Author Todd McLeish first became fascinated with narwhals when he was 9 years old and came across a photograph of these strange Arctic creatures in a World Book encyclopedia.

"When I started writing about nature, it was one of the animals I always wanted to write about," said McLeish, a science writer for the University of Rhode Island, who lives in Burrillville, R.I., in the state's rural northwest corner.

In 2009 and 2010, McLeish traveled to the Canadian Arctic and Greenland to see and learn about these singular-tusked whales up close, spending two weeks with researchers who netted them and a week at an Inuit narwhal hunting camp. Those experiences provided the material for his third nature book, "Narwhals: Arctic Whales in a Melting World," published in 2012.

On April 1, McLeish will talk about his book and his Arctic travels during a program at the Denison Pequotsepos Nature Center in Mystic. The program kicks off a monthlong series of Earth Day-inspired events at the nature center, "Celebrate Earth!"

"I suspect a number of people haven't even heard of narwhals," he said in a phone interview Monday.

Male narwhals sport an 8-foot spiral tusk that has led to speculation about connections to the unicorn myth and is still something of a mystery to marine biologists, he said. Once believed to be used for defense or digging up prey in the sandy ocean bottom, experts now believe the oversized tooth is an ornament, akin to a lion's mane or a buck's antlers, intended to attract a mate. But, McLeish added, a dentist who has studied the tusk believes they are sensory organs, sending information about temperature, salinity and other conditions of their icy world.

"It's a heavy piece of ivory attached to their face," he said. "That's what first got me intrigued."

Averaging about 15 feet long, narwhals are a relatively abundant whale species, their population estimated at 80,000 to 90,000 animals. But dramatic changes in the Arctic spurred by climate change are posing new threats to these animals, he said. With less sea ice, narwhals will have less protection from killer whales; increased human traffic from shipping, oil and gas exploration and extraction and fishing is disrupting their previously isolated world, McLeish said.

During his talk, McLeish will show photographs from his trip to the Arctic and describe his encounters, including the unearthly sounds narwhals make underwater.

"They're amazing Arctic creatures," he said.

If you go

What: "Narwhals: Arctic Whales in a Melting World," talk by Todd McLeish

When: 6 - 7:30 p.m., Wednesday, April 1

Where: Denison Pequotsepose Nature Center, 109 Pequotsepos Road, Mystic

Admission: $15.30 for members, $18 for nonmembers

Information and registration: www.dpnc.org; (860) 536-1216

If you go

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