Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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Click here for a larger view of the nesting owls here for the Tern

Great Horned Owls Feed Terns to Their Babies

This seems to be an unusually good year for great horned owls near our house in Englewood, FL. There is a pair using an osprey nest directly over our house up 50 feet in the top of a Norfolk Island pine although we are not sure that they have been successful in raising young. A lower and more visible nest is found several miles south of us in Stump Pass State Park where a pair of owls is using an osprey nest in a dead Australian pine. All of the pines have been killed by the park in an effort to eradicate exotic plants- a somewhat controversial move to birders since in the future there will be no tall places for raptors and owls to nest. Of course they can use lower native trees such as mangroves and sea grapes, but these provide a poorer refuge from terrestrial predators and from the humans that use the beaches and bays.

A neighbor (Paula Kaye) sent me a photo she took recently of the two babies in this nest (see attached). An interesting note about the food supply of this pair of owls- there are few mammals of the appropriate size available for the owls to catch so they are apparently preying heavily on roosting seabirds, especially royal terns (see photo). Does it bother you that this ferocious predator is killing beautiful terns as food for its young? I guess it does bother me somewhat in that I would rather they eat rabbits, rats and mice. On the other hand this is nature's food web in action and I suppose we should not pass judgment on the consequences. This is one thing about the ecosystem immediately along the coast on barrier islands- it is different in biodiversity from inland sites and predators have to adjust their feeding behavior to take advantage of the prey available in each habitat. In this case there are lots of tasty seabirds sitting out on sandbars relatively easy for owls to catch. So can we blame them for doing so? Some solace can be found in the ecological truism that there are very few large predators such as the owls and a lot more prey (in this case a fish predator the tern).

Bill Dunson
Englewood, FL & Galax, VA