Date: Tue, 19 Jun 2001 13:03:37 -0700
From: ron <ron@NVWETLANDS.COM>
Reply-To: BB for Hummingbirds and Gardening for them in
the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Fwd: species differences in color
vision?

Lanny,
There may be other reasons than color that explain why
hummers choose the
flowers that they choose. John, the sender of the message,
seems to assume
that all flowers that are acceptable to hummingbirds are equally
acceptable. I
don't believe this is the case, because I know Dennis
Demchek. It may be that
the red and orange flowers are better nectar producers than the
nearby blue
and purple ones. Huntington Garden (a great place to observe
hummers) has an
outstanding collection of aloes, which absolutely drip with
nectar and have
flowers in the red/orange/yellow range. These would, I
suspect, be much better
nectar sources than any agapanthus or blue delphinium, and
better than many
blue salvias, just based on the volume and sugar content of
nectar. They also
have other advantages, including height and number of
blossoms. The aloes are
really large. For those who don't live in Southern California,
many of the
aloes that are grown there get shrub or tree sized and may have
hundreds of
blooms at one time. I think hummingbirds prefer taller flowers,
and they
prefer massed flowers of a single type, rather than lots of
different types of
flowers. So perhaps the Annas and Allen's hummingbirds,
which may be the
dominant hummers due to size (Annas) or aggressive nature
(allens?) select the
larger, taller, more abundant aloe flowers, leaving the lesser
flowers to the
costa's and blackchins, which are typically less aggressive.
Bottlebrush ( a
small tree ) and lions tail ( a large shrub in CA) may have
similar advantages
over agapanthus and delphiniums. John might also be
observing a difference in
feeding strategy. Blackchinned hummingbirds, at least those
few that winter in
LA and the ones that I see in my backyard in Reno, seem to
"trapline" rather
than defend a territory. Traplining is the practice of visiting
small groups
of flowers scattered around an area, thus following a set route,
like a
trapper following a line of traps. I don't know about the set
route part, but
they do visit scattered flowers. This strategy may allow them to
coexist with
larger or more dominant hummingbirds, and may help explain
why blackchins
visit different flowers than Annas or allens.

Finally, I will add my own observation. My in-laws in
Whittier, CA (not too
far from Huntington Garden) have several salvias, cupheas,
and other flowers
in their yard, including lots of salvia greggii and its hybrids (in
many
shades of red, yellow, white) and cuphea "david verity" and
cuphea micropetala
- both orangish. When the large purple-flowered salvia
mexicana nearby blooms,
it becomes the favorite flower of the local annas, as well as the
other
hummers, which in dec. through feb when the s. mexicana
blooms, include only
allens. Generally there are lots of flowers on the cupheas right
next to the
salvia mexicana, but the salvia is preferred. I think this is
because the
salvia is much taller and has hundreds of flowers
simultaneously, while the
cupheas are shorter, and have fewer floowrs (but still many).
The cupheas are,
at other times of the year, a highly preferred flower. Sure, it
could simply
be that the salvia has more nectar than the cupheas, but I think
there is
something else at play.

I could be wrong, but I don't believe that some hummers are
more attracted to
flowers of one color instead of another color,a nd I don't
believe that
hummers prefer flowers that are similar in color to the gorgets
of the species
of hummingbird in question. I have heard such a theory
before, and have never
been able to observe any such preference. this might be due to
my limited
experience with blue-gorgeted hummingbirds, and I promise I
will try to spend
more time watching hummingbirds. I think that the nectar
volume and sugar
content, height and and number of flowers, and the position of
a plant
relative to perching places or cover are the things that make a
flower
attractive to hummingbirds. I will keep my eyes open to see if I
can notice
differences in flower use between the hummingbirds I see here
in reno this
summer, but I don't expect to find any clear preferences by
color.

