Rook nests

Hello sitting here watching a pair of rooks starting a new nest and am wondering how they keep the first small twigs on the 'Y' of the branch without using their legs.  Do they somehow entwine them, or trust to luck  I must say I havn't seen them jumping up and down on the twigs or losing their temper but it seems a miracle of nature to me.  I make a pile of small branches from a tree that fall during the winter and watch them picking them up, dropping them, searching searching for the right ones. I have built up a rookery of so far this year10 nests, it has been bigger from nothing by feeding the birds daily with anything from the kitchen that can be smushed up into a clump, plus grain and by the time I get back to the kitchen to watch more often than not it has all disappeared.  The sentinel always is the first to arrive and call out that it is feeding time and then like a scene from The Birds it disappears. Love it.  So, how do they keep the first twigs in place? 

Many thanks and nice to have joined you all