YSK: Deer and rabbits "park" their babies and spend most of the day away from them. If you find a baby all alone, it is almost definitely not abandoned.
Why YSK: DON'T bring it somewhere to 'save' it unless it's in immediate danger - you're probably just kidnapping it from its mom. People find baby deer or rabbits with no parents nearby and think they're abandoned, so they bring them to shelters to try to "save them". In reality they're just forcibly separating the animal from its mother and greatly reducing its survival chances.
Infant rabbits without their mothers don't do well. Even in professional care settings, they have about a 90% mortality rate. Taking them away from the nest should be a last resort, only when death is guaranteed otherwise.
Deer used to drop off their young in our back yard to hang out with our old dog. Ash was a large and impressive shepherd mix with the most zen attitude I've ever seen in a dog. They all trusted him completely. And he did, in fact, take care of them and made sure no animals or humans bothered them.
My back yard is often a sort of "nursery" for a whole crew of doe. Theyll leave them in this patch of tallish grass and ferns and go forage.. They're all sisters, cousins, aunts, etc. I have names for them and watch them grow. The litter bambies right now are so damn cute.
Shitty YSK: Deers and rabbits "park" their babys, spending most of their day away from them. If you find a baby, give them a ticket for parking violation.
Never thought I'd be jealous of parenting techniques from a rodent. Rabbit parents get to JUST PEACE OUT FOR A BIT? Like, I get it...kids are shitty...but the organizational prowess it takes to just get a coffee with my wife away from the little terrors makes work seem easy.
To piggy back on this, you can touch "baby" animals. The mother will not leave them. If you disturb a nest, den, etc, place the young back to where they came and the mother will come back,.