Nest-building styles

Birds certainly have a range of both nest-building styles and sites. Sites are usually chosen to be accessible to food, and inaccessible to predators — including humans. Nevertheless, a few species have discovered that human structures meet their needs better than natural sites. I show three styles seen this last week, sticks, moss, mud, but all built on human structures. 

Ospreys eat fresh fish and so a lakeside nest is ideal. I have seen osprey nests back from the water’s edge and in trees, but most ospreys around here have discovered that few sites meet their needs better than a structure humans have erected in the water, such as, dolphins, bridges, and pilings. This osprey has just built its stick nest on a pylon (marking underwater cables) which was erected only last year.

Dippers seem to favour the underside of bridges where they build domed nests of small sticks and moss This site has been used before, but in the spring it gets rebuilt. The site over a raging stream is beautifully protected from land predators, while the bridge deck fends off rain and diving falcons. When the nest is completed, there will be a small opening on the side (see last year’s pictures of the same site: dipper nesting, dipper chicks). The dipper on the left has flown in with a beak full of moss. A second dipper inside the nest appears to be tamping moss around what will become the small opening.

Cliff Swallows once built their nests on cliffs, but have discovered that buildings and bridges work beautifully and even offer overhangs to protect them from the rain. These swallows build their nests out of about a thousand mud pellets which are first fashioned and then carried to the site individually. These nests are under reconstruction.

Here a Cliff Swallow is about to place another mud pellet.

The swallow that was working on the nest’s interior is now flying off for more supplies while the other one is tamping a pellet in place around the nest’s opening.

“Hey, you down there, hurry up with that mud; we have a schedule to keep.”