Is 25x25mm wire mesh suitable to allow smaller birds such as blue and great tits, maybe even bullfinches to pass through whilst stopping larger starlings?

Sorry no one has replied but the forum is a little quiet the now..... I have no experience with using mesh. I use a feeding pole with hanging feeders and it's only really when I put out suet /fatballs/raw pastry that the starlings and bigger birds take interest...

You only need to post once as its seen by all regardless what category you post it in...as I said its only because the forum is a little quiet the now or nobody has the answer to your question that you haven't had replies 

Hi, I have a couple of feeder guardians with mesh 3cm wide and 5cm high. These keep out starlings but let in tits, siskins and goldfinches. I have seen greenfinches, chaffinches and robins squeeze in too although they have to try a little harder. I have not seen a bullfinch go into a feeder guardian.

2.5 x 2.5 sounds a bit small but it may be OK for the smaller birds. I have no experience with a mesh that size.

I don't use the guardians around feeders any more because the local sparrowhawk learned to trap birds inside and catch them that way. But if you are going to have a larger cage-like structure, it's probably OK.

RSPB, CJ Wildlife, etc sell guardian cages to keep out larger birds. They are somewhat expensive and I don't think they are guaranteed to keep out starlings.

25mm x 25mm is a little less than an inch!

However, I've never measured feeders though I have found a link to an RSPB feeder with guard

https://shopping.rspb.org.uk/bird-feeders-boxes-tables/bird-care-accessories/feeder-guardians/rspb-ultimate-bird-feeder-guardian-small.html

The gaps there are quoted as 4 x 3.5cm, or in mm 40mm x 35mm.

Taking those measurements as a guide from a bird conscious organisation, you need bigger than what you have 25mm x 25mm and also what you desire, 30mmx30mm.

Thanks for the response. Where did you get your feeder guardian from? I did see some online that stated a similar mesh size and the starlings could still fit in. I was looking to do a tray on the ground with a guard around it.

Thanks. Hadnt seen that. Will look to see what else the RSPB has.

Sorry first time posting had no idea.