Make these 30 animals look cool

Question

Place the following 30 animals in the grid:

Albatross   Alpaca   Anaconda   Ara   Bear   Bison   Chicken   Dog   Eagle   Elephant   Emu   Hummingbird   Ibex   Ibis   Impala   Kangaroo   Lark   Nightingale   Parrot   Quail   Raccoon   Raven   Rhinoceros   Swan   Tiger shark   Toucan   Unai   Viper   Wolf   Yak

Based on the following clues:

• E5: their babies are without 'en'
• A row has only birds in it
• C5 and E1 are related to each other
• B3 and E5 ends the same
• The two largest mammals are in the center
• C1: slowest mammal in the world
• The alpaca is diagonally between two snakes
• B2: could be bald
• E2 and D4 are the largest mammals of North America
• A3: sacred
• A4, C3, D1, D2 are the longest animals of this list
• D6: rocket
• A2: last boars
• Column 6 starts and ends with an Australian animal
• D2: smallest bird
• The anaconda is below the rhinoceros
• E4: Too hot to hoot
• The impala is above the chicken
• B6 has one letter more than B5, which has one letter more than B4
• E2: Teddy
• A1: Raptor?
• The wolf is between the ibex and the elephant
• A5: Ramphastidae
• The lark is next to the bear

Done? Then make these 30 animals look cool!

Answer 1

Wow, these animals look so cool ...

... with their classy shades!

Solving starts ...

... with a little legwork to fill in the obvious animals: Chicks are chickens without "en"; the elephant and rhino are the largest mammels here and the bear and the bison are the lergest animals from North America; the sloth is the slowest mammal and a unai is a two-toed sloth; bald eagles and holy ibises are things; the hummingbird is the smallest bird; emu and kangaroo are Australian animals; Ramphastidae is what we disiples of Linneaus call our toucans; "Last boars" and "Raptor" look like animal-related information, but really are anagrams of albatross and parrot respectively; and so on.

Some of the hints that use relative positions ("The alpaca is diagonally between two snakes") can be applied now, too.

The grid should be pretty filled by now and we see a pattern: The first letters of the animals seem to spell a sentence when read line-wise from top to bottom. That immediately places the Quail before the Unai and the rest more or less falls into place:

    1           2           3           4           5           6

A   Parrot      Albatross   Ibis        Nightingale Toucan      Emu

B   Viper       Eagle       Raven       Yak         Swan        Quail

C   Unai        Alpaca      Rinoceros   Elephant    Wolf        Ibex

D   Tiger shark Hummingbird Anaconda    Bison       Impala      Raccoon

E   Dog         Bear        Lark        Ara         Chicken     Kangaroo

So now, ...

... as per the instructions given, we should paint every square with a bird black, and that gives us the cool smirking face with the sunglasses.