Looking for answers

by Steve Eno

In past years the most common comments on the directory reports were about wrens and house sparrows. In the last few years, the number of comments about Tree Swallows has dramatically increased.

In the mid-1990s when BAN started collecting trail reports, the number of Tree Swallows were very low and they were only reported to be found in specific areas. Along with the large increase in Nebraska’s bluebird population, the Tree Swallow numbers have also grown. They are now common across the state, and from the comments taken from your directory reports they’re becoming much too competitive on bluebird trails.

In response to the growing concern about Tree Swallow competition for bluebird boxes, I contacted some very knowledgeable bluebirders I know from across the country who have had many years of experience dealing with Tree Swallows on bluebird trails. Keith Radel of Minnesota and Bob Niebuhr of Montana have both written articles to share in this newsletter.

Here in Nebraska, I have had paired boxes on my trails for 15 years and feel  that box pairing has worked effectively for me in dealing with Tree Swallows. I would advise that if you pair your boxes, pair them no more than 10 feet apart. However, judging from comments on the directory reports, pairing is not working well for some people. If your boxes are paired, try going back to single boxes on part or all of your trail.

When I asked Kevin Berner, past Research Chairman of the North American Bluebird Society who lives in Richmondville, N.Y., for his two cents worth on Tree Swallows, he responded: “I’ve had pretty much universally paired nest boxes since 1988 or 1989. Most of my bluebirds are nesting next to Tree Swallows and I haven’t noticed any problems. Yes they swoop at each other, but both seem to be able to bring off broods. I do believe that boxes need to be very widely spaced or every Tree Swallow in the neighborhood will come when another pair gets upset. I have gotten rid of most boxes that were approaching 100 yards of another pair, except in my yard where they are a little closer. I see no problem with pairing from my experience. With an unpaired box if a swallow comes first, I would guarantee that you won’t have bluebirds. If the second box is there, you may have bluebirds too. That’s my two cents.”

One thing seems certain: Unless you have perfect bluebird habitat, the longtime recommended spacing of 100 yards apart is too close and gives Tree Swallows the edge as their nesting territory is much smaller than that of bluebirds. Try placing your boxes 150 yards apart or more and see if that helps.