Calabarzon babbler

Calabarzon babbler
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Zosteropidae
Genus:	Sterrhoptilus
Species:	S. affinis
Binomial name
	Sterrhoptilus affinis; (McGregor, 1907)

The Calabarzon babbler (Sterrhoptilus affinis) is a species of bird in the family Zosteropidae. It is endemic to the Philippines found in the island of Luzon. Contrary to its name, it is also found outside the Calabarzon region where it also inhabits Central Luzon, Bicol Peninsula and Catanduanes. Its natural habitat is tropical moist lowland forest. It previously was considered a subspecies of the black-crowned babbler (Sterrhoptilus nigrocapitatus).^[1]

Description and taxonomy

EBird describes it as "A fairly small bird of lowland and foothill forest and edge. Has a gray back and cheek with fine pale streaks, dark wings and tail with white outer tail feathers, white underparts, a pale rufous throat, and a black crown. Note the slender black bill. Often joins mixed-species flocks and sometimes hangs upside down while feeding. Somewhat similar to green-backed whistler, especially from below, but smaller, with a pale rufous throat and a black crown. Voice includes a medium-pitched 'poo piuu!' with the second note downslurred."^[2] This species is monotypic.

The golden-crowned babbler has been known to interbreed with the Calabarzon babbler in areas where their range overlaps.^[3]

It was formerly conspecific with the Visayan babbler but is differentiated by it is differentiated from its southern counterpart by having a more intense orange chin and olive-toned upper parts. Its validity as a species were also further validated by sequencing its mitochodrial DNA.^[4]

Ecology and behavior

Diet is assumed to primarily be insects, berries and vegetable matter. They are spotted foraging alone, in pairs or in mixed flocks with other species. ^[5] like Blue-headed fantail, Rufous paradise flycatcher, Lemon-throated leaf warbler, Yellow-wattled bulbul, white-eyes, sunbirds and flowerpeckers. Forages in all levels but is usually seen in the understorey where it methodically gleans on leaves searching for insects.

Breeding season is believed to from April to July, which is the general breeding season for most Philippine forest birds. One nest was found that was cup shaped made out of moss and woven together with roots with small twigs just one meter above the ground. This nest contained 3 eggs but this single nest is not enough to assume average clutch.^[4]

Habitat and Conservation Status

It is found in lowland and foothill forest, second growth and forest edge until 1,140 meters above sea level.

The International Union for Conservation of Nature still recognizes the Black-crowned babbler as a single species which is assessed as least concern. This specis is believed to be on the decline. This species' main threat is habitat loss with wholesale clearance of forest habitats as a result of logging, agricultural conversion and mining activities occurring within the range.

There are currently no targeted conservation plans for the species. It does occur in the protected areas in Quezon Protected Landscape, Bicol Natural Park, Bulusan Volcano Natural Park and the Angat Watershed Forest Reserve but enforcement from loggers and hunters is still lax. ^[6]

References

^ "Species Updates – IOC World Bird List". Retrieved 18 June 2021.
^ "Black-crowned Babbler". Ebird. Archived from the original on 30 March 2020.
^ Allen, Desmond (2020). Birds of the Philippines. Lynx and Birdlife International Field Guides. pp. 296–297.
^ ^a ^b Collar, Nigel; Robson, Craig (2023). "Calabarzon Babbler (Sterrhoptilus affinis), version 1.0". Birds of the World. doi:10.2173/bow.bkcbab3.01species_shared.bow.project_name. ISSN 2771-3105.
^ Arlott, Norman. Birds of the Greater Sundas, the Philippines, and Wallacea.
^ IUCN (1 October 2016). Sterrhoptilus nigrocapitatus: BirdLife International: The IUCN Red List of Threatened Species 2016: e.T22716204A94484596 (Report). International Union for Conservation of Nature. doi:10.2305/iucn.uk.2016-3.rlts.t22716204a94484596.en.

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[1] "Species Updates – IOC World Bird List". Retrieved 18 June 2021.

[2] "Black-crowned Babbler". Ebird. Archived from the original on 30 March 2020.

[3] Allen, Desmond (2020). Birds of the Philippines. Lynx and Birdlife International Field Guides. pp. 296–297.

[:0-4] Collar, Nigel; Robson, Craig (2023). "Calabarzon Babbler (Sterrhoptilus affinis), version 1.0". Birds of the World. doi:10.2173/bow.bkcbab3.01species_shared.bow.project_name. ISSN 2771-3105.

[5] Arlott, Norman. Birds of the Greater Sundas, the Philippines, and Wallacea.

[6] IUCN (1 October 2016). Sterrhoptilus nigrocapitatus: BirdLife International: The IUCN Red List of Threatened Species 2016: e.T22716204A94484596 (Report). International Union for Conservation of Nature. doi:10.2305/iucn.uk.2016-3.rlts.t22716204a94484596.en.

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