Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
TOGIAK:Seeing Double
Alaska Region, June 22, 2012
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A young cow shows off her new collar.
A young cow shows off her new collar. - Photo Credit: USFWS/Togiak NWR
Biologist Andy Aderman (left) and a colleague attach a collar to one of Togiak's many cow moose.
Biologist Andy Aderman (left) and a colleague attach a collar to one of Togiak's many cow moose. - Photo Credit: USFWS/Togiak NWR
Twins again! A relatively common sight on Togiak Refuge.
Twins again! A relatively common sight on Togiak Refuge. - Photo Credit: USFWS/Togiak NWR

Radio telemetry is a critical component to large mammal research and management on Togiak Refuge, and some of the refuge’s moose are its biggest stars. Thanks to radio tracking, one cow moose in particular, referred to as 02-50, has achieved a pretty unique distinction.


On May 27, 2012 Togiak Refuge Pilot Mike Hink and Wildlife Biologist Andy Aderman radio-tracked onto cow moose 02-50’s signal five miles west of the village of Togiak. It took a couple of passes in the Piper PA-18 SuperCub aircraft before they were finally able to spot her lying in a small patch of alders surrounded by semi-snow-covered, mottled tundra (picture a Bev Doolittle landscape and you’re on the right track). With her was a pair of rusty brown-colored calves not more than a couple of days old. “Twins!” called out Aderman. “Twins!” said Hink, thereby confirming the other’s observation. So what’s the significance of the twins? Well, moose 02-50 is reproductively unique among the 83 female moose radio-collared since the tracking project began in 1998. The project is a cooperative effort between the Togiak Refuge and the Alaska Department of Fish and Game to monitor moose population size, calf production and recruitment, and survival of adult females and their offspring within the Togiak Refuge.

Moose 02-50 was enlisted into the program back in mid-April of 2002. She was captured, weighed, and radio-collared when she was about 11 months of age. At 184 kg (a bit over 405 pounds), she was the lightest of 10 moose caught and weighed that year. Her first radio collar was expandable as female moose continue to grow until four years of age. Males continue to grow until seven to nine years of age. Biologists radio-tracked her and the other collared moose once a month throughout the year and weekly during the calving period (mid-May to mid-June). However, because moose are not sexually mature until 16 or 28 months of age, weekly calving flights are conducted only for females >2 years of age. Yearling females on a high nutritional plane generally breed and produce a single calf.

On May 28, 2003, at the ripe old age of 2 years, moose 02-50 was observed with newborn twins! While twins are not that uncommon for older age females, they are quite rare for a moose on her 2nd birthday. In support of that, according to the Wildlife Management Institute’s Ecology and Management of North American Moose twins are rarely produced by cow moose that age, and research suggests that cows that do breed that young produce fewer calves over the course of their breeding lives. Apparently cow 02-50 missed reading that particular book, and the moose population of Togiak Refuge has benefited from it.

The moose population in the eastern half of Togiak Refuge increased rapidly during the mid- 1990s through the mid-2000s. In fact, when compared with other places in Alaska, moose in the Togiak area rank first/highest in female short-yearling mass, age at first twinning, percentage of parturient 2-year-olds, and multiyear adult twinning rates (see Boertje et al. 2007. Journal of Wildlife Management 71:1494-1506). Moose 02-50’s first set of twins both survived to about 1 year of age, at which time they became independent from her. 2003 though turned out to be just the beginning. On May 18, 2004 she was observed with another set of newborn twins.

The moose population on Togiak Refuge continued to grow in size and range (see Field Notes April 2011 article) and 02-50 continued to produce twins. In early April 2007, she was recaptured and fitted with a nonexpendable collar with a 10 year battery. A month and a half later she was observed with her fifth consecutive set of twins. Fast forward another five years to 2012. Yep, you guessed it. That set of twins with 02-50 this past May is her 10th consecutive set. Twenty calves and she is only eleven years of age. Nine of the first 18 calves have survived to 1 year of age. Additionally one of these calves born in 2007 was captured, weighed, and radio-collared in early April 2008. This moose, 08-09, weighed 214 kg (almost 472 pounds) at capture, and produced a single calf on her 2nd birthday. However, since then she’s turning out to be a lot like her mother. She too was spotted this year on the same day as 02-50, and she was observed with her third consecutive set of twins!

For more information about the moose of Togiak Refuge, contact Andy Aderman at 907-842-8406.

Contact Info: Terry Fuller, 907-842-1063 ext. 8419, terry_fuller@fws.gov
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