Justification of Red List Category
This species is listed as Endangered because its population is estimated at fewer than 250 mature individuals. It occupies an extremely small range and is restricted to one location, but has been increasing in numbers since 2003 thanks to intensive conservation efforts, most importantly the protection of habitat and control of a nest parasite. Its status, however, is precarious, and continued conservation efforts will be vital if it is to survive and further improve. Future changes that constrain the level of conservation work implemented so far would risk a worsening in the species's status, in which case it would quickly become eligible for uplisting to Critically Endangered.
There were 113 territories recorded in 2009 (D. Wege in litt. 2009), hence the total population appears to number 226 mature individuals, roughly equivalent to 340 individuals in total.
Population estimates based on yearly counts by N. Krabbe in litt. (2007) are as follows (numbers indicate occupied territories): 1999: 12-22; 2000: 15-27; 2001: 35-37; 2002: 20-35; 2003: 30-34; 2004: 42-45; 2005: 50-52; 2006: 59-61; 2007: 81-83. In 2008, there were an estimated 110-120 occupied territories (M. Juiña in litt. 2008), and in 2009 the number of occupied territories was estimated at 113 (Krabbe et al. 2011). Counts of singing males found 99 in 2011, 107 in 2012 and 112 in 2013 (S. Hartmann in litt. 2014). An extremely rapid increase has occurred over the past eleven years (estimate of three generations), but the species may reach carrying capacity at around 150 pairs (N. Krabbe in litt. 2011).
Atlapetes pallidiceps occurs in the río Jubones drainage, in Azuay and Loja, south Ecuador. There were no records between 1969 and 1998, when intensive studies found five pairs and two presumed immatures in two habitat patches in the Yunguilla Valley, near Girón, Azuay, and a further 1-2 pairs that were suspected to be supported by habitat in small ravines in the 1 km between the two patches (Agreda et al. 1999a, 1999b). Despite repeated searches, it is unknown elsewhere within its presumed historical range (Agreda et al. 1999b). The breeding population in 2003 was conservatively estimated at 33 pairs, with 17 pairs in the Yunguilla Reserve, 4 pairs immediately adjacent to it and 12 further pairs in the next valley (Schmidt and Schaefer 2003); it has since shown a consistent increase owing to intensive conservation management, reaching an estimated total of 113 pairs in 2009 (Krabbe et al. 2010). The population may have effectively reached saturation point within the available habitat (D. Wege in litt. 2009), although this is contested and saturation may occur at between 150 and 200 occupied territories (Krabbe et al. 2011, N. Krabbe in litt. 2011). Increases beyond this may be constrained by high land prices and the difficulty of exercising cowbird control in areas the cowbirds can access from several directions.
Its habitat is typical of regenerating landslides and fallow fields, with the species occurring at 1,650-1,950 m (Agreda et al. 1999a, 1999b) in the transition between arid and humid areas with dense low scrub (Schmidt and Schaefer 2003), which is interspersed with small clearings and some patches of 2-3 m tall Chusquea bamboo (Krabbe 2004). Birds feed on invertebrate prey, fruits and flowers during the rainy season (M. Schaefer in litt. 2012), the rest of the year also taking a variety of fruit and seeds (Agreda et al. 1999a, Oppel et al. 2003, Krabbe 2004, M. Juiña unpubl. data). It often gleans prey from twigs of the composite bush Steiractinia sodiroi (Krabbe 2004). It is usually seen in pairs, mainly foraging on and within 2 m of the ground (Agreda et al. 1999a, Schmidt and Schaefer 2003, Krabbe 2004). Historical records are all from the edges of arid intermontane valleys, at 1,500-2,100 m (N. Krabbe in litt. 2012). Nests are placed within dense thickets of small bushes or bamboo (Schmidt and Schaefer 2003). A single clutch is raised every year, unsuccessful birds relaying (Oppel et al. 2003). Egg-laying takes place between late February and mid-April (N. Krabbe in litt. 2012), with a few relaying as late as May (Oppel et al. 2003, N. Krabbe in litt. 2012, M. Juiña unpubl. data), and young are fledged by late May (N. Krabbe in litt. 2012). Recent studies have investigated its breeding ecology and habitat usage (M. Schaefer and V. Schmidt in litt. 2002, Schmidt and Schaefer 2003). It coexists with Rufous-naped Brush-finch Atlapetes rufinucha and Stripe-headed Brush-finch Arremon torquatus, but is subordinate to the latter (Krabbe 2004, Oppel et al. 2004b, M. Schaefer in litt. 2012).
