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Understanding the nature of social groups may help explain the genetic structure of populations. Recently, a finescale genetic structure was found in the Greater Snow Goose (Chen caerulescens atlantica) among adults captured in different brood-rearing sites. Such a structure requires assortative pairing among birds coming from the same brood-rearing site, a process that could be enhanced if individuals maintain stable associations over time. We verified whether stable groups persisted throughout the annual cycle of this migratory species. We used an 18-year data set of females marked on brood-rearing sites in the Arctic (n = 16,060) and recaptured on those sites or resighted on the breeding, staging, or wintering grounds in subsequent years. We used a probabilistic method to compare the number of associations observed with the number expected by chance alone. Our results provide no evidence that stable groups persist in flocks during migration or in winter among adult females. However, females m...

Although mesic tundra is a habitat commonly used by arctic-nesting geese, their feeding ecology in this habitat is little known compared to wetlands. Our objectives were to determine the diet and food selection of Greater Snow Goose (Chen caerulescens atlantica) goslings in relation to the nutritional quality of plants growing in mesic tundra habitats on Bylot Island, Nunavut, Canada. We used two different but complementary approaches: examination of esophageal contents of sacrificed wild goslings, and direct observation of the feeding activity of captive, human-imprinted goslings. The latter method was innovative and provided a reliable description of the diet, with results comparable to those obtained from wild goslings. Although mesic habitats have a more diverse floristic composition than wetlands and sparse graminoid cover, Gramineae were preferentially selected and dominated the diet (~50%). The rest of the diet consisted mainly of members of the Juncaceae, Polygonaceae, and Leguminosae families. The diet of very young goslings was diverse, but as they aged and gained efficiency, they concentrated on a few taxa. Goslings ate mostly leaves (~80%), but flowers (~20%) were also important. Food selection was influenced by nitrogen and total phenolic compounds content of plants, but the ratio of phenolic compounds to nitrogen in plant organs was most determinative of food choice. Neutral detergent fiber content of plants did not influence plant selection. Both plant nutritional quality and availability determined gosling diet across different mesic habitats and growing goslings appeared to maximize their intake of metabolizable proteins.

Many precocial birds make long-distance movements with their young after hatch to reach the best foraging sites. On Bylot Island, Nunavut, a large number of Greater Snow Goose ( Chen caerulescens atlantica L., 1758) families move 30 km from the main nesting colony (MNC) to reach the main brood-rearing area (MBR) soon after hatch. Geese moving from the MNC to the MBR generally rear lighter and smaller goslings than geese that avoid this movement by both nesting and rearing their brood at the MBR. In this study, we tested the hypotheses that use of low-quality habitats and an increase in the time spent walking at the expense of foraging during movements could explain the reduced growth of goslings in those families. We conducted visual observations to compare habitat use and selection as well as behaviour of geese during brood movements from the MNC to the MBR (i.e., at a transit area) with those of families that had already settled at the MBR. We also conducted aerial tracking to monitor habitat use of 16 radio-marked females during and after brood movements. Streams, wet polygons, and lakes, considered high-quality habitats in terms of feeding opportunities and predator refuges, were preferred, while upland, a low-quality habitat, was avoided at both the transit area and the MBR. However, broods were found in the upland habitat more often during movements than once settled on a rearing site. The behaviour of unmarked geese at the transit site did not differ from that of geese at the MBR. We suggest that reduced food intake in low-quality habitats during movements, but not the increase in time spent walking, may explain the reduction in growth observed at fledging in goslings moving from the MNC to the MBR.

Summary 1. We examined impacts of nutrient loading, particularly of nitrogen and phosphorus, from greater snow geese (Chen caerulescens atlantica) on a reservoir in south-eastern Pennsylvania, U.S.A. Approximately 100 000 geese use the reservoir for 2–6 weeks prior to their spring migration northward. 2. We estimated the magnitude of nutrient loading by geese during their presence and compared that to surface input and output rates. We also conducted nutrient limitation bioassay experiments to examine patterns of algal nutrient limitation upstream and downstream of the reservoir. 3. During their presence from 1 February to 27 March 2001, snow geese contributed 85–93% of the phosphorus and 33–44% of the nitrogen loaded to the reservoir. Both nutrients were exported from the reservoir slowly rather than as a quick pulse. Consequently, phosphorus concentrations in the outflow were higher than in the inflow from February to the end of July. However, nitrogen concentrations were consistently lower in the outflow than the inflow. 4. Nutrient limitation bioassays conducted in June and July indicated that primary production in the outflow was limited by nitrogen whereas the inflow was co-limited by nitrogen and phosphorus. Further downstream from the reservoir, primary production was consistently phosphorus limited. Therefore, nitrogen limitation persisted long after the geese had left, but was relatively localised.

