Justification of Red List Category
This species is thought to have declined by more than 30% over the past three generations and this decline is projected to continue into the future. It also has a small range and is found at a limited number of locations. It is therefore evaluated as Vulnerable.
The global population size has not been quantified, but this species is described as 'uncommon' (Stotz et al. 1996). The population size on Santa Cruz in 2008 (largely confined to higher altitudes) was estimated at c. 12,000 singing males (Dvorak et al. 2012).
The population had been suspected to be stable in the absence of evidence for any declines or substantial threats. However a recent study by Dvorak et al. (2012) used quantitative census data to describe the distribution and abundance of the land birds of Santa Cruz, the second largest island in the Galápagos archipelago. The results revealed that the species had declined significantly between 1997 and 2010, with declines of >65% in the dry zone, >20% in Scalesia forest and >50% in the agricultural zone. Changes in insect abundance or availability could be driving the decline, although other factors such as habitat alteration and introduced species may also be influencing declines (Dvorak et al. 2012). No census data currently exists for the islands of Isabela and Santiago but given the level of habitat destruction and degradation by introduced herbivores on those islands (Henderson and Dawson 2009), similar declines are suspected.
This species is found only on the Galápagos Islands (Ecuador). It is found on the islands of Fernandina, Isabela, Santiago, Pinzón, Santa Cruz, and San Cristóbal. Its status on Fernandina and Pinzón is uncertain (P. Grant in litt. 2013).
The species uses a variety of habitats and elevations, especially montane evergreen forest (Jaramillo and Christie 2013). It is common in Scalesia evergreen forest (dominated by treelike Scalesia pedunculata) and the Cinchona zone (dominated by Cinchona pubescens) on Santa Cruz (Dvorak et al. 2012). It feeds on arthropods, including wood-boring beetle larvae (Jaramillo et al. 2015). Ecologically fills the role of a woodpecker or nuthatch and uses tools, such as sticks, to extract larvae from timber.
Habitat loss owing to human activities is thought to be a major threat. Endemic Scalesia forest on Santa Cruz had decreased to 1-2% of its original size by 2009 and has been invaded by introduced tree species (Dvorak et al. 2012). Spraying with herbicides to control these invasive plants may have reduced invertebrate abundance. Introduced herbivores are also thought to have had a negative impact on the species, causing significant damage to native vegetation. The species is known to be susceptible to the parasitic fly Philornis downsi and highly susceptible to avian pox (Dvorak et al. 2012). Droughts may have a negative impact on the species (Dvorak et al. 2012).
Conservation and Research Actions Underway
The species is found within the Galápagos National Park.
Conservation and Research Actions Proposed
Implement a full-scale monitoring programme for birds on the Galápagos islands in order to assess the impact of threats including diseases and habitat change and the effects of restoration (Dvorak et al. 2012). Continue research into Philornis downsi and implement management to limit its negative impact on Woodpecker Finch. Control introduced species. Protect remaining suitable habitat. Ensure management to control invasive plants does not impact negatively on the species.
15 cm medium-large Darwins's finch. Bill long, apparently twice as long as base depth. Strong legs and large feet, tail short and weak. Male is sandy brown, unstreaked and rather pale with sandy brown face and pale area above and below eye. Iris dark and bill black during breeding, lower mandible paler at other times. Female resembles male in plumage however bill dull orange, not becoming black during breeding. Juvenile resembles female (Jaramillo et al. 2015). Voice Song loud e.g. chup-tupupupu chup-tupupupu or cht-trrr cht-trrr or chik-tip-tip-tip-tip chik-tip-tip-tip-tip. Calls include nasal phew (Jaramillo et al. 2015).
Text account compilers
Ashpole, J, Butchart, S., Ekstrom, J. & Sharpe, C J
Grant , P. & Cisneros-Heredia, D.F.
BirdLife International (2020) Species factsheet: Geospiza pallida. Downloaded from http://www.birdlife.org on 26/02/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/02/2020.