Preliminary Assessment of Lepidoptera Biodiversity on Isla Guadalupe, Mexico, a Critically Threatened Ecosystem Currently Recovering from Extensive Habitat Degradation

Abstract

Little is known of insect biodiversity on Isla Guadalupe, a large (c. 250 km2) Pacific island located off the west coast of Baja California, Mexico, which has undergone more than 150 years of extensive habitat degradation owing to grazing by feral goats. Goats were successfully eradicated in 2007, and thus Isla Guadalupe provides a rare opportunity to study changes in biodiversity in the flora and fauna as the habitat in this isolated geographic region begins to recover. We conducted a preliminary survey of Lepidoptera biodiversity by collecting and observing mainly adult individuals during July–August, 2019. We also included previous observations from 2003–2016, and two historical records dating back to 1874 and 1922. Our annotated inventory includes 31 species of Lepidoptera (10 species of butterflies from four families, and 21 species of moths from seven families), and includes one butterfly species recorded 100 years ago that we did not find and which may be extirpated. Although life history stages were not recorded (except for the cosmopolitan Vanessa cardui), we also comment on the availability of potential larval host plants based on literature records from other regions. Most of the Lepidoptera species in our inventory (n = 22) have also been recorded from at least one of the comprehensively studied Channel Islands in southern California, USA, and all 31 species are also present on the California mainland. Thus, the Lepidoptera fauna on Isla Guadalupe recorded here corresponds to that associated with Californian Biogeographic Province.