Baby Bird

This is a baby bird, a fledgling actually.

And is one of the thrushes most likely.

"People often want to help fledglings, as they appear vulnerable, but it is best to leave them alone", and I did leave it alone; in fact, it left me alone as it ran away.

But other sources claim that you have to place it somewhere off the ground:

Although out of the nest, a fledgling does not need to return to its nest. Since fledglings are able to use their feet to grip, hold out your index finger like a perch and use a bird treat to encourage the fledgling to perch on your finger. Once the fledgling is on your finger, gently place it on some shrubbery or a tree branch.^[7]

• If the fledgling does not want to perch on your finger, try gently wrapping it in a towel to pick it up and place it on higher ground.
• If you try to place the fledgling back in its nest, it will likely fall out of the nest again.^[8]
• The fledgling needs to be above the ground to protect it from predators.

HoroLex: Птенец чей?: Чей птенец, кто знает? В общем, это, скорее всего, кто-то из дроздов - певчий или рябинник.