Ron Rovansek
Reno, NV

Lanny Chambers wrote:

> What do y'all think about this theory? [message shortened]
>
> Feel free to copy John NacGregor on your replies.
>
> ---------------- Begin Forwarded Message ----------------
> Date: 6/19/01 11:50
> Received: 6/19/01 13:14
> From: John MacGregor, jonivy@earthlink.net
>
> Over a period of 30 years in Southern California--in large,
complex
> gardens
> with many kinds of plants (the Huntington Botanical
Gardens where I was
> Chief Horticulturist for more than a decade, a commercial
nursery, and
> several large, complicated gardens which I now supervise)--I
have observed
> that in summer when many good nectar flowers of all colors
are in bloom,
> Anna's hummingbirds and Allen's tend to concentrate on the
> pink-red-orange-yellow ones while Costa's and
Black-Chinned usually
> gravitate to blue and purple ones (especially agapanthus,
delphiniums, the
> blue and purple salvias) that the Anna's are ignoring. I don't
claim
> exclusivity for either group, nor do I wish to generalize
about other
> species' flower color preferences. I realize that
Ruby-throated don't
> have
> similar preferences and that even Anna's visit blue and
purple flowers
> when
> other equally-desirable red ones are not available in the
immediate
> vicinity. But when good red or orange nectar sources are
available (like
> bottlebrush, lion's tail, etc.), I don't recall ever seeing an
Anna's
> hummingbird feeding on blue agapanthus, while Costa's and
Black-chinned
> (when the latter are present here) do so consistently.
>
> I first noticed this phenomenon in the early 1970s at the
Huntington
> where a
> planting of deep blue agapanthus, delphinums in several
shades of blue,
> and
> blue and purple salvias were located adjacent to the Herb
Garden where
> several red- and pink-flowered salvias and other nectar
flowers were
> blooming at the same time. The omnipresent Anna's were
entirely occupied
> with the flowers in the Herb Garden while Costa's and
Black-chinned fed at
> the blue-range planting. Since that time, I have made similar
> observations
> hundreds of times.
>
> The only reason I can think of for this is that male
Black-Chinned and
> Costa's hummingbirds have purple gorgets and perhaps
there might be some
> sex-linked preference in their vision mechanism that favors
the blue range
> over red. Could their species' recognition of conspecific
males slant
> their
> color-preferences (or at least color recognition) toward blues
and
> purples?
> Could they see the blue and purple flowers more easily, or at
least pick
> them out against a green background, more easily that
species whose
> sex-related coloring is red?
>

#################################

Date: Tue, 19 Jun 2001 14:39:32 -0700
From: John MacGregor <jonivy@EARTHLINK.NET>
Reply-To: BB for Hummingbirds and Gardening for them in
the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Fwd: species differences in color
vision?

Ron.

which are typically less aggressive.

You are introducing time and place differences into the
equation that were
not in my observations. The aloes at the Huntington bloom in
January, and
the Desert Garden where they are concentrated is at the
opposite end of the
grounds from the Rose and Herb garden areas where I made
my initial
observations. Yes, the aloes are superb hummingbird plants,
and the Desert
Garden is full of hummers in winter, but these are mainly
Anna's with an
occasional Allen's. There is little opportunity to make
comparable
observations in winter because the same species are not
present.

Agapanthus, delphiniums, and summer-blooming salvias like
S. guaranitica
were (and are) the important plants in these observations made
mainly in
summer. My first observation of this phenomenon was made
about 1973. My
most recent one, in a different garden I care for about a mile to
the east
of the Huntington was this last weekend. There have been
many more in
between. The agapanthus and the delphiniums are at their peak
right now and
they are both numerous and spectacular. So, for that matter,
are the
bottlebrushes and the leonotis and the phormiums. Right now
there seems to
be a very definite division of feeding between the Anna's and
Allen's, who
like the reds and orange best, and the Black-Chinned and
Costa's who appear
to favor the blues. This cannot be explained entirely by the
more
aggressive Anna's and Allen's defending the warm-colored
flowers, because
there are delphiniums located in other parts of the garden--well
out of site
of the red and orange plants, and they are still mainly visited by
Costa's
and Black-chinned hummers. There is no attempt by the
Anna's males to
exclude them from these areas.