Changes in harvest rate over the past 3 decades have been shown to be closely related to population growth of greater snow geese (GSG; Chen caerulescens atlantica). We used band-recovery and harvest survey data from 1970 to 2001 to study temporal variations in geographic harvest distribution and composition of GSG in Quebec, Canada and the Atlantic Flyway states (AF) in the United States. We sought to determine whether (1) geographic variation in harvest was associated with temporal trends in total harvest rates observed during this period; (2) spatiotemporal distributions of harvest varied with age and sex; and (3) harvest distribution and composition differed between the spring conservation harvest initiated in 1999 and the regular fall hunt in Quebec. We detected over time a gradual spreading in the geographic distribution of the fall harvest from the upper St. Lawrence estuary toward southwestern Quebec. During winter, a sudden northward shift in the distribution of the United States harvest in the mid-1980s was associated with a high concentration of geese in mid-Atlantic Flyway states (Maryland, Delaware, and New Jersey), possibly due to short-stopping during migration. We argue that this led to a reduction of hunting pressure on GSG and may have contributed to the sudden decline in harvest rate that occurred at that time and ultimately to the ensuing population increase. We observed a decreasing proportion of juveniles in the kill throughout the hunting season within fall staging grounds in Quebec and between Quebec and the United States. We also found a much higher proportion of adults in the spring harvest than in the fall that is consistent with the conservation goal of increasing the adult harvest. We recommend that management actions focus on increasing harvest in mid-Atlantic Flyway states if further control of population growth is desired.

International audience; An assumption of mark-recapture studies is that the marker has no effect on the animal. Neck bands have been used extensively for goose research, but there has long been concern that they may have negative effects on some demographic parameters, and recent studies have yielded contradictory results. We evaluated the effects of neck bands on adult female greater snow geese (Chen caerulescens atlantica) by contrasting breeding propensity and apparent survival of geese marked with both a plastic neck band and a metal leg band and those marked solely with metal leg bands over an 11-year period on Bylot Island, Nunavut Territory. The use of multistate mark-recapture models also allowed us to estimate neck band loss and to obtain survival and capture probabilities that were not biased by such loss. Finally, we tested the effects of neck bands on other reproductive parameters (laying date, clutch size and nest success) over a 3-year period. Neck-banded females had decreased clutch size and capture probabilities, but their apparent survival rate, nest initiation and hatching dates, and nest survival were not affected compared to leg-banded only or unbanded females. Breeding propensity, indexed by capture probabilities of neck-banded females was, on average, 48% lower that that of leg-banded-only females but clutch size was only 10% lower. Neck band loss of females was low in this population (3% per year). We urge researchers to be cautious in the use of neck bands for estimation of population parameters, and that the potential negative effects of neck bands be assessed as it is likely to be species-specific. JOURNAL OF WILDLIFE MANAGEMENT 69(1):91-100, 2005

International audience; Recruitment is an important determinant of fitness and population growth rates, but few studies have examined the effect of environmental stochasticity on this life history trait. Furthermore, most studies have been unable to separate the influence of juvenile survival and age-specific breeding proportions on recruitment. We used a recently developed approach, based on capture-mark-recapture methods, in which local recruitment is analyzed in a multistate model with an unobservable ''nonbreeder'' state. The data are drawn from a long-term study of a long-lived, arctic-nesting bird, the Greater Snow Goose (Chen caerulescens atlantica), and include marking and recaptures of female goslings and breeding adult females of unknown age between 1990 and 2000. The model considers four parameters: the probability that an individual aged i with no breeding experience starts breeding (a i), juvenile and adult apparent survival (), and capture probability of breeders (p). The flexibility achieved allows us to assess the influence of environmental conditions encountered during early life and at breeding on juvenile survival and the probabilities of starting to breed at a given age. Recruitment was a gradual process (probability of starting to breed at age 2 yr 0.25 [95% CI, 0.12-0.45]; at age 3 yr 0.57 [0.20-0.87]) and was completed by age 4 yr (i.e., all remaining immature females started to breed at that age). Juvenile survival was higher in early-hatched than in late-hatched females. Juvenile survival varied considerably among cohorts, but our environmental covariates could not explain these differences. Probabilities of starting to breed were less variable, except in lemming crash years, when they were considerably reduced. Snow cover at breeding or hatch date did not affect probabilities of starting to breed. These results suggest that environmental conditions can have an impact on life histories of birds in seasonal environments, but that variations in juvenile survival probably account for most of the fluctuation in the proportion of birds from a cohort that recruit into the breeding population. Use of multistate models to estimate recruitment increases precision in parameter estimates with the addition of data from adults of unknown age. However, we are still restricted by some assumptions, most notably the absence of temporary emigration.

