Survival and extinction of breeding landbirds on San Cristóbal, a highly degraded island in the Galápagos

Abstract

SummaryWe documented the consequences of large-scale habitat loss on a community of Galápagos native bird species on San Cristóbal island, based on point counts conducted between 2010 and 2017. Surprisingly, despite considerable habitat change and a variety of other threats, the landbirds of San Cristóbal have fared much better than on the neighbouring islands Floreana or Santa Cruz. While two species went extinct very soon after human colonisation, the majority have adapted well to subsequent vegetation change and habitat loss. The endemic San Cristóbal Mockingbird Mimus melanotis is more widespread than previously thought and its population seems to be stable since the 1980s. We thus propose a change in IUCN classification from ‘Endangered’ to ‘Near threatened’. We present evidence gained by interviewing locals which suggests that a small population of the Least Vermilion Flycatcher Pyrocephalus dubius, classified as ‘Extinct’ by BirdLife International, may have persisted until very recently. Although extensive searches in 2018 and 2019 were unsuccessful, the possibility remains that a few birds may have survived in remote parts of the island. Further searches that involve the general public and other interested parties are therefore deemed necessary.

Effect of an introduced parasite in natural and anthropogenic habitats on the breeding success of the endemic little vermilion flycatcher Pyrocephalus nanus in the Galápagos

“…However, due to a rapid increase in tourism and resident human population over the past decades, the Islands, particularly the four inhabited islands (Santa Cruz, San Cristóbal, Isabela, and Floreana), are increasingly affected by habitat alteration and invasive alien animals and plants (Lindström et al , Toral‐Granda et al ). This also affects the unique land bird fauna of the Galápagos with population declines in 17 of the 28 endemic and native small land bird species (Dvorak et al , , , Fessl et al ). The International Union for Conservation of Nature (IUCN) considers now 14 species as threatened, and one species, the least vermilion flycatcher, Phyrocephalus dubius of San Cristóbal, as extinct (BirdLife International 2017a but see Dvorak et al ).…”

“…This also affects the unique land bird fauna of the Galápagos with population declines in 17 of the 28 endemic and native small land bird species (Dvorak et al , , , Fessl et al ). The International Union for Conservation of Nature (IUCN) considers now 14 species as threatened, and one species, the least vermilion flycatcher, Phyrocephalus dubius of San Cristóbal, as extinct (BirdLife International 2017a but see Dvorak et al ). Its close congener, the endemic little vermilion flycatcher Pyrocephalus nanus , originally living on ten islands, has recently gone extinct on Floreana (Merlen , Dvorak et al ), is rare on Santiago (D. Anchundia and B. Fessl, pers.…”

Avian disease surveillance on the island of San Cristóbal, Galápagos

“…relictum ) remain absent from San Cristóbal. Additionally, the absence in our samples of Haemoproteus multipigmentatus , an introduced haemosporidian circulating in the Galápagos Dove ( Zenaida galapagoensis ), reflects the decline of this bird species on the island (Dvorak et al, 2017 , 2019 ; Jaramillo et al, 2017 ). Our results suggest that endemic birds of San Cristóbal are not significantly impacted by avian malaria, which may in part be due to the relatively recent establishment of C .…”

Urban living influences the nesting success of Darwin’s finches in the Galápagos Islands

“…Our nonurban area, the Jardín de Opuntias, is named for the large presence of the arboreal cactus, Opuntia megasperma which is one of the preferred nesting locations of small ground finches. However, cacti are rare across San Cristóbal, likely due to destruction by introduced mammals in the 1800s, but are locally abundant within the Jardín de Opuntias (Dvorak et al., 2019; Phillips et al., 2012). Small ground finch nests are commonly found in cacti as well as trees such as matazarno ( Piscidia cathagenensi ) and Galápagos acacia ( Acacia rorudiana ), and nests are common in both the nonurban and urban area.…”