In the gardens I have designed, I
generally assign a separate color palette to each section. This
helps to
unify the design in plantsmen's gardens with a great diversity
of plant
material. In fact, I believe that this practice is what allowed me
to
notice the phenomenon in the first place.

> I could be wrong, but I don't believe that some hummers are
more attracted to
> flowers of one color instead of another color,a nd I don't
believe that
> hummers prefer flowers that are similar in color to the
gorgets of the species
> of hummingbird in question.

Do you know of any research with a bearing on this question?
What is the
basis of this belief?

> I have heard such a theory before, and have never
> been able to observe any such preference. this might be due
to my limited
> experience with blue-gorgeted hummingbirds, and I promise
I will try to spend
> more time watching hummingbirds.

I would be interested in knowing where you might have heard
this theory
before. I just managed today to formulate it into a a definite
hypothesis
when writing to Lanny. I have never found anyone else who
has even heard
such a suggestion, and the other birders I have mentioned it to
(in a
less-carefully worded version) have rejected it quickly and
without serious
consideration. I have always questioned the validity of my
observations,
but I have noticed this happening repeatedly over three
decades. I know
that many closely-related bird species distinguish mates by
color markings,
and other pollinators, like bees, have definite flower color
preferences
based at least partly upon the physiology of their vision, so I
suggest that
it might be worth investigating. UnfortunatelyI am not
equipped to carry
out these investigations. In case there might be someone else
on this list
who could study them, I repeat my query worded a little
differently:

Male Black-Chinned and Costa's hummingbirds both have
purple gorgets. Might
there be some sex-linked mechanism in their vision that either
favors the
blue range or at least lets them perceive the blue range more
readily than
do red-gorgeted species? Could their species' recognition of
conspecific
males slant their color-preferences (or at least color
recognition) toward
blues and purples? Could they see the blue and purple flowers
more easily,
or at least pick them out against a green background, more
easily that
species whose sex-related coloring is red?

At least you and Lanny seem to have enough of an open mind
to consider the
possibility.

John MacGregor
jonivy@earthlink.net

===================================================

Date: Tue, 19 Jun 2001 17:47:43 -0700
From: ron <ron@NVWETLANDS.COM>
Reply-To: BB for Hummingbirds and Gardening for them in
the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Fwd: species differences in color
vision?

John,
I am happy to agree that you are seeing real differences in
flower use between
hummingbird species, and I stipulate that you have observed
that blackchinned and
costa's hummingbirds prefer blue and purple colored flowers,
while anna's and
allen's hummingbirds prefer warm colors -red/orange/yellow.
The question is why. You
suggest that costas and blackchins select blue and purple
flowers instead of reds
and yellows because they have an attraction to blue and purple.
I suggest that
blackchins and costa's may be excluded from red flowers by
Annas and Allens, forcing
them to select blue and purple. One way to discover which
theory is right is to
observe blackchins or costa's in a place where Annas or allens
are not present, but
both red and blue flowers are. If, in such a place, blackchins
and costas still
select blues, then you may be right, I may be wrong. Of
course, such a place would
be hard to find in CA, and it would be hard to determine that
the reds and the blues
are really equivalent resources differing only in color. But still,
I think that
enough observation might shed light on this. If, in this
imaginary blackchinned
heaven, blackchins select red and blue flowers equally, or
prefer reds, then I may
be right and you wrong. It would also be interesting to observe
annas or allens
without other species present, or even without other members
of their own species
present. I doubt that interspecific competition for flowers
impacts only the less
dominant species; probably both the dominant and subordinate
species are affected,
and in reality it is probably not always the same species that is
dominant.. The
presence of blackchins might encourage anna's and allens
hummingbirds to select an
easily defended patch, or perhaps select a red patch which they
might recognize
instintively as representing a better resource, to defend.

