2017-02-15 Our First Afternoon At Isla Socorro

We left Isla San Benedicto early this morning and drove the boat 32 miles south to Isla Socorro and arrived to anchor about 8:00am. Even though we had all the permits required to land on this island and do all the biological collecting, the Marines stationed on the base here had not received the paperwork and were not expecting us. After several hours of negotiations and several trips by Sula and Exequiel from the boat to the shore, they worked out all the arrangements. After lunch we were allowed to go ashore and begin our explorations. We confined our first afternoon’s explorations to the dock and the military compound on the bluffs above the shore.

The military established the base here in 1957. In the late 1970s, there was a larger military presence here; 250 people lived on the base, counting the soldiers and family members. When the military decided to reduce the number of enlisted men and their families, they abandoned the family cats they brought with them. The Spanish introduced sheep in 1869. Seven years ago, they finally removed the sheep from the island, but the cats have proved to be a bigger problem. They remain a threat to the endemic species and the seabirds (shearwaters) that nest here.

There are five endemic birds to be found on this island. We found two right away. The Socorro Wren is a relative of the House Wren, and the Socorro Parula is very much like the Tropical Parula. We found both as soon as we stepped ashore. To our delight, we also found numerous migratory birds. We had Yellow-Rumped Warblers, Lucy’s Warblers, Palm Warblers, Vermillion Flycatcher, Killdeer, Ruddy Turnstone, Common Ground Doves (resident), Northern Mockingbird (resident), Brown-Headed Cowbird, Lincoln’s Sparrow, Wandering Tattler, Great Blue Heron, Snowy Egret, Red-Tailed Hawk, Osprey. However, it was a Groove-Billed Ani I enjoyed the most.

It is worth mentioning the Socorro Dove in this discussion. Zoos had collected for years these exquisite birds, and distributed them around the globe. Many collectors treated these birds casually and allowed them to interbreed (hybridize) with other species. Introducing house cats to the island spelled a quick end to these native birds. People last reported these birds in 1972. After the birds died out, people searched for birds to repopulate the island. One such plan involved sending 12 doves in 2006 to the zoo in Albuquerque (New Mexico). There, they await the time when feral cats could be removed, allowing the birds to be reintroduced to their native soil. We visited the ‘aviary’ that was built on the base in 2003-2005, but it is well run down and does not appear to be suitable to protect the birds yet.

The remaining three endemic birds on this island confine their range to the upper slopes of the shield volcano they call Mount Evermann (elevation 3770’). These are the Socorro Parakeet, the Socorro Towhee, and the Socorro Mockingbird. We arranged for the marines to give us a lift up the mountain in the bed of their pickup trucks early the next morning to explore the cloud forest on high.