Search

Oceanic seabirds are generally thought to avoid overland flight, perhaps limiting larger-scale distribution, but examples exist to the contrary. We asked whether Blue-Footed Boobies Sula nebouxii, Brown Pelicans Pelecanus occidentalis, or frigatebirds Fregata spp. crossed the Perry Isthmus (width 12.25 km, minimum height 23 m), a low point in the wasp-waist shape of Isla Isabela, Galapagos. Except for the Perry Isthmus, Isla Isabela presents an elongated, high-elevation challenge to movement between the central and western waters of Galapagos. Daytime observations over 3.5 d in June 2012 revealed ≥48 crossings by boobies and more than two crossings by frigatebirds. Overland crossing of a terrestrial barrier of this size may be facilitated by the seabirds' ability to see water across the Perry Isthmus from an altitude of 42 m looking west and 43 m looking east, altitudes that both the boobies and frigatebirds attain during foraging. [ABSTRACT FROM AUTHOR]

The endemic Little Vermilion Flycatcher (LVF), Pyrocephalus nanus , has suffered a drastic decline on Santa Cruz Island, where it was common 30 years ago. Currently, less than 40 individuals remain in the last remnants of natural humid forest in the Galapagos National Park on this island. This small population has low reproductive success, which is contributing to its decline in Santa Cruz. Previous studies have identified Avian Vampire Fly, Philornis downsi , parasitism, changes in food sources, and habitat alteration as threats to this species. In Santa Cruz, invasive plants may strongly affect the reproductive success of the LVF because they limit accessibility to prey near the ground, the preferred foraging niche of these birds. Since 2019, we restored the vegetation in seven plots of one hectare each by removing invasive blackberry plants and other introduced plant species. In all nests that reached late incubation, we also reduced the number of Avian Vampire Fly larvae. In this study, we compared foraging and perch height, pair formation, incubation time and reproductive success between managed and unmanaged areas. As predicted, we found significantly lower foraging height and perch height in 2021 in managed areas compared to unmanaged areas. In 2020, daily failure rate (DFR) of nests in the egg stage did not differ between management types; however, in 2021, DFR in the egg stage was significantly lower in managed areas than in unmanaged areas. The DFR during the nestling stage was similar between managed and unmanaged areas in 2020, but in 2021, only nests in managed areas reached the nestling stage. Females brooded significantly more during the incubation phase in managed areas. Additionally, we found significantly higher reproductive success in managed areas compared to unmanaged areas in 2021, but not in 2020. Habitat restoration is a long-term process and these findings suggest that habitat management positively affects this small population in the long term., Competing Interests: Competing interests: The authors declare no competing interests.