My experience with blackchins includes mainly a few lonely
individuals that end up
in Louisiana in the winter. There I have never observed a color
preference by
blackchins or any other species. It may be that color
differences are observable
only in large open spaces with lots of flowers and lots of
hummingbirds. You may be
right that your designing large, color segregated gardens is
what allows you to
observe color preferences that the rest of us, in
patchwork-colored gardens, don't
see. It is not often that hummingbirds have a wide selection of
good nectar plants
of various colors available in one place.

I think I saw the theory that hummingbirds like flowers that
match their gorgets in
a Golden Field Guide - a really old one. Perhaps Miriam D.
can shed light on this,
since I believe I have discussed the theory with her (and other
HUMNETters?). I
don't currently believe this because I haven't observed it, and
until recently
hadn't even heard of anyone who had. I'll reiterate that even if
hummingbirds do use
flowers of different color according to species, it doesn't
necessarily tell us why
they do this. it doesn't surprise me that birders discount your
theory without
really thinking about it. Birder often belive they know alot
more than they are able
to prove with data or reason. HUMNET was invented to
counteract this tendency, and
it works pretty well.

As for this statement: "At least you and Lanny seem to have
enough of an open mind
to consider the
possibility." I have another, conflicting theory. Perhaps Lanny
and I are just
egomaniacs who have to try and convince everyone we
encounter that we are right, and
we're willing to browbeat or exhaust you with endless emails
if necessary. (I am
pretty sure this is the case with Lanny.)

Ron Rovansek
Reno, NV

==============================================

Date: Tue, 19 Jun 2001 20:26:34 -0500
From: Lanny Chambers <lanny@HUMMINGBIRDS.NET>
Reply-To: BB for Hummingbirds and Gardening for them in
the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Fwd: species differences in color
vision?

On 6/19/01 19:47, ron ron@NVWETLANDS.COM wrote:

> You may be
>right that your designing large, color segregated gardens is
what allows
>you to
>observe color preferences that the rest of us, in
patchwork-colored
>gardens, don't
>see.

However, clustering all flowers of one color into one area
introduces
another basis for choice, which you touched on: defensibility.
Perhaps
the areas with red flowers are more easily dominated. Random
distribution
of flowers (with careful observation of which ones are actually
used)
could eliminate this as a potential source of bogosity.

>As for this statement: "At least you and Lanny seem to have
enough of an
>open mind
>to consider the
>possibility." I have another, conflicting theory. Perhaps
Lanny and I are
>just
>egomaniacs who have to try and convince everyone we
encounter that we are
>right,

I plead the 5th...

>and
>we're willing to browbeat or exhaust you with endless emails
if necessary.
>(I am
>pretty sure this is the case with Lanny.)

Not this time. I always try to take it easy on new subscribers
on their
first day. :-)

Welcome, John. Humnet is a nifty place where the best-loved
theory is the
one with no data, to be argued from all angles for mental
stimulation as
well as in the pursuit of truth. Any fly-on-the-wall grad student
need
merely to take a few notes, and his/her dissertation experiment
would
practically design itself. For this reason, consider that
examinations of
anyone's new theory tend to be microscopic, lest our
unexercised science
muscles atrophy. But we also have true experts in many fields
here, and
when they speak, we listen. Usually.

Aside from designing experiments, a few Humnet members
actually carry
such things out for a living. They keep us all honest (more or
less), and
we have fun while learning. You should also know that no real
animosity
exists here, only playful jibes from time to time for mutual
amusement.
For example, while I've never met Ron in person, I'm sure I
would
probably be able to tolerate him, as long as he didn't speak to
me. :-)

Lanny Chambers
St. Louis, USA
Humnet Rogues' Gallery:
http://www.hummingbirds.net/rogues.html

=======================================================

Date: Tue, 19 Jun 2001 22:47:24 -0500
From: Lanny Chambers <lanny@HUMMINGBIRDS.NET>
Reply-To: BB for Hummingbirds and Gardening for them in
the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Fwd: species differences in color
vision?

On 6/19/01 22:05, Maurice Duvic Sr. jsb8@WEBTV.NET
wrote:

>Could some species have evolved in a habitat that provided
only blue
>flowers, causing them to favor that color?

