Biology Reference
In-Depth Information
Q My wife is a birder and when we went to Florida, she wanted to see a rare bird,
the Florida Scrub-Jay. We went to a park where the birds are supposed to be and
quickly spotted one perched at the top of a tree. She was about to take pictures but
as she got her camera set up, a noisy group of people arrived. Instead of flying away,
the bird flew right up to them and suddenly in flew five more scrub-jays! They actu-
ally landed on the hands of all these noisy people, taking peanuts that the people had
brought to offer the birds! Are these birds endangered because they're too friendly
or curious for their own good?
A
Florida Scrub-Jays are threatened because their habitat, sandy areas of Florida covered
withnative scrubvegetation suchaspalmettos andevergreenoaks,isbeingdestroyedfor
citrus groves, housing projects, and shopping malls. These jays are adapted physically
and behaviorally to this special habitat, which once covered much of central Florida and
was maintained in low, open condition by frequent wildfire. Now at least 35 of the plant
species in their scrub habitat are listed as endangered or threatened.
These jaysarehighlysedentary —themostsuccessful onesnevermovefarfromtheir
parents' territory, staying within a total area of about one square mile their entire lives.
When their territory is developed, the jays must disperse but cannot find a new territory
because all the scrub around them is already occupied by territorial jays.
Ashumanhousingprojectsmultiply,theremainingscrubgrowstallanddensebecause
of fire suppression management. These areas become unsuitable for the jays, and predat-
ors such as house cats have an easier time catching the young birds, so the local Florida
Scrub-Jay population becomes extinct. This is happening in every region where this spe-
cies exists.
Florida Scrub-Jays feed on a variety of arthropods, small vertebrates, berries, and
acorns.Theirjawsupportandbeakshapearespeciallyadaptedforopeningacorns,which
they can feed on year-round, even when acorns are not in season. During the fall acorn
season, each jay stores thousands of acorns in the sand all around its territory. During
the winter, when insects are scarce, they dig up and eat their stored acorns. They're also
known to land on the backs of deer, cattle, and feral hogs, to pull off ticks to eat.
Theyalsofrequentlylandonpeoplewhoofferacorns,peanuts,orotherfood.Thebird
you and your wife found first was a sentinel, watching for predators and rival jay famil-
ies. When the people arrived with peanuts, the bird probably alerted its family and they
quickly appeared in hopes of a handout.
Q I spent a day at an ocean beach watching as Brown Pelicans dived straight into
the water, dozens and dozens of times. I've been watching American White Pelicans
for years without ever seeing them do that. Why do two birds that look so similar
act so differently?
