Question on Macro mode for Sigma 70-300 APO super II

Hi all,
Just received my new extra toys: Nikon 50 F1.8 D and Sigma 70-300 APO super II. Nice new toys
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Just a question- when I put this lens in Macro mode it is at 200-300, what is the advantage if it's in macro or normal mode and focal length set at 300mm. for example for shooting bird ( feather variety offcourse ! ), all I can see is the same zoom at 300mm. Thanks in advance.
Just received my new extra toys: Nikon 50 F1.8 D and Sigma 70-300 APO super II. Nice new toys

Just a question- when I put this lens in Macro mode it is at 200-300, what is the advantage if it's in macro or normal mode and focal length set at 300mm. for example for shooting bird ( feather variety offcourse ! ), all I can see is the same zoom at 300mm. Thanks in advance.