This comment really makes me wonder if people understand the internal dynamics of a company. You really think because Frontier has announced layoffs 2 weeks ago that means "welp no Anniversary animal now" like ??? Obviously the team has been working on the anniversary content and the winter DLC long before they decided to make cuts so those are not going to get affected, if anything next years content will, even then I doubt it given they will try to reduce expenses without hindering the market performance for their biggest sellers, which includes Planet Zoo.
Also why are people giving up on birds when it is so obvious their omission is intentional

I am still excited to see what birds they add in the future



Gimme duckies and parrots!!!
Froniter is notoriously cryptic about what is actually happening behind their doors but pack and updates take time not only to build but also to playtest and get ready for release it wouldnt surprise me that what ever they do for the anniversary was already done and ready by mid to late October. We also know nothing about pack timelines so we have all just assumed its finish one start the next but who knows they could be running 2 at a time having them take 6 months to make instead of 3. The layoffs may affect planet zoo but I dont think in a large meaningful way since this and jwe2 are frontiers babies and cash cows they will avoid firing as many people working on these games as possible I think the largest hit planet zoo will see is in marketing and community management we may see less community and franchise challenges or official engagement but content production is likely going to be unaffected. But we honestly have no clue how this is going to affect frontier or when we will start seeing the affects since frontiers beautiful strategy of silence means we have no idea how much is already in development.
I cant speak for other but I have personally given up on birds for a couple of reasons. One is that I think adding a completely free flight system is too much for the engine to handle with out it being very unoptimised and they likely gave up on that idea a long time ago my guess around the time of the europe pack which is when I think frontier really started to think about adding birds with the egg props being released along side the pack seemingly at random.
The bat in the twilight pack was I think frontiers way of testing the waters for flying exhibit animals as an alternative solution because when it first released it screamed flying birds but after the backlash from the bat itself or just the general idea that birds could be in the box I think frontier had trashed the idea of birds at least initially. I think thats at least why up until this point we havent seen free flight birds.
The probable reason why we havent seen more other birds is simply because mammals tend to be easier to make rigs for especially when they all share a similar body plan and we have alot of them and that in general mammals tend to be more charismatic. Up until the last 2 years we havent really started to run out of really iconic mammals so frontier didnt need to focus on birds but I have a feeling there will be a shift to at least include more ground birds such as the 2 in the last pack or that is potentially just a one off.
We may yet see flying birds in the walkthrough boxes because people have slowly at least in the forums changed their minds about whether birds should appear in them and the butterflies as an exhibit animal have done incredibly well proof that flying animals can work. They are also running out of viable options for walkthrough exhibits since as a concept the are pretty limited they are essentially just avairies they too big to repurpose as large exhibits since everything big enough to be in there could be a habitat animal anyways so it has to have another reason for needing lopped animations sloth had speed bats and butterflies had flying. If frontier doesnt want to spend the time making complicated rigs I could see them adding tree snakes and gliding animals to the walkthroughs to try and extend their lifespan but gliding animals are 100% possible as habitat animals and snakes could be. So unless they add birds, gliding animals or snakes the choice for exhibit boxes are limited since people screamed at the viper for being a regular exhibit and screamed at the flying fox for being a reuse.
A theory that is plausible but I also dont like is that they are waiting for a sequel to add birds since that would be a major selling point and would make the sequel standout from the original and yes I do think they have at least planned for maybe even started a pz sequel.
Keep in mind this is all just heavy speculation and my personal opinion. Sorry for the long post.