I don't believe many hummer species have been tested, but in
the
less-than-rigorous tests of feeder colors I've read, all bright
colors
attracted hummers equally well. The only poor-performing
feeders had been
painted brown, gray, or black. Even then, once a feeder's
location had
been learned by the birds, color ceased to matter, as did the
type of
feeder--the hummers seemed keyed on the resource's location.
This agrees
with the many anecdotes of early returnees hovering in the
(empty) air
where a feeder had hung the previous summer.

It's my understanding that hummingbirds learn to associate red
with food,
rather than responding to any genetic imperative. Red
apparently works
for two reasons: first, about half the plants that evolved away
from
insects and toward hummers as their primary pollinators
changed their
flower color to red, presumably from blue, to avoid
encouraging insect
visits and the resulting waste of pollen; second, hummers
investigate any
brightly-colored object as a potential source of food, and red
offers a
nice contrast against the green of foliage.

Do we know any of this stuff for sure? Don't be silly, of
course not! We
all know Bob Sargent talks to hummingbirds; once he learns to
understand
what they're saying back to him, he's sure to get answers for
us and post
them here...assuming anything a hummer says is repeatable in
mixed
company.

Lanny Chambers
St. Louis, USA
Humnet Rogues' Gallery:
http://www.hummingbirds.net/rogues.html

==================================================

Date: Wed, 20 Jun 2001 11:47:15 -0700
From: Sheri Williamson <tzunun@mindspring.com>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] species differences in color vision?

Ron <ron@NVWETLANDS.COM> wrote:

> Vic, I think that people who talk about color typically call
reds /
yellows
> the warm colors and blues / greens cool colors. I don't know
why they do
> this.

Though part of it is psychological (as John has pointed out),
there's also a physical logic to it. Colors in the red to yellow range are nearer
the infrared end of the spectrum, while colors in the blue to violet
range are nearer the ultraviolet. We sense light in the infrared spectrum
as heat, and very hot things (branding irons, toaster coils, etc.) glow red to
yellow to white in addition to throwing off invisible infrared radiation.
Ultraviolet light, at the opposite end of the visible spectrum from infrared,
really is cool (especially when you shine it on a Grateful Dead poster).

For anyone interested in how certain variables affect flower
choice in
hummingbirds, I recommend the following articles:

Stiles, F. Gary. 1976. Taste preferences, color preferences,
and flower
choice in hummingbirds. Condor 78: 10-26.

Wheeler, Thomas G. 1980. Experiments in feeding behavior
of the Anna
Hummingbird. Wilson Bulletin 92: 53-62.

In a nutshell, Stiles' study suggested nectar source selection is
based on the following hierarchy:

1. energetic factors (quantity and concentration)
2. "taste" (sugar composition, sucrose preferred over simpler
sugars)
3. color

Wheeler introduced a wild card when he opted to dye the sugar
solution
rather than paint the feeder, but his results showed little
difference among
the solution colors (even green and undyed) as long as the
feeder was in an
accustomed location. Only when a feeder was placed in a new
location did the
birds gravitate toward red over yellow, green, blue, and
colorless solutions
(in descending order). This idiot... er, respected ornithological
colleague
also used strong salt solutions to test the birds' ability to learn
to avoid
an aversive stimulus, describing the violent reactions when
birds took a sip
from a feeder in which salt water had recently replaced sugar
water.

Neither of the studies above addressed competition, flower
morphology,
flower density, or other variables that may affect flower
choice, especially
where multiple species are present. Other articles that I can't
seem to lay
my hands on reported that the "favorite" color of wild
hummingbirds in
western Mexico coincided with that of the most abundant
natural nectar
source at the time, and that very strong solutions were found to
be no more
attractive than moderately strong ones, perhaps because higher
viscosity
reduces lapping efficiency.

All this suggests that if differences in color perception or innate
color
preferences play a role in flower selection, they're likely to be
overridden
by more practical considerations.

Sheri Williamson
Bisbee, AZ
tzunun@mindspring.com

============================================================