Holes in felt

[aidf72]

Hi,
I've found a hole in my roof felt in the loft. It appears to have been caused by birds. The hole is bigger than a grapefruit but smaller than a football and the edges are pushing inwards - as if an object had punctured from the outside into the loft. There's no evidence of leakage. The felt is as old as the house, approx 30 years. How do I fix it, and how do I keep the birds out?
Thanks.
Aid.

 

[marksson]

The felt is only a secondary protection, there are thousands on thousands of water tight roofs without any felt, so no need to repair if no leak.
Could keep birds out by any method that blocks the hole, but doesn't interfer with roofing.