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KODIAK: An Early Berry Crop Effects the Kodiak Brown Bear’s Taste for Salmon
Mountain-Prairie Region, November 14, 2014
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Bear fishing at the Lower Falls of the Dog Salmon River
Bear fishing at the Lower Falls of the Dog Salmon River - Photo Credit: Will Deacy, USFWS
Biological Science Technician Caroline Cheung checking a time lapse camera at O'Malley Stream
Biological Science Technician Caroline Cheung checking a time lapse camera at O'Malley Stream - Photo Credit: Louisa Pless, USFWS
Biologist Bill Leacock observing bears above Connecticut Creek
Biologist Bill Leacock observing bears above Connecticut Creek - Photo Credit: Louisa Pless, USFWS
A bear fishing for salmon in the shoals of Karluk Lake
A bear fishing for salmon in the shoals of Karluk Lake - Photo Credit: Marie McCann, USFWS

By Volunteer Field Researcher, Marie McCann

During the long days of summer, Kodiak’s brown bears beat well-worn paths along Refuge streams foraging for spawning sockeye salmon. The large quantity of this nutritious food has allowed the Kodiak brown bear to reach sizes and densities matched by only a few other places in the world.  In fact, over 2,500 Kodiak brown bears call the Refuge home, more than the entire lower 48 states. But in recent years salmon runs in southwestern Kodiak have been erratic and scientists have seen a drop in bear numbers within this area of the Refuge.  The bear population across the Archipelago and entire Refuge has remained largely stable. 

Since 2012, teams of researchers led by William Leacock, Refuge Biologist, and Will Deacy, University of Montana PhD student, have been using innovative techniques to better understand the role salmon play in bear ecology. This summer, the research team monitored 11 of the most important spawning streams in the remote southwest corner of the Refuge and the bears using these streams.

The team of volunteers and staff used time lapse photography, remote video systems, and radio-telemetry to track salmon and bears.  A better understanding of this relationship will help managers determine the effect food sources like salmon and berries have on bear ecology.  This intimate bear-salmon relationship can also serve as an indicator of overall ecosystem health for one of the most productive habitats in Alaska. 

Salmon Stakeout

To count spawning salmon, the team designed remote, solar-powered camera systems that recorded photos and video 24 hours a day.  They installed white panels on the streambed to highlight passing salmon and used infrared lights to detect the fish at night. Over the course of the summer, hundreds of hours of video and 4.6 million photos were collected and reviewed. The dedicated field team was able to analyze all the photos and footage as it was collected. From this data, scientists were able to gauge density, mortality, and daily abundance of salmon in the 11 streams. 

Bear Watchers

At the same time, the team documented how the bears responded to salmon across the study area. First, researchers used GPS collars to closely track habitat use of 16 collared bears.  Secondly, they placed over 30 remote time lapse cameras along study streams to measure bear use.  Finally, aerial surveys of salmon streams were conducted to further determine patterns of bear use and family composition.

The Confounding Role of Berries

This field season of monitoring bear movements revealed the complicating role berries play in  bear ecology. Elderberry on the island, normally ripen in late August, after most salmon runs have faded. In 2014, the berry crop was early and abundant due to an early and warm spring. Remote camera and GPS collar data showed that bears largely abandoned salmon streams in July and August to exploit elderberry patches, suggesting that they preferred berries over salmon.  This surprising preference highlights the importance that both food sources play in bear ecology. Researchers hope to study berry production in the future to better understand how a changing climate is impacting this productive island ecosystem and its iconic bears.

Special Thanks

This research was made possible only with a dedicated and adventurous team of volunteers and staff, who put in long field hours and analyzed millions of salmon photos and video footage. This project was supported with funds from the National Wildlife Refuge System’s Inventory and Monitoring Program. The Inventory and Monitoring (I&M) program nationally coordinates the collection and analysis of  wildlife and habitat data spanning the Refuge System, enabling wildlife refuges to better adapt management to the  rapid and large-scale changes like climate change.


Contact Info: Marie McCann, 6185349694, marie_mccann@fws.gov
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