Betula utilis to overuse of the tree for firewood. "Betula utilis" was described and named by botanist David Don in his "Prodromus Florae Nepalensis" (1825), from specimens collected by Nathaniel Wallich in Nepal in 1820. "Betula jacquemontii" (Spach), first described and named in 1841, was later found to be a variety of "B. utilis", and is now "Betula utilis" var. "jacquemontii". In its native habitat, "B. utilis" tends to form forests, growing as a shrub or tree reaching up to tall. It frequently grows among scattered conifers, with an undergrowth of shrubs that typically includes evergreen "Rhododendron". The tree depends on moisture
Northern rough-winged swallow Northern rough-winged swallow The northern rough-winged swallow ("Stelgidopteryx serripennis") is a small, migratory swallow. It is very similar to the southern rough-winged swallow, "Stelgidopteryx ruficollis". The genus name, "Stelgidopteryx", is from Ancient Greek and means "scraper wing" and the species name, "serripennis", is derived from Latin and means "saw feather". In the common name, "rough-winged" refers to the serrated edge feathers on the wing of this bird; this feature would only be apparent when holding this bird. Six subspecies of the northern rough-winged swallow are currently recognized. It has been proposed that another race be recognized, "aphracta", but this is