This is what we hear every night lately, It's a Great Horned Owlet - a baby owl - calling for his dinner. (You can hear it, too, if you click here. then, click on 'Nocturnal Shriek'. (I can't figure out how to get an mp3 file into my blog). The same site says that the young owlets start roaming from the nest when they are 6 or 7 weeks old, the age of the little one in this picture. At this point they can't fly very well and won't for another 3 or 4 weeks and they are called 'branchers'.
The adults continue to feed them for several weeks after they leave the nest, slowly weaning them. This second picture is a bit older juvenile.
They will stay as a family group until fall, when the juveniles disperse widely - over 150 miles, perhaps. The breeding pair will maintain the same territory for a period of years, although they are solitary except during nesting season.
We heard them last year, too, so the pair is sticking around. The Son of..., who knows birds, says we should look for them in the evening. They are often visible against the sky then.