Ruby-throated Hummingbird

Anna’s Hummingbirds
Surviving Winter

Anna’s Hummingbirds are an interesting species,  but some details about them are frequently misunderstood, especially regarding their winter habits. These birds once ranged from northern Baja California north to the San Francisco Bay area.

Over the past 100 years, Anna’s Hummingbirds’ began to expand their range northward and eastward. These hummingbirds can now be found as far north as southern British Columbia and, along the coast into southern Alaska. The eastward expansion has taken these birds from southern California into western Texas. Northern populations (Oregon and north) are also slowly expanding eastward in recent years. Some individual hummingbirds have now been seen as far East as Boise, Idaho, in winter. 

Range Expansion

It is not known what prompts birds’ range expansion but it is thought that an increase of exotic plants aided the Anna’s Hummingbirds’ range expansion once it began. They were already seen year-round in California but much of the land east of California was barren and not well-suited to support them. As white settlers moved into these lands, they frequently planted exotic plants, many of which proved to be attractive to Anna’s Hummingbirds, both in terms of providing nectar as well as attracting insects that the birds could then also eat. Much later, it became popular for people to put out and maintain hummingbird feeders, which also benefited the birds. Many of these small insects are important food sources for hummingbirds.

Food Needed 

But, all hummingbirds need more than just nectar to survive. They need proteins and other micronutrients that they get from insects, eggs on plants and spiders, an important part of their diet. People mistakenly assume that these insects and spiders are not available during the cold winter months, but that is not the case. Actively flying insects are dramatically reduced during long cold periods, but many other insects can be found on plant surfaces, and there are over-wintering egg masses or larvae as well. Anna’s Hummingbirds are very good at finding these!

Studies of captive Anna’s Hummingbirds show that they can exist on pure sugar water for about 10 days, although then they show significant weight loss. So more than sugar is needed and these other nutrients come from insects, spiders and their eggs throughout the year.

If you care about hummingbirds, attempting to provide extra nutrients besides nectar is to possibly put the birds at risk! Hummingbirds have very tiny bodies and providing even small amounts of micronutrients could be far in excess of what is needed. The quantity of such nutrients (boron, copper, etc.) would have to be measured in 10-thousandths of a gram. To weigh out such a small amount requires an analytical balance costing several thousand dollars—not something you can do at home. Such small quantities are easily obtainable in a hummingbird’s daily diet, even in winter’s cold. Proteins are also obtained daily from the insects and spiders. Providing more is completely unnecessary and the excess could put the birds at risk.

Do NOT Add Red Coloring

It is also completely unnecessary, and probably unsafe, to add red dye. Some makers of commercial hummingbird nectars add red dye and tell you that there are no studies showing any harm to hummingbirds from red dye. Technically, this is true: there are no such studies. However, there are some very good studies done in Japan showing a dramatic increase in cancers, especially of the gut and colon, in mice that were fed red dye. Since the size and physiology of mice and hummingbirds are similar (hummingbirds weigh less), there is every reason to believe that tumors could also be caused if hummingbirds were fed similar concentrations of dye. There are records from hummingbird rehabilitators that show damage to birds that arrive in care with red dye in their system from eating at feeders containing it. A study on hummingbirds really isn’t necessary when we already have sufficient data on similar sized animals that shows harm was caused.

Most hummingbird-favored flowers are red, and tend to be tubular, downward-pointing and odorless, characteristics that help prevent insects from enjoying them, to compete for the nectar. Red color on the feeder is fine (although, completely unnecessary), but definitely avoid any red color in the nectar.

Anna's Hummingbirds' Movements

Anna’s Hummingbirds are the only hummingbirds north of Mexico that do not migrate latitudinally: north to south. Since they are in various places within their range all year long, it is easy to assume that the birds at your feeders during the spring and summer are the same birds you see in the winter. Many studies now show that that may not be the case: many birds may move about during different parts of the year. There is much about Anna’s Hummingbirds and their movements that we still do not know, but it is clear that many populations do have annual movements, which may vary from population to population. There are Anna’s Hummingbirds in southern California that move eastward into the mountains after breeding. Some populations in the central portions of California may be sedentary, but others may wander to unknown areas. Migratory movements  of birds north of California are largely not understood; some appear to move eastward and it’s thought that some move to coastal areas. Aside from whole populations moving, individuals are known to move to different locations from season to season. So don’t assume that if the number of hummingbirds at your feeders diminishes over the course of the winter that it means some birds have died. It is much more likely that individuals have simply flown off to a different location.

