What types of flowers do you have? If they aren't the types of flowers favored by hummingbirds, you could add some hummingbird-friendly flowers and attract more hummingbirds. Hummingbirds will roost in shrubs as well as trees, so I suspect there is plenty of cover for them in cold weather. Adding a few trees might help attract them year-round.

Regardless of wether you have hummer friendly flowers or not they will still come to your feeders if you keep the nectar fresh, in phoenix I suggest every day, at least untill you get some then every other day. Fresh nectar is a must when it is hot or they will go elsewhere, good luck.

Is that Phoenix Arizona? If so then I don't think you have anything to worry about in winter. The maps in the books I have show that hummingbirds normally live there year round. But there may not be enough food (insects) and shelter for them in summer for you to have more than two. Try planting a couple of desert shrubs in your yard that they can get shade and build nests in.

I have planted a number of flowering plants(do not know all their names right now) but all geared towards the humming birds.. recently tore out 8 plants that were called Russian Sage.. pretty but not the plant for hummers.. Replaced them with the Butterfly bush. YEAR AROUND.. No.. they all go except two that stay at my place... in the colder(chilly) times, I actually warm up a little.. the nectar and put it out... Four trees(ficus) died due to an extraordinary/unusual winter here in Phoenix and will replace them eventually with fruit trees.. but did try a type of bird house for the hummers but did not work

I was just trying to say that the maps in the books say that you SHOULD have hummingbirds year round. And you DO. If you only have two in winter, maybe that's how it's supposed to be. Maybe the ones that go are the ones that can't stand the winter and the ones that stay are the ones that can tough it out. The books say that Anna's is the winter hummingbird where you are and that they nest in winter, so maybe its a territory thing. Or maybe there's not enough food and shelter nearby for more than two. Maybe planting flowers isn't good enough if the other habitat isn't there. That's why I suggested planting some shrubs for shelter. I hope you don't take this the wrong way but I think you should learn to trust nature more - those birds have been surviving for millions of years without our help.

Well.... I have been criticized because I keep FEEDERS OUT ALL WINTER.. Garden people HERE(and bird lovers) state that everyone SHOULD stop putting their feeders out in October so the hummers can migrate to Central America.... Critics say that yes, I have 2-3 hummers at my place BECAUSE I KEEP THE FEEDERS out

Your critics are wrong. The books written by real experts say that even in Alaska and Minnesota and Maine you can leave hummingbird feeders out as long as you want and the birds will still leave when they need to. If not wouldn't they all just stick around up north indefinitely and starve to death when the first frost killed the flowers? If you need something in writing to back you up, try Enjoying Hummingbirds More by Nancy Newfield or the Peterson Guide to Hummingbirds by Sherri Williamson. They're both bonafide hummingbird experts that post on other forums. And maybe the Audubon Society can recommend a hummingbird expert who can give a talk to your garden club about hummingbird myths. Those people could use some straightening out.

Here are a couple of links I found with Google:

http://www.birds.cornell.edu/pfw/News/HummingbirdsInWinter.htm
"During the last FeederWatch season, a number of CostaÂs and Black-chinned hummingbirds wintered in the Phoenix area and points south, and AnnaÂs Hummingbirds were frequently seen across the state."

http://www.sabo.org/hbfaqs.htm#migrate
"If you live along the Gulf or Pacific coasts or in the desert Southwest, you may have hummingbirds visiting your yard all year long."

I also checked the Audubon Christmas Bird Count website and on the latest count in Phoenix on December 19, 2006 they counted 23 Anna's and 2 Costa's. And I'll bet most of them were seen around feeders.