Data Zone
Justification of Red List category
This species is assessed as Vulnerable because it is restricted to a single island and has a small population, estimated to number less than 1,000 mature individuals.
Population justification
The species is described as reasonably common across the island (Brewer 2020, see also eBird 2023). An informal census along roads counted 90 individuals in 2003 (T. Marks in litt. 2003), and preliminary censuses along the trail to Mirante dos Golfinhos e Baia do Sancho in 2003 counted 84 birds (F. Olmos in litt. 2005). Point counts along almost the entire the trail system in 2009 found 304 individuals (Mestre et al. 2016). Based on these surveys it is assumed that the total population numbers at least 1,000 individuals (Mestre et al. 2016, ICMBio 2018, L. Mestre in litt. 2020). Consequently, because not all those counted will have likely been breeding adults, a very preliminary estimate is of 700-c.1,000 mature individuals is used here.
Trend justification
The population trend has not been quantified, as differences in survey methodologies in 2003 and 2009 complicate detecting changes in abundance (Mestre et al. 2016). It is hypothesised that the species used to be more widespread prior to anthropogenic changes in habitat (Olson 1994, Mestre et al. 2016). However, as all large trees on the island were cut with human colonisation several centuries ago, the species seems to show considerable resilience to habitat conversion (Olson 1994). While there are indications that the population has declined in the past this reduction appears to be largely historical. The presence of exotic species such as lizards, cats and rats, in addition to invasive exotic flora, are considered the biggest problems for this species (C. Licarião in litt. 2024, R. Subirá in litt. 2024). Cats and rats were introduced to the island in the 19th century, though likely even much earlier (Russell et al. 2018). Of 18 nests monitored from February to May in 2023, 34.4% of eggs and 36.3% of nestlings were predated (C. Licarião in litt. 2024). This species' continued presence on the island however suggests that predation is unlikely to be driving particularly rapid declines. Precautionarily therefore, a slow decline is suspected.
Vireo gracilirostris is restricted to the Atlantic Ocean island of Fernando de Noronha, Brazil (Olson 1994).
This species is common in woodland, forest, gardens or scrub, particularly where there are small fig trees (Oren 1982, Olson 1994, Mestre et al. 2016). It is absent from cleared areas, but persists readily in secondary habitats (Mestre et al. 2016, Brewer 2020).
Its absence from cleared areas suggests that this species was presumably historically more widespread, as the island was reportedly covered in forest when discovered in 1503 (Olson 1994). All large trees have long since been cut and all remaining vegetation on the island is secondary (Olson 1994). However, this appears to have had little effect on the viability of the population, even though the species' preference for and higher abundance in well-conserved areas and natural vegetation suggests that there may be some sensitivity to human disturbance (Mestre et al. 2016). Habitat loss and degradation is however still ongoing slowly; the main driver being touristic infrastructure developments (Mestre et al. 2016). The presence of exotic species such as lizards, cats and rats, in addition to invasive exotic flora, are considered the biggest problems for this species (C. Licarião in litt. 2024, R. Subirá in litt. 2024). Cats and rats were introduced to the island in the 19th century, though likely even much earlier (Russell et al. 2018). Of 18 nests monitored from February to May in 2023, 34.4% of eggs and 36.3% of nestlings were predated (C. Licarião in litt. 2024). This species' continued presence on the island however suggests that predation is unlikely to be driving particularly rapid declines.
Conservation Actions Underway
Large parts of the range are protected within Fernando de Noronha Marine National Park. Monitoring and environmental education activities are carried out as part of the Endemic Bird Project of Fernando de Noronha (C. Licarião per L. Mestre in litt. 2020). Sterilisation of feral cats is ongoing (C. Licarião per L. Mestre in litt. 2020).
Conservation Actions Proposed
Survey to provide an updated and accurate estimate of the population size. Research the species' habitat requirements and tolerance of habitat conversion and degradation. Investigate potential impacts of introduced species on the population trend. Carefully monitor the population trend. Effectively protect areas of suitable habitat. Continue to raise awareness for the species.
14 cm. A dull olivaceous arboreal bird. Upperparts dull olivaceous brown, slightly greener on wings and tail. Narrow buffyish supercilium. Below pale greyish white, washed with dull greyish olive on sides. Bill slim and slender dusky with pinkish mandible. Similar spp. The only vireo in the island; the Noronha Elaenia Elaenia ridleyana shows wing-bars. Voice Song is a melodious weet weet, chew-eyoo, whut whít. Also a harsh tschrr note. Hints Confiding and sedentary, they are quite mobile in the trees.
Text account compilers
Hermes, C., Vine, J.
Contributors
Gilroy, J., Harding, M., Marks, T., Mestre, L., O'Brien, A., Olmos, F., Schulz Neto, A., Sharpe, C.J., Subirá, R. & Licarião, C.
Recommended citation
BirdLife International (2024) Species factsheet: Noronha Vireo Vireo gracilirostris. Downloaded from
https://datazone.birdlife.org/species/factsheet/noronha-vireo-vireo-gracilirostris on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.