Trying to capture this fox running into deep shadow had the camera deciding to move down to ISO 3200, nice and sensitive in low light, but this has introduced a lot of “heat” noise. This occurs as coloured speckles, usually most noticeable in flat single tone areas. The noise is primarily caused by the sensor (CCD or CMOS) itself which needs to be charged to record the intensity of light falling on it. When the illumination is low and the exposure long one pixel’s charge can trick the adjacent pixels on the sensor to thinking it has received more light, leading to the little speckles.
So what can be done about it? there are many despeckling filters, often they will be supplied with the software you got with your camera. These generally look for out of place coloured specks and average (blur) them using the tones of adjacent pixels, trouble is this smart blurring often gets a bit over enthusiastic. Luckily I have found the Noiseware’'s Community Edition program very useful in “filtering” out this noise, but avoiding the over blurred look.
Remember Higher ISO,Low Light and Long Exposures will increase noise in your digital photos.