Friday 1 December 2023

A Tour Of The Western Galápagos Archipelago

The Galápagos archipelago is one of those must-visit destinations for anyone with an interest in ecology, evolution, or biogeography. The islands are located in the eastern Pacific where a “hotspot” deep within the earth has been spewing magma for millions of years. The oldest islands have been aged to around 5 million years, while the younger, westernmost islands may only be 100,000 years old. Because of the unique geographical position of the archipelago right on the equator, ocean currents from the northeast (Panamic Current), southeast (Humboldt Current) and west (Cromwell Current) all reach Galápagos. 

Santiago Lava Lizard (Microlophus jacobii)

American Flamingo (Phoenicopterus ruber)

This has allowed many species from different regions to colonize the newly formed islands over time. Some, such as lizards, snakes and rice rats, likely made it there on floating vegetation. Others, such as insects and birds either followed wind currents or were displaced during migration. 

male Brujo Flycatcher (Pyrocephalus nanus)

female Brujo Flycatcher (Pyrocephalus nanus)

And still others, such as the famous Giant Tortoises, floated with the assistance of the Humboldt Current. What all of these colonizers found were harsh living conditions, but also, untapped niches. While most of the colonizers were unable to establish a foothold, some were successful and over time ecosystems were established. 

Opuntia galapageia on the island of Rabida

Our tour commenced in the city of Quito on the Ecuadorian mainland. Some had spent the preceding days on a pre-tour extension to the Amazon lowlands or Andean cloud forests, while others had just arrived in Quito. We set out on a city tour with our local guide Gloria, where we visited some of the historic buildings, explored the birds and the orchids in the Botanical Gardens, and enjoyed some delicious meals at fine local restaurants. 

On October 25 we boarded our early morning flight from Quito to Baltra (the main hub for Galápagos), and within minutes of landing we were already observing our first Galápagos Land Iguanas, Small Ground-Finches and more. 

Galápagos Land Iguana (Conolophus subcristatus)

That first day was unforgettable. We drove into the highlands of Santa Cruz where we were captivated by wild Western Santa Cruz Giant Tortoises. Around fifteen forms of tortoise occur in the Galápagos, each confined to a particular island or volcano and with very different shell shapes (these are considered different species or subspecies, depending on your perspective). Some of these are extinct, while others would be without conservation actions. 

Western Santa Cruz Giant Tortoise (Chelonoidis niger porteri)

It was hard to focus on other species with the distraction of monstrous tortoises ambling around! The bird diversity was excellent here and we found several species of endemic finch, our first of many Galápagos Mockingbirds, Galapagos Flycatchers and a skulky Paint-billed Crake. Our excellent local guide, Juan, pointed out many of the interesting plant species found here as well. 

Medium Ground-Finch (Geospiza fortis)

Paint-billed Crake (Mustelirallus erythrops)

We visited the Charles Darwin Research Station later that day. While Juan described the tortoise breeding program, we also kept an eye out for some of the endemic birds and quickly found our first Lava Gull, the world’s rarest gull, as well as our first of many marine iguanas. That evening we embarked on the M/Y Beluga, a 34-meter chartered yacht that would be our home for the next seven nights. 

Marine Iguanas (Amblyrhynchus cristatus)

Most days would follow a similar pattern. Some of us were up on deck with a coffee for sunrise, eager to watch for wildlife around where the boat was anchored. We would eat a delicious breakfast at 7 AM and by 8 AM would climb into the two pangas (zodiacs) for our first landing of the day. After a roughly two-hour walk, we would return to the M/Y Beluga to change into our swimming gear and wetsuits. Our snorkeling session would last for around an hour, after which we would return to the boat for lunch. After lunch, the captain would move the boat to the location for our afternoon landing, giving us several hours of downtime or, in my case, time to scan for seabirds and whales from the deck.

Galápagos Petrel (Pterodroma phaeopygia)

Elliot's Storm-Petrel (Oceanites gracilis)

Magnificent Frigatebird (Fregata magnificens) following our boat

In the afternoon we would either have another 1.5-2 hour walk, or perhaps a second snorkeling session, or both. And finally, we would enjoy a delicious dinner followed by the daily tally of our species checklists. The days were full but with enough downtime to suit everyone’s needs, and with no shortage of exciting wildlife sightings. 

