The Feeder Flood:

One Hobbyist’s Answer to Attracting Hummingbirds to a Small Suburban Plot

By Wigi Tozzi

An extended visit to the Silicon Valley area of California rekindled my interest in hummingbirds. I had the good fortune to stay with a friend who lived in a house in an established suburban location. A male Anna’s Hummingbird (Calypte anna) held a prominent perch above the back yard. He would spend most of every day there, singing and chasing the occasional intruder. I purchased two commercially-made hummingbird feeders and placed them in the yard. After about a week, I observed the hummingbird (as well as other songbirds, including a nesting pair of hooded orioles) using the feeder.

I had lived in the area previously, and maintained hummingbird feeders. One observation that I had made was that by adding more feeders to my plot, I would attract more hummingbirds. However, the layout of my friend’s yard did not lend itself to attracting lots of birds, because it is quite small, with an open area in the center, surrounded by hedges and small trees. There were a limited number of locations that I could place feeders that would not be easily guarded by a male hummingbird from any one of several locations, including the telephone wires or the tops of trees.

I noticed that I would have an occasional visitor to the yard that was not the dominant bird. However, these visits were infrequent, and only at times when the dominant bird had set off on his trapline.

This location is in many respects a very good location for hummingbirds. The lot is in an established residential neighborhood with many large trees of various types. Like many residential neighborhoods, many of the yards are landscaped with annual and perennial flowers and trees that attract nectar seeking birds and insects. A small river runs nearby, which flows year round. The river right-of-way itself is wooded with significant native plants and wetlands bordering the water. Human access is limited by fencing. The lot itself is quite small, but has four fruit trees. All of these trees have fruit on them much of the year, and have significant numbers of dead but standing branches and twigs. The trees and their fruit attract a number of small flying insects.

Over a period of months, I built and experimented with a number of feeders and placements. I experimented with different color feeders, and arranging them in different ways in order to improve the number and variety of hummingbirds in the yard. I noticed that as the number of feeders increased, the ability of dominant birds to defend the entire yard became less. A larger number of feeders prevented a dominant bird from monopolizing the feeder resources. If the dominant bird was feeding or chasing, not only was he not watching for other intruders, but the number of possible locations for intruders had increased. Dominant birds began dividing the yard into smaller territories in order to direct their attention in the most effective way. The result was an increase in the number of territories, an increase in residents, and an increase in occasional visitors.

In building and placing feeders, I made an assumption about hummingbirds and their perception of feeders. I assumed that for a hummingbird, the size of the reservoir of stored nectar was not important, provided nectar was available when the bird visited. In other words, the desirability of a feeder from the perspective of the bird is independent of the size, provided the feeder is kept full. The only significance the size of a feeder had was in relation to the period during which I would have to service the feeder. If a feeder had a large capacity, it would be serviced less frequently than one with a small capacity, for a given level of feeding activity.

This assumption provided me with an important degree of freedom. I chose to focus my attention on building small feeders. These feeders were easy and quick to build, could be moved easily, and provided a source of food for hummingbirds. Each was able to hold ½ ounce of nectar. By building small feeders, I could create a significant display of “flowers” for the birds to see, and they would reliably produce nectar, provided I kept them full.

Eventually I began attracting between five and ten hummingbirds a day to the lot, and some feeders were more popular than others. Within an hour, a ½ ounce feeder could be depleted by birds. At the same time, a feeder just a few feet away might go three or four days without a significant drop in level. As I added feeders and the number of birds increased, the interval between fillings of the small feeders got shorter, to the point where many needed to be filled between two and four times in a day. I began to shuffle feeders around, so that larger-capacity feeders were in preferred locations. However, this was not a complete solution, because the birds seemed to have preferences for certain shapes and colors over others, and would remember the old shapes and colors when seeing them in their new locations. Thus, birds changed their feeding habits in response to the location, color and design of the feeders (independent of capacity).

