The Pygmy Nuthatch (Sitta pygmaea) is a non-migratory bird that lives primarily in Ponderosa and Jeffrey Pine forests in western North America.
These Pygmy Nuthatches were seen in June nesting in a pine tree at Lassen Volcanic National Park in Northern California. Click on photos for full sized images.
They are one of the few cooperatively breeding passerines in North America and a third of the breeding pairs have 1–3 male helpers, usually progeny or other relatives. These helpers feed incubating females, nestlings, and fledglings and participate in defense of the nest site1.
These little 4 1/4 inch birds roost in cavities, which it selects depending on season and weather. It picks roosts based on insulation and ventilation provided by roost cavities and relies on hypothermia to survive cold winter nights. Although a few other North American birds are capable of controlled hypothermia, only the Pygmy Nuthatch links hypothermia with protected roost sites and communalism.
Pairs roost together; juveniles roost with parents, and collectives of several flocks roost together. Stacks of 6, 8, and 10 birds, and more, roost together in formations of squares, oblongs, triangles, diamonds, wedges, and tiers. Two articles report more than 150 individuals roosting in one tree1.
What a nice, close knit family! They sure are cute when you see a group of them fluttering around. This is a video of someone hand feeding these energetic little birds.
References:1Birds of North America Online