The insecticide DDT harmed many songbirds by
killing and poisoning the insects they eat. Bluebirds were especially badly hurt. Their
numbers also dropped because starlings and sparrows took over their nesting spots.
In recent years, many people have built birdhouses
and this has helped the bluebirds make a comeback.
If there are bluebirds hanging around your house,
you may notice that there are fewer insects in your yard.