International audience; 1. Understanding how climate change will affect animal population dynamics remains a major challenge, especially in long-distant migrants exposed to different climatic regimes throughout their annual cycle. 2. We evaluated the effect of temperature throughout the annual cycle on demographic parameters (age-specific survival and recruitment, breeding propensity and fecundity) of the greater snow goose (Chen caerulescens atlantica L.), an arctic-nesting species. As this is a hunted species, we used the theory of exploited populations to estimate hunting mortality separately from natural mortality in order to evaluate climatic effects only on the latter form of mortality. 3. Our analysis was based on a 22-year marking study (n = 27 150 females) and included live recaptures at the breeding colony and dead recoveries from hunters. We tested the effect of climatic covariates by applying a procedure that accounts for unexplained environmental variation in the demographic parameter to a multistate capture-mark-recapture recruitment model. 4. Breeding propensity, clutch size and hatching probability all increased with high temperatures on the breeding grounds. First-year survival to natural causes of mortality increased when temperature was high at the end of the summer, whereas adult survival was not affected by temperature. On the contrary, accession to reproduction decreased with warmer climatic conditions during the non-breeding season. 5. Survival was strongly negatively related to hunting mortality in adults, as expected, but not in first-year birds, which suggests the possibility of compensation between natural and hunting mortality in the latter group. 6. We show that events occurring both at and away from the breeding ground can affect the demography of migratory birds, either directly or through carryover effects, and sometimes in opposite ways. This highlights the need to account for the whole life cycle of an animal when attempting to project the response of populations to future climatic changes.

Breeding propensity, i.e., the probability that a mature female attempts to breed in a given year, is a critical demographic parameter in long-lived species. Life-history theory predicts that this trait should be affected by reproductive trade-offs so that the probability of future reproduction should depend on the current reproductive investment. However, breeding propensity is one of the most difficult parameters to estimate because nonbreeders are often absent from the breeding area, thereby requiring the inclusion of unobservable states in the analysis. We developed a new methodological approach by integrating a robust design sampling scheme within the multi-event capture–recapture framework. Our new model accounted for uncertainty in state assignation while allowing for departure of individuals between secondary sampling occasions. We applied this model to a long-term data set of female Greater Snow Geese (Chen caerulescens atlantica) to estimate breeding propensity and to investigate potential reproductive costs. We combined resightings during the nesting stage and recapture at the end of the breeding season to estimate breeding propensity and nesting success, and added recoveries to improve survival probability estimates. We found that both breeding propensity and nesting success depended upon breeding status in the previous year, though not survival. Successful breeders had a lower breeding propensity than failed breeders in the following year, but a higher nesting success. Individuals absent from the breeding colony had a low breeding propensity, but a high nesting success the following year. Our results suggest a cost of reproduction on breeding propensity in the next year, but once females decide to breed, nesting success is likely driven by individual quality. An added benefit of our model is that, unlike previous models with unobservable states, all parameters were identifiable when survival and breeding probabilities were fully state dependent. Our new multi-event framework is a flexible tool that can be applied to a large range of species to estimate breeding propensity and to investigate reproductive trade-offs.

