Bubbles from the Naturalist Jerry's tank - by Jerry Ligon

August 2005: Owls and fish

Making observations about creatures and storing them in memory is one of the things that naturalists do, and my favorite creatures to study are fish, birds and primates. It so happens that each of these diverse groups can see colors in their world just like us primates can, so we share some thing in common. But each of these groups of animals have very different habitats in which they live, and one may not think that there are other ways in which they share things in common.

Owls and fish. . . . While living in Colorado I was fortunate enough to find a nesting Pygmy Owl, not much bigger than a common robin, but with such a demeanor that every bird feared this little predator. Whenever the owl flew from his hidden perch, each and every bird that was paying attention immediately followed the owl and communicated with all the other woodland birds with a commonly understood mobbing call until the little owl fell under assault by as many as fifty or sixty birds of many different species. It was in their survival interests to follow and give the mobbing call and to alert other birds that the killer was changing his location. The owl would duck into some thick foliage and try his best to hide and wait out the storm that it had created. The birds continued to return to the site, show their agitation by giving the mobbing call and cautiously peering into the tangle where the beleaguered little owl was sitting, then they would fly off to resume their normal activities, but within a few minutes would return to continue checking to see if the owl had moved.

Diving on Bari Reef, many times I have observed Spotted Scorpionfish moving from one location to another but more often I see them motionless, waiting for a small fish to come near, and when moving, I pay particular attention. This is when I see many small fish showing special attention on the scorpionfish as it moves to another location. These small fish, mainly brown chromis, blue chromis, bicolor damselfish follow this predator and pay particular attention when it settles on the bottom. They appear to be rehearsing the behavior of all species, whether terrestrial or marine, who find their worst predator on the move from its normal behavior of lying motionless. One question that I have is, "Do fish also give off auditory signals to the nearby fish alerting them of the new location of the predator, just like the small birds in the woodlands of Colorado after their feared predatory owl makes its move to another location?" Perhaps they do, but we are not able to pick up their alarm signals because we are not citizens of the marine world-only temporary visitors.

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