Tuesday, March 22, 2011

Valley of the Cranes. Monte Vista, Colorado

Sunrise over Colorado's San Luis Valley photo:nell
Nell and I headed down the Monte Vista, Colorado with River and the Brown Dog last weekend so she could study the Sandhill Cranes (Grus canadensis). These birds migrate through Colorado every year in March with numbers estimated at 25,000. Incredible birds with up to 7foot wingspans and weighing in at nearly 12 pounds these things fly like refueling tankers (C-17’s), very deliberate and controlled, even in gusty winds. It was amazing to learn from Nell about this species. Her going back to school has stoked the fire for her ornithology. So we took off, she’d take the pictures and I’d man the parabolic microphone to record the sounds in an attempt to capture the wonder of this migration.

The first real recording with the Homemade Parabolic mic. photo:nell

We visited the cranes at the Monte Vista wildlife refuge. This area was perfect for sound recording as there are a couple trails that get you a little closer to the birds and it is located away from the roads. The parabolic microphone and recording gear got its first actual use this trip. I even had a high wind day to test the windscreen(dead kitten) on day one. That recording was well trumped by day two’s morning recording of the cranes with no wind or highway noise. Nell and I have tried to count the number of different calls in the 2:50 min recording. There is at least 5 different species that I can make out.
Over all I think the parabolic preformed as expected. No real issues except for user jitters and movements that can be heard with the mic.

Users note: I had to hold the parabolic at the perfect levels for recording, sometimes way over my head, above reeds and cattails. I found that when the mic was well above the ground, pointed away from the road, holding still I got the best recordings.

Nell shows me her favorite shot from the day in the Skamper.
She read from her bird books, we had margaritas and she teased me that I should dance like the Cranes do.

Sandhill Cranes in flight, dig the 7 foot wing span. photo:nell

The Rig in the San Luis Valley photo:nell

Brown, River, Jasper, Linus. The guys waiting to hike. photo:nell
Our trip finished with a trip to South Fork to visit our friends Mo&D. We got in a hike and a mountain bike ride. Nobody else out in South Fork! We didn’t really see anybody this weekend on the trails. It felt really good to get away from the crowds on the Front Range. Is Southern Colorado the perfect place or what?

Also: I saw the largest mountain loin scat to date on our ride. BIG cats in the area!

Also, also: Brown Dog got worked by what we assumed was barbed wire on our hike day two. He pulled in (at full speed) with three major lacerations on his chest and legs. What the?!
So much garbage left in these hills from the cattle ranchers it tends to complicate things. Good thing DB's a fast learner.


  1. Awesome time! Great post!

  2. Anonymous5:50 PM

    Recordings sound great! How did you make your parabolic mic? What kind of mic and recorder?

    Joe Verica

  3. Thanks for your comment Joe.

    First, I ripped off the design by finding the most expensive parabolic recording system on the market and reverse engineering it.

    For me this was the:
    Crystal Partners Big Ears Parabolic Microphone Kit ($4500)

    BTW, I made mine for less than $500 total (including all electronics).

    I am no sound expert so I studied the professional grade system for the specs and design and did some reading on the concepts of the device.

    Next was online shopping for parts.
    The hardest thing to find is the parabolic reflector. I found this one on eBay after a couple weeks of poking around.

    http://www.ebay.com/itm/Parabolic-project-Reflector-Dish-Microphone-Science-/330596257541 ($39)

    Resist using a large punch or salad bowl as the shape is not quite right, very close, but they are usually not a true parabolic dome and it would be difficult to find the focal point(location of the microphone) for recordings.

    I went with all Sony electronics.

    1.Sony MD Walkman MZ-R70 MiniDisc player ($350)
    2.Sony ECM MS907 microphone ($60)
    3.Sony MDR NC7/BLK – headphones ($40)
    4.Sony 80 Min Premium Gold MiniDisc 20 pack ($20)

    After I completed and used this system, I continued to research nature recording. (I made this for my girlfriend for recording nature sounds.)

    I found that the MiniDisc format while perfect for recording human audible sounds misses high and low frequency sounds that humans cannot hear. By design it compresses those frequencies to save space on the disc. Not a big deal for this initial build, but for professional level sound ecology applications or bioacoustics (nature recordings), i.e., recordings to be processed with software (like Raven), this is a huge and important missing chunk of data.

    Also: The moving parts of the MiniDisc system and the media have been problematic in harsher climates. In cold or humid conditions it has failed to produce quality recordings, introduced mechanical noise, shortened battery life, skipping or one time I dropped it and it completely broke. I had to replace the MiniDisc.

    If I had to change one thing (and eventually will), I’d use a different storage device, something solid state with no moving parts or media, like the Sony PCM-D1. Yeah it will cost you some coin but for a professional level recording it is a must, both to capture the complete sound frequencies and to avoid mechanical issues in the field.

    After I picked up the electronics online, I hit Home Depot (~$50) for the rest of the parts to build the thing.

    Basically the build descried from where my hands are holding the device in the picture, is:
    Bicycle handle bar tape.
    Large wooden dowel (pine) for main vertical handles. (Make them long so you can hold it over your head.)
    Smaller wooden dowels (oak) both fitted and screwed into the larger dowels. These hold the the dish brackets to the vertical handels.
    The dish brackets I made from 16-gauge wieldable steel sheet, cutting the ‘C’ shape with a Dremel tool. Use card board to mock up the bracket shape and points where it is screwed into the dish.
    The microphone is held facing the dish exactly 4 inches from the center by a horizontal cross bar made from a 1/8 inch steel Angle bar(1-1/4) that is screw to the dish brackets. This provides rigidity and is thin enough not to have a large reflective profile.

    We use Raven lite and Audacity software to process and analyze the recordings.

    I had tons of fun researching and building this for her. It is not perfect, yet. But got her recording in nature and introduced us to the world of bioacoustics.
    Good luck!

  4. Anonymous11:47 AM

    how do you make it for a sience fair project

  5. haa! oh.