it's a little hit and miss (esp with tumblr starting to suck - it's not happening as quickly as other sites but some things are creeping in to make it messy. if it's broken everyone has likely accepted it as broken)
keep in mind though! this is why i didnt have my friend post it - gifs are put into public rotation, in one-button use by everyone. credit is embedded next to the gif when it's done that way. so if they'd posted these on their tumblr, the gif would be released to the general crowd with their name on it, and not yours. like, they wouldn't do that to you. this is 'reposting' over there and while frowned on, it does happen
so if you did have your own post, then we could show it to someone to go oh hey neat, and you'd retain credit; and if they like/reblog it, the notes
you will also discover all the ways tumblr is messing things up for gifmakers. ehehehe v__v
but yah, the number of people who love puns, pixel art, creatures, birds.
it's also halloween / pumpkin spice season which is practically a sacred holiday (tumblr has many of those). fastest way without going into askboxes, just reblog your own post with someone's username like @todaysbird and i think there's a popup or dropdown box to make it an active link... and it will come up as a 'mention' in their notifications. it's not foolproof but like no one will see that as a breach in etiquette, just a hey here i am
whatever you do, tho, put up a new icon as soon as tumblr allows it! otherwise you'll look like a bot, and blocking them is a civic duty