Report : setinfo

RESPONDENT
Gilles Gauthier

SITE NAME
Bylot Island, Nunavut, Canada

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

PROJECT DETAILS

Project name:

Start of survey:	End of survey:	Team size:
16.05	20.08

WEATHER CONDITIONS

Season phenology:

early

Weather conditions:

In 2007, we continued our long-term study of the population dynamics of Greater Snow Geese and of the interactions between geese, plants and their predators on Bylot Island. Field work was conducted during the period from 16 May to 20 August over a total study area of ca. 400 km2, where we had 2 camps as usual, the Camp-1 (Base-camp) and the Camp-2, 30 km away. Most activities were conducted on foot in two core areas of about 50 km2 around each camp.
We retrieved weather data from our 3 automated recording stations without problems. The early spring was cool but from mid June to our departure in August we had exceptionally sunny, warm and dry weather. Our snow-depth transects showed that snow-melt was nonetheless early, in part because the snow-pack was thin at the end of the winter, and we had warm temperatures starting after the first week of June.

Season temperature:

warm

Season humidity:

Date of 50% snow-cover:

Date of ice-break on rivers:

Date of final loss of snow:

BIOTIC CONDITIONS

Rodents abundance evaluation:

low

Breeding conditions:

We found 60 out of 99 fox dens with signs of activity and 17 of them were used for reproduction. Ten litters of Arctic Fox were produced, ranging from 3 to 12 cubs (a total of 67 cubs were observed). Four litters were moved between dens, some of them several times. We captured 22 adult and 50 juvenile Arctic Foxes. Four adults had already been captured and tagged in 2003-2006. No Red Fox was observed. All dens with reproduction were located at least 18 km south of Camp 1, most of them around the goose colony or further south. Argos collars show that foxes are still on their territories by the end of September.
We found 17 Snowy Owl nests but none near Camp-1, which is usually a prime nesting area for them; most nests were scattered over a large area between Camp-1 and Camp-2 (up to 300 km2). We were able to trap 12 female owls at the nest and to mark them with ARGOS transmitters. By the end of September, all transmitters were still operational, 9 had left Bylot Island, and at least 7 of them were clearly migrating south (up to 700 km away from Bylot Island). Nesting success of owls was relatively low with a lot of clutch attrition, both before and after hatch, and several total failures during chick-rearing. We also found 9 Rough-legged Bazzard nests but these were scattered over a very large area and few of these nests could be monitored. We found 22 Glaucous Gull nests, 29 Long-tailed Skua nests and 1 Arctic Skua nest. Nesting success (proportion of nests successful in fledging at least one young) was moderate for owls (60% vs. 95% in 2004) and gulls (40% vs. 38% in 2006) but was low for skuas (9% vs. 0% in 2006). Average clutch size was 6.4 eggs for owls (vs. 7.1 eggs in 2004), 2.3 eggs for gulls (vs. 2.1 eggs in 2006), and 1.9 eggs for skuas (no data available in 2006).
We surveyed about 400 nests of Snow Geese in the colony (Camp-2) and monitored their reproductive success. Snow Goose arrival was one of the latest on record, possibly due to harsh conditions encountered during the spring migration in northern Quebec where the spring melt was very late this year. Geese started nesting immediately upon arrival but the peak laying date was delayed compared to the long-term average. The nest density in the colony was slightly higher than last year (3.0 nests/ha in 2007 compared to 2.57 nest/ha in 2006) but slightly below the long-term average. The average clutch size was 3.91, which is higher than the long-term average. Predation rate on nests was low, especially by foxes, and thus nesting success was very high (82%, a value well above the long-term average). Survival of young during the summer was apparently good because the young/adult ratio in our banding drives in August was above the long-term average. Overall, these results indicate a good production of young on Bylot Island by the end of the summer.
We documented the presence of 8 shorebird species. Twenty-seven shorebird nests of 5 species were monitored. The most abundant nesting birds were the Baird's and White-rumped sandpipers. Nest density was low and arrival and lay dates were late relative to previous years. This was likely caused by harsh weather conditions encountered in the low arctic during the spring migration. In addition to the monitoring of natural nests, 160 artificial nests were deployed. Predation pressure on natural and artificial nests was low probably due to an increase in the abundance of lemmings on the island. The Arctic Fox was the only shorebird egg predator (identified using remote camera). Nesting success of the Baird's and White-rumped sandpipers was much higher in 2007 (78% and 73%, respectively) compared to the previous two years. We also found 78 nests of Lapland Buntings, whose nesting success (proportion of nests successful in fledging at least one young) was high (62% vs. 9% in 2006).

Rodent dynamics:

Our different indices of lemming abundance yielded variable results. Live-trapping at Camp-1 indicated a very low abundance of lemmings, comparable to 2006. Snap-trapping in July suggested a moderately low abundance of lemmings at both camps, higher than in 2006. Winter nest surveys also indicated moderate lemming abundance. Field impressions suggest that lemmings were quite abundant at snow-melt but relatively scarce by late summer. However, the most noteworthy was that in both snap-trapping and live-trapping, Greenland Lemmings were much more abundant than Brown Lemmings. These data suggest that the former reached a peak this year but not the latter, which is unusual (in previous peaks, both species were synchronous, and Brown Lemmings far outnumbered Greenland Lemmings in a peak year). The failure of Brown Lemming to peak this year apparently explains why overall abundance of lemmings was at best moderate this year.

Rodent species recorded:

Latin	Abundance

Summary of fauna studies:

Group of species	Presence	Abundance	Breeding
arctic foxes	Yes	common	breeding
lemmings	Yes	rare
waders	Yes	rare	hatching
geese	Yes	abundant	hatching
buzzards	Yes		breeding
skuas	Yes		hatching
gulls/terns	Yes		breeding
owls	Yes	common	hatching