Looks like a copperhead but might be a diamondback rattlesnake in the yard at twilight.
Exposure Date: 2014:09:10 19:16:48;
Make: Canon;
Model: Canon EOS 5D Mark III;
ExposureTime: 1/50 s;
FNumber: f/4;
ISOSpeedRatings: 3200;
ExposureProgram: Manual;
ExposureBiasValue: 0/1;
MeteringMode: Partial;
Flash: Flash did not fire, compulsory flash mode;
FocalLength: 182 mm;
Software: Adobe Photoshop CS5 Windows;