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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.

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.

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...

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.

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 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.

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

We describe summer migratory movements by female greater snow geese ( Chen caerulescens atlantica ) breeding on Bylot Island, Nunavut. We followed 121 radio-collared females between 1997 and 2001 to determine the frequency and timing of their departure from the colony in relation to breeding status, nesting success, and molting chronology. We found that 90% (n = 51) of non-breeders (no nest found) and 97% (n = 29) of failed nesters (nest destroyed or abandoned before hatch) departed the island before molting. The few non-breeders that remained on Bylot Island all summer molted earlier than adults with young, and they appeared to initiate the fall migration before breeding geese. In contrast, only 2% of successful nesters (n = 41) left Bylot Island to molt, and those that did presumably had lost their offspring in the early stages of brood rearing. Thus, the occurrence of a molt migration in greater snow geese appears to be strongly dependent on reproductive status and nesting success. The area used by molt migrants and their habitat requirements during molt remain unknown. We suggest that the paucity of predator-safe areas (such as large water bodies) on Bylot Island may be an important factor that drives the geese to molt elsewhere.

We assessed the effect of nest visits by researchers on the activity of nest predators and predation rate of eggs in a High Arctic Greater Snow Goose (Chen caerulescens atlantica) colony. The study was conducted in years of moderate (1996) and low (1997) overall nest predation rate. We first compared activity rate (number of presences per h) and behavior of nest predators in the colony with and without investigator disturbance. In one year out of two, activity rate and time spent in the colony were higher during nest visits than under undisturbed conditions for Glaucous Gulls (Larus hyperboreus) and Parasitic Jaegers (Stercorarius parasiticus). Moreover, presence of investigators significantly increased (4.8 times) the probability of nest attack by predators in one year. Nevertheless, the immediate revisit technique showed that the percentage of goose eggs robbed by predators in monitored nests was low (

(1) The faecal output of geese (Anseriformes) is often measured in the course of bioenergetic or flock management studies. The first objective of this investigation was to examine the influence of method on the field assessment of defaecation rate in greater snow geese (Chen caerulescens atlantica (Linnaeus)). (2) We introduce the 'hourly block method', the only one which produced unbiased estimates of this parameter: 'direct interval estimate' and 'short-cut' methods (in particular Owen's half-time interval) were found to produce biased and/or high variance estimates and were deemed unreliable in most circumstances. Computer modelling confirmed these conclusions. (3) The second objective of the investigation was to identify the sources of bias and variance affecting dropping-count estimates obtained in sample plots. (4) The observation method chosen (observer standing or crouched, observer single or paired) had a great effect on the size of the bias encountered. Variance due to observer, plot and habitat was also assessed. (5) Suggstions to stabilize and/or remove causes of bias and to improve the precision of dropping-count estimates are given.