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Fly Way

By Office of Communication Services    Published on 12/23/2014 More stories >>

Egrets: not as innocent as they
appear.

Egrets: not as innocent as they appear.

“Egrets, 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.

The 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 for humans.

Egrets 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.

A 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.

Largeflocks of egrets can make airplane takeoffs and landings hazardous..

Large flocks of egrets can make airplane takeoffs and landings hazardous.

The 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.