Manu Minute: Cattle Egret, The Elegant Invader

Dec 30, 2020

Cattle egrets are about 20 inches tall and mostly bright white in color with touches of pale orange on their heads, necks, and backs. Their bills and eyes are yellow, and their legs are yellowish-grey.
Credit Ann Tanimoto-Johnson

Special thanks to the Macaulay Library at the Cornell Lab of Ornithology for use of their field recordings in today's Manu Minute.

The State Department of Agriculture introduced Cattle egrets to Hawai'i in 1959 in order to control fly populations that were harassing cattle herds. But like the non-native Barn owl, the Cattle egret's introduction has had some unintended consequences for native bird species.

You've likely seen a Cattle egret (or a whole flock of them) perched atop the backs of cows or other livestock. From this vantage point, these egrets can forage for flies or other insects that live in the tall grasses of pastureland.

It's a bucolic picture, but it's not the whole story. In reality, these graceful birds have a rather indelicate palate; Cattle egrets eat just about anything they can fit in their mouths, including frogs, mice, and fish.

A pair of juvenile Cattle egrets sit in a tree.
Credit Ann Tanimoto-Johnson

Unfortunately, they are also nest predators of native waterbirds and will eat young aeʻo (Hawaiian stilts) and ʻalae keʻokeʻo (Hawaiian coots).

By 1982, an estimated 13,000 Cattle egrets could be found throughout the Hawaiian islands, about 120 times  their original introduce population of 105.

They nest in large colonies that are often near bodies of water, and they fly in flocks to their foraging grounds at higher elevations.

Due to their comparatively large size and habit of nesting near airports, Cattle egrets are also considered airstrike hazards.

To listen or read more about the birds of Hawai'i, visit our Manu Minute page.