Wow, those are so beautiful! Gotta love the contrast. Nice creativity in approaching the birds.
I found some tips online that I hope will help in your birding with a “short” telephoto lens:
Here are some really great tips for Wildlife Photography with a Short Telephoto Lens by Spencer Cox
Here’s a Poor Man’s Guide to Bird Photography.
And I really like sections #3, Locating birds, and #4, Approaching birds, in this article on How to Photograph Birds by Nasim Mansurov.