Injured Magpie - is there anything I can do?

I have a pair of Magpies who visit my garden daily.

Unfortunately in the last 2 days, only the larger (I assume male) has been around and he's limping very badly.

He can fly, but he's really struggling to walk. I'm providing plenty of food for him, and he's burying some in my plant pots for later as always, but he's finding it difficult to get about on the ground. Is there anything else I can do?

Am I right in thinking that because he's still flying, the sspca wouldn't be able to help?

It's really sad to see him in such a state, and to see him on his own as they're always together in the garden.

I'm just concerned he won't do too well with an injured leg and I'd be really upset to see him deteriorate.

Thanks