NT
Woodpecker Finch Geospiza pallida



Justification

Justification of Red List Category
This species is thought to have declined by up to 30% over the past ten years. It is therefore evaluated as Near Threatened.

Population justification
The species is locally common and widespread (Jaramillo et al. 2020). In recent surveys, the population was estimated at 2,693 pairs (1,583-5,091) on Santiago, at 31,500 pairs (26,783-64,432) on Isabela, at 28,914 pairs (18,350-46,807) on Santa Cruz and at 10,121 pairs (8,237-16,781) on San Cristóbal (Galápagos Landbird Project unpubl. data per M. Dvorak and B. Fessl in litt. 2021). The population on Fernandina is likely below 1,000 pairs (Galápagos Landbird Project unpubl. data per M. Dvorak and B. Fessl in litt. 2021). The total population is therefore estimated at roughly 75,000 pairs, equating to 150,000 mature individuals, with a minimum of roughly 55,000 pairs (110,000 mature individuals) and a maximum of roughly 135,000 pairs (270,000 mature individuals).
The species is thought to form three subspecies (Jaramillo et al. 2020): Subspecies striatipecta occurs in San Cristóbal (10,121 pairs, equating to 20,242 mature individuals), subspecies producta in Fernandina and Isabela (32,500 pairs or 65,000 mature individuals) and subspecies pallida on Santiago, Santa Cruz and potentially Santa Fé and Pinzón (31,607 pairs or 63,214 mature individuals).

Trend justification
A study using quantitative census data to describe the distribution and abundance of the land birds of Santa Cruz revealed that the species had declined significantly between 1997 and 2010, with declines of >65% in the dry zone, >20% in humid Scalesia forest and >50% in the agricultural zone of the island (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. On San Cristóbal however, the species was found to be in a better state with no declines noted (Dvorak et al. 2019).
The species reaches highest densities in humid zones (Dvorak et al. 2019), where declines of >20% were observed over 14 years (Dvorak et al. 2012), which equates to a rate of decline of >15% over ten years. Accounting for faster declines of populations in the less frequented dry zones, the overall rate of decline is precautionarily inferred at 20-29% over ten years.

Distribution and population

This species is found only in the Galápagos Islands (Ecuador), where it occurs on the islands of Fernandina, Isabela, Santiago, Santa Cruz and San Cristóbal. Its status on Pinzón and Santa Fé is uncertain (P. Grant in litt. 2013; eBird 2021).

Ecology

The species uses a variety of  habitats and elevations, especially montane evergreen forest (Jaramillo et al. 2020). It is most common in humid zones of Scalesia evergreen forest (dominated by treelike Scalesia pedunculata), where it can reach densities ten times higher than in arid or agricultural zones (Dvorak et al. 2012, 2019). It feeds on arthropods, including wood-boring beetle larvae (Jaramillo et al. 2020). Ecologically, it fills the role of a woodpecker or nuthatch and uses tools, such as sticks, to extract larvae from timber.

Threats

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; Bulgarella et al. 2019). Droughts may have a negative impact on the species (Dvorak et al. 2012).

Conservation actions

Conservation and Research Actions Underway
The species is found within the Galápagos National Park.

Conservation and Research Actions Proposed
Quantify the overall population size. Implement a monitoring programme. Assess the impact of threats including diseases and habitat change and the effects of restoration on the population trend. Continue research into the impacts of Philornis downsi. Protect remaining suitable habitat. Implement management to limit the negative impact of P. downsi on the species. Ensure management to control invasive plants does not impact negatively on the species. Control introduced species.

Identification

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. 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".

Acknowledgements

Text account compilers
Hermes, C.

Contributors
Ashpole, J, Butchart, S., Cisneros-Heredia, D.F., Dvorak, M., Ekstrom, J., Fessl, B., Grant , P. & Sharpe, C.J.


Recommended citation
BirdLife International (2022) Species factsheet: Geospiza pallida. Downloaded from http://www.birdlife.org on 05/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/12/2022.