use std::bind in lambda with std::unique_ptr

// By const l-value reference
auto func2 = std::bind([](const std::unique_ptr< std::vector<int> >& pw) // fine
{
    std::cout << "size of vector2: " << pw->size() << std::endl;
}, std::make_unique<std::vector<int>>(22, 1));

//By non-const l-value reference
auto func3 = std::bind([](std::unique_ptr< std::vector<int> >& pw) // fine
{
    std::cout << "size of vector3: " << pw->size() << std::endl;
}, std::make_unique<std::vector<int>>(22, 1));

// By Value
auto func4 = std::bind([](std::unique_ptr< std::vector<int> > pw) // error
{
    std::cout << "size of vector4: " << pw->size() << std::endl;
}, std::make_unique<std::vector<int>>(22, 1));

// By r-value reference
auto func5 = std::bind([](std::unique_ptr< std::vector<int> >&& pw) // error
{
    std::cout << "size of vector5: " << pw->size() << std::endl;
}, std::make_unique<std::vector<int>>(22, 1));

Question> Why func4 and func5 fail to compile?

Thank you