|Black-Chinned Hummingbird (Archilochus alexandri)|
L=3.75" (10cm). Males and females both are green above. Males have
black chin with violet band (seen only in the right light) beneath that
contrasts sharply with white throat. Females have white chin and throat
that may show faint, green streaks. Call is a soft "tchew."
Hummingbirds are "warm-blooded" (endothermic) animals, thus generate their heat metabolically (physiological thermoregulation), using energy from their body to maintain their high body temperature (105-109 degrees F). Being an endotherm and maintaining a high body temperature is like keeping a car running constantly (to keep the engine warm contantly). Being small, hummingbirds have a large surface area to volume ratio, thus lose heat quickly (like a car running contantly, but with a very small gas tank). To replace the lost heat energy, hummingbirds must eat frequently (about 15 times/hour) and must eat great quantities of high energy foods. Hummingbirds may consume nectar weighing over 8 times their body weight per day! Because nectar is mostly water, this actually is equivalent to close to their body weight in solid food each day, and the rest comes out as urine (this is why you never want to stand under a hummingbird). Hummingbirds will starve to death in just two hours when their engines are running, so at night and other times they cannot feed, they must shut down their "engines." They will find a safe perch and allow their body temperatures to drop close to the outside temperature. This dropping of the body temperature below the temperature they keep it when active is called torpor. During torpor, hummingbirds reduce their energy and water expenditures dramatically, allowing them to survive.
Hummingbirds tend to be very territorial and can be very aggressive around feeding territories (e.g., area around your hummingbird feeder), courtship territories, and nesting sites. After mating with the female, males, uncharacteristically for birds, play no more role, leaving nest-building, incubation, and feeding of the young (usually 2) up to the female (commonly takes about 5 weeks before young fledge [leave nest]).