Elevational range extension of Drab Water Tyrant, Ochthornis littoralis (Pelzeln, 1868) (Passeriformes, Tyrannidae)

The Drab Water Tyrant, Ochthornis littoralis (Pelzeln, 1868), is a small flycatcher occurring across lower Amazonia. Its usual habitat is the edges of rivers, and it is easily observed flying over sandbanks and among the trunks of fallen trees and branches. Here, I present a new locality in the Ecuadorian Andean foothills which represents a significant increase in this species’ elevational range from the Amazon lowlands. The new record is also from a previously unknown habitat for the species.


Introduction
The Drab Water Tyrant, Ochthornis littoralis (Pelzeln, 1868) (Passeriformes, Tyrannidae), is a small flycatcher occurring across northern South America in Colombia, Venezuela, Guyana, French Guyana, Brazil, Ecuador, Peru, and Bolivia. It is associated with sandbanks along the edges of rivers (Farnsworth and Langham 2019). Its usual altitudinal range is 400-900 m a.s.l. (Hilty 2003;Restall et al. 2006;Schulenberg et al. 2007;Ber Van Perlo 2009;Herzog et al. 2016;Freile and Restall 2018), and the highest record is from Bolivia. In Ecuador, O. littoralis is occurs throughout the Amazonian lowlands below 400 m on the eastern slope of the Andes (Rigdely and Greenfield 2001; McMullan and Navarrete 2017; Freile and Restall 2018) (Fig. 1). In this region, this flycatcher species is considered to be a resident, and it usually observed flying low between tree trunks and branches (Ridgely and Greenfield 2001). On 26 January 2018, five individuals were observed as part of routine transect observations for a bird-monitoring project, in a location that is here reported as a new elevation record for this species.

Methods
Field methods consisted of fixed-band line transects with a length of 1000 m. Two transects were placed across the facilities of the Topo River hydroelectric power plant, Tungurahua, Ecuador. The transects were conducted at 06:00-10:00 in the morning and at 15:00-18:00 in the afternoon. Although there was a mist-net catching station in place, Ochthornis littoralis was not caught. The mist nets were opened during the same times mentioned above. The birds were observed around the concrete wall in the water-catchment area of the hydroelectric power plant. Two individuals of O. littoralis were observed pecking and foraging in moss on the ground ( Fig. 2A). The other three individuals were observed at the same time on the road to the plant; they had a similar foraging behavior, pecking the ground for small insects (Fig. 2B). On the second day, I saw two individuals which were pecking for invertebrates on the ground.

Ochthornis littoralis (Pelzeln, 1868)
The vegetation in the area is characterized by the presence of ferns, herbs, and human-maintained lawn. The river's edge showed signs of heavy erosion. The surroundings are a human-modified secondary open forest.
The vegetation height was ~5 m and the vegetation consisted mostly of succulents and a few trees. The south side of the water catchment area had less disturbance than the north side and had a slope of ~75° and ~8 m high vegetation of trees and shrubs.
Identification. The identification was based on the plumage pattern (Fig. 2), which is consistent with the descriptions in the literature: sandy brown body, browner crown, darker tail and wings, and facial pattern with pale supercilium. The position of the body in a more inclinedhorizontal posture and foraging behavior were determinants. A similar species in Ecuador is River Tyrannulet (Serpophaga hypoleuca Sclater & Salvin, 1866), but it has a clearer neck, chest, and ventral area, and also lacks the facial patterns and dark shades on the wings; it is also a less frequently encountered species in the lower Amazon region than O. littoralis. Little Ground Tyrant (Syrtidicola fluviatilis (Sclater & Salvin, 1866)) is also similar, but its slimmer bill, longer tail, and absence of a pale supercilium differs from O. littoralis (Rigdely and Greenfield 2001;McMullan and Navarrete, 2017;Freile and Restall 2018).

Discussion
This report expands the elevational range of Ochthornis littoralis by 1160 m in Ecuador (Freile and Restall 2018), 660 m higher than the highest known occurrence anywhere in its range. The general vegetation in the water-capture area of the hydroelectric plant was typical of the Low Montane Evergreen Forest found on the eastern Andes, which differs considerably from the Evergreen Forest of the Amazonian lowlands and other riparian ecosystems where the bird is usually observed (MAE 2013). Referring to the system of bioclimatic classification used for the Ecuadorian fauna, this species is now known to occupy not only the Oriental Tropical Area but also the Oriental Subtropical Area (Albuja et al. 2012). The habitat at the new locality presents human disturbance and lacks the typical sandbanks of the usual riparian habitats where O. littoralis usually occurs. The vegetation is also lower, and the current in the river is much greater.
Although the habitat differs at the site of the new record from what is typical for O. littoralis, the strong relationship between this species and water was observed at this site. Precipitation and temperature in the species' usual range is, on average, 200 mm and 25 °C, respectively, whereas in the new site reported here, temperatures average 20°C, although precipitation is the same (Albuja et al. 2012;MAE 2013). The species may be seasonally moving, following the rains and precipitation patterns. Young individuals may also be exploring new territories looking for food before to start the breeding season. The closest localities where O. littoralis has been recorded are approximately 70 km north or south from the new record, but considering that the Topo River is a tributary of the larger Pastaza River, where this species is known to occur, it is likely that the newly recorded individuals originated from the southern population.