Sunday, June 13, 2010

Espanola trip synopsis

Just back now from the 10-day-long Espanola expedition, which was by all accounts a grueling experience but a great success. “We” were 24 Galapagos National Park Service park guards, that is, 7 groups of three plus a roving group of three more plus me. All groups worked independently out of 4 base camps. We were greatly aided by a fiberglass launch provided by the Park Service that was on call each day for to move groups to different entry points of the island as needed, secure extra provisions as needed, and provide a backup in case a safety issue arose. Groups were guided into the interior of the island by the hand-held GPS units, which had pre-determined locations of plots where vegetation was measured and counts were made of tortoises, albatross, and cactus. Movement of each group was recorded with the GPS units’ tracking function so we know where everyone actually went.

Suffice it to say that we now know a tremendous amount about the interior of the island and the south central coast where few if any have visited in recent decades. The park guard crews were amazing, covering some of the toughest terrain there is in Galapagos in terms of thorny, dense vegetation, under extreme conditions of heat most days (the garua season has not yet completely arrived). The crews that spent the entire time in the interior camp away from the coast deserve much credit – they completed the work without the opportunity to bathe and did so on limited food and water rations. Two porters were vital in supplying them with food and water on two trips per day. Here we all are at the interior campsite (parts of various groups converging for a shared lunch) under the venerable "caco" tree prior to heading to the southern coast:

I am now staring at a massive pile of datasheets the contents of which will take 2 weeks to enter into the computer and probably another 2 to make sense of but here are some highlights:

  • Our new method of estimating tortoise densities via counts of plots worked well in terms of logistics…we had some handy little gadgets known as Haglof DME’s that measure distance through dense vegetation with ultrasound and hence without the stress and difficulty of threading a meter tape back and forth to determine which individuals were in versus out. With these “DME’s” were able quickly complete counts on fixed radius plots. In terms of tortoises, we were impressed by the number of “natives” of many size, from palm-sized to very large. These animals are unmarked and have different shell growth patterns. There are the offspring of the repatriated animals, thus representing a “closing of the loop” via reproduction of the repatriates. They were a large number in our sample, which is a very good indication of a self-sustaining population. It was especially interesting to see the natives amongst the original repatriates…I came across an old friend – Number 12 – a massive tortoise that was likely among the initial small tortoises released back in the 1970’s. Once the data are entered we will be not only estimating current population size but also survival rates and past population sized to determine what has transpired with the tortoise population on Espanola in recent decades and what future options for its management might be.
  • Park guards recorded extensive data on the arboreal cactus through the island, including regeneration on plots and adults wherever they were found. The cacti are rare by any measure but perhaps not as rare as they have been characterized. We look forward to plotting their distribution, estimating their population size, as well as looking at levels of cactus regeneration in areas with and without tortoises.
  • We counted well over a thousand of albatross on plots and adjacent areas – there is a large population yet nesting in interior zones were they had thought to have been extinguished by incursion of woody vegetation following goat eradication. There is also a substantial population nesting on the margin of the central south coast in the area of Punta Albatros. It will take a month or more to estimate distribution and population size with any definitiveness but suffice it to say we were all impressed by the numbers of albatross yet nesting throughout the interior of Espanola. Clearly some albatross experience difficulties with the vegetation – we have photos of a dead albatross hanging and pinioned by branches and also freed a bird that had crashed into and become entrapped in dense woody vegetation for what must have been several weeks given the status of its plumage and the amount of guano. But whether the regrowth of woody vegetation limits population growth is a more complex question best approached through long-term monitoring. Through our studies we will at least be able to determine the relationship between distribution and abundance of albatross and amount of woody vegetation in an area.
  • We dug at great effort 2 pits and sampled material from different depths to look at carbon isotope ratios back in the lab. Woody plants and grasses have different carbon signatures which are integrated into the soil horizon. What was the vegetation originally on Espanola? Mostly open and grass dominated or mostly woody like the present? What is "natural" for the island? Measuring carbon ratios at different depths of soil should tell us much about history of occurrence of woody plants versus grass on the island. On the practical side, let’s just say that digging a 1.5 m pit on Espanola even in the softest of material is a sweaty day-long proposition! We did this with a shovel and cursed all day for lack of a sledge hammer and spike to help break up the compacted material. One pit we dug in a low area that collects much water during the wet season and el Nino years…this was a remarkable area insofar as it was still very green with luxuriant sedge growth despite the rest of the island already having shifted to the dry season. The bird populations were stunning in this area – seemingly every dove and finch in the island was in this area taking advantage of the last of the green vegetation, sedge seeds and invertebrates. It’s also been a good year for the massive centipedes that call Espanola Island home – they were in great abundance.

It will take some time to make sense of the information the Park Guards worked so hard to collect but suffice it to say there are many insights lurking within the data about tortoise-albatross-cactus-woody plant interactions that we will be ferreting out in the months to come. Internet bandwidth here on Santa Cruz is limited but in the next day or two we will post some images for you from this remarkable expedition. For the meantime below is a quick mosaic of the images from this trip (all taken by Isabela park guard extraordinaire Pedro Ramon, who is the one leaning against the cactus tree below).

On a personal level despite working in Galapagos for 29 years over 31 trips I was absolutely giddy about the possibility of seeing the unvisited-in-decades southern coastline of Espanola. The previous day we trekked up to the central camp at el Caco (so-named after the magnificent "caco" or Erythrina tree that towers over this tortoise release site) and set up my tent on the rocks. Despite the uneven ground it was a joy to lie on my back that night upon the backbone of Espanola Island under a waning moon and with the Southern Cross brilliant overhead with little audible except the occasional breeze flapping the tent fly, the "gwak" of a night heron stalking the massive centipedes that rove about at night, the occasional cry of an albatross pair adjusting themselves somewhere out in the darkness, and, far off, the muffled roar of the surging sea pounding the cliffs of the southern Espanola coast. The source of that roar would be our destination the next day. We got up at 4 AM and headed out in the darkness for the south coast, Park Guard Manuel Masaquiza leading the way. He had already secured an nice route over the top of the island which lead to some extensive areas of open lands populated by albatross that then lead us 3/4 of the way down the southern slope of the island. Pretty easy walking. But nearer to the coast the vegetation got extremely dense. We hacked a trail through the dense muyuyo (Cordia), more often stooping than standing, and at times went on all fours for a couple of hours. It got stuffy and exceedingly hot and humid in the lee side of the coast as we approached it. My pack was constantly hanging me up on newly cut branches that served as effective coat hooks, and tore a hole in the top of my hat that lead to a rather odd patch of sunburn on my thinning pate by the end of the day. We encountered hundreds of albatross even in the densest of vegetation, each one a gem to observe. The most remarkable experience was actually coming to the coast, pushing through the dense vegetation and thick hot air, to literally emerge over the course of a few meters at the top of a 90 m vertical cliff with a steady cold wind blowing off the expanse of rolling sea below with a multitude seabirds of veering past. The contrast was stunning. Here is a view of what we emerged onto -- the southern central coast of Espanola:

We rested a bit and then began our marine bird count, quickly arriving at Punta Albatros, which was fittingly covered in albatross, including this large group, some of which were nesting but others lingering prior to take-off, which involved dropping head first off the edge off the cliff followed by a spreading of wings:

After trekking along the coast for 3 km counting all seabirds, we hacked our way back up through the coastal thicket and eventually picked up an earlier trail made by the guards. You never really know when you are on a trail in Galapagos but you quickly know when you are off one! It was a long hard day but a rewarding one.

- James Gibbs, Santa Cruz Island

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