Sunset on Rabida Island

Our route focused on the western half of Galápagos. We circled the island of Isabela - the largest in the archipelago – and also visited Fernandina, Santiago, Santa Cruz and Rabida. The western side of Galápagos has the youngest islands, while it also has the most productive waters due to upwellings from the nutrient-rich Cromwell Current. This means that Galápagos Penguins and unique Flightless Cormorants do well in these areas. Spending quality time with penguins and cormorants – both above and below water – was a big highlight for most of us. 

Galápagos Penguin (Spheniscus mendiculus)

Flightless Cormorant (Nannopterum harrisi)

Galápagos Penguin (Spheniscus mendiculus)

Flightless Cormorant (Nannopterum harrisi)

Our snorkelling excursions were highly anticipated and for good reason. We had multiple chances to swim with Green Sea Turtles, playful Galápagos Sea Lions, and zippy Galápagos Penguins. Sharks were frequent sights, while we always kept an eye out for rays or eels, of which several species were found. The fish diversity was mind-boggling as we tallied over 60 species.

Galápagos Bullhead Shark (Heterodontus quoyi)

Panamic Cushion Star (Pentaceraster cumingi)

Spotted Boxfish (Ostracion meleagris)

Green Sea Turtle (Chelonia mydas)

Bluebarred Parrotfish (Scarus ghobban) and Razor Surgeonfish (Prionurus laticlavius)

Cortez Rainbow Wrasse (Thalassoma lucasanum)

Galápagos Gregory (Stegastes arcifrons)

One evolutionary concept that is readily apparent in the Galápagos archipelago is the process of adaptive radiation, and we were able to see many examples throughout our tour. With this process, one species diversifies rapidly into a multitude of new forms over time. An excellent example is the group referred to as “Darwin’s Finches”. 

Green Warbler-Finch (Certhidea olivacea)

At some point in time, a small number of one type of finch were able to colonize the Galápagos archipelago from mainland South America. Since few to no landbirds existed in Galápagos, this finch faced little competition and spread out across the islands. Over time, the growing population of finches specialized on different foods. Natural variation in beak size meant that finches with slightly larger bills fed on larger seeds, and finches with smaller bills chose smaller seeds. The large-billed birds tended to breed with each other since they shared habitat most of the time, as did the smaller-billed birds. Over time, the two forms become more distinct, not just physically but genetically as well. 

Large Ground-Finch (Geospiza magnirostris)

Small Ground Finch (Geospiza fuliginosa)

Now, there are over a dozen species of finches in Galápagos, all of which can be traced back to one common ancestor. We saw many of the forms – cactus finches, small, medium and large-billed ground finches, small and large tree finches, warbler finches and more. 

Small Tree-Finch (Camarhynchus parvulus)

The shorelines were always teaming with life - migrant and resident shorebirds feeding voraciously, piles and piles of Marine Iguanas basking after successful foraging excursions, Galápagos Sea Lions nursing young, hundreds of fish and crabs in the tide-pools, Lava Herons blending in with the volcanic rocks, and Galápagos Fur Seals resting on inaccessible crags along the shoreline.

American Oystercatcher (Haematopus palliatus)

Marine Iguanas (Amblyrhynchus cristatus)

Galápagos Sea Lions (Zalophus wollebaeki)

Sally Lightfoot Crab (Grapsus grapsus)

Lava Heron (Butorides striata sundevalli)

Galápagos Fur Seal (Arctocephalus galapagoensis)

During our final morning we visited the productive seabird colony on North Seymour Island. Magnificent and Great Frigatebirds nested side by side. Some of the male Magnificent Frigatebirds were expanding their red gular sacs in a bid to attract females. 

Adult male and juvenile Magnificent Frigatebirds (Fregata magnificens)

juvenile Great Frigatebird (Fregata minor)

Blue-footed Boobies were displaying here as well, providing quite a show!

Blue-footed Booby (Sula nebouxii) displaying

Blue-footed Booby (Sula nebouxii) displaying

We enjoyed the beautiful Swallow-tailed Gulls (the world's only nocturnal gull) and cartoonish Galapagos Doves, capping off an amazing eight days of exploration. 

Swallow-tailed Gulls (Creagrus furcatus)

Galápagos Dove (Zenaida galapagoensis)

Each day provided incredible vistas, unforgettable wildlife experiences and stimulating conversations about this unique corner of the globe. The captain and crew were extremely capable and professional and our local guide Juan was exceptional, meaning that we were in good hands. This was the trip of a lifetime for many, and it won’t be easily forgotten.

View from the island of Bartolomé

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