Anna's Hummingbird - a year-round resident of Las Vegas

How could a hummingbird stay all year in Las Vegas? Anna’s hummingbird does just that.While summer temperatures in Las Vegas hover near the 110 degree mark, winter temperatures regularly drop down into the 20s. Surely nothing as fragile as a hummingbird would want to live here all year. How does Anna's manage it?

By Alan Vernon [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

·         Resident: If you look at the range maps, Anna’s does not live in Nevada. Sorry, they are either wrong or outdated. Possibly Anna’s is able to stay in northern climates during the winter because it has access to plenty of sweet nectar in the form of hummingbird feeders and temperatures are getting warmer.

·         Cold Adaption: Anna’s has two ways of handling the cold nights. The first way is the yo-yo principle. It eats so much during the day it gains weight – this doesn’t have to be much, it weighs less than two pennies. Then at night it burns its reserves to keep it warm. It also has the ability to go into a state of suspended animation called torpor when nighttime temperatures drop too low or it didn’t gain enough weight during the day. At this time the bird’s body metabolism falls as much as 95% so as to burn as little fuel as possible. Its interior temperature lowers to just above the critical point. If it went down any further the bird would die. This enables the bird to survive the cold nights winter or summer, but it also means it takes time to awaken in the morning. No rise and shine for this hummer.

Feeders are kept busy in the early morning. I often see an Anna’s hummingbird at my feeder in Las Vegas NV before sunup. As soon as there is enough light to navigate by, the Anna’s is refueling at the feeder. In the evening, long past sundown, but before it is truly dark, the Anna’s is at my feeder taking long drinks of sweet water. This is its last chance to get the energy it needs to stay alive through the cold night.

·         Song: The Anna’s is a rarity among North American hummingbird because it has a true song that it sings from a perch. It sits on a tree limb and chatters away: chee-chee-chee with a sharp chip thrown in.

·         Keys to identification: It is slightly larger than three of the other species that frequent my patio feeder in Las Vegas. The flash of bright red throat and forehead on the male clinches its identification.