Egrets: not as innocent as they
I’ve had a few, but then again, too few to mention…” This might have been Hawai‘i’s
theme song in 1959, when a mere 105 cattle egrets were imported to prey on
insects plaguing cattle, but no longer: There are now far more than a few
egrets bobbing cockily around. Dr. Christopher Lepczyk, a specialist in natural
resources management, notes that the 2013 Audubon Christmas Bird Count counted over
1,100 egrets within the Islands’ urban areas and that egrets have spread across
all the major islands.
slender, jaunty white birds may be more charismatic than some other invasive
pests; however, they can and do have serious impacts on the Islands’ ecology
and on agricultural producers’ livelihoods, and they can also be a safety hazard
haven’t helped mitigate the horn flies they were brought in to control. Instead,
local shrimp farmers complain that their easily accessible catch is being snapped
up by these fast-moving predators. The birds compete with native birds for the
same diet of wetland invertebrates, but worse than that, they also eat the
young of the native birds themselves. Their prey include the endangered ae‘o, ‘alae
kea, ‘alae ‘ula, koloa, and pu‘eo.
possible danger to humans is that egrets roost close to airfields, and their
large flocks pose a risk to airplanes taking off. After a few close calls, the
Federal Aviation Administration became concerned, and is one of ten federal and
state organizations now collaborating on a plan to control these birds.
flocks of egrets can make airplane takeoffs and landings hazardous.
plan, under consideration, would allow designated officials to trap and destroy
both egrets and the equally predacious introduced barn owl or their nests and
eggs. Dr. Lepczyk, a bird expert, notes that the plan may use “egg oiling,” one
of the least invasive and safest methods of control. A thin layer of liquid
paraffin is spread over the eggs, closing off the pores necessary for
respiration. It’s safer than ovocontrol, a birth control added to birds’ diets
that is non-species specific and could have unintended consequences to native
birds. CTAHR is only beginning to work on vertebrate pests since he’s been at
the college, he points out, but this important area of conservation is a
much-needed component of the school’s research and outreach, as well as a
much-needed service to the Islands’ ecology.