The number of birds visiting continued to increase, so I modified older or built new feeders to hold larger amounts of nectar. In addition to the increase in number, I have also observed at least two other species of hummingbird visiting, black-chinned (Archilochus alexandri) and a member of the genus Selasphorus (either S. sasin or S. rufus). The number of birds now visiting has become too large to estimate from visual counting, because many of the individuals are juvenile birds, and their markings change daily as adult plumage becomes more prominent. Also, there are often as many as 20 individuals in the plot at a time in the air engaging in displays and moving from feeder to feeder. Each of these three or four species appears to have different tolerances for territorial violations, and so this mix in the current situation is very interesting to watch.

The current configuration of feeders in the yard is one that I have arrived at in order to address several issues. First, I want to attract as many birds as I can to the yard within reasonable levels. While hummingbirds are nimble fliers, from a practical standpoint, the density of birds in the yard at one time is probably reaching its maximum during high traffic times. Even at low times, at least three or four birds can be seen in the yard at any given time. Second, given the number of birds, I want to optimize the nectar capacity of the feeders in place. I still maintain a small number of ½ ounce feeders, but use them to keep an even physical distribution of “flowers” in the yard in order to reduce the amount of conflict between individuals. The remainder of the feeders range in capacity from two to eight ounces. When a feeder location becomes popular, I move larger capacity feeders into that location. Ultimately, my goal is to make each feeder carry between one and two days worth of nectar. Thus, I will be able to refill and clean feeders by making rounds once a day.

For the purposes of this discussion, I would like to use the following notation to describe the number and location of feeders in the plot. All of the feeders that I have built have a single “flower” or opening where a hummingbird can get nectar. Some commercial feeders have multiple “flowers” so that more than one bird can feed at a time. For the sake of this discussion, I will use “flower” and “feeder” to mean feeding ports at that location, whether it is a single feeder with multiple ports, or multiple feeders with single flowers at a single location. My reasoning is that hummingbirds that are defending feeding territories are not defending objects, but rather areas within which they have found nectar. For some, that is a single feeder, and a single “flower”. For others, it might be three or four feeders encompassing ten flowers. When they choose not to defend their territory, it does not matter whether the “flowers” are attached to a single device or a number of devices at a single location. From the perspective of the bird, each “flower” is separate from all the others, even if it is on the same feeder (which helps to explain why a bird might feed from one “flower” and fly to an adjacent perch and feed again from the same feeder, but a different port).

The following diagram shows the number of feeding ports (flowers or feeders) at each location, and the total nectar capacity (in ounces) of the feeders at that location.

If every feeder is filled to capacity, there is a total of 92 ounces of total nectar capacity in the yard. However, the total nectar consumption (hummingbirds + bees + leakage) is approximately 30 ounces a day. Most of the feeders are kept at a level of about 60 percent of capacity.

From these figures it is possible to estimate the number of individuals visiting the yard on a regular basis. This method has some inherent inaccuracies, but is probably correct to within 25 percent. To estimate the number of individuals visiting the yard, I make the following assumptions:

Given the large number of honeybees in the yard, and the amount of leakage from my homemade feeders, I will assume that only 20 ounces of nectar reaches the hummingbirds each day.

If we choose the median values for the ranges above, then the number of individuals visiting the plot:

Total calories going to hummingbirds = 24,000 X 20 ounces = 480,000 calories (480 kcal)

Average hummingbird receives 40 percent of daily calories (12,000 X .40 = 4800)

Total calories / calories per hummingbird = hummingbirds

480,000 / 4800 = 100 hummingbirds

I don’t believe this number to be an exact measurement of the number of birds. However, I would say that the number of visiting birds is closer to 100 than it is to 10. Increasing the calorie contribution to 80 percent of 12000 calories per day still leaves 50 individuals.

Given the above calculations, each ounce of nectar consumed per day probably supports between 3 and 5 hummingbirds.  

