I want to know what Western movie this tune is from.    It is a
mournful, lonesome whistling tune that I have heard used in several
places to evoke the Western movie feeling.

There are no words, so there's been no way for me to search for it. 
The only thing I could figure out to do is record myself whistling it
and post that here.  So here's a crappy recording of me whistling,
probably off-key:

http://homepage.mac.com/uniace/mysterywesterntheme.wav

I know that it is NOT from any of the following, as I have rented them
all and not heard the tune in them:
-The Good, the Bad, and the Ugly
-Fistful of Dollars
-For a Few Dollars More
-Once Upon a Time in the West
-The Magnificent Seven
-High Noon
-The Searchers

For an answer I would like the name of the movie the theme is from,
and the name of the track if there is one.  Thank you.

I am delighted to learn that the theme from "Il Pistolero Dell' Ave
Maria" is indeed the correct song. I am reposting the link to a CD of
the soundtrack:

Soundtrack Corner
http://www.soundtrackcorner.de/lochiamavanotrinitailpistolerodellavemaria_221/product_info.html
 
A friend who is a big fan of "spaghetti westerns" gave me this lead.
I'm sure he will be gratified to know that it helped!

Very best regards,
pinkfreud

One of the last great mysteries of our time... SOLVED!!!

I believe this is the same tune that is used on the website of the
video game 'Red Dead Revolver':

http://www.rockstargames.com/reddeadrevolver/index2.htm

If so, you are not the first person to want to find out its origin!

There are several threads in various forums dedicated to the topic
but, as far as I can ascertain, no-one has yet come up with the
answer...

http://adtunes.com/forums/index.php?showtopic=3154&st=0

http://www.whatsthatcalled.com/forum/index.php?showtopic=3343&hl=whistling

Your tune may be "Ballata Per Un Pistolero" (Ballad for a Gunman),
from the film "Il Pistolero Dell' Ave Maria," composed by Franco
Micalizzi and Roberto Pregadio. I have not been able to find an audio
file which confirms this.

Amazon's listing of compilation CDs of Western themes looks promising,
as it has previews for all tracks.  Maybe the "Ballata Per Un
Pistolero" theme is buried in one of the compilations, perhaps a
"Spaghetti Western" one.  Another option is to rent the movie, which I
can try doing this week.

Here's a European CD that contains the song. Pricey, though:

http://www.soundtrackcorner.de/lochiamavanotrinitailpistolerodellavemaria_221/product_info.html

nproctor: YES, that is the song!  So from reading through those posts,
it appears the song in question was not used in the actual game and is
only used on the website for the game.  You'd think SOMEONE in
Rockstar Games would know what the song is.  I did a search for the
credits of the game and found this:
http://www.mobygames.com/game/ps2/red-dead-revolver/credits

The soundtrack compiler is listed as Patrick Whitaker.  Now maybe he
had nothing to do with the website that features the song we're
looking for, but at least it's a lead.  I'm going to increase the
price for this question.

Hello, I believe I have your answer, the song is by Ennio Morricone,
and can be found on the soundtrack of "E Per Tetto Un Cielo Di
Stelle," the film which it first appeared in.  Here is a link to the
moviegrooves site where they refer to it being in red dead revolver,
and have some samples, although unfortunately i believe the main theme
does not have a listening button available.
http://www.moviegrooves.com/shop/epertettouncielodistelle.htm
Hopefully this satisfies your quest for knowledge... I would recommend
renting the movie so that you can enjoy the tune in its original
intent.
Let me know if you need anything else.

Also here is something i found listing all the songs found in red dead
revolver in case you are interested. (you can see the last song, "main
titles," is the one i refered to above, and i was wrong they do have
parts of the main titles song to listen to... but it seems a
compilation of multiple themes from the movie and the sample does not
include the one we are looking for (buy the soundtrack i guess):

"Gringos A Caballo and Bloody Sunset"
by E. De Masi, taken from 'Sette Dollari Sul Rosso'

"Suspence Al Villaggio, L'Assulto Di Santana, and Johnny Sulla Croce"
by E. De Masi, taken from 'Quella Sporca Storia Nel West'

"Un Uomo, Un Cavallo, Una Pistola, Faccia A Terra, Le Pistole
Attendono, Sentiero Rosso, and Esterno Saloon"
by S. Cipriani, taken from 'Un Uomo, Un Cavallo, Una Pistola'

"Long Neck, Jackie, Siddle Sack, Sombrero, and Tumble Weed"
by P. Piccioni, taken from 'Minnesota Clay'

"Pistoleros In Agguato"
by G. Ferrio, taken from 'Un Dollaro Bucato'

"T.5, T.10, and T.13"
by B. Niccolai, taken from 'Anda Muchaco Spara!'

