When I moved to Bellevue this year I was happy to see my first Anna's, and
astonished when my neighbor said that they stayed here all winter. So, I
have kept the feeders running, and have recently been weighing them each
night to track consumption. I have also used a web cam with motion detection
software to get some idea of the number of birds using the feeders.



I make the sugar solution to about 50 Brix (% sucrose by weight); though in
the recent cold snap I increased this to 70 Brix. I have since gone back to
50 Brix after reading that too concentrated a solution may cause liver
problems. More on the birds' reaction to this later. The advantage of
tracking the sugar solution strength in Brix is that it is simple to convert
the reduction in feeder weight to grams of sugar to kilocalories (1 gram of
sugar = 3.75 kCal).



Territory.



When the dominant Rufous male (Eric) left in the early summer, his position
was taken up by a young Anna's male (Attila). Eric was content to spend most
of his time in a low tree located close to the two backyard feeders, from
where he would drive off most other hummers as they approached the feeders.
Attila also uses this tree, but also uses three other, larger, trees, from
where he launches his attacks as soon as an intruder is detected. The
pattern in which he uses the trees, plus the perches he selects in them,
leads me to believe that the same bird has maintained this territory since
Eric left.



Attila is now fully developed, and for the last six days has been busy
singing to, and doing dive displays for, visiting females. There was an
intruder male today, who perched in one of Attila's trees. Attila went
through the whole song and dive display ritual, and then attacked and drove
off the visitor. I recently added a third feeder at the front of the house.
This was found by female(s) almost immediately. Two days later Attila found
it also, and added a fourth tree, from which the new feeder is visible, to
his patrol route.



Sugar consumption.



Starting out with two feeders, the daily consumption averaged about 12g of
sugar. Just as the cold weather started I wanted to set up a web cam to
track the number of visits, so I went to a single feeder. At the same time I
increased the solution to 70 Brix. The next day the consumption went up to
14g, and then dropped to about 9g for each of the following two days. I
think that the birds regarded the two feeders as independent food sources,
and were now going elsewhere for more of their needs. This theory is backed
up by the fact that Attila was missing for significant amounts of time. I
re-instated the second feeder, and the consumption increased from 13 to 17
to 22 grams for the next three days, peaking on 13-Jan. If then declined
back to about 13g per day, and has remained there even with the addition of
the third feeder, and a reduction in strength to 50 Brix.



Web cam results.



I wanted to try and estimate how many birds were using the feeders. It
seemed to me that a 4g hummingbird would have a lot of trouble choking down
13g of sugar (26g of 50 Brix sugar solution) per day, yet most times I had
observed activity it was either a male feeding leisurely (presumably
Attila), or a brief visit by another bird that was cut short by an attack
from Attila. So I rigged up a web cam hooked up to a laptop with motion
detection software - this triggered recording whenever the field of view
changed. I can supply details of the set up, and some lessons learned, to
anyone who is interested. Checking the recordings for an entire day, the
following emerged.



Male(s) fed in a leisurely manner for a total of 16 minutes in 10 visits.
The first and last feed of the day were for about 3 minutes. The longest
(second feed, 30 minutes after the first) was for 5.3 minutes. Seven other
visits of 0.5 to 1.2 minutes were spread out through the day.



Male(s), that perched when feeding, managed a total of 3 minutes in 33
visits, probably all terminated by an attack from Attila.



Male(s), that hovered when feeding, got in a total of 2 minutes in 11
visits, again probably all terminated by attacks.



Females managed a total of 18 minutes in 18 visits. Of these 7 were
leisurely (1.0 to 3.3 minutes), the others were terminated by attacks.



My best guess is that Attila accounted for the majority of the leisurely
male visits. At least two other males were present (by feeding behavior). At
least three females were present, as there were three 2-minute plus visits
in close proximity just after the start of the day. The total time the
feeder was occupied was about 40 minutes, and on that day 8.4 grams of sugar
were consumed by at least 6 birds. Unfortunately my camera position was not
good enough to make out details of the individual birds.



Interesting behavior.



I believe that Attila associates me with the feeders. In the fall, when I
would refill the feeders during daylight, he would usually fly around
"chipping" when I took the feeders in, and then shadow me as I took them
back out, often perching on one immediately after I had hung the feeder up.
In the winter, when it is cold, I bring the feeders in late at night and put
them back out very early in the morning, so there is usually no interaction
with Attila.



The exception was on 16-Jan, when I had changed the sugar solution from 70
Brix to 50 Brix. I stepped out of the back door about an hour after sunrise.
Immediately, Attila zoomed down from a high tree, flew right past my head,
perched on the nearest feeder, and then flew past my head again and zoomed
back to the tree - "chipping" all the time. I went back in the house, and
stepped out again about 15 minutes later. Attila went through the same
maneuver. The same thing happened again about 15 minutes later, but the
fourth and subsequent times Attila ignored me. Could this be interpreted as
a protest?



Thanks for reading to the end!





Dave Nuttall

Bellevue, WA

MailTo:dave_nuttall at yahoo.com