Based on allometric considerations, goose species with larger body masses should spend more time on their nest during incubation than smaller ones. We documented hourly and daily variations in incubation behaviour of large goose species nesting in the Arctic, the greater snow goose (Chen caerulescens atlantica), and examined the effect of weather conditions on recess frequency and duration. Incubation behaviour was inferred from variations in temperature recorded by adding artificial eggs to clutches. Mean nest attentiveness during the incubation period was 91.4%, indicating that it can be relatively low even for a large goose. Females took 5–6 recesses/day, which lasted for an average of 22.7 min each. Variability in incubation behaviour over time was greater within females than among females. Recesses were more frequent, and of longer duration, in the afternoon than at night. Females were also less attentive to their nest as incubation progressed, a consequence of both an increase in recess frequency and duration, except in the days before hatching, when nest attentiveness rose abruptly. The relatively low nest attendance of incubating greater snow geese may be a consequence of the opportunity to feed close to the nest during recesses. Weather parameters influenced movements away from the nests in 11 of the 12 females monitored. Females took more recesses when wind velocity was low and, to a lesser extent, when air temperature and solar radiation were high, but the response was quite variable among females. Although females seem to adjust their behaviour in order to limit egg cooling, variations in risk of predation according to time of day may also influence incubation patterns.

We studied survival immediately after banding of Greater Snow Geese (Chen caerulescens atlantica) captured in mass banding drives on Bylot Island (Nunavut, Canada) during the late brood-rearing period. Shortly after release, the banding sites and the surrounding areas were checked for dead banded birds. Logistic regression was used to model post-banding survival in relation to mass and age at banding, size of catch, banding year, and their interactions. Between 1993 and 1996, 6577 adults and 6736 juveniles were banded, of which 6 adults and 192 juveniles (goslings) were found dead. Apparent survival immediately after banding was high for juveniles (0.971 ± 0.002) and close to 1.00 for adults. The post-banding survival of juveniles decreased with catch size and increased with mass at banding, although the magnitude of the latter effect varied among years. Age at banding also affected survival in interaction with banding year and catch size. Post-banding survival was lowest for the youngest gosling...

1. Using four heated taxidermic mounts of Greater Snow goose goslings of different ages (3–30 d), we found that exposure to wind (up to 5 m/s) or artificial radiation (up to 500 W/m 2 ) could change the standard operative temperature of gosling mounts by up to −20 or +18°C, respectively. 2. These values could vary by as much as 9°C due to the interaction between wind and radiation, or to changes in body orientation with respect to both these variables. In the presence of wind, radiative heat gain was reduced, and the interaction was generally more important when wind was perpendicular to the incoming radiation. 3. Predictive equations based on these results can be used to estimate the standard operative temperature of goslings in the field and their ability to modify their thermal environment by changing orientation with respect to wind and sun.

Growth rate in geese is sensitive to the feeding conditions during the broodrearing period, and late-hatched goslings grow at a lower rate than early-hatched ones.We examine how the seasonal decline in food supply affected the development of body components of late-hatched and early-hatched goslings in male and female Greater Snow Geese (Chen caerulescens atlantica). We collected and autopsied 48 early-hatched (EH, mean age at capture = 42.4 days) and 48 late-hatched goslings (LH, mean age = 34.8 days), divided equally among sexes, near fledging at four different sites on Bylot Island, Northwest Territories. After statistically adjusting for differences in body size between the two groups, EH goslings had more body protein than LH ones. However, the development of all organs was not affected equally. The mass of most supplying organs (the food acquisition apparatus: legs, esophagus, intestine. and liver), which develop early during growth, was similar between EH and LH goslings. In contrast, LH goslings had much smaller breast muscles than EH goslings, even after adjusting for size differences. Body fat was very low and similar in both groups. Body mass, body protein, intestine, and breast muscles showed a sexual dimorphism favoring males in EH, but not in LH, goslings. These results show that poor feeding conditions encountered by LH goslings disproportionately affected late-developing organs compared to early-developing ones, and males compared to females. Differences in organ development could reflect an adaptive response to reduced food availability. Prioritizing the development of supplying organs at the expense of other organs when food availability is low could help goslings maintain a high nutrient intake.

