CARIBOU CLAN Wildlife biologist Karsten Heuer discusses his adventures following a herd of Porcupine caribou as it migrated to its endangered Alaskan calving grounds from its Yukon winter range. He and his wife tracked the caribou on foot and on skis, over mountain ranges and rivers for more than 1,000 miles. Mr. Heuer is the author of the new book “Being Caribou” (Mountaineers Books). Tonight, 6:30 p.m. reception, 7 p.m. lecture, Explorers Club, 46 E. 70th St., between Park and Madison avenues, 212-628-8383, $15 general, $5 students, free for members.

PHOTOGRAPHY AND IDENTITY In a lecture presented by Aperture magazine, writer and critic Deborah Willis discusses the transformation of the black image in photography and how African Americans used the medium to change their self-image. The lecture coincides with the release of the spring issue of Aperture magazine, which features an article by Ms. Willis with photographs by Keith Calhoun and Chandra McCormick, who will join Ms. Willis to talk about their work. Thursday, 6:30 p.m., Aperture Gallery, 547 W. 27th St., between Tenth and Eleventh avenues, fourth floor, 212-505-5555, free.

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