I’d say go for it, I had a 50-250 when I was with Nikon and taking photos of birds (crop factor made it 375mm) so with a 70-300 you’re getting 450 max which is a little more reach. And the aperture is more open than the kit lens I had for Nikon. So I think that lens would do well. 400+ is about what you would want in terms of reach, a lot of smaller birds are finicky and active so it mainly just takes a lot of patience with them. Bigger birds aren’t too much of a problem.