Sigma 150-500mm OS for bird photography?

[visprod]

I use a Nikon D3100. I am planning on doing bird photography, and need to upgrade from my current Tamron 70-300mm VC. I am planning to buy a Nikon-mount Sigma 150-500mm OS lens for bird photography, as other prime lenses are not within my budget. What is your opinion about the lens? Is it a good investment? I found some fantastic images created with this lens on 500px: 500px / Search

Is there any better lens around this budget?


Also, what body would you recommend with the lens? I currently have a Nikon D3100. Should I upgrade the body?

 

[KmH]

For the money, the Sigma 150-500mm cannot be beat.

 

[MSnowy]

Here's a few.

 

[SCraig]

And a few more ...