When we pay lip service to Providence then everything depends on us and we should be VERY worried.
But we have a God who feeds the birds and clothes the lilies!
I think it is the song of birds that makes them so special!
While birds look for food, feed their young, and build nests there is not the frantic desperation that is the characteristic of many human beings. Amongst birds there are only a few who are lazy (like cuckoos). The rest are industrious and active. Jesus was not advocating sitting back and doing nothing. There is a lot of contentment and meaning to be gained from a good day's work.
Jesus' concern is that human beings suffer from the disease of discontentment—we always want more. We barely attain one gadget, vehicle, or house when we fix our eyes on the next desirable. Worry about our stuff consumes us and quality of life disappears.
Birds have learned to enjoy the moment and have learned the secret of contentment: Their song is often heard as they bask in the morning sun and they take the most incredible pleasure in the sprinkler on the lawn on a hot summer's day. It is terribly unfortunate when we become so obsessed with collecting, earning, and hoarding that we have forgotten how to play and sing.