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| Steller's Jay |
One of my more vivid memories from college was learning how
monarch butterflies protect themselves from predation. Their diet is high on
the bitter-tasting toxins in milkweed. The moment a bird bites into a monarch, it
is repulsed by the bitter taste, and if it actually swallows a monarch, the
toxins quickly induce vomiting.
Birds are intelligent creatures that learn from
experiences, and link that horrible reaction to the bright orange and black
colors of a monarch, so if a bird does eat one, it never does it again. Another
butterfly, the viceroy, is safe from predation because it looks so very much
like a monarch, even though viceroys aren’t toxic or bitter tasting at all.
The classic textbook example that made such a profound impression on me involved an
experiment on Blue Jays, and two black-and-white photos of a Blue jay eating a
monarch and then vomiting left a vivid impression.
That memory instantly came to mind as I was reading an
article about a new approach to saving the endangered Marbled Murrelet, a plump
seabird little bigger than a robin who nests in old-growth coniferous forests.
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| Marbled Murrelet |
The species declined by more than 90 percent since the 1800s, due to
over-logging in its nesting areas, over-fishing in its feeding waters, and
pollution. Populations are more robust in the northwest, but those nesting in
California’s redwood forests are in dire straits. Those forests now get some
protection, but the murrelets continue to disappear. Researchers discovered an
important contributing cause: egg predation. Marbled Murrelets lay only a
single egg per year on a mossy flat branch of a giant redwood, and the worst
predation comes from a handsome and intelligent little culprit, Steller’s Jay. Once
a jay develops a search pattern for murrelet nests, it becomes a repeat
customer, and Steller’s Jay longevity, combined with their intelligence, means
that they grow ever more effective, year after year, at finding nests.
Identifying the problem is essential for solving it. Researchers clearly
couldn’t get rid of the Steller’s Jays—if they did remove them from one area,
others would move in, and it seemed like an unfortunate solution in every way,
especially because Steller’s Jays have always shared habitat with Marbled
Murrelets. But fortunately, those scientists working on the problem, perhaps
remembering those Blue Jay vomiting experiments, came up with a scathingly
brilliant idea. They are training
the jays to avoid eggs patterned like Marbled Murrelet eggs by setting out
small chicken eggs dyed blue-green and speckled with brown paint, that had been
laced with carbachol. Moments after piercing one of these eggs to eat the
contents, a jay vomits. And voila—that jay is done with Marbled Murrelet eggs
forever. It’s obviously impossible to train every Steller’s Jay to avoid these
eggs, but in 2010 and 2011, after researchers zip-tied hundreds of these fake
eggs on redwood branches in several California parks, egg-snatching dropped by
from 37 percent to more than 70 percent.
Jays are territorial and many remain on their territories for a decade
or more, so this learned behavior is likely to reap long-term benefits to the
Marbled Murrelets. Who would have guessed that saving a tiny sea-faring bird
would involve vomiting jays?
