Search

Post-hatch brood movements to high-quality foraging sites are common in precocial birds but may entail costs for young. We assessed effects of overland movements of broods between the nesting and rearing areas in Greater Snow Geese (Chen caerulescens atlantica) breeding on Bylot Island, Nunavut, Canada, to determine whether these movements affected gosling survival and growth. We monitored 51 radiomarked females over rive years to quantify movement distance, movement duration, and gosling survival. Gosling growth was compared over four years using a sample of web-tagged broods recaptured shortly before fledging among adults that (1) nested and reared their young in a dense colony, (2) left the colony and moved ~30 km to reach the main brood-rearing area, or (3) nested and reared their young in the main brood-rearing area. Brood movements by radiomarked birds were highly variable (2.6-52.5 km, depending on rearing areas used) and fairly rapid ([less than or equal to]6 days after hatch for 72% of the females). Gosling survival was not related to distance moved between nesting and brood-rearing areas. However, gosling growth was influenced by areas used and whether or not they had to move to reach their brood-rearing area. Geese nesting at the main brood-rearing area generally reared heavier and larger goslings than those that moved ~30 km from the main nesting colony to rear their brood at the main brood-rearing area. On the other hand, goslings leaving the nesting colony after hatch were heavier and larger than those that stayed there throughout brood rearing in one of two years. Although brood movements allow goslings access to high-quality habitats, they entail some costs. Thus, minimizing such movements through nest-site selection should provide a selective advantage by allowing goslings to maximize their growth. Key words: brood movements, Bylot Island, Chen caerulescens atlantica, goslings, Greater Snow Goose, growth, prefledging survival. Le deplacement des familles vers les sites d'alimentation de haute qualite apres l'eclosion est repandu chez les oiseaux nidifuges, mais peut comporter des couts pour les jeunes. Nous avons evalue l'effet de ces deplacements entre les sites de nidification et d'elevage sur la survie et la croissance des oisons chez Chen caerulescens atlantica nichant a l'Ile Bylot, Nunavut, Canada. Durant cinq ans, nous avons suivi le deplacement de 51 femelles munies de radio-emetteurs afin de quantifier la longueur et la duree de leurs deplacements, ainsi que la survie de leur couvee. La croissance des oisons a ete evaluee durant quatre annees a partir de recaptures effectuee peu avant la periode d'envol de jeunes marques a l'eclosion. Nous avons compare la croissance des oisons entre des familles qui (1) ont niche et eleve leur couvee dans la colonie principale a densite elevee, (2) ont niche a la colonie principale et se sont deplacees sur ~30 km apres l'eclosion vers le site d'elevage principal ou (3) ont niche et eleve leur couvee au site d'elevage principal. Les deplacements des familles suivies par telemetrie etaient hautement variables (2.6-52.5 km selon le site d'elevage utilise) et rapides ([menor que o igual a]6 jours apres l'eclosion pour 72% des femelles). La survie des oisons n'etait pas affectee par la distance parcourue entre les sites de nidification et d'elevage. Cependant, leur croissance etait influencee par les sites utilises et le fait de quitter ou non le site de nidification pour atteindre le site d'elevage. Les oisons des familles nichant au site d'elevage principal avaient generalement une masse et une taille corporelle plus elevees que ceux des familles nichant a la colonie principale et ayant parcouru ~30 km pour atteindre le site d'elevage principal. Par contre, pour une annee sur deux o la comparaison etait possible, les oisons des familles qui ont quitte la colonie principale ont connu une meilleure croissance que ceux qui y sont demeures. Ainsi, bien que les deplacements des familles puissent permettre aux oisons d'avoir acces a des habitats de haute qualite, ils comportent egalement des couts. Minimiser ces deplacements par le choix du site de nidification devrait donc procurer un avantage selectif en permettant de maximiser la croissance des oisons.

