Laura Erickson's For the Birds

This time of year I get a lot of pleas from people with problems with birds. One of the biggest is from robins or cardinals repeatedly bonking into windows or car mirrors.

These birds are defending their territory against what looks like an intruder. Normally when one bird sneaks into another’s territory, the intruder is meek and secretive. If a territory holder discovers a trespasser, it’s normally quite easy to scare him off by assuming an aggressive posture. But a reflected image’s aggressive posture matches the territory owner at every level of aggression. Only rarely in nature is an actual chase necessary, and a chase against a real intruder is virtually 100% effective. But a chase against a reflection is 100% ineffective. This can’t help but rile the bird, who works harder and harder to chase off the perceived enemy to no avail. Birds are extraordinarily set in their ways when they are at that hormonal time of year, and this territorial behavior is very exaggerated.

Usually the problem lasts only a few weeks at most–once the eggs hatch, the adult birds suddenly develop an even more powerful hormonal need to feed babies than they do to chase off territorial intruders. But meanwhile, it can be frustrating and annoying for us, and dangerous for the birds. How do you stop it?

The only sure way is to break the reflection, which can be done by soaping the window or mirror, or by taping paper or cardboard over the window. This rather destroys the purpose of having a window in the first place, at least temporarily, but overall is often worth the price in peace of mind for you and safety for the bird. Often the bird forgets all about the intruder after two or three days, but if it suddenly catches a glimpse of its reflection again after you’ve removed the covering, you’re back where you started, except that it will at least be sooner before the bird gets busy with child care.

Another problem people have is with swallows, phoebes, robins, and finches nesting on their houses. I personally not only don’t consider this a problem–I think it’s a bonus to have a pair of birds gracing our home with their presence. But some people do reasonably object to mud and droppings on their porch, or being dive-bombed after the babies hatch.

A good hosing of the porch now and then will solve the cleaning problem. To minimize the preemptive strikes against you after the babies hatch, spend as much time as you can on the porch as soon as you discover birds building a nest. Don’t go out of your way to avoid disturbing them during the building, laying, and incubating stages, so the birds will be accustomed to you and your children as normal presences. This often greatly reduces their concerns when you’re there after the babies hatch.

Of course, although curiosity may lead you to peek into the nest occasionally, if birds catch you in the act, they will put you on their hate list, and set after you with a vengeance. And some birds that were doing just fine when you were coming and going before the eggs hatched suddenly go ballistic against anything moving about near the nest as soon as the babies hatch out. That’s when I would switch to going in and out the other door myself. The nestling stage only lasts for two weeks at most. For a bird, defending its babies is a matter of life and death. And that should reasonably trump a week or two of minor inconvenience for us.