Home
Field Notes
 
U.S. Fish & Wildlife Service
Field Notes Entry   
KODIAK: Brown Bear Stream Surveys Suggest Lean Times in Bear Country
Alaska Region, April 21, 2010
Print Friendly Version
Aerial Survey of Bears on Salmon Streams
USFWS/WB Leacock
Aerial Survey of Bears on Salmon Streams USFWS/WB Leacock - Photo Credit: n/a
Kodiak Brown Bear Sow with Cubs of the Year, USFWS/WB Leacock
Kodiak Brown Bear Sow with Cubs of the Year, USFWS/WB Leacock - Photo Credit: n/a
Bear Composition 1985-2005, USFWS/WB Leacock
Bear Composition 1985-2005, USFWS/WB Leacock - Photo Credit: n/a
Bear Composition 2009, USFWS/WB Leacock
Bear Composition 2009, USFWS/WB Leacock - Photo Credit: n/a

Kodiak National Wildlife Refuge biologists have monitored the brown bear population almost since the creation of the Refuge. Aerial surveys of bear numbers and age and gender composition along salmon streams – has been a tried and true technique since the 1950s.  Biologists have conducted systematic surveys of the same six salmon streams on southwestern Kodiak Island since 1985 – perhaps the longest running systematic brown bear survey in all of Alaska. These surveys allow us to compare bear numbers and, more importantly, composition – proportions of single bears, sows with cubs of the year, and sows with one-year-old and two-year-old cubs.  In conjunction with intensive aerial surveys, our stream surveys allow us to assess population trends.

 

We carried out sixteen surveys on this network of streams between 1 July and 26 August, 2009.  The last year’s average, 58 bears per survey, was lower than the 21-year average of 85 bears/survey. This lower density of bears along streams is likely related to lower than average salmon runs.  Perhaps more importantly, composition differed last year compared to the long-term average. In particular, the proportion of cubs was significantly lower than the long-term average. Maternal bears or family groups accounted for 18% of the total between 1985-2005, whereas last year they made up only 11% of the total.  Cubs of the year and yearlings accounted for 9% and 11% in 2009 whereas; the long-term average was 11% and 24 % of the total.   The downturn in numbers may reflect diminished productivity of sows and reduced survival of cubs of the year probably due to reduced availability of berry crops during the summer and fall of 2007 and 2008 and lower than average salmon runs in 2008. But without hard data on both berry production and salmon runs on all southwest Kodiak network streams this remains speculation.  Refuge biologists will investigate this relationship as part of a more comprehensive long-term bear project beginning in 2010.

 


Contact Info: William B. Leacock, (907) 487-2600 ext. 249, william_leacock@fws.gov



Send to:
From:

Notes:
Find a Field Notes Entry

Search by keyword

Search by State




Search by Region


US Fish and Wildlife Service footer