In article , Sacha
writes

It's funny you say that about leylandii (and I'm not being sarcastic) but I
had a long and high hedge of it at one house and rarely saw birds on it or
in it.

But that hedge was along the road, wasn't it? In a rural area where
there were plenty of quieter alternatives

The Leylandii hedge next door is at least a perching post for quite a
number of birds, and the goldcrests nest in it.
--
Kay
"Do not insult the crocodile until you have crossed the river"