We studied annual variation in the distribution of greater snow goose (Chen caerulescens atlantica) nests and colonies at a High Arctic breeding site (Bylot Island, Northwest Territories, Canada) from 1988 to 1994. Annual distribution and size of colonies within the study area were highly variable. The distance between colony centres in successive years ranged from 2.9 to 6.9 km [Formula: see text], with no overlap of the areas occupied. Timing of snowmelt and nest-site availability were also very variable. In some years, the area was snow-free at the time the geese arrived, whereas in others, snow persisted for up to 3 weeks after their arrival. However, even in the 3 years of earliest snowmelt (1988, 1993, and 1994), geese used markedly different nesting areas, in both lowland and upland areas. Geese nested in association with snowy owls (Nyctea scandiaca) in the 2 years that owls nested and their nesting success was markedly improved, probably because of the deterrent effect of owls on arctic foxes (Alopex lagopus), the main nest predator. This suggests that protection from nest predators is an important determinant of nest-site selection. The lack of fidelity to a specific nesting location is unusual in geese. We suggest that large annual variability in timing of snowmelt, predation pressure, and availability of feeding areas during the prenesting period, combined with the need to lay at an optimal date because of the short arctic nesting season, probably explain the low nest-site fidelity in this population.

We describe the foraging behaviour of staging greater snow geese (Chen caerulescens atlantica) as they feed in depressions caused by ice scouring in tidal marshes along the St. Lawrence River. We compared feeding success during the fall and spring staging season as the birds extracted rhizomes of Scirpus americanus. In these marshes, every growth cycle (summer) is followed by two distinct episodes of intensive exploitation by geese (fall and the following spring). Two kinds of foraging bouts were considered: (1) successful (i.e, with one or more ingestions) and (2) unsuccessful (i.e, without any ingestion). Geese sampled fewer depressions in the fall than in the spring because the proportion of depressions sampled with success was greatest in this season. Geese spent less time per depression in the spring, whether they were successful or not, but sampled more depressions instead. There was a decrease in the number of depressions sampled over the spring period. It is concluded that geese adjust their use of ice-scoured depressions to both inter- and intra-seasonal food availability (depletion). Behavioural mechanisms they might use to do so are discussed.

International audience; Baseline glucocorticoid (CORT) levels in plasma are increasingly used as physiological indices of the relative condition or health of individuals and populations. The major limitation is that CORT production is stimulated by the stress associated with capture and handling. Measuring fecal CORT is one way to solve this problem because elevation of fecal CORT usually does not occur before 1-12h after a stressful event in captive animals. However, the effect of capture and handling on fecal CORT levels has seldom been investigated in the wild. In a first experiment, we validated that fecal CORT levels starts to increase in droppings (a mixture of fecal and urinary material) about 1-2h following injection of CORT-release hormone (ACTH) in captive greater snow geese (Chen caerulescens atlantica). In a second experiment, we investigated whether dropping and plasma CORT were related and if the capture affected fecal CORT levels in wild birds. Baseline CORT was obtained by bleeding individuals within 4 min after capture. No relationship was found between baseline and CORT in droppings shortly after capture (

Using correlation analysis, Bety, Gauthier, and Giroux confirmed that individuals of the migrating snow geese (Chen caerulescens atlantica) arriving earlier on their breeding grounds experienced longer prelaying periods but laid earlier than late‐arriving birds. They concluded that these birds strategically adjusted timing to optimize fitness. This test is, however, not sufficient to indicate strategic behavior. We show analytically that, without assuming strategic behavior, arrival date, prelaying period, and laying date are correlated with each other because of their sequential occurrence. We conclude that correlation tests on sequentially occurring variables are not sufficient to detect nonrandom relations.

We studied the foraging behavior of greater snow geese (Chen caerulescens atlantica) staging in a Scirpus tidal marsh along the St. Lawrence Estuary in Quebec during fall 1985 and 1986 and spring 1986 and 1987. Among all foraging activities, grubbing (feeding on underground plant parts) ranked first (>50%), but important seasonal differences were observed. Geese spent less time grubbing and more time searching and grazing on newly emerging shoots in spring than in fall. Our study also revealed differences in the foraging behaviors of birds of differing social status. We found that juveniles spent more time searching for food than adults, particularly in fall. Males also spent more time alert than females, at least in fall. We also observed behavioral differences among adults of different social status (member of a family, paired bird, and unpaired bird). Solitary unpaired birds devoted less time grubbing and, consequently, more time searching for food, than paired birds in fall. Finally, paired and family-member adult birds adopted a similar foraging strategy, spending more time searching and grazing in spring than in fall.

