All birds have a pecking order - who eats first and so on. Even common birds of north Texas do this, like the Carolina Chickadee (the species found here).
The "top" male feeds before anyone else. The younger "squires" draw
the short straw - the perilous sentinal duty of watching for the most dominant birds of all; hawks.
BEFORE YOU BUY JUST ANY BIRDSEED! A recent univerity study examined ten popular brands of birdseed. Half of them contained seeds of at least six species of weeds - things you very likely don't want in your landscape. Not only would you be paying for seeds of noxious weeds, but wild birds rarely eat them - leaving them to sprout and spread.
Since nobody prints "contains weed seeds" on the birdseed bag, I suggest you buy from a trusted marketer who cares about reputation and not just profit; where the bag hasn't been sitting on a shelf for an unreasonably long time.