Marañón valley

Country/Territory Peru
Area 11,000 km2
Altitude 200 - 3200m
Priority urgent
Habitat loss major
Knowledge incomplete

General characteristics

The Marañón valley in north-west Peru (Cajamarca, Amazonas and La Libertad departments) is one of the most important biogeographic boundaries in the Andes, and is itself a discrete area of endemism. The EBA includes the Marañón river primarily from north-east Ancash/south-east La Libertad departments, north to the confluence of the Chinchipe and Utcubamba, the lower parts of these valleys (nearly into Ecuador in the case of the Chinchipe), and to the Chamaya. Thus defined, the Marañón drainage embraces a relatively small area, primarily from the valley floor up to c.2,000 m, although some restricted-range species occur higher into temperate zones, where they extend into the Peruvian high Andes (EBA 051).

The Marañón is in a rain shadow created by mountains to the east (the Cordilleras Central, del Condor and de Colán). The resultant arid tropical and subtropical vegetation is (as far as is known, for the region has been under cultivation for a long time) characterized by desert scrub including cactus Prosopis desert, dense herbaceous scrub with small Acacia and cacti, seasonally dry forest dominated by Ceiba with Acacia and Prosopis admixed, and riparian forests comprising Salix and Schinus (Collar et al. 1992, Wege and Long 1995). Some of the areas within the upper Marañón are characterized by more humid vegetation (J. Fjeldså in litt. 1993). Temperate zone vegetation comprises shrubs and Alnus and Eucalyptus trees, but also open Acacia woodland, grass and thorny montane shrubbery (Collar et al. 1992, Wege and Long 1995).

Restricted-range species

Most restricted-range species appear to inhabit the dry forest and scrub, the riparian forest obviously being an additional important component for the avifauna. With similar vegetation types in the Tumbesian region (EBA 045), these two EBAs have clear avifaunal similarities (e.g. seven restricted-range species are shared between them), although the far larger Tumbesian region is substantially more diverse both floristically and avifaunally. There is a broad range of altitudinal distributions shown by the species in this EBA, although in general the birds restricted to the upper Marañón tend to occur at higher altitudes, and will at times be found alongside Peruvian high Andes species (EBA 051). There is also a real possibility that some species (e.g. Columba oenops) may undertake seasonal altitudinal movements upslope into the deciduous forest (Collar et al. 1992).

The restricted-range species in this EBA can be split into two groups: those concentrated within the northern, lower portion of the Marañón valley (in the vicinity of Jaén and northwards, i.e. north of 6°S); and those primarily to the south in the upper Marañón. The birds shared with the Tumbesian region are all northern, lower Marañón species, and those shared with the Peruvian high Andes are all from the southern, upper Marañón. Of species confined to the valley, Columba oenops, Forpus xanthops, Turdus maranonicus and Thlypopsis inornata are found throughout the Marañón; Synallaxis maranonica, Melanopareia maranonica and Incaspiza watkinsi are primarily confined to the northern part; and Aglaeactis aliciae, Siptornopsis hypochondriacus, Phacellodomus dorsalis and Incaspiza laeta are essentially southern Marañón species. Melanopareia maranonica and a number of other northern Marañón species have recently been found in southernmost Ecuador in the Zumba region of Zamora-Chinchipe (Ridgely and Tudor 1994, Williams et al. 1997), suggesting that this EBA may extend further up the Chinchipe into Ecuador.

Species IUCN Category
Peruvian Pigeon (Patagioenas oenops) NT
Scrub Nightjar (Nyctidromus anthonyi) LC
Grey-bellied Comet (Taphrolesbia griseiventris) EN
Purple-backed Sunbeam (Aglaeactis aliciae) VU
Spot-throated Hummingbird (Leucippus taczanowskii) LC
Yellow-faced Parrotlet (Forpus xanthops) VU
(Thamnophilus bernardi) NR
Maranon Crescentchest (Melanopareia maranonica) LC
Chestnut-backed Thornbird (Phacellodomus dorsalis) NT
Maranon Spinetail (Synallaxis maranonica) CR
Great Spinetail (Synallaxis hypochondriaca) NT
(Synallaxis stictothorax) NR
Slaty Becard (Pachyramphus spodiurus) VU
Sooty-crowned Flycatcher (Myiarchus phaeocephalus) LC
Grey-breasted Flycatcher (Lathrotriccus griseipectus) VU
Maranon Thrush (Turdus maranonicus) LC
(Arremon abeillei) NR
Rufous-backed Inca-finch (Incaspiza personata) LC
Grey-winged Inca-finch (Incaspiza ortizi) LC
Buff-bridled Inca-finch (Incaspiza laeta) LC
Little Inca-finch (Incaspiza watkinsi) VU
Buff-bellied Tanager (Thlypopsis inornata) LC

Important Bird Areas (IBAs)
IBA Code Site Name Country
Balsas Peru
Hacienda Limón Peru
Norte de la Cordillera de Colán Peru
Soquian y Chagual Peru
Sur de la Cordillera de Colán Peru
EC090 Zumba-Chito Ecuador
PE051 Santuario Nacional Tabaconas-Namballe Peru
PE052 San Jose de Lourdes Peru
PE054 Chinchipe Peru
PE055 Bagua Peru
PE056 Cordillera de Colán Peru
PE061 Río Marañón Peru
PE062 El Chicche Peru
PE063 Río Cajamarca Peru
PE064 San Marcos Peru
PE065 El Molino Peru

Threat and conservation

The Marañón drainage has been under cultivation for a long time, and has progressively deteriorated, much of the original riparian and dry forest habitat now being lost (Collar et al. 1992). The spread of oil palms, cattle ranching and logging are all serious threats, and oil extraction is a potential future problem (Dinerstein et al. 1995). Most forest around Huancabamba, for example, has been totally cleared for agriculture, and little forest remains on the Cordillera de Colán due to clearance for cattle-grazing and drug cash crops (Wege and Long 1995).

Five of the EBA's restricted-range species are considered threatened. Confined to the area are two arid-vegetation species found throughout the valley-Columba oenops (threatened by hunting) and Forpus xanthops (threatened by the pet trade)-and Aglaeactis aliciae, a poorly known bird of montane shrubbery in the upper Marañón (Collar et al. 1994, Begazo 1996). Lathrotriccus griseipectus is threatened within its main range in the Tumbesian region as well as here, and Taphrolesbia griseiventris is extremely poorly known and found at very few localities (including one in the Peruvian high Andes, EBA 051) (Collar et al. 1992, 1994). A further six species are considered Near Threatened. The widespread but threatened (Endangered) Little Woodstar Acestrura bombus has also been recorded (Collar et al. 1992).

Nine Key Areas have been identified for the threatened species in the EBA, and the Cordillera de Colán stands out as critically important (Wege and Long 1995). Unfortunately, none of the Key Areas (indeed no area within the EBA) currently has any form of protected status (IUCN 1992a), suggesting an urgent need for conservation measures.

Recommended citation
BirdLife International (2022) Endemic Bird Areas factsheet: Marañón valley. Downloaded from http://www.birdlife.org on 03/10/2022.