Night Photography usually require longer exposure times (because there is less light) so therefore you probably need a tripod to avoid camera shake. IS lenses might also help. Rule of thumb, if the exposure time is longer than the focal length then camera shake is likely. Example, at 50mm, handheld exposures are usually fine under 1/50 sec, at 200mm under 1/200 sec.
Also, if your exposure is only around 1s and you already have your camera on a tripod, what you're likely getting blur from is when you depress the shutter. With night photography a remote release or a timer is a good idea. Good, heavy tripods also help.
Any kind of photography where you have to use "Night" to describe it... screams TRIPOD . Also you will need a cable release or use the timer built into the camera, as was stated above. If you get the chance to shoot the scene another evening, if the egrets come often, I'd love to see a shot