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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 in 2005; Monitoring the environmental and ecological impacts of climate change on Bylot Island.
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Start of survey:
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End
of survey: |
Team
size: |
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30.05
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22.08
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9
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WEATHER
CONDITIONS
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| Season phenology: |
average
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Weather conditions: |
The snow pack in spring 2005 was near normal with an average snow depth of 33.6 cm on 1 June compared to a long-term average of 31.5 cm. Despite the deeper snow pack in 2005 compared to 2004, snow-melt was relatively fast this year.
The spring of 2005 was characterized by a normal snowmelt at the Base-camp and close to normal temperatures. Air temperature averaged -0.40øC between 20 May and 20 June (0.24°C below normal) and 1.52°C during 1-15 June (0.12°C below normal).
The summer 2005 was the second wettest on record on Bylot Island, with 132 mm of rainfall compared to a long-term average of 97 mm. Precipitation was high in June (40.5 mm of rain) but concentrated over just 5 consecutive days. Precipitation was very high in July (a record 87 mm) but August was characterized by exceptionally good weather with lots of sunshine, warm temperatures, and little precipitation (5 mm up to 20 August).
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| Season temperature: |
average
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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: |
low
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Breeding conditions:
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In 2005, we visited 108 fox dens during the summer and we detected signs of activity (fresh digging and/or footprints) at 80 of them. The breeding activity of foxes was low as we found 7 litters (7% of known denning sites with a different litter) of Arctic Foxes and none of Red Foxes. This level of use is lower than last year (15%) but typical of the proportion of fox dens used in years of relatively low lemming abundance (~5%). Minimum litter size varied between 3 and 9 pups (mean of 6.9 pups ñ 0.8, n = 7). This value is higher than the long-term average litter size (Arctic Fox: 4.0 pups).
Snowy Owls only nest in peak lemming years, which occur every 3-4 years on Bylot Island. Owl nests were thus previously found in 1989, 1993, 1996, 2000 and 2004. In 2005, no Snowy Owls were found nesting in our study area.
In 2005, we found 11 nests of Glaucous Gulls in the Qarlikturvik Valley and 1 at the goose colony, and 9 nests of Long-tailed Jaegers at each study site. Mean egg laying date of gull nests was 13 June and 16 June for jaegers; mean hatching date were 10 July and 11 July, respectively. Mean clutch size was 2.9 in gulls and 1.8 eggs in jaegers. Nesting success of gulls was 80% while most jaeger nests were predated and only 8% of them produced young.
Overall, the median date that the first egg was laid in Greater Snow Goose nests (i.e. egg-laying date) in 2005 was 12 June, which is also the long-term average. Our field observations suggest that the reproductive effort of geese was moderately high at the main colony (Camp-2). Although nest density appeared slightly lower than usual in the center of the colony, the colony tended to be more spread-out this year. Only 5 nests were found at the Base-camp Valley (predominantly a brood-rearing area), a situation common in years when no Snowy Owls are nesting.
The mean number of eggs per nest (i.e. total clutch laid) was 3.60 ñ 0.08 eggs (n = 156) in 2005, very close to the long-term average (3.70). Activity of predators at goose nests, especially Arctic Foxes, was moderate but slightly higher than in 2004. Nesting success (proportion of nests hatching at least one egg) in 2005 was good (66%, n = 226) and very close the long-term average (64%).
The young:adult ratio observed during our banding operation suggests that, overall, production of young on Bylot Island was relatively good this year. Based on this youg:adult ratio, we anticipated a proportion of young in the fall flock of 23%. This prediction was upheld as juvenile counts conducted in Quebec indicated a proportion of young of 21% (n = 29,022) in the fall flock, a value slightly below the long-term average (24%).
Thus, in 2005 Snow Geese nested at usual dates, and their reproductive effort was moderate (i.e. moderate nesting density). Even though no Snowy Owls have nested this year, geese still benefited from a relatively low predation pressure, due to low abundance of foxes and jaegers, which enabled them to have a relatively high nesting success.
Our new monitoring of shorebird species was successful in 2005. Among the eight species monitored, five of them were found nesting, mostly in the Qarlikturvik Valley. The most abundant shorebirds were the White-rumped Sandpiper (39 nests), the Baird's Sandpiper (20 nests) and the American Golden Plover (6 nests). Black-bellied Plover (1 nest), Red Phalarope (1 nest), Common Ringed Plover, Purple Sandpiper and Ruddy Turnstone were also observed on the island during the summer. Clutch size of all shorebird nests monitored was 4.0 eggs. Mean laying and hatching dates were between 10 and 18 June, and 4 and 18 July, respectively. Overall, Baird's Sandpipers had the highest nesting success (25%) followed by American Golven Plovers (19%) and White-rumped Sandpipers (11%).
In 2005, we found a record number of Lapland Longspur nests (68). Large annual variations in number of nests found in part reflect variations in sampling effort among years. Egg-laying and hatching dates of longspurs in 2005 were 21 June (n = 32; long-term average: 17 June) and 3 July (n = 19; long-term average: 4 July), respectively. The clutch size was 5.1 ñ 0.1 eggs (n = 57), slightly below the long-term average (5.3) and no temporal trend was detected. Nesting success was very low (19%, n = 62) and below the long-term average (54%).
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Rodent dynamics:
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During our small mammal survey using snap traps, we accumulated 1196 trap-nights in the Base-camp Valley at our 2 trapping sites from 23 July to 3 August, and 548 trap-nights at the Camp-2 from 5 to 20 July.
In the Base-camp sites, we caught 2 Collared Lemmings (Dicrostonyx groenlandicus) in the mesic site and none in the wet meadow site, and no Brown lemmings (Lemmus sibiricus) were caught, which yielded a combined index of abundance of 0.17 lemmings/100 trap-nights, a low value. In the Camp-2 site, 4 lemmings were caught, 1 Brown and 3 Collared Lemmings for an index of 0.75 lemmings/100 trap-nights. Lemmings at the Base-camp Valley had decreased considerably following the moderate peak of last year and were in the low phase of their cycle. However, similar to the situation observed during the previous peak, it appeared that the peak in lemming abundance at the Camp-2 area was delayed compared to Camp-1.
For the second year of our live-trapping monitoring program for lemming populations, we captured a total of 55 lemming individuals. Preliminary analyses based on capture-recapture models indicate that average densities of Brown Lemmings in 2004 was 2.2 lemmings ha-1 and 0.4 lemming ha-1 for Collared Lemmings, and in 2005, 0.3 and 0.2 lemming ha-1, respectively.
Results from our dead and live-trappings showed that lemming abundance was quite low in 2005, and confirmed that 2004 was a peak in lemming abundance at the Base-camp, even though the numbers captured last year were relatively low compared to previous peaks.
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Rodent species recorded:
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| Latin | Abundance |
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| Lemmus sibiricus | rare |
| Dicrostonyx groenlandicus | rare |
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Summary
of fauna studies: |
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