Jackdaw suddenly stopped coming?

Hello Emily and welcome to the Community.

I'm not sure anyone is going to be able to give you a definitive answer.

Just a few thoughts. Jackdaws usually pair for life. The fact that this one was on its own might indicate that it had lost its partner or that it was an immature bird that hadn't acquired a partner. If the former, from what I've read, they can be ousted from colonies when widowed and have a tough time fending on their own. This might explain why it was a regular to your bird table. Their life span is typically 5 years so conceivably it could have died or of course been killed by something.

If it was an immature bird it might have gone looking for a partner. They don't breed until their second year and most corvids breed quite early in the year.

Lets' hope it's survived and returns to your garden. Let us know if it does.

Hello Emily and welcome to the Community from me too.   I can't add any more to what TJ has written and all we can do is speculate as to what might have happened, as TJ says, Jackdaws pair up for life much like the Jays who are also part of the same family of Corvidae.   We also had a single Jackdaw (unpaired up) in our garden who was amazingly bold (it used to sit on the garden chair next to me !  and would take food from the ground just 2 feet away from me which was unsual for a wild Jackdaw)  and although he spent time on his own he did join the larger flock too so hopefully your's has joined the larger flock (unless it has been ousted from the group) or perhaps found a mate.  Hope you see it again and it is not alone !  

This is the friendly Jackdaw who was in our garden August and September 2013    (we usually have a large flock of Jackdaws, Magpies, Jays and Crows on daily basis)

I've noticed the past few weeks that a flock of Jackdaws has formed and there are increasing numbers of the bird around on house roofs and visiting our garden. So fingers crossed he has joined a flock!