Wasn't it Richard Brooks who wrote:
tox wrote:

Blackbirds adore Sultanas...May I suggest you try Morrisons on Festival
Park, where they are very reasonably priced?

HTH
tox

Would soaking them first to get the water back in be a good idea ?

They're just as keen on them either way, but if you switch from soaked
to dry or from dry to soaked it takes then a while to become convinced
that the unfamiliar new version is safe to eat. So you might as well
keep things simple and use them dry.

The only downside to that is that if some sultanas get left out in the
rain and swell up, the blackbirds will treat them as unfamiliar, and
avoid them.

You get to see a couple of odd blackbird behaviours with dried fruit
when they are collecting food for their chicks:

1. They take an awful lot of time trying to get the absolute maximum
number of raisins in their beak on each trip. Rather than being happy
with five, they'll keep trying to pick up a sixth. They don't seem to be
smart enough to figure out that there are so many available that
there'll still be some around on for the next trip.

2. Some individual blackbirds don't seem to like clean dried fruit.
After spending ages collecting a maximum load, they don't return
directly to their nest, but go to a nearby flower border and carefully
wipe each one in the soil.

--
Mike Williams
Gentleman of Leisure