The bird has already disappeared from Floreana Island and is very rare on other large islands such as Santiago and Santa Cruz.
The Charles Darwin Foundation (CDF) and the Galapagos National Park Directorate (DPNG) reported, through a statement, that new individuals of the witch bird have joined the critically endangered population of Santa Cruz Island. This increase occurs for the second consecutive year.
According to the CDF, this is due to an ambitious experimental management program to reduce the impacts of invasive species on this iconic bird.
The witch bird (Pyrocephalus nanus), classified as Vulnerable to extinction by the International Union for Conservation of Nature (IUCN), It has already disappeared from Floreana Island and is very rare on other large islands such as Santiago and Santa Cruz.
In Santa Cruz, their numbers have dropped dramatically in recent decades and scientists estimate that there are as many as 30 pairs left. Most of them are in the area of Mina de Granillo Rojo, a Scalesia forest heavily altered by blackberry, considered an invasive species, and other introduced plants.
The biggest threat to this bird is the avian vampire fly. However, the treatments of their nests to eliminate the fly larvae were not enough to ensure the success of the nests and prevent their abandonment. This suggested that other factors were affecting this species.
From observations of foraging behavior, the scientists hypothesized that the birds were not getting enough high-energy-quality prey to support themselves and their chicks. This because the dense thickets of the blackberry were preventing the birds from accessing the ground and obtaining their preferred food, such as caterpillars and spiders.
In 2018, the CDF and the University of Vienna, together with the GNPD, initiated a 3-year holistic management pilot program that included restoration of the Scalesia forest through mulberry removal, rodent control and injection into the Base the nests with a low-impact insecticide to reduce the number of avian vampire fly larvae.
This experimental management turned out to be successful and new birds are being incorporated into the population of Santa Cruz.
“In 2020, these interventions resulted in the incorporation of at least six fledglings into the population. We were unable to visit the remaining nests due to closure restrictions due to the COVID-19 pandemic. This year, eight birds left the nests, the most since we started monitoring in 2017. This is good news, as each fledgling gives you more hope of keeping this extremely small population alive.“Said David Anchundia, project scientist.
Meanwhile, Danny Rueda, director of the Galapagos National Park, affirmed that these results are encouraging, so they plan to expand the intervention area, which will contribute to increasing the population size of this bird in the next season “for the witch bird to regain its spaces on the island of Santa Cruz”.
Studies have shown that an integrated management approach, including habitat restoration, is necessary to ensure nesting success. Without this, nests are abandoned at a very early stage of incubation, indicates the CDF.
“In the six experimental plots of one hectare in which the blackberry has been eliminated, the natural recovery of several species of endemic and native plants is being observed, among them the threatened giant daisy tree, the Galapagos coffee tree and the tree ferns. Thus, these management actions are also benefiting the restoration of the Scalesia forest, one of the most threatened habitats in the archipelago ”, stated the CDF. (I)
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