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Greater Snow Goose Update
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2010 SPRING POPULATION SURVEYS OF GREATER SNOW GEESE IN SOUTHERN QUÉBEC AND POPULATION STUDY ON BYLOT ISLAND, NUNAVUT
Since 1965, the Canadian Wildlife Service conducts its annual aerial photographic survey on greater snow geese during their spring migration in southern Québec. This year the survey was carried out on April 30 when five aircraft were used simultaneously during a warm and sunny day. During these favorable weather conditions, the geese tend to roost on water bodies in mid-day, facilitating the coverage. The aerial survey covered a large territory extending from Lac Champlain (south) to Lac St-Jean (north) and from east Ontario (west) to Baie-des-Chaleurs (east).
Following the 2009 results which showed an important population increase that was difficult to explain biologically, we hired Service de Consultation Statistique (SCS) from Université Laval to verify the sampling and analyses methodology. During this process, some gaps were found which brought us to make some corrections for the 2010 spring survey. For this year, the preliminary estimate of the size of the spring population was 814,000 ± 77,000geese. Based on SCS recommendations, a revision process has been undertaken to check last years estimates to verify their accuracy.
Breeding conditions of greater snow geese are near average this year on Bylot Island. There was a very deep snow-pack in early spring, one of the deepest on record. However, temperatures in late May and early June were very mild with little precipitation; thus, even though the snow melted fast, the melt was still later than normal. Weather has been very warm and sunny throughout most of June and beginning of July.
Because of the delayed snow-melt, geese density was lower than usual in the center of the colony but geese were much more spread out than usual. They used any snow-free patch available in early June to set their nest. In addition, we have a peak in lemming abundance this year and a large number of snowy owls are nesting on the island. As usual in those years, many snow geese nested in association with these owls, which also contributed to the spread of nesting geese this year. As a result, it is somewhat difficult to evaluate the overall reproductive effort of geese but I would rate it as near normal.
Here are some preliminary productivity data from 2 sites (site 1: center of the colony, site 2: neat snow owl nests); 20-year average values are given in parentheses:
Mean initiation date: Site 1: 14 June; Site 2: 10 June (12 June)
Mean clutch size: Site 1: N/A, Site 2: 4.20 eggs (3.71)
Mean nesting success to late incubation: Site 1: N/A; 90% (64%)
Thus, nesting phenology is variable depending of the sites but near normal; clutch size is quite a bit higher than normal, probably because partial predation on nests is low this year. Indeed, most predators have switched to lemmings due to their high abundance, which explains the high nesting success of geese so far.
Therefore, based on these preliminary data, we expect a good fall flight for greater snow geese, possibly above average.
Prepared by Josée Lefebvre, CWS and Gilles Gauthier, ULaval
Greater Snow Goose Update
--------------------------------------------------------------------------------
2010 SPRING POPULATION SURVEYS OF GREATER SNOW GEESE IN SOUTHERN QUÉBEC AND POPULATION STUDY ON BYLOT ISLAND, NUNAVUT
Since 1965, the Canadian Wildlife Service conducts its annual aerial photographic survey on greater snow geese during their spring migration in southern Québec. This year the survey was carried out on April 30 when five aircraft were used simultaneously during a warm and sunny day. During these favorable weather conditions, the geese tend to roost on water bodies in mid-day, facilitating the coverage. The aerial survey covered a large territory extending from Lac Champlain (south) to Lac St-Jean (north) and from east Ontario (west) to Baie-des-Chaleurs (east).
Following the 2009 results which showed an important population increase that was difficult to explain biologically, we hired Service de Consultation Statistique (SCS) from Université Laval to verify the sampling and analyses methodology. During this process, some gaps were found which brought us to make some corrections for the 2010 spring survey. For this year, the preliminary estimate of the size of the spring population was 814,000 ± 77,000geese. Based on SCS recommendations, a revision process has been undertaken to check last years estimates to verify their accuracy.
Breeding conditions of greater snow geese are near average this year on Bylot Island. There was a very deep snow-pack in early spring, one of the deepest on record. However, temperatures in late May and early June were very mild with little precipitation; thus, even though the snow melted fast, the melt was still later than normal. Weather has been very warm and sunny throughout most of June and beginning of July.
Because of the delayed snow-melt, geese density was lower than usual in the center of the colony but geese were much more spread out than usual. They used any snow-free patch available in early June to set their nest. In addition, we have a peak in lemming abundance this year and a large number of snowy owls are nesting on the island. As usual in those years, many snow geese nested in association with these owls, which also contributed to the spread of nesting geese this year. As a result, it is somewhat difficult to evaluate the overall reproductive effort of geese but I would rate it as near normal.
Here are some preliminary productivity data from 2 sites (site 1: center of the colony, site 2: neat snow owl nests); 20-year average values are given in parentheses:
Mean initiation date: Site 1: 14 June; Site 2: 10 June (12 June)
Mean clutch size: Site 1: N/A, Site 2: 4.20 eggs (3.71)
Mean nesting success to late incubation: Site 1: N/A; 90% (64%)
Thus, nesting phenology is variable depending of the sites but near normal; clutch size is quite a bit higher than normal, probably because partial predation on nests is low this year. Indeed, most predators have switched to lemmings due to their high abundance, which explains the high nesting success of geese so far.
Therefore, based on these preliminary data, we expect a good fall flight for greater snow geese, possibly above average.
Prepared by Josée Lefebvre, CWS and Gilles Gauthier, ULaval