Throughout the process, I noted that my philosophy about what I was trying to achieve changed as I made progress. At first, I simply wanted to attract hummingbirds to the yard. Hummingbirds are by their nature curious and thorough, so eventually a feeder placed in the yard will be found. However, the gardener who wants to attract hummingbirds generally wants relatively quick results. A quick scan of the available literature (especially that which is online) suggests that feeders be placed in shaded locations. There are lots of good reasons for this, including keeping the nectar from fermenting and keeping feeders from leaking (inverted bottle-type feeders may leak as the air gap in the top of the bottle expands with warmer temperatures, and pushes nectar out of the ports). However, shaded locations are often difficult to see from above, and objects within the shade are certainly more difficult to resolve visually than the same object in direct sunlight.

I found that the best way to address this issue was to place feeders in easily visible locations when first starting out. If you can afford to do so, or are handy, placing multiple feeders out increases the chances of being noticed by a passing hummingbird. My experience (in California) has been that the birds will find your feeders in about a week or two.

While I was establishing a new hummingbird feeding sanctuary, I was concerned about the possibility that a new hummingbird would happen across the yard at a time when I was cleaning the feeders. While the chance of this is probably small, if you have a small number of feeders, you can ease your mind about this issue by waiting until after dark to handle your feeders and refill them. At this stage of the game, a typical feeder would hold at least three to four days worth of nectar, if not more. If your nectar in a typical feeder (between four and eight ounces) is being emptied more than once in two days, you either have a significant amount of bird traffic, or a leaky feeder or nectar-seeking insects. In typical summer weather, especially when it is very hot, or the feeder is in a very sunny location, you will need to change the nectar daily, regardless of its capacity, because of the potential for bacterial and fungal growth in the nectar.

Once you have a regular group of birds visiting your feeders, your needs will change. While it is entertaining to watch hummingbirds engaging in territorial displays, these generally will reduce the total number of birds visiting your garden, especially if the feeder or feeders can be seen from a perch that commands a good view of incoming trespassers. I dealt with this change by introducing new feeders in rather secluded locations, favoring cool, shady spots, while leaving old feeders in their locations. Eventually the new feeders will develop a following. When they do, you will notice that birds will take up perches in the yard to defend their territories, but that those territories will be much smaller than they had been when there were just a few birds. I also change my philosophy about filling the feeders in the presence of birds, once I reach this stage. I want the birds to see me handling the feeders, and to get used to my presence around them. I make it a point to add nectar and change feeders during daylight hours.

This strategy can quickly get out of hand, because maintaining a large number of feeders becomes time consuming. This leads to the third philosophy change, which caused me to watch the amount of nectar consumed at each location, and place larger capacity feeders in the more popular spots. My goal is to make the garden so that it only requires attention once a day.

You will note that while I refer to this plot as a garden, I do not talk about planting hummingbird-friendly plants. In this particular case, my ability to make changes to the landscape was limited because I was not the owner of the property. However, there is no question that maintaining garden plants that encourage hummingbirds may be every bit as important as maintaining feeders. Nonetheless, in California, and other arid and semi-arid areas, the contribution to the well-being of hummingbirds made by feeders is great as the number of native nectar-producing plants goes down due to months without rainfall. In urban areas, this is offset somewhat because of the high degree of irrigated landscaping that contains nectar-producing flowers.

Notes:

Orme offers information as to the number of calories burned by a hummingbird during its migration across the Gulf of Mexico. I use this figure as an approximation of the number of calories consumed by a hummingbird on a typical day, acknowledging that daily foraging is not as demanding as migration, but that growth and the need to store energy as fat makes his figure a reasonable estimate of the number of calories consumed in a day by a typical non-migrating hummingbird.

References:

Orme, F. (2001). Energy units. Biology 1A online notes. Available at: http://members.aol.com/BearFlag45/Biology1A/Reviews/energy.html

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