Nest characteristics of endemic Dull-blue flycatcher in Horton Plains National Park and surrounding habitats, Sri Lanka

Abstract

Nest characteristics of endemic dull-blue flycatcher (Eumyias sordidus) were studied at the montane cloud forests of Horton Plains National Park (HPNP) and surrounding habitats from January 2015 to January 2017. Five main habitats were classified as cloud forest, cloud forest die-back, grassland, Eucalyptus plantation and tea plantation. Five quadrats (25m x 25m) were marked in each habitat using a Global Positioning System device. Nest sites were searched on three consecutive days from each month from 06.00h to 18.00h. Pole and mirror method was used to check the nests. Nesting materials were identified by observing adult birds carrying nest materials from the resources during the nest construction period. Nest parameters such as nest cup external diameter, cup internal diameter, the depth of incubation chamber, and total nest length were recorded. A total of 68 nests were recorded during the study period. E. sordidus built open cup nest in the cavities of road banks (n=43) and trees (n=25). Mean measurements of the nests were 93.5 ± 14.7 mm for the external diameter, 59.5 ± 10.5 mm for internal diameter, 41.0 ± 9.1 mm for the depth of the incubating chamber, and 90.9 ± 20.1 mm for the total nest length. Nests were mostly composed of Meteoriopsis sp, Thuidium sp, Selaginella brachystachya, Lycopodiella caroliniana, Sinarundinaria densifolia, Garnotia exaristata, Pteridium aquilinum, Eucalyptus sp, and Camellia sinensis. Nesting materials were fixed to the supporting substrate with aid of mud and spider webs. All nest cups were lined with black fern roots and all incubating chambers were facilitated with the smooth scales/ ramenta of Cyathea crinite. Therefore, the availability of this unique nest materials may be the most essential factor for nest construction of this endemic species.