Because I don’t have a lot of experience, I thought I’d rely on you wonderful people! 
I will be going on my first backcountry camping trip since I got into whistling, and I am looking for a softer whistle that I could possibly bring with. Something that could compliment the beauty of nature but not disturb it. Does anyone have any recommendations?
I’ve taken whistles backpacking and cycle touring over the years. I find that a normal whistle works fine in most instances. If you think one would be too loud just mute it in the usual ways by covering part of the voicing window or the windway. Any reduction of air into or through the head will result in a reduction in volume. Worst case you can play it using the “whisper method” where you put the beak just below the lower lip and blow softly over the top towards the voicing window. You’ll hear the notes very faintly and it will be music to you but should not bother anyone else.
I carried a tunable Dixon polymer whistle (and a Dixon delrin flute) in my pack for several years before I made my own PVC whistles. It is light. It is durable (provided you keep it out of the camp fire). It sounds good and plays well. A piece of putty or chewing gum on the labium or an o-ring around the head at the window acts nicely as a mute (I used short cross sections of narrow road bike inner tubes) for playing quietly. But playing without the mute when you reach a campground will surely bring out the other musicians in the area - harmonicas abound on the trails.
I now have an O’Brien Rover made of delrin and brass. It breaks down into three small pieces. It fits in a shirt pocket. Delrin is very tough stuff. I can take this whistle anywhere. It would be the one I would pack these days. It is not a quiet whistle as delivered but the mute methods would still work fine on it. David O’Brien now makes and all delrin model called the Whispering Phantom which happens to be a bit more quiet to begin with. It still breaks down into three sections for transport. David’s Phantom whistles are available here: http://www.obrienwhistles.com/OBPWphantom.html
Carey Parks also makes a three piece PVC whistle called the Walkabout. Once again, it is very light and compact. But Carey’s whistle has the extra advantage of incorporating a built-in mute into the head design. It is a simple C ring which can be rotated to cover as much of the voicing window as you deem necessary. It can be seen here: http://www.parkswhistles.com/WalkaboutWhistle.html
Any of these can also double as an emergency whistle and should keep the Bears away as well. I still wear a Bear Bell though. I can’t whistle and walk all day long.
Have fun.
Feadoggie
I’m quite fond of the Clarke Woodstock, which, I think is about the same as the Sweetone. Very pleasant upper octave. Very chirpy. The whistle is also quite inexpensive. Definitely one of the quieter whistles I’ve played, and, for me, the upper octave is where nature might be “disturbed”, hence my fondness for this particular whistle.
The I bought a mouthpiece from Mack Hoover a number of years ago, to fit a Generation D barrel. It’s a lovely, sweet, and quite sound.
For hiking, you might have a look at his telescoping/travel D:
https://forums.chiffandfipple.com/t/mack-hoover-telescoping-c-and-d-sharing-greatness/85914/1
I’m a big fan of Mack Hoover’s quiet whistle, too. He makes very small scaled brass one that is a whistle everyone should have in their whistle arsenal.
reg
I completely understand why a low volume whistle might be a desirable thing. That nearby campsite may be filled with people that feel your music is an intrusion on their outdoor experience. So a Hoover or some other quiet whistle might be just the thing.
But my experience seem to indicate that whistles on the quiet side tend to be ones that do poorly in even moderate cross winds. My louder whistles – such as Susato, Sweetheart and Reyburn – do much better. So I compromise by using these whistles and I apply one of the mute techniques already discussed if I think the music will carry too far. Plus I try to be sensitive to situations where I should not play at all.
Hi ! Just my two cents : you can use a normal whistle and stick some tape across the window of the mouthpiece to make it quieter. It will alter the sound, but is reversible. Another convenient and cheap whistle for travelling is the clare two-parts, it accepts gen and feadog mouthpiece if the stock one isn’t satisfying.
You can also add Noah Herbison laughin whistle on your list of quiet whistles, and it’s a telescopic model as well. You can hear a sound sample on my soundcloud page
https://soundcloud.com/christophe17
Don’t do what I did when young while camping in Guernesey : I sheltered in the toilets to work Bach’s cello suites on the recorder. The sound would resound and everybody around hated me and Bach suites as well.
Microwave,
Take heed! I generally consider any comments made by Feadoggie regarding whistles as gospel. In fact, I often seek his outstanding counsel on matters involving whistles, music, and related gear, only to be graced with his most comprehensive answers to my inquiries.
As for bears, they fall more within the domain of my expertise. I am also the very fortunate
owner of a David O’ Brien set of Delrin Rover Whistles in the keys of D/C/Eb.
PLEASE NOTE, there is a subspecie of the Black Bear known as Ursas Americanus Dublinicus, also known as the Irish American Black Bear. They are known to slip into camp when one is soulfully playing his David O’Brien Rover and to break into a mad jig around one’s campfire. They are also rumored to pillage the campsite making off with any Guinness they might find among more lowly considered delicacies.
So have at it with your whistle in the woods, just don’t say you were not warned of the rogue bears. 
Have fun and welcome to C & F!
Cheers Mate,
Cayden
Cayden, it is very difficult to determine where the hyperbole begins and ends in that post.
Christophe, I am now beginning to understand some things that have long troubled me regarding recorders and latrines.
So that’s why they find the historical examples among the… you know…that stuff…how do I put this?..you know…the other artifacts. That’s it. Well, it must be a real bother for the conservators.
Feadoggie
That’s what I come to the whistle forum for… a thorough, and well rounded, perhaps ‘softer’ worldly education.
Welcome to the whistle forum and have fun! 
I second this Sweetone model especially for a trip so cheap you should bring two 
Feadoggie,
i have no idea what you make reference to as " hyperblarney". My warning regarding Ursas Ameicanus Dublinicus is fully confirmed as I heard it from a fella who knew another who said it’s true!
Regarding “that stuff” one finds ancient recorder type artifacts among, we might heretofore refer to such matter as “coprolites”.
Yours in paleontology,
Cayden
I’d prefer we keep religion out of this.
Its getting deep!
MO might have to look into getting one of those deep low whistle things. Maybe a walking stick whistle for the backcountry.
Nature’s calling…
Feadoggie and Ytliek,
What’s a Lad to do to get fair credit from the likes of ye both? You tinks I just pull this dinoshite out of me arse? 
Pondering geologic time and the present,
Cayden
Another suggestion, use smaller metric pea or remove completely for undercover whistling, click Blow Me for demo tune
To get back to the original question: +1 for the Parks Walkabout and the “Parks tone ring”. There is so much travel in the tuning slide that you can get it in tune even with the tone ring nearly closing the window.
That said, I didn’t know David O’Brien made a Delrin Rover until reading this thread. He also does very nice work. I have an olivewood Rover, but I’d never take it on a hike. It’s too nice.
My Parks Walkabout, on the other hand, is always in my shirt pocket.
I’ve played a few Parks and didn’t care for them. Changing the size of the voicing window in effect de-tunes the whistle. Sometimes this can be compensated for by adjusting the tuning slide, but each note does not necessarily go out of tune by the same amount. It’s a neat idea, but the ones I’ve seen function more as a gimmick than a real solution. As always, your experience may differ.