Ensenada Grande, Isla Partida/Los Islotes
A visit to Baja California and the Sea of Cortez provides a chance to see endemic species: unique plants and animals that cannot be seen anywhere else in the world. Biogeography refers to the distribution of species; island biogeography is especially fascinating. Isolation on islands allows organisms to evolve from the parent species as they adapt to different environments. If Charles Darwin had come here instead of the Galápagos Islands, he may still have come to the same conclusions, but he would have had a species of lizard named after him instead of a finch. Known as Mexico’s Galápagos, there are species or subspecies found only on one or a few islands within the Sea of Cortez.
Isla Partida Sur is a great place to search for endemic animals. Ecologically and spatially close to Isla Espiritu Santo, the two islands are often considered as a complex and share many species in common. Ashore in the west-side bay called Ensenada Grande, we were delighted by the antics of the antelope ground squirrel (Ammospermophilus insularis) as it bounced over rocks with its tail curled over its back. This animal is able to be active during the day while most desert animals are sleeping. The female pictured is foraging on flowers and pods in a shrub. When she reached up, we could see that she was eating for her nursing babies as well as herself. Another mammal endemic to the complex is the black jackrabbit (Lepus insularis). We observed a lot of evidence of the existence of this lagomorph but only a quick glimpse on a high cliff revealed its telltale long ears and dark back.
Islas Partida and Espiritu Santo have many interesting reptile species, and we saw two that are only found here – a whiptail lizard (Cnemidophorus espiritensis), its bright blue tail clear in the photo, and an Espiritu Santo Island striped whipsnake (Masticophis barbouri). Several of us also had good views of the Baja California banded rock lizard (Petrosaurus thalassinus) and a Baja California spiny lizard (Sceloporus zosteromus).
Everything is thriving here due to precipitation in recent months. Water has brought life to the desert. Vines and annual plants have formed mats that cover the desert floor and climb up on cacti and shrubs. There are many blooms and fruits. We enjoyed numerous butterflies such as the queen (Danaus gilippus) pictured here. Although not endemic, it is common in Baja California. As a relative of the famed monarch, it lays its eggs on bitter-tasting milkweed plants on which the larvae feed, retaining the chemicals for protection as they metamorphose into adults. Even dragonflies are about, having had standing pools of water to harbor and nurture them as aquatic larvae.
Bird sounds filled the air. Most notable was the beautiful descending song of the tiny canyon wren. We called for and were answered by great horned owls, but never got a glimpse of them. Verdins, black-throated sparrows, and mockingbirds were busy and vocal.
During lunch, the Sea Lion swung around the corner to the north and anchored at Los Islotes (Little Islets) where we rode Zodiacs along the ash-flow tuff formations that are the remnants of a very explosive period of volcanism that occurred before the Baja Peninsula was ripped from mainland Mexico. California sea lions mate and give birth here in the summer, but now they bask in the sun, saving energy for more demanding times. Some females are still nursing last year’s pups.
Another Baja California endemic species was viewed at Los Islotes – the yellow-footed gull. Brown pelicans and Brandt’s cormorants coming into breeding plumage preened on the lower rocks, trying to keep cool in the afternoon sun. On the higher cliffs, blue-footed and brown boobies perched on ledges and in small caves. We also had a chance to snorkel here, slipping into the cool water to marvel at the colorful world beneath the surface.
We capped our remarkable day with a beach barbecue as the sun set over the peninsula. Tuna, ribs, salads, watermelon and blondies sated us for the day, but we will be hungry for more adventures tomorrow...
A visit to Baja California and the Sea of Cortez provides a chance to see endemic species: unique plants and animals that cannot be seen anywhere else in the world. Biogeography refers to the distribution of species; island biogeography is especially fascinating. Isolation on islands allows organisms to evolve from the parent species as they adapt to different environments. If Charles Darwin had come here instead of the Galápagos Islands, he may still have come to the same conclusions, but he would have had a species of lizard named after him instead of a finch. Known as Mexico’s Galápagos, there are species or subspecies found only on one or a few islands within the Sea of Cortez.
Isla Partida Sur is a great place to search for endemic animals. Ecologically and spatially close to Isla Espiritu Santo, the two islands are often considered as a complex and share many species in common. Ashore in the west-side bay called Ensenada Grande, we were delighted by the antics of the antelope ground squirrel (Ammospermophilus insularis) as it bounced over rocks with its tail curled over its back. This animal is able to be active during the day while most desert animals are sleeping. The female pictured is foraging on flowers and pods in a shrub. When she reached up, we could see that she was eating for her nursing babies as well as herself. Another mammal endemic to the complex is the black jackrabbit (Lepus insularis). We observed a lot of evidence of the existence of this lagomorph but only a quick glimpse on a high cliff revealed its telltale long ears and dark back.
Islas Partida and Espiritu Santo have many interesting reptile species, and we saw two that are only found here – a whiptail lizard (Cnemidophorus espiritensis), its bright blue tail clear in the photo, and an Espiritu Santo Island striped whipsnake (Masticophis barbouri). Several of us also had good views of the Baja California banded rock lizard (Petrosaurus thalassinus) and a Baja California spiny lizard (Sceloporus zosteromus).
Everything is thriving here due to precipitation in recent months. Water has brought life to the desert. Vines and annual plants have formed mats that cover the desert floor and climb up on cacti and shrubs. There are many blooms and fruits. We enjoyed numerous butterflies such as the queen (Danaus gilippus) pictured here. Although not endemic, it is common in Baja California. As a relative of the famed monarch, it lays its eggs on bitter-tasting milkweed plants on which the larvae feed, retaining the chemicals for protection as they metamorphose into adults. Even dragonflies are about, having had standing pools of water to harbor and nurture them as aquatic larvae.
Bird sounds filled the air. Most notable was the beautiful descending song of the tiny canyon wren. We called for and were answered by great horned owls, but never got a glimpse of them. Verdins, black-throated sparrows, and mockingbirds were busy and vocal.
During lunch, the Sea Lion swung around the corner to the north and anchored at Los Islotes (Little Islets) where we rode Zodiacs along the ash-flow tuff formations that are the remnants of a very explosive period of volcanism that occurred before the Baja Peninsula was ripped from mainland Mexico. California sea lions mate and give birth here in the summer, but now they bask in the sun, saving energy for more demanding times. Some females are still nursing last year’s pups.
Another Baja California endemic species was viewed at Los Islotes – the yellow-footed gull. Brown pelicans and Brandt’s cormorants coming into breeding plumage preened on the lower rocks, trying to keep cool in the afternoon sun. On the higher cliffs, blue-footed and brown boobies perched on ledges and in small caves. We also had a chance to snorkel here, slipping into the cool water to marvel at the colorful world beneath the surface.
We capped our remarkable day with a beach barbecue as the sun set over the peninsula. Tuna, ribs, salads, watermelon and blondies sated us for the day, but we will be hungry for more adventures tomorrow...
