Metallic blue tree swallows nest in bird houses or in tree cavities. (Photo by Allan Hack) Our last two notable swallows, the tree swallow and the violet-green swallow, do not build mud nests.

Learn how to identify a male and female tree swallow. Find out about their nests, song, range map and ... and more blue-green ...

Tree swallows are easily identified by their glossy blue-green upperparts, snowy white breast and belly and short forked tail. They have a gently planing flight that’s quite different to that of other ...

Tree swallows are also shiny blue above, including in a dark helmet that scrunches down firmly over their eyes, and clear white below.

A “mesmerizing” electric blue tarantula species has been discovered in Thailand, according to new research. A group of Thai researchers found the spider during an expedition to Phang-Nga ...