Habitat restoration to conserve the Little Vermilion Flycatcher Pyrocephalus nanus on Santa Cruz Island, Galapagos

Abstract

The endemic Little Vermilion Flycatcher (LVF) Pyrocephalus nanus has suffered a drastic decline on Santa Cruz Island, Galapagos, where it was common 30 years ago. Currently, fewer than 40 individuals remain in the last remnants of natural humid forest in the Galapagos National Park on the 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 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 1 ha 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 with unmanaged areas. In 2020, the daily failure rate (DFR) of nests in the egg stage did not differ between management types; however, in 2021, the 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 with 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.