubators. With the concern that the gray spots in the nostrils and ears of all three chicks could be Philornis, Beau applied Vaseline to the openings with a Q-tip. Sure enough, as the Vaseline began to interfere with their ability to absorb oxygen, tiny Philornis larvae began to emerge from the nostrils and ears, and Beau extracted them with a pair of forceps. The weakest chick, the older one from the first nest, had nine larvae removed. The Foundation’s resident Philornis expert, Charlotte Causton, witnessed this and stated how valuable these observations had been in our understanding of parasitism by Philornis. From that point on, we started the hourly feedings for the chicks, aiming to restore their hydration and energy; these feeds lasted until midnight.

Sadly, some eggs didn’t survive the threats until their scheduled collection date. Franny Cunninghame holds some broken eggshell found on the ground during the third nest collection trip.

Sadly, some eggs didn’t survive the threats until their scheduled collection date. Franny Cunninghame holds some broken eggshell found on the ground during the third nest collection trip.

Unfortunately, the weakest chick died early the next morning. Despite our best efforts, it appeared to be too weakened by the Philornis larvae infestation. But the good news was that the two remaining chicks had quickly perked up and were rapidly settling into their new hand-rearing regimen. Just as exciting, we had seven eggs in the incubator (as suspected, the eight egg was not viable), and we anxiously waited to see if they would continue to develop and hatch.

Over the next three weeks, we carried out two further nest collections, which resulted in six eggs on February 11 and seven eggs on February 20. Beau transported the eggs for the second nest collection. The logistics of working in such remote locations can be challenging, so Beau’s trip to Playa Tortuga Negra was a little out of the ordinary: he hitched a ride on a tourist cruise boat that was scheduled to be passing the beach. As before, the eggs were flown back by helicopter.

On the third nest collection, I sailed up to Playa Tortuga Negra on the National Park’s boat. Having disbanded camp, the field team joined me on the return voyage the following afternoon, arriving at the Research Station in the early hours of the morning. The eggs arrived, none the worse for wear after their nine-hour voyage, although initially loading them into the Zodiac, which was to take us out to the boat moored offshore, among the breaking surf on the beach certainly created a bit of excitement!

In total, we had collected 21 eggs and 3 neonate chicks. For this first pilot year, it was as good a result as we could have hoped for.

Richard Switzer is an associate director of applied animal ecology at the San Diego Zoo Institute for Conservation Research.

One Response to Mangrove Finch: Nest Rescues Begin with Flying Start

  1. We are Francesca Cunninghame’s parents and would like to print this article and the other mangrove-finch article, but there seems to be a block which prevents this. If it is not possible to do this from our computer, would you forward hard copies to us for the family records.

    Monitor’s note: We have not applied any blocks to our blog posts, but the original text has been forwarded.