Birds
Thousands of nesting brown boobies and pelicans on San Pedro Nolasco, the Gulf’s own yellow-footed gull, and the herons and spoonbills of Estero El Soldado.
Background photo: Megan Applegate (Malpelo, Colombia)
Island colonies
Seen on the boat ride to the sea lions
Key marks: Dark chocolate-brown head, neck and back sharply divided from a white belly, with a pale yellowish bill and feet (Wikipedia).
At San Carlos: San Pedro Nolasco is a Key Biodiversity Area for its nesting colony of about 6,000 brown boobies (Key Biodiversity Areas).
Key marks: A large, grey-brown pelican with a long bill and throat pouch that dives head first from the air to catch fish (Wikipedia).
At San Carlos: About 3,000 brown pelicans nest on San Pedro Nolasco (Key Biodiversity Areas). In the 1930s the island was the main pelican nesting colony on the Sonora coast, with several thousand pairs (van Rossem 1945).
Key marks: Bright blue feet, a brown back and wings, a white belly and a streaked pale head (Wikipedia).
At San Carlos: Recorded at San Pedro Nolasco and Guaymas (van Rossem 1945); boat tours from San Carlos visit islands where they nest (GetMyBoat).
Coast
Along the shore between dives
Key marks: Long, narrow, angled wings and a deeply forked tail; males black with a red throat pouch, females with a white breast (Wikipedia).
At San Carlos: Recorded at San Pedro Nolasco and Guaymas, but no frigatebird colony was known in Sonora in the 1940s (van Rossem 1945).
Key marks: A large raptor, dark brown above and white below, with a dark stripe through the eye; it plunges feet first for fish (Wikipedia).
At San Carlos: Seen at Estero El Soldado (Sonoran Joint Venture).
Possible but unconfirmed
Red-billed tropicbirds bred on San Pedro Mártir and George islands in the 1940s (van Rossem 1945); no record of them nesting on San Pedro Nolasco was found.
Wetland
A mangrove estuary at the edge of town
Estero El Soldado, about 20 km from Guaymas, has been a state protected natural area since 2006 and is a Ramsar wetland of 349.89 ha with three species of mangrove (Mongabay Latam; Ramsar). Sources give different bird counts: more than 200 species (Sonoran Joint Venture), or 75 of the 408 species recorded there (Mongabay Latam).
Birds seen there on a World Wetlands Day visit included the roseate spoonbill, osprey, white-faced ibis, long-billed curlew, reddish egret, little blue heron and American oystercatcher (Sonoran Joint Venture).
Land
Found nowhere but San Pedro Nolasco
Vulnerable on the IUCN Red List (Wikipedia).
Key marks: A spiny-tailed iguana found only on San Pedro Nolasco (Wikipedia); it eats mainly cactus fruit and stems (Wikipedia).
Also: The island also has its own cactus, Echinocereus websterianus, and had its own deer mouse, now extinct (Wikipedia). The island is protected as a nature reserve (Wikipedia); watch from the boat.
Credits
Reference photos and their sources
There are no photos from San Carlos on this page yet. The frigatebird is a reference photo taken elsewhere, credited below; the other animals link to photos online.
| Species | Photographer | Licence | Source |
|---|---|---|---|
| Magnificent frigatebird | Andrew Turner from Washington, DC, United States | CC BY 2.0 | Wikimedia Commons |