Rhinoceros hornbills return to Gladys Porter Zoo

Seen from over the shoulder of associate curator of birds Natalie Lindholm, a male rhinocerous hornbill holds a grape in its beak Wednesday at Gladys Porter Zoo in Brownsville. (Ryan Henry/The Brownsville Herald)

After a 45-year absence, rainforest-dwelling rhinoceros hornbills are back on display at the Gladys Porter Zoo. The ostentatiously adorned birds are considered vulnerable by the International Union for Conservation of Nature.

Natalie Lindholm, associate curator of birds, said zoo staffers were excited when the Sacramento Zoo offered the male and female rhinoceros hornbills named Petey and Millie. The pair arrived Oct. 27 and underwent a 30-day quarantine before settling into their home in the Indo-Australian Aviary.

“We’re going to get back to working with … some exotic species that haven’t been at the zoo in a number of years,” she said. “Being way down here in the Valley, we can show off the animals in this region instead of (residents) having to go up north.”

The birds are somewhat rare both in captivity and in the wild, Lindholm said, as only two other zoos in Texas and about 35 in the United States have rhinoceros hornbills.

They are native to the rainforests of Malaysia, Sumatra, Java and Indonesia where Lindholm said the vibrant yellow-oranges casques on their beaks are thought to help amplify their calls. Like human fingernails, the casques are made of keratin.

“In a dense, moist jungle you need to project your calling card, as it were,” she said, “so it’s almost like an instrument on their head.”

If the rhinoceros hornbills’ casques seem prehistoric, that’s no coincidence.

“This is a feature shared with duckbilled-dinosaurs, also known as hadrosaurids, which existed more than 60 million years ago,” according to a Gladys Porter Zoo news release.

The vibrant yellow color of their casques and beak comes from the oil produced by their preen gland, located above their tails, which Lindholm said conditions their feathers. Males can be identified by their red irises while females’ are white.

In addition to their distinctive appearance, Lindholm described the rhinoceros hornbills’ unique mating behavior. The birds wall-in the female in the hollow of a tree, she said, and the male feeds her and the chicks through a small hole before the brood emerges in about four months.

The arrival of the birds is an opportunity for the zoo to educate visitors about the habitat destruction and perils the species faces, she said.

Rhinoceros hornbills are mistaken by poachers for critically endangered helmeted hornbills, which have casques made of solid keratin that Lindholm said are more valued than ivory. Rhinoceros hornbills are also killed for their meat and by native peoples of the region who use their feathers for cultural adornments.

In addition to hunters, Lindholm said rainforest deforestation by the logging and palm oil industries is eroding the birds’ habitat.

The birds’ home in the Indo-Australian Aviary was formerly an area where visitors could walk through and feed birds. Lindholm said the exhibit allows them space to fly and gives Gladys Porter Zoo one of the largest avian enclosures in Texas.