Brood parasitism by the Shiny Cowbird Molothrus bonariensis has a significant impact on breeding success (M. Schaefer and V. Schmidt in litt. 2002), with an overall parasitism rate of 42% in 2002 (Schmidt and Schaefer 2003, Oppel et al. 2004b). The positive population trend observed in A. pallidiceps since the initiation of cowbird control in 2003 adds further weight to the significance of this threat (Krabbe et al. 2011). The impacts (positive and negative) on the species of livestock grazing are not well understood and require further study. Fires potentially threaten the species (J. Freile in litt. 2011, M. Schaefer in litt. 2011), but also result in an improvement to its habitat (N. Krabbe in litt. 2011). An annual turnover of 40% in singing males, as calculated from data obtained in 1999-2007 (Krabbe et al. 2011), indicates that the impact of a change in management or a new threat would be rapid.
Conservation Actions Underway
Research studying the species's life history and habitat use is on-going (M. Schaefer in litt. 2012). Management for this species has been extremely successful and very probably saved the species from extinction. The remaining 27 ha of suitable habitat, where it was observed in 1998, was purchased in 1999 and securely fenced off to remove grazing pressure (Sornoza Molina 2000, N. Krabbe in litt. 2012). Cowbird removal in 2003 resulted in a strong increase in reproductive output; 16 chicks fledged in the Yunguilla Reserve in 2003 compared to only 5 in 2002 (Schmidt and Schaefer 2003). Removal of this parasitic species is on-going (M. Juiña in litt. 2008, N. Krabbe in litt. 2012). A habitat management scheme was implemented in November 2002, in order to halt vegetation succession and create suitable habitat by selective thinning of dense thickets. This has mostly been successful, although some succession has occurred and at least one territory has been lost (M. Schaefer in litt. 2012). A habitat occupancy monitoring scheme was set up in 2004 to assess the success of this habitat management (Schmidt and Schaefer 2003). The reserve now encompasses between 150 and 200 ha and holds over 90% of the known brush-finch territories (M. Schaefer in litt. 2012). Further land purchases, mainly immediately to the north of the reserve, are planned. There are plans to establish a second reserve in the adjacent valley (N. Krabbe in litt. 2013).
16 cm. Pale grey-and-white passerine. Pale brownish-grey upperparts, old males have nearly white head, females and younger males more dingy head, with ill-defined buff stripes on crown sides and behind eye, and whitish underparts. Similar spp. Buff stripes on whitish head and lack of black hindcrown and nape separates this species from similar White-headed Brush-finch A. albiceps. Voice Song typical of genus, fairly high-pitched, 2-7 different phrases given at regular intervals of 7-14 s, virtually indistinguishable from song of White-winged Brush-finch. Interaction calls of the pair include a variety of fairly high-pitched notes by the male, and a low-pitched trill by the female. Contact calls very high-pitched.
Text account compilers
Bird, J., Capper, D., Harding, M., Isherwood, I., Pople, R., Sharpe, C J, Stuart, T., Symes, A., Taylor, J., Temple, H.
Sornoza, P., Krabbe, N., Juiña, M., Isherwood, I., Schaefer, H.M., Hartmann, SH, Wege, D., Freile, J., Schmidt, V.
BirdLife International (2020) Species factsheet: Atlapetes pallidiceps. Downloaded from http://www.birdlife.org on 19/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/09/2020.