Early Spring in the Sonoran Desert

The birds around my house are really getting fired up.  A week or two of seventy-degree weather (albeit interspersed with snow squalls) seems to have sent them into overdrive.  They start chirping at first light, and by 6:30 am the dawn chorus is in full swing.  Unfortunately, that is also when my little community on the outskirts of Tucson fires up for their commute into town.  Eastward and westward trains of the Union Pacific pass through at the same time; the traffic on Interstate 10, just 6 miles south, really starts to pick up; and jets out of Tucson International fly over on their way to points east.

The nighttime inversion enhances the spread of sounds, by deflecting sound off colder layers of air up in the atmosphere.  This makes the sounds of the trains and freeway seem even louder (see also “Bouncing off the sky”).  Conversely, as the sun rises and starts to warm the ground, the lifting air deflects the sounds upward.  I decided to try to take advantage of this principle of physics to see if I could record the birds during mid-day, with hopefully less background noise.  It worked – the distant roadways and trains were reduced to a dull roar which I could minimize in the recording.  Between the barking dogs and low flying aircraft, I managed to get in a couple of minutes of birds singing.

I missed some of the earliest birds, but I did manage to record the Great-tailed Grackles that show up in my neighbors pine trees later in the morning.   Their hoops, hollers, and cackles just tickle me, although I can imagine a huge flock of them could really get on your nerves.  All of the birds I recorded are resident birds.  The migrants won’t be here for a couple of months.   Then White-winged Doves will join the other doves: Mourning, Eurasian Collared, and Inca.  Also by then the dawn chorus will occur well before the morning commute, providing, hopefully, quieter opportunities for recording.

The House Sparrows have already started setting up house-keeping in a neighbor’s saguaro, which is large enough to provide several nesting sites.  Holes in the cactus are created by Gila Woodpeckers, but once created, a number of other birds, including Elf Owls, will take advantage of them.  The Cactus Wrens have started chasing each other around, and the doves and Curve-billed Thrashers have started to pair up.

Sound recording has really opened my ears to the way animals make sounds, but also how the atmosphere and solid substrates affect sound transmission.  I’ve certainly learned a whole new appreciation for professional sound recordists.

References:

 Bradbury, J.W. and S.L Vehrencamp. 2011.  Principles of animal communication, 2nd ed. Sinauer Associates.

More sounds of the Sonoran Desert can be found in my album, Sonoran Desert Spring.

Recorded with Sony PCM-M10 with Audio-Technica AT2022 and FEL SK3.5 pre-amp.  Recording subject to high-pass filtering to reduce traffic noise..