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. Key words: diet, food quality, food selection, Greater Snow Goose, mesic tundra. Aunque la tundra humeda es un ambiente usado comunmente por los gansos que nidifican en el artico, la ecologia alimentaria en este ambiente es poco conocida en comparacion con la de los humedales. Nuestros objetivos fueron determinar la dieta y la seleccion de alimentos de los polluelos de Chen caerulescens atlantica en relacion con la calidad nutricional de las plantas que crecen en los ambientes humedos de la tundra en la Isla Bylot, Nunavut, Canada. Usamos dos enfoques diferentes pero complementarios: examenes del contenido del esofago de polluelos silvestres sacrificados y observacion directa de la actividad de alimentacion de polluelos cautivos que se vieron sujetos a impronta por parte de humanos. El ultimo metodo fue innovador y brindo una descripcion confiable de la dieta, con resultados comparables a aquellos obtenidos para polluelos silvestres. Aunque los ambientes humedos poseen una composicion floristica mas diversa que los humedales y que la cobertura rala de pastos, las gramineas fueron seleccionadas con preferencia y dominaron la dieta (~50%). El resto de la dieta estuvo constituida principalmente por elementos de las familias Juncaceae, Polygonaceae y Leguminosae. La dieta de los polluelos mas jovenes fue diversa, pero a medida que envejecieron y se tornaron mas eficientes, se concentraron en unos pocos taxones. Los polluelos comieron principalmente hojas (~80%), pero las flores (~20%) tambien fueron importantes. La seleccion de los alimentos estuvo influenciada por el contenido de nitrogeno y de compuestos fenolicos totales en las plantas, pero el cociente entre compuestos fenolicos y nitrogeno en los organos de las plantas determino en gran medida la seleccion de los alimentos. El contenido de fibras neutras de detergente de las plantas no influencio la seleccion de las plantas. Tanto la calidad nutricional de las plantas como su disponibilidad determinaron la dieta de los polluelos a traves de los diferentes ambientes humedos y los polluelos en crecimiento parecieron maximizar el consumo de proteinas metabolizables.

Post-hatch brood movements to high-quality foraging sites are common in precocial birds but may entail costs for young. We assessed effects of overland movements of broods between the nesting and rearing areas in Greater Snow Geese (Chen caerulescens atlantica) breeding on Bylot Island, Nunavut, Canada, to determine whether these movements affected gosling survival and growth. We monitored 51 radiomarked females over five years to quantify movement distance, movement duration, and gosling survival. Gosling growth was compared over four years using a sample of web-tagged broods recaptured shortly before fledging among adults that (1) nested and reared their young in a dense colony, (2) left the colony and moved ∼30 km to reach the main brood-rearing area, or (3) nested and reared their young in the main brood-rearing area. Brood movements by radiomarked birds were highly variable (2.6-52.5 km, depending on rearing areas used) and fairly rapid (≤6 days after hatch for 72% of the females). Gosling survival was not related to distance moved between nesting and brood-rearing areas. However, gosling growth was influenced by areas used and whether or not they had to move to reach their brood-rearing area. Geese nesting at the main brood-rearing area generally reared heavier and larger goslings than those that moved ∼30 km from the main nesting colony to rear their brood at the main brood-rearing area. On the other hand, goslings leaving the nesting colony after hatch were heavier and larger than those that stayed there throughout brood rearing in one of two years. Although brood movements allow goslings access to high-quality habitats, they entail some costs. Thus, minimizing such movements through nest-site selection should provide a selective advantage by allowing goslings to maximize their growth. [ABSTRACT FROM AUTHOR]

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 (bsnow=-2,05 ± 0,96 SE) and tended to be reduced in years with a spring hunt (b = -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

The benefits and challenges of integrating traditional ecological knowledge and scientific knowledge have led to extensive discussions over the past decades, but much work is still needed to facilitate the articulation and co-application of these two types of knowledge. Through two case studies, we examined the integration of traditional ecological knowledge and scientific knowledge by emphasizing their complementarity across spatial and temporal scales. We expected that combining Inuit traditional ecological knowledge and scientific knowledge would expand the spatial and temporal scales of currently documented knowledge on the arctic fox (Vulpes lagopus) and the greater snow goose (Chen caerulescens atlantica), two important tundra species. Using participatory approaches in Mittimatalik (also known as Pond Inlet), Nunavut, Canada, we documented traditional ecological knowledge about these species and found that, in fact, it did expand the spatial and temporal scales of current scientific knowledge for local arctic fox ecology. However, the benefits were not as apparent for snow goose ecology, probably because of the similar spatial and temporal observational scales of the two types of knowledge for this species. Comparing sources of knowledge at similar scales allowed us to gain confidence in our conclusions and to identify areas of disagreement that should be studied further. Emphasizing complementarities across scales was more powerful for generating new insights and hypotheses. We conclude that determining the scales of the observations that form the basis for traditional ecological knowledge and scientific knowledge represents a critical step when evaluating the benefits of integrating these two types of knowledge. This is also critical when examining the congruence or contrast between the two types of knowledge for a given subject.