Biology Reference
In-Depth Information
into the water. They don't call during this dance, but the pattering of their feet on the wa-
ter is distinctive and thrilling to witness.
Greater Sage-Grouse, Greater and Lesser Prairie-Chickens, and Sharp-tailed Grouse
— all large chicken-like birds of the American West through the northern plains — have
wonderful displays. Males gather together on a breeding ground called a
lek,
inflating
brightly colored air sacs, stomping their feet, erecting some body or head feathers, and
openingtheirwings.Femaleswanderthroughandchoosethemaleswiththebestdisplays
to mate with. These grouse form no pair bond: the females build their nests and care for
eggsandchicksentirely ontheirown.They'llflyinfromseveralmilesawaytoalekking
ground to choose the finest males.
Many species of manakins, from Central and South America, have amazing displays,
Orange-collared Manakins. In these, males clear a patch of ground as a lek and leap back
andforthbetweenthinuprightbaresticks,givingaloudwingsnapwitheachjump.When
afemaleispresentmalesjumptogether,crossingeachotherabovethebaredisplaycourt.
They erect their throat feathers to form a beard during displays.
Many male hummingbirds have spectacular courtship flights to attract females. For
example, the male Calliope Hummingbird, the tiniest North American species, living in
the mountainous West, makes a spectacular dive: climbing to about 100 feet (30 m) and
then plunging at high speed and braking abruptly, then climbing again, following a U-
shaped trajectory. During this, the flight feathers make a buzzy
hum.
Many tropical wrens have an auditory rather than a visual courtship display, singing
elaborate duets so seamlessly integrated that it can be difficult to discern that more than
one bird is singing.
Q I was watching birds at the feeder and noticed a male Rose-breasted Grosbeak
feeding either its mate or a fledgling, which was perched very close by waiting for
the male to bring it seed. Why wasn't the female or fledgling going to the feeder it-
self?
A
During courtship, males sometimes offer food to females — the females may use this
to determine how good a provider each of her suitors could be. After the babies fledge,
it takes them a while to figure out what foods are appropriate to eat, and they may still
be clumsy fliers. So it is probably safer for a young bird to sit in the relative shelter of a
shrub while the adult flies through the open to and from the feeder bringing it food.
Birds of a Feather
Q Why do robins lay blue eggs? Is it possible to tell males and females apart?
