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A nest of the Marble-faced Bristle Tyrant (Pogonotriccus ophthalmicus) with comparative comments on nests of related genera.

Article Excerpt
The genus Pogonotriccus comprises seven species of small flycatchers (Tyrannidae) distributed from northern Venezuela to northern Argentina (Fitzpatrick 2004). Molecular evidence suggests that Pogonotriccus forms part of a well defined clade which includes Corythopis, Pseudotriccus, Phylloscartes, Leptopogon, and Mionectes, and that together this clade is sister to the tody-tyrant-flatbill group (Ohlson et al. 2008, Rheindt et al. 2008). The Marble-faced Bristle Tyrant (P. ophthalmicus) ranges from northern Venezuela to northern Bolivia at elevations of 750-2,400 m and includes three currently recognized subspecies (Fitzpatrick 2004). Only two species of Pogonotriccus have had nests described, the most recent of which was Variegated Bristle Tyrant (P. poecilotis) (Londono and Munoz 2006).

Characters derived from nesting behavior have proven to be phylogenetically informative in a variety of avian groups (e.g., Lanyon 1988, Sheldon and Winkler 1999, Zyskowski and Prum 1999, Miller and Greeney 2008). Nest placement, composition, and detailed architecture in particular, are key characters which often remain undescribed or are reported without sufficient detail (Zyskowski and Prum 1999). I describe the first nest of Marble-faced Bristle Tyrant from northeastern Ecuador and compare these findings to related genera.

METHODS

Study Site.--I made all observations on the private reserve of Cabanas San Isidro, adjacent to the Yanayacu Biological Station and Center for Creative Studies. Yanayacu (00[degrees] 36' S, 77[degrees] 53' W) is 5 km west of Cosanga at an elevation of 2,100 m in Napo Province of northeastern Ecuador.

Chronology of Observations.--Oscar Manzaba-B. showed me the nest on 24 September 2007 at which time we observed an adult carrying moss to a partially constructed nest. The nest was checked daily until, on 25 November, I found it had been completely ripped from the tree, and I was unable to locate any portions of the nest on the ground below. Adults frequently vocalized as they approached or exited the nest after feeding. I videotaped the nest on several occasions, capturing these vocalizations on tape. I recorded the distinctive eskeek e' ti'ti'ti'ti'ti' described for this species (e.g., Hilty and Brown 1986) on multiple occasions. These tapes were subsequently examined by Mitch Lysinger who, based on both vocalizations and appearance, concurred with my identification.

RESULTS

General Observations.--Two adults were present in the area during construction, but I was unable to confirm if both participated in construction. The first egg was laid on 11 October, prior to 1030 hrs EST. The second egg was not laid until 13 October, prior to 1115 hrs. Both eggs hatched on 9 November, giving an incubation period of 27 days from clutch completion. I confirmed that two adults participated in...