It is too difficult to find all the cats and trees.

[cynergy]

I do have areas with zero trees needing to be planting, but I also have areas that need ten or more. I've traveled over them multiple times, for naught. Cats drive me crazy. I hear their meows, but can't find them, no matter how hard or long I look. *wimper*

[Meth and Phetamines]

I always hear the cats at night and only night, so I can't see anything and just wander around until daytime

[Jack_Miller]

If you can't actually find them i think you're just doing something wrong :D
I'm mean also I'm going crazy for some of the cats, too but after some time i always find them if i hear the meow.
Just don't get confused at the time when you hear it. They also could be under the map in a cave for e.g, the sound they make won't change except that its getting quieter.

[Weizen1988]

I do wish it was a little easier to make out tree spots in heavily grassed areas, I find it gets obscured by the grass and things (likely intended so we cant just spot them all immediately and complete that without trying.)

[Vanadeis]

For the cats:

Some can only be found at certain times (Midnight runner between 10pm and 3am) or during certain seasons (mountain moggie/heartwind vale and summer longtail/crestfall coast only during summer, etc).

See this guide for more help on all locations and times/seasons:
https://yonder.gamepedia.com/Cats

As for trees...

Yeah, it does get rather frustrating. I have criss-crossed all over Heartwind Vale and Dapplewood forest, but am still missing ONE tree. Gah.

A couple tricks that help though: get to high area and look around - you should be able to spot any hiding in tall grass. Going through an area by a different path and seeing things via a different angle also helps.

[Pesky]

You don't have to plant all the trees. You can get your 95% satisfaction rating for a region with five or six vacant plots. Don't get obsessed with it.

[Koitenshin]

I hate necros as much as anyone else, but that wiki is wrong or the game is trolling me.
I somehow found 10 Spotted Brown Cats, not just 9.

[LieseDenise]

Originally posted by Koitenshin:

I hate necros as much as anyone else, but that wiki is wrong or the game is trolling me.
I somehow found 10 Spotted Brown Cats, not just 9.

They added more cats in one of the last updates, the Wiki must not have been updated. But lucky you! Bonus cat!