Hi all,

Since hummingbirds are migrating back north from their wintering areas
south of the United States, I think this topic is the most important at
this time. Sorry that this is so long, but the problem takes a bit of
explaining and so far, I have not gotten anyone to do anything to save
the hummingbirds from unnecessary death or save eggs and young from
dying while the mother bird is too hypothermic to get back to the nest.
What we need is more people complaining about the problem. I hope that
will help anyway.
In spring of 1983, my husband, a wildlife biologist, observed
something wrong with Rufous Hummingbirds sitting on perches, feeding at
our hummingbird feeders in the cold morning hours before sunrise. He
watched as a male hummer sat on the perch and took several long sips of
the ice-cold fluid. Then the bird fluffed up, slowly tipped over
backward and fell from the perch to the ground. He rushed out and
picked it up, finding that it was still breathing, but very cold. He
warmed the bird by holding it in his cupped hands and blowing his warm
breath onto the bird. After ten or fifteen minutes, the bird had warmed
enough so that it had regained its ability to fly normally and it was
released. Since I am a wildlife rehabber, I followed the bird around
from a distance after it was released, watching it through binoculars
to make sure it was alright. It appeared to be completely fine with no
after effects from its mishap. After finding and warming three more
birds the next day, two hanging upside down from the perch and one on
the ground, we removed the perches from all the feeders. My husband
continued to watch the feeders early in the morning to see what effect
having no perches would have on the feeding birds. He found that the
hummingbirds had no trouble feeding while flying and would take a few
sips of the icy fluid then fly to their favorite branch to digest it,
then back for a few more sips and back to the branch. No more birds
were found on the ground under the feeders and no more problems were
observed. Meanwhile, I checked my rehab records for hummingbird
injuries and found that I had gotten predominantly Rufous Hummingbirds,
predominantly early morning cat or dog bites, predominantly early
spring. That seemed like an ominous pattern.
This was the scenario that we concluded. Hummingbirds normally hover
when feeding. They also normally fly from flower to flower, getting
only a small amount of fluid from each sip. Even early risers like the
Rufous won’t get chilled with that scenario. Enter bird feeders, which
provide large volumes of superchilled fluid to the birds coming to feed
before sunrise. Humans add perches to allow easier viewing.
Hummingbirds that perch while feeding are not generating heat energy
needed to warm the fluid they ingest, and they are eating larger than
normal (what they would get from flowers) helpings of the ice cold
sugar water. If a hummingbird sips a cropful of cold fluid, it lowers
their body temperature as much as ten degrees, or more if the outside
temperature is in the thirtys. After two cropfuls without flying to
generate heat, the birds temperature will be low enough to cause
serious hypothermia and the bird can no longer control its muscles, so
it is not able to fly. We concluded that the Rufous Hummingbirds, by
feeding in early morning, are more likely than other hummingbird
species to suffer Perch Hypothermia (PH) as I named the phenomenon. PH
has been reported being seen by many other people, to several other
species of hummer, especially Ruby-throated Hummingbirds. Any
hummingbird that becomes so hypothermic that it can not maintain normal
flight or falls to the ground is apt to end up dead, often as cat or
corvid food. People usually do not get up early enough to view the
hummingbirds sitting on the perches between 4:30 or 5:00 and sunrise,
so most do not observe PH when it happens to the birds. As the
hypothermic hummers are usually snatched up and eaten by Crows, Magpies
or cats, no evidence is left by the time people get up.
In 1986, after researching the problem and collecting reports of other
observations of PH, I launched a crusade to inform the public about the
problem. I wrote to ornithologists, outdoor magazines, bird magazines
and the local newspapers. I was ridiculed and many said that PH could
not possibly happen. Even after connecting with hummingbird researchers
in Texas who had done controlled studies that showed that Ruby-throated
Hummingbirds’ flight muscles were adversely affected by sitting
motionless on a perch while consuming cold fluid, some people claimed
that I had no scientific proof of the PH "hypothesis." Hypothermia has
long been a proven physical fact, it has not been a hypothesis for
decades. Actually, hypothermia was quite well understood by ice age
cave man.
Unfortunately, after twenty years of trying to have the problem of PH
addressed, the companies that make hummingbird feeders have not removed
the perches or put warnings on the boxes that having perches on the
feeders can have adverse effects on hummers feeding on ice cold sugar
water. More and more people have built homes in western states and put
up hummingbird feeders with perches. In that time Rufous Hummingbirds
have gone from being the most populous species of hummingbird in the
western United States to being placed on Audubon’s species of special
concern list because of precipitous population decline.
I am hoping that others might have advice on how to get something done
about this unnecessary (and according to the US Fish and Wildlife
Service, who did nothing) illegal killing of hummingbirds. Anything man
made that deliberately causes the deaths of migratory birds is illegal.
Putting up feeders for hummingbirds with perches on them is deliberate.

Thank you for any help you can provide.


Judy Hoy
Bitterroot Wildlife Rehabilitation Center
2858 Pheasant Lane
Stevensville, MT 59870 USA