This is "A Sparrowhawk" painted in the 1510s by Jacopo de' Barbari. This Venetian artist worked in the noble courts of Germany and the Netherlands, producing highly realistic works that showcased his incredible skill as a painter. What we have here is probably a fragment from a larger painting made quite late in Jacopo's life, possibly while he was working in the Netherlands.
The bird itself is incredibly lifelike - you can almost imagine it spreading its wings to take flight. The way the light falls on it, casting a strong shadow on the wall behind, really adds to this sense of movement and life. Take a closer look at the little bell just above the bird's left foot - that would have been used by its handler to keep track of where it was when it was flying.
Despite being tied with a slender piece of rope, the bird's eye looks incredibly alert - like it could take off at any moment. This attention to detail is what really sets Jacopo de' Barbari apart as an artist.
A Sparrowhawk hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.