Activity Changes

After breeding and after juveniles have fledged, many people see a decrease in activity at their feeders. From mid to late summer, this may be in part because there remains an abundance of flowers and insects available and feeders are less important. But, it could also be because some of the birds have left your area and moved to a different location. Birds returning in late summer to fall may actually have bred elsewhere and have only recently found your feeding station. They may stay through the winter or they may move elsewhere later.

Erroneous Assumptions?

Additionally, assuming that cold weather has killed many Anna’s Hummingbirds is likely an erroneous assumption in most cases. These are very hardy birds that are able to survive very cold weather remarkably well. Not many years ago, there was a period of prolonged sub-freezing temperatures in Eugene, Oregon. There was fear that many hummingbirds would die from the cold and decreased food supply. However, just a couple of weeks after the bitter cold ceased, the annual local Christmas Count found a record number of Anna’s Hummingbirds. So these birds survived quite well. During cold weather, hummingbirds may depend on feeders more than at warmer times, but other foods are still found and relatively few birds are lost. 

If you keep your feeder up, fresh with nectar, making sure it does not freeze in extremely cold weather may be important at that time. Such condition are hard for the birds to survive for long periods of time. Using a heated feeder that keeps the nectar from freezing is often a good idea if really cold wether. Making sure you have two feeders on hand and swap them before dawn can work, thawing nectar each morning and replacing it before putting a thawed feeder out, etc. and all known strategies for making sure the nectar doesn't freeze over. Now there is a feeder heater called the Hummer Hearth, too, a hummingbird feeder heater, too, designed and made my a retired Northwest engineer!

What Nectar Proportions to Use!

There is much misunderstanding about what to feed hummingbirds, especially during cold weather. The correct mixture you should use in your feeder is 1 part sugar and 4 parts water. Use this ratio throughout the year! The nectar in the flowers that hummingbirds prefer is nearly a pure solution of sucrose and usually contains 20-21% sugar (a 1:5 ratio). Pure white table sugar is sucrose, and this most closely mimics what is found in flower nectar, and is the sugar hummingbirds prefer and best tolerate. Don’t use any other type of sugar! Period!

Hummingbird Studies

In controlled studies, hummingbirds presented with sucrose, glucose (also called dextrose), fructose and maltose will always feed primarily on the sucrose solution and largely avoid the other sugars. Many other kinds of sugars cannot be digested at all by hummingbirds. Highly processed pure, white table sugar only is what should be used at all times. Avoid organic sugars. Most organic sugar that you buy is less pure and may contain contaminants. These may be irrelevant to us humans, but can easily become concentrated in the very small body of a hummingbird. More importantly, the pale tannish color of most organic sugars is due to molasses residues, and hummingbirds cannot digest molasses. Why provide them an unnatural food when pure sucrose is what they would be normally feeding on in nature? Of course, never use any artificial sweetener! That is not what’s in flowers! Artificial sweeteners provide no nutritional value whatsoever to the birds, and if they fed on it, they would soon starve. Honey is also to be avoided; it is not a natural food, being a product manufactured by bees. No hummingbird would feed on honey in nature, and it is composed of many different kinds of sugars, many of which a hummingbird cannot digest. Additionally, many honeys can contain fungal spores that can infect the tongue and gut of a hummingbird making it difficult or impossible to feed. If you see a hummingbird with its tongue continually extended, unable to retract, it may be a victim of such a fungal infection.

As I indicated, most hummingbird flowers have a sugar ratio of 1:5. Most knowledgeable bird experts recommend using a sugar ratio of 1:4. Sometimes, uninformed people suggest increasing the sugar ratio to 1:3 during the winter in the belief that the higher sugar provides more energy to the hummingbirds. This is NOT a good idea if you care about hummingbirds’ health. Rufous Hummingbirds may like sweeter nectars and are easily attracted to this mixture, but Rufous Hummingbirds are NOT found in the Pacific Northwest during the winter. Anna’s Hummingbirds, which are the only winter hummingbird in the Pacific Northwest, prefer less sweet nectars in the wild. While they will drink a 1:3 nectar, it is harder on their bodies physiologically.