Denver Holt: Highlights of 30 Years Studying Snowy Owls and Brown and Collared Lemmings at Utqiagvik, Alaska - 14 April 2022
When: Thursday, 14 April 2022 - 9:00am to 10:00am (EST)
For 30 years (1992-2021) Denver and colleagues have been studying the breeding ecology of Snowy Owls at Utqiaġvik, Alaska. It is the longest continuous breeding study in the world, and conducted by the same researcher. They have studied 284 nests and banded ~800 owls, mostly nestlings.
Researchers have recorded >43,600 prey from pellets, and >3,300 prey cached at nests, of which >2,500 have been lemmings. For lemming carcass cached at nests, they recorded sex, body mass, relative age, and reproductive status.
Researchers have also monitored lemming population fluctuations through snap-trap methods. Over 30 years, more than 3,600 lemmings have been snap-trapped. They have recorded; sex, body mass, relative age, reproductive status, embryo counts, parasites, infectious diseases, and so forth. Although population fluctuations do exist, predictable cycles in the strictest definition of the word do not.
Additionally, researchers attached the first satellite transmitters to Snowy Owl in the world, recorded nest site characteristics, established genetic markers for estimating population, conducted hormone research in relation to pre-fledging nest departure of young, conducted growth rates and plumage development studies, and behavioral studies. Additionally, they have conducted an entire review their world ecology and population estimates.
Snowy Owl nesting numbers at Utqiaġvik have been declining since about 2009. Reasons are not known but climate change is suspected.
However, alternative questions for this decline do exist. For example, did the ~10 years of killing Arctic foxes to protect the threatened Steller’s Eider disrupt the entire ecosystem around Utqiaġvik? Do Brown and Collared lemmings and Arctic Fox have a relationship that benefits all three species? Did the removal of Arctic fox increase White-fronted, Brandt, and Snow goose numbers? And, in turn does the grazing impact on tundra plants, compete with lemmings, and reduce forage quality, quantity and ground cover, important for lemming survival?
These questions will be addressed in future analysis.
Denver Holt is a wildlife researcher and graduate of the University of Montana. He is founder and president of the Owl Research Institute, a nonprofit organization located in Charlo, Montana. As a dedicated field researcher, Holt believes that long-term field studies are the primary means to understanding trends in wildlife populations.
Since 1978, Holt’s research focus has been owls and their ecology. He has published over 100 papers and technical documents, including four species accounts for the Birds of North America project. He was team leader for the Strigidae Family owl species accounts for The Handbook of the Birds of the World, volume 5, covering 189 species of the world’s owls. In collaboration with elementary school teachers, he has co-authored two children’s science books on owls: "Owls Whoo Are They", and "Snowy Owls Whoo Are They". In 2006, he was a chapter author on owls for the book "Arctic Wings", highlighting the birds of the Arctic National Wildlife Refuge, Alaska. The forward was written by former United States President, Jimmy Carter.
In 2000, he was named Montana's Wildlife Biologist of the Year, by the Wildlife Society of North America. Holt’s research was the cover story for National Geographic Magazine in December 2002. His work has been subject of television bites on ABC, CBS, NBC, CNN, and Disney. His owl research has also been featured on Audubon's Up-Close Series, PBS's Bird Watch, and David Attenborough's Life of Birds, among others. His research on Snowy Owls has been showcased in documentaries for National Geographic Explorer, NHK Natural History Unit of Japan, and the Norwegian Broadcasting Company Natural History Unit. His Snowy Owl research was also featured in the British Broadcasting Company’s (BBC) documentary series Frozen Earth, a sequel to the Planet Earth series.
In May 2011, Holt’s research was featured in the New York Times. In 2011, Holt also advised and worked in the field with a PBS Documentary team, filming "The Magic of the Snowy Owl" at his research site in Barrow, Alaska. in 2012, he was inducted into the World Owl Hall of Fame. In 2021, Hakai Magazine featured Holt’s 30 years of research on Snowy Owls and in 2022 he gave his first TED talk.
When not researching owls, Holt is involved in wildlife watching tourism as a natural history tour guide and co-owner of Wild Planet Nature Tours. He also guides private natural history tours, and is a part-time trip leader for Victor Emanuel Nature Tour Company, one of the largest nature tour company in the world.
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