Fresh AfieldMore posts

Best Laid Plans of Birds and Men

Sep 09, 2011

Good intentions have been known to go astray, and here’s another example. For several years, conservation-minded groups such as Missouri’s Stream Teams have been placing receptacles for used fishing line at popular fishing spots. Called monofilament recycling bins, the receptacles are a length of PVC pipe mounted vertically on a 4-by-4 post with a cap on the bottom and an uncapped elbow at the top. The idea is for anglers to place any scrap line in the pipe so that it is not on the ground or in the water where it becomes a hazard for wildlife. The loose line had been shown to create problems for birds and other wildlife that can become entangled in the rat’s nest of plastic line, hooks, etc.

dead swallows caught in fishing lineIt recently came to our attention that the receptacles themselves could be hazards to some cavity-nesting birds. Tree swallows and prothonotary warblers were found dead and entangled in fishing line inside similar receptacles in other states. The birds apparently see the plastic tubes as potential nest sites but become entangled in the used line upon entering.

diagram of receptacle with rubber cap

We are in the process now of retrofitting our used line receptacles with rubber covers with a slit to allow line to be inserted but to prevent birds from seeing them as suitable nesting cavities. The covers are made from a section cut from tire inner tubes or rubber sheeting used on house roofs. They are held on with a clamp that is made to attach a clothes dryer hose to the exhaust vent on a dryer. A cap could have been used on the openings of the bins but the success of that method would depend on users replacing the cap after each use.

This scenario reminds me of the situation several years ago when plastic insulators for electric fences were made of red-colored plastic. After a number of hummingbirds were electrocuted by inserting their beaks into the insulators, the manufacturers stopped using the red-colored plastic and ended the birds’ fatal attraction. The good news is that both problems were resolved with relative ease and our birds now face fewer threats.

photo of dead tree swallows above courtesy of Dianne Fieri

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