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RESPONDENT
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Joseph Liebezeit
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SITE NAME
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Prudhoe Bay Oilfield, USA
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| Contact details
(phone/fax//e-mail//address): |
| 503-241-7231/503-241-7925(fax) // jliebezeit@wcs.org // Wildlife Conservation Society, North America Program - Pacific West office, 718 SW Alder Street, Suite 210, Portland, OR 97205, USA
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PROJECT DETAILS |
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Project name:
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Nest success and nest predators of tundra-nesting birds in the Prudhoe Bay Oilfield - Long-term monitoring
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Start of survey:
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End
of survey: |
Team
size: |
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4.06
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17.07
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2
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WEATHER
CONDITIONS
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Weather conditions: |
Daily temperature information is available on-line at
http://www.wunderground.com. This years' early season (20 May to 30 June) average air temperatures were cold, similar to 2003 and 2005 (within ~1°C) while in 2006 and 2004 temperatures were noticeably warmer (by >1.5°C). Despite the colder air temperatures in 2007, snow melt was complete earlier than in the 4 previous years (approximately 5 days earlier than in 2006). We believe snow depth at the site was lower this year so, despite colder temperatures, snowmelt occurred earlier because less snow covered the ground. On 4 June, when we initially began monitoring snow cover, it was at 30%, and it completely disappeared approximately on 9 June. The Sagavanirktok River broke prior to 2 June. This year was relatively dry with little precipitation. Water levels in all water bodies (rivers, creeks, ponds, etc.) were lower than usual and was particularly noticeable as the season progressed. There were no major snow storms during the field season. The first mosquitoes emerged in mid-late June.
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| Date of ice-break on
rivers: |
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| Date of final loss of
snow: |
9.06
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BIOTIC
CONDITIONS
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| Rodents abundance evaluation: |
low
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Breeding conditions:
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In accordance with low lemming abundance, Pomarine Skua abundances were also much lower than in 2006 and were not seen at the site after early June. We found no evidence that they or Snowy Owls that were rare, nested at this site this year. Arctic Foxes were common breeders; also a Red Fox was recorded.
In 2007, we documented the second lowest overall nest density and the highest nest predation rates we've observed since we began monitoring at this site in 2003. Overall nest densities declined significantly from 2006 to 2007 (59.8 vs. 101.6 nests/km2). Nest densities declined most precipitously from 2006 to 2007 for Lapland Buntings (25.0 to 11.7 nests/km2) and Greater White-fronted Geese (10.0 to 2.5 nests/km2). We did not find any plover nests this season. Despite the lower densities for most species, nest density for Semipalmated Sandpipers remained consistent between years. Willow Grouse and Rock Ptarmigan were both common on breeding.
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Rodent dynamics:
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| We also conducted incidental surveys for lemmings (i.e. tallied lemmings the entire time we were on our study plots on predator count days). We detected only one lemming this year compared to 3 seen in 2005, and 19 seen in 2006. Thus, in 2007 lemming abundance returned to low levels from the high observed in 2006 (from 0.085 to 0.002 lemmings encountered per 30 minutes). We did not capture lemmings.
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Rodent species recorded:
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Summary
of fauna studies: |
We discovered and monitored all nests on (or near) 12 10-hectare study plots. Nests were monitored every 3-6 days until nesting fate was determined. We discovered 81 nests of 10 species from 10 June to 15 July. Of the 81 nests, 7 were discovered off-plot. Thirty-three nests successfully hatched/fledged and 37 failed. We were unable to reliably assess the fate of 11 nests. Nest predation was the most important cause of nest failure (35 of 37 nest failures, 95%). Other sources of nest failure were abandonment (n=1) and Caribou trampling (n=1). Mayfield estimates of nesting success for the four most common species were: 63.4% in Semipalmated Sandpiper (n=25), 14.0% in Lapland Bunting (n=15), 20.4% in Pectoral Sandpiper (n=12) and 44.9% in Red-necked Phalarope (n=10). For three of the four most common species, these estimates of nest survivorship were less than 50% which contrasts with 2006 when 7 of 10 species had nest survivorship exceeding 50%.
We conducted point count surveys for potential nest predators on each plot at eight different times during the course of the season. A total of eight potential predators were detected (n= number of detections): the Glaucous Gull (n=98), Arctic Skua (n=65), Arctic Fox (n=17), Long-tailed Skua (n=7), Arctic Ground Squirrel (n=5), Common Raven (n=2), Peregrine Falcon (n=2), Short-tailed Weasel (n=1).
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