more open habitats at other locations in Missouri and elsewhere.
Both sexes return to my
research area in November and
remain throughout the winter
when open water is available, or
return as soon as wetlands are ice-free in spring. I have encountered
courtship throughout winter, and
with higher frequency as spring
approaches. Hoodies select nest
sites where cavities and boxes
are over water or immediately
adjacent to water, a necessity as
hoodie legs are set well back on
the body—well adapted for diving
but not for walking.
Their large, nearly spherical,
whitish eggs are laid at a rate of
one egg every 1. 75 days to create an average clutch of 11 eggs,
which tend to hatch simultaneously about 30 days after incubation
begins—the same as wood ducks.
Early season hatching may take
as much as 34 days when ambient
air temperatures are low, but later
clutches may hatch in less than 30
days. During cold springs it is not
uncommon for merganser eggs to
freeze before incubation begins.
Young are imprinted to female
vocalizations beginning a few days
before hatching. The hatchlings
remain in the nest only 24 hours
after hatching. The call stimulates
young to exit the cavity when a
female is satisfied conditions are
safe for brood movement. At
times female vocalizations chal-
birdwatchersdigest.com • MARCH/APRIL’ 17 • BIRD WATCHER’S DIGEST
lenge us in banding the hatchlings
because it stimulates exit behavior.
A gentle hand on the brood will
settle them down; thus I carry a
heavy rag or use my hat to cover
excitable broods to prevent early
exit. Sharp-clawed toenails enable
the young to climb up the cavity
walls for the exiting jump. They
quickly form a tight group, and
the female leads the way to brood
habitat as soon as all her young
are in the water.
Males depart northward before
incubation is complete, but their
secretive nature and effective
camouflage make it difficult to
determine if northward movements occur before, during, or
soon after egg laying is complete.
Females and young—fledging
occurs around day 70—also head
north. Many direct recoveries of
banded hoodies come from prairie
and forested habitats in Canada
and north-central states well north
of my Missouri banding stations.
The Mergini do not reach sexual
maturity until age two.
Hoodies seem to have a less
precise homing instinct than the
precisely homing wood duck.
Although hoodies return to their
natal area, local movements of
eight or more miles occur, and
individuals are unlikely to use
the same cavity or box in subsequent years.
Hooded mergansers are brood
parasites—they dump eggs into
other hooded merganser nests