Archived 2010-2011 topics: Tapajós Hermit (Phaethornis aethopyga): a valid species, so list as Near Threatened?

Tapajós Hermit Phaethornis aethopyga is treated by BirdLife as a valid species following a decision by the AOU South American Classification Committee (http://www.museum.lsu.edu/~remsen/SACCprop442.html) based on the findings published by Piacentini et al. (2009), who demonstrated that aspects of the population’s plumage, distribution and behaviour provide strong evidence that it is not a hybrid (Piacentini et al. 2009).

In the region of Brazil in which this species is found, habitat destruction and fragmentation as a result of conversion to pasture, road construction and subsequent development and settlement, accompanied by illegal logging, are significant threats to any forest-dependent species, with the Novo Progresso area currently experiencing one of the highest rates of deforestation in the Amazon (F. Olmos in litt. 2007). Current plans to pave the BR 163 Cuiabá-Santarém road are expected bring even greater habitat destruction, opening up soya markets in the Mato Grosso for rapid transfer to Santarém, unless strong government action is taken (A. Lees in litt. 2007).

Observations of P. aethopyga in disturbed habitats (Piacentini et al. 2009) suggest that it tolerates some level of habitat degradation, which is not unusual for a hummingbird species; however, along with the loss of nest-sites and lekking sites for example, the loss and fragmentation of forest could have other insidious consequences such as the disruption of its pollination mutualisms. This suggests that the population trend is negative, and in the absence of more detailed information the rate of decline is assumed to be in the range of 1-29% over 12 years (estimate of three generations) and probably approaches the threshold for Vulnerable under the A criterion (a decline of at least 30% over three generations). This indicates that the species may be eligible for Near Threatened status.

Mapping of its known range, based on the map produced by Piacentini et al. (2009), suggests that its Extent of Occurrence (EOO) is c.178,000 km2, which means that it does not approach the thresholds for Vulnerable under the B criterion (an EOO estimated at less than 20,000 km2 combined with a declining or fluctuating range size, habitat extent and/or quality, or population size and a small number of locations or severe fragmentation). The estimate for the range size suggests that the population numbers more than 10,000 mature individuals, implying that the species does not approach the thresholds for Vulnerable under the C criterion; however, it has been noted that the species may be patchily distributed (Piacentini et al. 2009), thus further information is requested on the likely population size.

Comments are invited on the proposal to list this species as Near Threatened and an additional request is made for more information on potential threats, as well as the present level of habitat fragmentation (percentage of suitable habitat in patches too small to support viable populations) and the subpopulation structure (maximum number of individuals in any one subpopulation or maximum percentage of all mature individuals that form one subpopulation).

Piacentini, V. de Q., Aleixo, A. and Silveira, L. F. (2009) Hybrid, subspecies, or species? The validity and taxonomic status of Phaethornis longuemareus aethopyga Zimmer, 1950 (Trochilidae). Auk 126: 604-612.

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One Response to Archived 2010-2011 topics: Tapajós Hermit (Phaethornis aethopyga): a valid species, so list as Near Threatened?

  1. This species is probably under a similar-level of threat as Lepidothrix villasboasi, albeit it has a larger range-size. Recent fieldwork in Santarem (A. Lees, N. Moura, C. Andretti and B. Davis pers obs) has found this species to be largely restricted to primary forest although tolerant of once-burn and logged sites. Its distribution may be edaphically controlled and data from the BIODIVERSIDADE E USO DA TERRA NA AMAZÔNIA project may reveal what determines its patchy distribution within its range.

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