Knitting Those Little Sweaters

Image: American Tree Sparrow.

Providing shelter for birds is another hobby many take seriously.

In nature, here are birds' winter habitats:

• Bobwhites sleep in a tight circle on the ground, all heads facing outward. The contact enables them to conserve precious body heat, and the outward orientation allows them to detect danger in all directions. Leaving long weeds and grasses helps insure a warm nest.
• Crows and turkeys roost in trees.
• Some birds will build winter roosts in open chimneys.
• Starlings and Pigeons often roost under brides or other infrastructure. In rural areas, old barns and sheds often have enough holes to allow birds shelter.
• When there's lots of snow cover, ruffed grouse sometimes bury themselves in snow drifts, where the snow itself insulates them from plummeting outside air temperatures.
• Owls sleep in tree cavities and sometimes in large nesting boxes.
• Song birds, such as cardinals, blue jays and finches, retire to dense thickets of vegetation. Even greater protection is found in evergreen refuges such as conifers and ivy covered walls.
• Woodpeckers, wrens, titmice and nuthatches sleep in cavities much like the ones in which they nest.
• Sparrows use thick vegetation, vines next to houses or available roof spaces. Some small birds will wedge between the bark and tree trunk.
• Even solitary birds will often sleep in large communities to keep warm.

A bird's first line of defense against the cold is its feathers. They repel water and insulate. Each feather is controlled by a group of small muscles that can raise and lower the feather.

By fluffing their feathers, birds create many tiny air spaces that drastically reduce heat loss. On extremely cold nights, birds reduce heat loss further by burying naked body parts into their feathers.

Birds have a network of blood vessels in their feet and legs that minimizes heat loss.

Two or more days without energy food, in severe weather, and a bird will not survive.

In the fall, birds often build nests in nesting bird houses. They have decided to prepare it for cold night roosting. Birds will often pack these little houses although they aren't ideal.

Nesting boxes (bird houses) are where birds lay eggs and raise their broods. They are made for a family.

Roosting boxes are for winter shelter and warmth. They are made for a community.

Many man-made roosting boxes are sold commercially. Do not waste your money on those cute little woven homes - they don't conserve heat or shelter from rain.

Real roosting boxes are rather large wooden structures with perches, grooves or shelves inside. They will accommodate a large number of birds. The perches and shelves keep them from smothering the ones on the bottom. There are few or not vent holes at the top and the entrance is near the bottom so body warmth doesn't escape. When hanging the roost, face the opening south and shelter from the wind. Hang about 12 feet off the ground.

The same birds that nest in cavities and nesting boxes will use roosting boxes. One blueprint source for roosting boxes is http://allaboutbirds.org/

"Poor indeed is the garden in which birds find no homes." Rev. Abram L. Urban, author.