I bought some netting to cover my Silkie yard since I have previously lost the little chickens from chicken hawks.  Then my neighbor told me about stringing kite string from pole to pole to form a web over the yard.  It does not have to be a tight web either.  I have gaps that are four or five feet wide.  But it works.  But be smarter than I am and use tall enough poles that you can walk under the webbing.