I can shoot with it handheld,. 
.......for a few seconds!
But no ,. it is a tripod lens for sure! In fact I was convinced my existing tripod/head would be of little use,. but as it is the lightest 500mm prime around it works quite well with my set-up. I do think I will want a beefier head,. like a gimble mount (Wimberly is the pricey one but Manfrotto makes one that looks really good)
Allow me to show my ignorance by asking what kind if heron this is anyway?
And what were your A, T., and Focal Length settings ?
Great Blue heron,
EXIF;
The "Wingshot";
Shutter speed: 1/250 sec
Aperture: 5.0
Exposure compensation: -1/3
Flash: Off
Metering mode: Partial
Drive mode: Continuous
ISO: 200
Lens: 500.0 mm
In the marsh;
Shutter speed: 1/1000 sec
Aperture: 9.0
Exposure compensation: -2/3
Flash: Off
Metering mode: Partial
Drive mode: Continuous
ISO: 400
Lens: 500.0 mm
Flight;
Shutter speed: 1/1000 sec
Aperture: 10
Exposure compensation: -2/3
Flash: Off
Metering mode: Partial
Drive mode: Continuous
ISO: 400
Lens: 500.0 mm