We studied the dynamics of fat and protein reserves in greater snow geese (Chen caerulescens atlantica) during winter and spring migration, and examined the influence of a recent expansion of their staging grounds and change in habitat use on fat and protein storage. We collected 63 geese during the winter of 1989–1990 at Bombay Hook National Wildlife Refuge in Delaware, 158 geese in spring 1989 and 1990 at Lake Saint-Pierre and Cap-Saint-Ignace along the St. Lawrence River in southern Quebec, and 17 geese at the end of the 1990 migration on By lot Island, N.W.T. In both sexes, protein reserves did not change in winter but fat declined from a peak in December to a low point in early March, just before spring migration. Geese collected 3 weeks later at Lake Saint-Pierre (800 km north) had considerably larger fat reserves (90% larger in females and 40% in males). Geese accumulated large fat reserves at both sites along the St. Lawrence River. Although geese staged for a shorter period at Lake Saint-Pierre (a recently used area), males stored as much fat as those staging at Cap-Saint-Ignace and females only slightly less. A small amount of protein was stored between late winter and the end of staging. Spring conditioning of geese along the St. Lawrence River seems to have improved over the past decade. We found weak evidence that larger females stored more fat. The cost of migrating from the St. Lawrence to Arctic nesting grounds (2900 km) is considerable, as half of the fat reserves accumulated in spring were used for the migration. There is no evidence of fat or protein storage between the St. Lawrence estuary and the Arctic nesting grounds.

We studied the duration of the pre-laying period, female feeding activity, male vigilance, and the potential for parent-offspring conflicts in high-Arctic nesting Greater Snow Geese (Chen caerulescens atlantica). The pre-laying period is unusually long for a goose species nesting at high latitudes (73” N). Geese arrived at Bylot Island around 27 May but the peak initiation of egg-laying was around 12-14 June. During pre-laying, paired females fed for 75% and were alert for 6% of the 24-hr day, whereas males fed for 44% and were alert for 33% of the day. In one year that laying geese were observed, females fed less than during pre-laying and time spent at the nest increased. Time budget was not related to time of day or number of days before egg-laying. Although male vigilance apparently enabled females to devote more time to feeding, male alert behavior was poorly synchronized with female feeding. Pair copulations were recorded frequently (0.23/hr) and 2 extra-pair copulations were observed. Males were involved more often than females in aggressive interactions (2.55 vs. 0.36 aggressions bird-l hr-I) and often attacked neighboring pairs. The proportion of pairs with yearlings was low (6.3%) and parents frequently attacked their young (1.53 bird-’ hr-I). However, presence of yearlings did not influence time budget of pairs. The long pre-laying delay and the intense feeding activity of females suggest hat, in addition to energy reserves accumulated during the spring migration, food intake on the nesting ground may also be an important source of energy for laying Greater Snow Geese.

Breeding propensity, defined as the probability that a sexually mature adult will breed in a given year, is an important determinant of annual productivity. It is also one of the least known demographic parameters in vertebrates. We studied the relationship between breeding propensity and conditions on spring staging areas (a spring conservation hunt) and the breeding grounds (spring snow cover) in Greater Snow Geese (Chen caerulescens atlantica), a long distance migrant that breeds in the High Arctic. We combined information from mark–recapture, telemetry, and nest survey data to estimate breeding propensity over a 7–year period. True temporal variation in breeding propensity was considerable (mean: 0.574 [95% CI considering only process variation: 0.13 to 1.0]). Spring snow cover was negatively related to breeding propensity (􀀒snow = –2.05 ± 0.96 SE) and tended to be reduced in years with a spring hunt (􀀒 = –0.78 ± 0.35). Nest densities on the breeding colony and fall ratios of young:adults were good indices of annual variation in breeding propensity, with nest densities being slightly more precise. These results suggest that conditions encountered during the pre–breeding period can have a significant impact on productivity of Arctic–nesting birds., La propensión reproductora, definida como la probabilidad de que un adulto sexualmente maduro se reproduzca en un determinado año, constituye un importante determinante de la productividad anual. También es uno de los parámetros demográficos menos conocidos de los vertebrados. Estudiamos la relación entre la propensión reproductora y las condiciones reproductoras en áreas de acumulación primaveral de nutrientes (cacería primaveral orientada a la conservación) y emplazamientos de reproducción (capa de nieve durante la primavera) en el ánsar nival (Chen caerulescens atlántica), un ave migratoria que recorre grandes distancias y que se reproduce en el Alto Ártico. Combinamos la información de marcaje–recaptura, telemetría y datos de supervivencia en el nido para estimar la propensión reproductora durante un período de siete años. La variación temporal verdadera en la propensión reproductora fue significativa [media: 0,574 (95% CI, considerando únicamente la variación en los procesos: de 0,13 a 1,0)]. La capa de nieve primaveral se relacionó negativamente con la propensión reproductora (􀀒snow = – 2,05 ± 0,96 EE), tendiendo a reducirse en los años en que se había producido una cacería primaveral (􀀒 = –0,78 ± 0,35). Las densidades de los nidos de la colonia reproductora y la tasa de jóvenes:adultos en otoño constituyeron buenos índices de la variación anual en la propensión reproductora, siendo las densidades de los nidos ligeramente más precisas. Tales resultados sugieren que las condiciones presentes durante el período previo a la reproducción pueden tener un impacto significativo en la productividad de las aves que nidifican en el Ártico.

