"Bird proof" on the allotment.

That is going to be a very tiny trap and a so and so to find once you put it down.
You could take up falconery that would keep a lot of the birds away. Could try playing recordings of predators or corvid alarm calls. Old cds work fairly well.
Recently rabbit populations have been hit by viral haemorrhagic disease 1 and 2; VHD2 seems to have crossed into hares and their population has dropped, unlike mxymatosis which is spread by fleas VHD1 and 2 are spread by rabbit to rabbit transmission.

 

I don't have allotment tis in our garden, but with all the heavy rain and some work going on the neighbour have upset a rats nest!

 

Biggest problem is obtaining the 'call bird'.....

 

But you need one from a different community, with a dialect, not a contemporary of the locals ! And a good defence from local activists who will cause you grief...

 

Put up a Hawk Kite. The only trouble is, is that it has to moved to a different position every second day. (Otherwise the birds will realize it's not real) Definitely works for pigeons, crows and blackbirds.

 

@Jiffy Paracetamol kills rats????

 

It seem to work at that time, my thinking was if a human can overdose on them so it should work with a rat, i only tryed it because i was out of bait, now i use a mouse/rat trap which works well so i'm not using bait any more i like a clean kill not a slow dead