To answer my own question about the 4 birds i thought about it all day and came to a simple conclusion.
As the last 4 birds i want a duck, a pelican, a seabird and a wild card.
The first two were rather easy, we know the song and dance that the white faced whistling duck looks amazing and that a range across africa, madagascar and south america would fill one of africas last holes, throw madagascar a bone and give it finally a third animal type besides lemures and fossa and would give south america a bird and one that perfectly fits into tropical houses and wetland aviarys, fitting for the continent that features the worlds most iconic river system.
The Mallard duck might be the most wide spread and the mandarin duck the most visually striking but imo the white faced whistling duck strikes a great ballance between the two and while maybe not as usefull as a wild stand in as the mallard the fact that it fits perfectly into tropical displays makes me gladly take it over the mallard, atleast if we have to choose just one.
For the Pelican i just stuck to the great white. Its the most common in zoos and has the largest range of any pelican and helps out africa, india and the south coast of the middle east, aswell as a more sporadic pattern of breeding ranges in south eastern europe and western asia, mostly located around the black and caspian sea. The reason for a pelican itself is simple. They are big and iconic birds, common in zoos, an abc animal most people know and one of the most unique looking things on the planet, being just a smidge away from passing as a pokemon. Its propaply the best generalist bird option left to add and feels allmost wrong as "a bird" slot as it really is among the most iconic animals left that deserves way more talk then just being a token "bird of the pack".
Now for my most likly hottest take and the animal i havent heard mentioned in these forums even once, the Masked Lapwing.
If you dont know this one, i dont blame ya i also didnt do it conciously till i was looking at seabirds for this slot and damn this one rocks. With 121 holdings its the by far most common seabird i found today on zootierliste and with its striking yellow face mask it stands out well while the rest of its body looks like that of a typical wading bird, making it a perfect base for many mods. Its range is another + as its from not just australia but also new guinea, tasmania and new zealand, living in both salt and fresh water adjacent areas in temperate, tropical and subtropical biomes while also being a common find in grasslands and both rural and urban areas. As the largest member of the Charatiidae, the family of plovers, dotterels and lapwings, with a lenght of ~35 cm and a wingspan of ~80cm it would be a bit larger then the chicken and fit as a habitat animal just fine.
So we got a sea bird that would be a great mod base, is decicivly large enough to be a habitat animal, covers many different biomes and every major island of oceania while also being possible the most common seabird in captivity and looking pretty fire? I think we have been sleeping on this one and it would be the perfect fit for any coastal pack if support should continue, but id also gladly take it for a grabbag pack even if i dont expect it. Its the bird i didnt know i wanted but defenetly would love to have.
For the last slot we gotta take a south american bird and while id love to take the roseate spoonbill 4 waterbirds would be quite much and theres one very important animal south america is still missing, the rhea, but what rhea?
If youd ask me and i hope you do id say the lesser, for multiple reasons.
First of, we want to max out our differences to this chick here, the female ostrich, measuring in average between 1,75 to 1,9 meters tall.
And first i gotta say, both do rather good here. The greater rhea (left) measures in average around 1,4 to 1,7 meters tall and the darwins (right) around 0,9 to 1 meter, making it roughly half as tall as the ostrich. Plumage wise both species look actually quite different from each other, with the greater being far more commonly silverish gray with black accents and the lesser coppery brown with white accents, but it should be noted that both species can be found in gray and brown, its just that its vastly more pronounced in one of them each. The other strong suit of the lesser Rhea is its range especally in biomes. Both inhabit primarly grasslands but also shrublands, deserts and marshes, but the greater rhea prefers those tropical or suptropical and the lesser temperate, alpine and colder. Its also of note that while the lesser rhea lives on both low and high alltitudes with a large northern population in the andes, the greater prefers flatland. Regarding how common they are in zoos the lesser rhea has a respectable 66 holdings, allmost all of them in europe in a recent effort to create a stable backup population for them, but the greater rhea wins this category with a landslide win of 545 holdings and being kept on every continent besides oceania. If your not from europe and have seen a rhea in a zoo, chances are they were from the greater variety.
Personally the significantly smaller size and less represented range of the lesser rhea makes it my choosen candidate, but i totally understand swinging the other way around in this surprisingly ballanced and different duo. In another timeline id even be down to get both in the game for their significant differences in size, plumeage, coloration, biome and range but beggars cant be choosers so id rather have 10 more birds before one of them is a second rhea.
I just find it uneccessary depressive, that's all. I am sorry if I ofended anyone.
I've been pretty neutral on this until recently because the evidence is so stacked up at this point.