International audience; Although much of life-history theory assumes increased mortality at certain stages (e.g., migration), survival rates are rarely estimated on a seasonal basis within the annual cycle of migratory species. We estimated variations in seasonal survival rates in a long-lived, hunted species in the presence of short-term (between consecutive seasons) and long-term (between years in the same season) dependence in sighting probabilities. We also tested the two contrasting hypotheses that hunting mortality is either compensatory or additive to natural mortality. This study was conducted on adult female Greater Snow Geese (Chen caerulescens atlantica) from 1990 to 1998, and is based on 3890 neck-banded birds and 13 657 resightings on the northern breeding grounds in summer, and southern staging areas in spring and autumn. Birds were 10-20% more likely to be seen in autumn and spring if they were seen on the previous occasion (summer and autumn, respectively). Birds were 30-40% more likely to be seen in autumn and spring if they were last seen in the same season in the previous year. Differences in behavior according to family status (pres-ence or absence of young) and heterogeneity in site fidelity may explain the dependence in sighting probabilities; failure to account for this may lead to biased survival estimates. Monthly survival rates from spring to summer (3-mo period) and summer to autumn (2.5-mo period) were equal (0.989 0.003, mean 1 SE) and showed little variation over the years, even though the two lengthy migratory flights (3000 km each) and breeding occurred during these periods. In contrast, monthly winter survival (from autumn to spring, 6.5 mo) was lower than during the other seasons and varied significantly over the years (range 0.936 0.021 to 0.993 0.008). Mean survival of adult females (corrected for neck band loss) was 0.96 from spring to autumn, 0.86 during winter, and 0.83 0.05 for the whole year. Natural mortality (i.e., excluding hunting) was equal among seasons and did not vary over the years, which suggests that mortality risk is not increased during migration or reproduction. There was a significant inverse relationship between winter survival and the kill rate (b 1.21 0.56), which suggests that hunting mortality was additive to natural mortality. This is probably a general feature of long-lived species because their low and relatively constant natural mortality rate does not allow them to compensate for an additional source of mortality such as hunting. Contrary to life-history theory, we did not find evidence that migration or reproduction entailed a survival cost in this long-distance migrant bird.

We examined whether the fall activity budgets of greater snow geese (Chen caerulescens atlantica) vary between years and sites by comparing time-budget data gathered from 1982 to 1984 at the Montmagny and Cap-Saint-Ignace sanctuaries in Quebec. Feeding and resting accounted for more than 70% of the activities during the daylight period. At Cap-Saint-Ignace, geese spent less time feeding and more time resting during the 2nd year of the study, whereas no such annual variation was found at Montmagny. Snow geese also spent more time feeding and less time resting at Montmagny than at Cap-Saint-Ignace. These differences are discussed in relation to energy requirements, quality of feeding sites, temperature, and disturbance associated with hunting.

