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RESPONDENT
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Gilles Gauthier
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SITE NAME
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Bylot Island, Nunavut, Canada
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| Contact details
(phone/fax//e-mail//address): |
| // Gilles.Gauthier@bio.ulaval.ca // Departement de biologie & Centre d'etudes nordiques, Universite de Laval, St. Foy, Quebec City, Quebec, G1K 7P4 Canada
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PROJECT DETAILS |
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Project name:
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Population Study of Greater Snow Geese on Bylot Island (Nunavut) in 2004
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Start of survey:
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End
of survey: |
Team
size: |
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1.06
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18.08
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5
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WEATHER
CONDITIONS
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| Season phenology: |
average
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Weather conditions: |
The spring of 2004 was characterized by a normal snowmelt despite cool temperatures. Although temperature was relatively warm in early and mid May, air temperature averaged -0.67øC between 20 May and 20 June (0.53øC below normal) and only
0.05øC during 1-15 June (1.34øC below normal). However, snow depth on 2 June was only 22 cm compared to a long-term average of 31 cm. The thin snow pack at arrival explains the near normal date of snowmelt despite the cool spring temperature and some light snowfall in mid June. July and August were also relatively cool compared to recent summers. Precipitation
was low in June (13 mm of rain) but very high in July (69 mm) and August (60 mm up to 21 August). However, whereas precipitation was frequent in August (12 days out of 21), rainy days were scarcer in July (11 days out of 31) but 65% of the month's precipitation fell in only 2 days (13 and 30 July). These torrential rains resulted again in flooding of lowlands in August, especially polygon tundra which was covered by several cm of water.
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| Date of 50%
snow-cover: |
8.06
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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: |
average
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Breeding conditions:
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The breeding activity of foxes was high as we found 16 litters (15% of known denning sites with a different litter), 15 of Arctic Foxes and 1 of Red Foxes. This level of use is much higher than last year (only 4% of the dens were used) and
typical of the proportion of fox dens used in previous years of peak lemming abundance (17%). Minimum litter size varied between 1 and 10 pups for Arctic Foxes (5.5 pups on average) and was 6 for the single Red Fox.
After 3 years of nesting absence, we found 9 Snowy Owl nests in the Camp-2 area and 13 in the Base-camp Valley, a record high. In previous lemming peaks, the number of owls nests ranged from 7 to 13 in the Base-camp Valley and only 1 to 2 in the Camp-2 area. The average egg-laying date for the first egg was 18 May (range: 10 to 28 May) and average
clutch size was 7.1 eggs (range: 4 to 10). All nests but one were successful in fledging at least one young. We also found 5 nests of Glaucous Gull, more than 20 nests of Long-tailed Skuas and 27 nests of Lapland Buntings.
Arrival dates of geese on Bylot Island were similar to previous years. However the number of geese counted on the hills surrounding the Base-camp Valley (the first area used by geese upon arrival) was very low this year. Such low numbers are usually typical of years where goose arrival is considerably delayed (e.g. 2002). Pair counts at arrival nonetheless suggest a reduced number of geese on Bylot Island this year.
The distribution of goose nests was highly unusual this year, probably due to a record nesting activity of Snowy Owls. For the first time in 12 years, most geese at the main colony (Camp-2) nested around owl nests, with a low density of nests in between, even in the central part of the colony. This rendered difficult the estimation of nesting density in the main colony but, overall, the patchy distribution of goose nests indicates a reduced nesting effort this year. Several geese nested in the Base-camp Valley (mostly a brood-rearing area) this year, also in close association with Snowy Owls. Overall, median egg-laying date was 11 June, which is very close to the long-term average. However, there was an usually high spatial
variation in laying dates as geese nesting in association with owls started laying on average on 10 June (n = 511) whereas those nesting away from owls (including the usual central portion of the colony) started laying around 16 June (n = 132). There was thus a bi-modal distribution of laying dates this year, with a smaller late peak. It is noteworthy that fresh snowfall occurred during the period in between the 2 peaks. Overall, mean clutch size was 3.65, which is again very close to the long-term average. As expected, clutch size was higher in nests located near owls (3.74, n = 490) than far away (3.30, n = 125).
Nesting success (proportion of nests hatching at least one egg) in 2004 was similar to last year and fairly good (78% for all nests, a value above the long-term average, 64%). Nesting success was higher in the Base-camp Valley (92%, n = 158) than at Camp-2 (colony, 74%, n = 480). At the colony, nesting success also tended to be slightly higher away from owls nests (82%, n = 121) than near them (72%, n = 353). Activity of predators at goose nests, especially Arctic Foxes, was low in the Base-camp Valley and moderate at the colony but slightly higher than in 2003. Peak hatch was on 7 July, also close to the long-term average.
The production of young on Bylot Island was relatively low in 2004 , which is somewhat surprising given the normal nesting dates and clutch size, and the high nesting success. This can be explained by 1) continueing spring harvest in Quebec, negatively impacting body condition of arriving geese; 2) severe climatic conditions during spring migration; and 3) cold temperatures throughout June despite a normal snow-melt due to a thin snow-pack.
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Rodent dynamics:
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During our survey using snap traps, we accumulated 1047 trap-nights in the Base-camp Valley at our 2 trapping sites from 22 July to 3 August, and 500 trap-nights at the Camp-2 from 7 to 17 July. In the Base-camp sites, we caught 8 Brown Lemmings (Lemmus sibiricus) in the wet meadow site and none in the mesic site for a combined index of abundance of 0.78 lemmings/100 trap-nights. In the Camp-2 site, 2 lemmings were caught, 1 Brown and 1 Collared Lemming (Dicrostonyx groenlandicus) for an index of 0.41 lemmings/100 trap-nights.
After 2 to 3 years of very low numbers, we expected that 2004 would be a peak in the lemming cycle. Although lemming increased over last year, their abundance, as indicated by our trapping index, appeared much lower than in previous peak years (e.g. 1996 and 2000). We captured 36 Brown Lemmings and 27 Collared Lemmings in the mesic habitat, and 117 Brown and no Collared ones in the wet habitat.
It is possible that 2004 was a genuine lemming peak and that our trapping underestimated its amplitude due to 1) a period with several days of heavy rain coinciding with the trapping in the Base-Camp Valley, and 2) rapid decline of lemming populations by late July, also caused by heavy predation.
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Rodent species recorded:
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| Latin | Abundance |
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| Lemmus sibiricus | common |
| Dicrostonyx groenlandicus | common |
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Summary
of fauna studies: |
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