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RESPONDENT
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Richard Anthony
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SITE NAME
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Yukon-Kuskokwim outer Delta south-west, Alaska, USA
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| Contact
details (phone/fax//e-mail//address): |
| (907)786-3508/(907)786-3636(f) // mike_Anthony@usgs.gov // Alaska Science Center, USGS, Biological Science Office, 1011 East Tudor Road, Anchorage, AK 99503, USA |
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PROJECT DETAILS
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Start of survey:
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End
of survey:
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Team
size:
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WEATHER CONDITIONS
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| Date of ice-break
on rivers: |
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| Date of final loss
of snow: |
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BIOTIC CONDITIONS
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| Rodents abundance evaluation: |
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Breeding conditions:
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Aerial surveys at five Black Brant colonies on the Yukon-Kuskokwim Delta - Kokechik Bay (KB), Tutakoke River (TR), Kigigak Island (KI), Baird Inlet Island (BI), and a peninsula northwest of Baird Inlet Island (BP) were conducted on 2.06. Timing of surveys was the earliest ever due to an extremely early break-up.
Nest predation by arctic foxes was greatly reduced throughout the coastal region this year compared to 2003. Numbers of unoccupied nests and nests with strewn down seen in images were reduced from last year. The nest estimate at KB was again low this year and the number of nests found on ground-truthed transects confirmed the decline in number of nests.
Only 14 active nests and 5 destroyed nests (apparently flooded by an extremely high tide) were found in 3.5 hectares intensively searched during ground-truthing at KB in an area with historically high densities of nests. Counts of all-terraine vehicle and boot tracks indicated an increase in human activity in the brant colony. Boot counts have increased from 30 in 2001 to 34, 160, and 166 in 2002-2004, respectively.
Coincidental with the apparent increase in human activity in the KB area estimates of the number of nesting brant has declined. Consistently the colony with the most nests among five colonies surveyed annually since 1992, KB had the fewest nests in 2003 (655 nests), which was a year of high fox predation. By comparison, KB had the largest nest population among all colonies in 2001, also a year of very high fox predation but with less evidence of human activity. Estimated number of nests in 2004 is 1996ñ116 nests, compared to an average of 6893ñ902 nests from 1995-2000. Although other factors influence fluctuations in productivity (fox predation, nesting conditions due to climatic factors, physical condition of females arriving from wintering areas) the dramatic decline in total nesting effort (i.e., evidence of failed nests as well as active nests) causes concern for the effect of disturbance by humans in this colony. Estimates of nests at TR and BI also were relatively low compared to previous years without high fox predation.
Brant nesting effort in 2004 increased in 4 of the 5 colonies on the YKD from 2003, but remained approximately 24% below the 8-year average. Clutch sizes and nest success on the YKD were higher than in the very poor year of 2003. Production of brant in 2004 should be improved somewhat over 2003, but the fall flight is expected to be similar to last year's. |
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Rodent dynamics:
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Rodent species recorded:
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Summary
of fauna studies: |
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