background birds breadcrumbs brown buff Camouflage camouflaged climate-tolerant common common-pest contrast dark ever-expanding populations fauna gray grey house sparrows insect-eaters introduced-species Matthew 10:29 mottled Old-World-sparrows passer domesticus passerine-birds pest plump powerful-beaks prolific seed-eaters small social sparrow sparrows textures true-sparrows two-a-penny worldwide-distribution ever-expanding-populations house-sparrows Luke 12:6-7 Matthew 10:29-31 passer-domesticus pavement climate tolerant feeding paving