Neck bands are a widely used marker in goose research. However, few studies have investigated a possible negative effect of this marker on survival. We tested the effect of neck bands on the survival of adult female greater snow geese (Chen caerulescens atlantica) by marking birds with either a neck band and a metal leg band or a leg band only on Bylot Island (Nunavut, formerly included in the Northwest Territories, Canada) from 1990 to 1996. Annual survival was estimated using leg-band recoveries in fall and winter and using neck-band sightings in spring and fall. Recapture rates were estimated using summer recaptures. Using recovery data, the selected model yielded a survival similar for the neck-banded and leg-banded only birds (S = 0.845 ± 0.070 vs. S = 0.811 ± 0.107). The hypothesis of equality of survival between the 2 groups was easily accepted under most constraints imposed on survival or recovery rates. However, failure to account for a different direct recovery rate for neck-banded birds would lead us to incorrectly conclude a possible negative effect of neck bands on survival. Using sighting data, mean annual survival of neck-banded birds was independently estimated at 0.833 ± 0.057, a value very similar to that estimated with band-recovery analysis. Raw recapture rates during summer were significantly lower for neck-banded birds compared to those marked with leg bands only (4.6% vs. 12.1%), but in this analysis, survival, site fidelity, reproductive status, and recapture rates were confounded. We conclude that neck bands did not affect survival of greater snow geese, but could possibly affect other demographic traits such as breeding propensity and emigration.

Numbers of giant Canada geese (Branta canadensis maxima), greater snow geese (Chen caerulescens atlantica), and lesser snow geese (C. c. caerulescens) have increased dramatically during the past 30 years. Now, these geese are causing serious ecological and/or economic problems on breeding and/or wintering areas. Attempts to control their burgeoning numbers via increased harvest have had little effect. Thus, I propose that creative, new approaches to increase harvests must be made available to managers. The prohibition against hunting during 11 March-31 August and the 3.5 month (107 day) limit on waterfowl seasons should be removed from the Migratory Bird Convention, and sale of migratory birds should be legalized and controlled by regulation. Further, currently banned but effective hunting techniques, e.g., electronic calls, live decoys, etc., should be legalized and controlled by regulation. Management practices on U.S. National Wildlife Refuges (NWR), e.g., planting food, that concentrate snow geese and thereby reduce harvests, should be discontinued. Waterfowl managers have successfully managed to prevent overharvest of geese for many years ; now it is time for them to manage overpopulations of geese.

We wanted to know if migration chronology of greater snow geese (Chen caerulescens atlantica) is affected by the intensive hunting pressure and crowded conditions prevaling on their staging grounds in Canada. Consequently, we neckbanded 2,150 individuals to study the chronology and rate of autumn migration in the St. Lawrence estuary from 1985 through 1987

Total, shared parental investment, measured in terms of forsaking digging sites to soliciting offspring, did not increase with brood size in foraging greater snow geese, Chen caerulescens atlantica . Individual levels of solicitation by brood members decreased with an increase in brood size. This may result from the higher occurrence of attacks by parents on offspring that was observed in larger broods. This is interpreted as an indication of greater parent-offspring conflict over shared parental investment in larger broods.

A spring conservation hunt (15 Apr-31 May) to control the exponential population growth of greater snow geese (Chen caerulescens atlantica) was introduced in 1999 during their staging in southern Quebec, Canada. We tested the hypothesis that disturbance by hunting negatively affected nutrient storage in spring. We compared the amount of fat and protein stored by staging geese during the hunt (1999 and 2000) to similar data obtained sporadically between 1979 and 1998 (no hunt). We collected adult females at 3 sites along the St. Lawrence River during years with (n = 235 geese) and without (n = 194) hunting. We used abdominal fat and dry breast muscle mass as corresponding indices of fat and protein reserves. The condition of geese arriving at the staging area did not differ between years with and without a hunt. Abdominal fat of geese at the end of the staging period was 29-48% lower (depending on site and year) during years with a hunt than in years without. Similarly, breast muscles of geese at the end of staging were 5-11% lighter in years with a spring hunt. Low stable-carbon isotope ratios (δ 13 C) in tissues of geese collected in spring 1999 suggested that they fed less on corn, a C4 plant and a major food source for geese, than in other years. This may have contributed to their reduced body condition that year. However, despite high δ 13 C values in 2000, indicative of a high proportion of corn in the diet, nutrient storage in geese was still reduced compared to years without a hunt. We conclude that hunting was the most important factor explaining the low fat and protein storage of geese in springs of 1999 and 2000. We suggest that hunting disturbance reduced nutrient storage of geese because of decreased feeding activity and increased flying time.