The N-Photo experts say…
UP THE ISO
When shooting wildlife, the faster the shutter speed the better. If shooting in low light conditions, ramp up your ISO as high as you need, to enable you to set a faster shutter speed. Modern Nikons cope with high-ISO noise extremely well, so there’s no reason to fear going up higher.
FIND THE ANGLE
If you see a nice image in front of you but your positioning isn’t quite right, by all means get a quick reference shot in case the scene changes. But do always then try to find a better vantage point if you can; it might mean the difference between a snap and a stunner.
Polarize the sky
When shooting upwards it’s often possible to deepen the blue of the sky with a circular polarizer. Giving the filter a twist can transform washed-out tones into deep, dark blues. Polarizers are also handy for getting rid of glare and reflections when shooting waterfowl.
The Sigma 150-600mm f/5-6.3 lens Rebecca used is relatively inexpensive for a super-telephoto lens, compared with the f/2.8s and f/4s of this world, which can run into the thousands. Those extra f-stops are incredibly useful, but you can always up the ISO to compensate.