For instance，when I say “the bear cubs need to be protected”，can I also say “need protecting” instead of "need to be protected"？
The bear cubs need to be protected.
The bear cubs need protecting.
The bear cubs need protection.
They all are correct sentence, and bear the same meaning. But the form need protecting is less used than the other two forms.
The verb - need - has this construction. Need + verb-ing + something.
For example -
These trees need watering.
I hope I have answered your question.