Biology Reference
In-Depth Information
Black-capped Chickadees
can use an old Downy Woodpecker cavity or bird house;
or they can excavate their own cavity in a rotten section of a birch, aspen, or other soft-
wooded tree. Once the cavity is excavated, usually by both the male and female, the fe-
male builds the nest inside. She starts out using moss to form the bottom and sides, and
then lines it with softer material such as rabbit fur.
House Wrens
nest inside old Downy Woodpecker or chickadee cavities, inside bird
boxes, and inside all manner of other small spaces. Wrens have successfully nested in-
sideoldboots,overallpockets,truckaxles,fishcreels,andcowskulls.Themalechooses
as many potential nest cavities as he can find, covering the bottom of each with a plat-
formofsmall sticks. The female chooses the onemost toherliking andfinishes building
theactualnestinadepressioninthestickplatform;shelinesthiscupwithsoftmaterials.
Tree Swallows
nest in old tree cavities or bird boxes. Females build the nest, which
they line with feathers, mostly brought by the males.
Common Loons
build their nests along a shoreline or on a mass of floating vegeta-
tion.Experiencedpairspreferfloatingmassesorfloatingartificialnestplatformsbecause
they rise with water levels and aren't as readily flooded as a shoreline nest. Both adults
work fairly equally on the nest, pulling or retrieving vegetation adjacent to the nest or
from the lake bottom, and then tossing it sideways onto the nest. They both shape the
nestbysittingandcontouringthematerialstotheirbodyshape.Whilesittingonthenest,
they may pull materials from their surroundings to add to the nest. Early in the season,
it usually takes more than a week for a pair of loons to build a nest, but later on it may
take only a single day. This may be partly because they're more hormonally primed later
on,partlybecausemorevegetationisavailablefurtherintothespring,andpartlybecause
late nestings may be replacement nests when the birds are in a bigger hurry to finish.
The Baltimore Oriole
female builds her complicated hanging nest in three stages.
First, she constructs the outer bowl of flexible plant, animal, or human-made fibers that
can be very coarse — these provide the structural support. After she's put together the
basicskeleton,sheoftenworksfrominsidethenestaddingmorefibers,especially asshe
movesontothenextstage.Atthatpoint,shebeginsweavingmorespringy,flexiblefibers
into an inner bowl, which fills in spaces and maintains the nest's shape. Finally, she adds
downy fibers to line the nest. It usually takes her about a week to build the nest.
Barn Swallows
work together to build their nest, though the female seems to take a
leading role. Both birds collect mud in their beaks, often mixing it with grass stems to
form rounded pellets, the basic “bricks.” As soon as they form a new pellet, they fly to
thenestsiteandattachit,firsttoawallorotherverticalstructure,ortothetopofabeam,
eave, or other horizontal support.
Little by little they construct a narrow mud shelf, just big enough for them to sit on,
and then build up the sides to form the inner bowl. If it's attached to a vertical wall, the