"T.19"
by B. Niccolai, taken from 'Django Spara Per Primo'

"Nevada, La Confessione and Nevada, Delitto Fra Le Montagne"
by S. Cipriani, taken from 'Nevada'

"Per Salvarsi"
by D. Patucchi, taken from 'Los Amigos'

Il Bandito Messicano, and Il Falso Soldato"
by B. Ghiglia, taken from 'Un Dollaro Tra I Denti'

"Fuga Dall'ovest"
by B. Niccolai, taken from 'Corri Uomo Corri'

"Umor Giallo"
by E. Morricone, taken from 'Stark System'

"Agguato A Dallas, Il Fischio, and Il Ponte"
by L. Bacalov, taken from 'Il Prezzo Del Potere'

"L'uccello Magico, L'uccello Magico A Roma, and Il Duca Di Wuttenberg"
by N. Rota, taken from 'Il Cassanova'

"T.5"
by G.P. Reverberi, taken from 'Ringo Il Cavaliere Solitario'

"T.15 and T.19"
by B. Niccolai, taken from 'L'ultimo Mercenario'

"T.4"
by A. Alessandroni, taken from 'Suor Omicidi'

"T.3, T.5, T.9, and T.10"
by B. Niccolai, taken from 'Buon Funarale Amigos...Paga Sartana'

"T.12, T.15, T.17, and T.20"
by B. Niccolai, taken from Gli Fumavano Le Colt...Lo Chiamavano Camposanto

"T.2, T.4, T.6, and T.7"
by E. De Masi, taken from 'Una Bara Per Lo Sceriffo'

"T.11 and T.22"
by E. De Masi, taken from 'Il Ranch Degli Spietati'

"T.12, T.13, and T.15"
by B. Niccolai, taken from 'Un Uomo Chiamato Apocalisse Joe'

"T.18, T.23, T.27"
by B. Niccolai, taken from 'Lo Chiamavano Tresette, Giocava Sempre Col Morto'

"T.26, T.28, T.29, and T.30"
by M. Migliardi, taken from 'Prega Il Morto E Ammazza Il Vivo'

"Al Tren!"
by L. Bacalov, taken from 'Quien Sabe?'

"Main Theme"
by L. Bacalov, taken from 'Lo Chiamavano King'

"Senza Scampo and Ballata Per Un Pistolero"
by F. Micalizzi and R. Pregadio, taken from 'Il Pistolero Dell'ave Maria'

"Trinity: A Mollo Nella Tinozza"
by F. Micalizzi and R. Pregadio, taken from 'Lo Chiamavano Trinita'

"Main Titles"
by. E. Morricone, taken from 'E Per Tetto Un Cielo Di Stelle'

You may find a link on this site:

http://www.whistlingrecords.com/

hobbes828: That's not it.  On that moviegrooves website, they say the
main theme was used in Red Dead Revolver.  Listen to a clip of the
main theme for "E Per Tetto Un Cielo Di Stelle" on that website and
you'll hear that, although it does contain whistling, it is definitely
not the song we're looking for.  I highly doubt that if one had the
full track it would suddenly switch to a different whistling theme and
be the one we're looking for.

Also, as I already said, it seems from reading the discussions on the
adtunes and whatsthatcalled forums that the song was in fact not used
in the game but only on the website.  For this reason, it seems that
"Ballata Per Un Pistolero" from the film "Il Pistolero Dell' Ave
Maria" is our best bet, as Pinkfreud suggested it, and it was also
suggested on those two discussions.  Although no one has given any
reason why they think that one is the song.

You may be right... but it is called "Main Titles" for a reason, and
if you listen to the clip you can already hear two completely
different themes in it. Also here is a reference to someone else
trying to find a similar answer, who swears that the song on the
website is the one I mentioned. (There are others that I found just
like this, which discuss the fact that this song is not found as a
main theme in Red Dead Revolver but instead is from the website).
http://66.102.7.104/search?q=cache:BfKJHOKEOa0J:www.fistful-of-leone.com/forums/index.php%3Fboard%3D2%3Baction%3Dprintpage%3Bthreadid%3D996+E+Per+Tetto+Un+Cielo+Di+Stelle+red+dead+revolver&hl=en&client=ig

Okay, I've just purchased the movie "Il Pistolero Dell' Ave Maria"
through an eBay store.  (I live in L.A. and the biggest cult/specialty
movie rental store on the West Side didn't have this one, despite
having a whole section for Spaghetti Westerns, so I figured there's no
choice but to buy it online.)

A soon as I receive it I'll watch it and report back.  Pinkfreud: if
this turns out to be the one, I'd like to give you credit for
answering the question.  Let's cross our fingers that the mystery may
be about to come to an end.

YES!!!  That was it!  I just got done watching the movie, "Il
Pistolero Dell' Ave Maria," and the main theme ("Ballata Per Un
Pistolero" most likely) was DEFINITELY the one I've been looking for! 
The movie wasn't half bad either.  And even though it was pricey, I
just put in an order for the CD that Pinkfreud found that contains the
soundtrack, since I couldn't find it anywhere else, and they probably
only have one copy.  Pinkfreud, if you put your prior comments as an
answer, I will accept.  I'm going to try and announce this on those
forum threads too.