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While wild waterfowl are known reservoirs of avian influenza viruses and facilitate the movement of these viruses, there are notable differences in the response to infection across species. This study explored differential responses to infection with highly pathogenic avian influenza in Snow Geese (Anser caerulescens) located in the California Central Valley. Though H5 antibody prevalence was high across years among birds sampled in the winter (75% in both years via hemagglutination inhibition), these values were even higher among birds sampled in summer that failed to migrate (i.e., August 2023 = 100% and August 2024 = 93% via hemagglutination inhibition). Birds that failed to migrate were also generally lighter than birds sampled in the winter and presented notable damage to cerebrum and cerebellum. In December 2022, a single individual positive for infection with H5N1 at the time of sampling indicated reduced movement during the 14 days following sampling but completed spring migration comparably with uninfected conspecifics. However, while no birds were actively infected during sampling and marking in 2023, two marked geese departed for migration late and one did not migrate at all. Additional banded birds marked in August have been reencountered in scenarios ranging from hunter harvest at a different site over a year later to found dead shortly after banding. Our data indicate that Snow Geese infected with HPAI have the potential to express variable outcomes following infection with highly pathogenic H5N1, ranging from rapid recovery within a migratory season to death. These data also suggest that the abnormal failure of some Snow Geese to migrate from the Central Valley is likely driven by HPAI infection.

Increasing abundance of Snow and Ross’s Geese ( Anser caerulescens and Anser rossii ; kangut and qaaraarjuk in Inuktut, respectively), referred to collectively as light geese, has caused alterations in various Canadian Arctic ecosystems. Inuit have harvested light geese for generations and hold knowledge that offers unique insights into the ecology and population dynamics of these species. By combining interviews with 40 light goose harvesters and Elders with results from aerial surveys in the Kivalliq region of Nunavut, we (1) describe changes in light goose distribution and abundance between the 1940s and the 2010s, (2) explore the effects of light geese on local ecosystems, and (3) identify factors driving these changes. Inuit observations gathered through lifetimes of land-based observations and results from aerial surveys concurred that (1) light goose numbers have increased regionally since the 1940s, and (2) light goose numbers decreased in several colonies within the Kivalliq region between the 1960s–1990s and the 2010s, including in two Migratory Bird Sanctuaries. Inuit have noted that habitat loss due to overgrazing and grubbing has pushed light geese to abandon altered habitats in favor of new breeding and foraging sites. Inuit observations also indicated that light geese have altered their migration behavior (how, when, and where they migrate and nest) in response to earlier spring snowmelt, the drying of ponds and lakes, and an increased number of predators. These conclusions add substantially to overall understanding about light geese in regions where aerial surveys are expensive and infrequent, and scientific studies are limited in geographic coverage.

While wild waterfowl are known reservoirs of avian influenza viruses and facilitate the movement of these viruses, there are notable differences in the response to infection across species. This study explored differential responses to infection with highly pathogenic avian influenza in Snow Geese ( Anser caerulescens ) located in the California Central Valley. Though H5 antibody prevalence was high across years among birds sampled in the winter (75% in both years via hemagglutination inhibition), these values were even higher among birds sampled in summer that failed to migrate (i.e., August 2023 = 100% and August 2024 = 93% via hemagglutination inhibition). Birds that failed to migrate were also generally lighter than birds sampled in the winter and presented notable damage to cerebrum and cerebellum. In December 2022, a single individual positive for infection with H5N1 at the time of sampling indicated reduced movement during the 14 days following sampling but completed spring migration comparably with uninfected conspecifics. However, while no birds were actively infected during sampling and marking in 2023, two marked geese departed for migration late and one did not migrate at all. Additional banded birds marked in August have been reencountered in scenarios ranging from hunter harvest at a different site over a year later to found dead shortly after banding. Our data indicate that Snow Geese infected with HPAI have the potential to express variable outcomes following infection with highly pathogenic H5N1, ranging from rapid recovery within a migratory season to death. These data also suggest that the abnormal failure of some Snow Geese to migrate from the Central Valley is likely driven by HPAI infection.

The Snow Goose Algorithm (SGA) is a new meta-heuristic algorithm proposed in 2024, which has been proved to have good optimization effect, but there are still problems that are easy to fall into local optimal and premature convergence. In order to further improve the optimization performance of the algorithm, this paper proposes an improved Snow Goose algorithm (ISGA) based on three strategies according to the real migration habits of snow geese: (1) Lead goose rotation mechanism. (2) Honk-guiding mechanism. (3) Outlier boundary strategy. Through the above strategies, the exploration and development ability of the original algorithm is comprehensively enhanced, and the convergence accuracy and convergence speed are improved. In this paper, two standard test sets of IEEE CEC2022 and IEEE CEC2017 are used to verify the excellent performance of the improved algorithm. The practical application ability of ISGA is tested through 8 engineering problems, and ISGA is employed to enhance the effect of the clustering algorithm. The results show that compared with the comparison algorithm, the proposed ISGA has a faster iteration speed and can find better solutions, which shows its great potential in solving practical optimization problems.

Allometric constraints associated with digesting leaves require relatively small avian herbivores to consume high‐quality forage. How such constraints are overcome during ontogeny when energy and nutrient requirements are relatively high has not been adequately explored. We compared growth trajectories of Canada and lesser snow goose goslings raised on grass‐based diets that differed in protein (10%, 14% or 18%) and fibre (30% or 45%) with those of free‐living goslings on Akimiski Island, Canada. This common‐garden experiment allowed us to test the hypotheses that (i) smaller‐bodied geese are more negatively affected by reduced forage quality than larger‐bodied geese, and (ii) goslings from subarctic brood‐rearing areas have a limited capacity to slow growth in response to reduced forage quality. Canada goose goslings fed low‐protein (10%) diets were on average 44% lighter in body mass, had slower growth rates and were delayed >20 days in reaching 90% of asymptotic size compared with Canada goose goslings fed 18% protein. In contrast, snow goose goslings were unable to survive on the low‐protein diets, and those fed high‐ or medium‐protein diets grew at a similar rate and achieved similar asymptotic size. Canada and snow goose goslings fed low‐protein diets had reduced growth rates of the tarsus and delayed emergence of the 9th primary. Free‐ranging Canada goslings on Akimiski Island were similar in mass and structural size to captive‐reared goslings fed low‐protein diets. In contrast, snow goslings were similar in mass and structural size to the captive‐reared goslings fed the high‐ and medium‐protein diets. This suggests that degraded habitats with mostly low‐protein forage may be able to support Canada goslings better than snow goslings which require higher‐quality forage to survive. Size‐related differences in gosling growth and survival in response to diminished diet quality may influence population size when available food reaches a lower threshold in protein content. However, goslings can avoid such density‐dependent population regulation if they are able to move their broods and find adequate quality and quantity of forage.

Understanding an organism's habitat selection and behavioural flexibility in the face of environmental change can help managers plan for future conservation of that species. Hyperabundant tundra‐nesting geese are influencing Arctic environments through their foraging activities. Goose‐induced habitat change in Arctic wetlands may influence the availability of habitat for numerous shorebird species that breed sympatrically with geese. We explore whether goose‐induced habitat alteration affects shorebird breeding density and nest site selection. Using habitat data collected at sites with High, Moderate and Low goose influence, and samples collected during two periods separated by 11 years, we document the habitat characteristics influenced by geese. We describe the habitat characteristics preferred by shorebirds and relate their availability to goose influence and shorebird density. Finally, we examine whether shorebird nest site selection has changed over time and whether shorebirds select nest sites differently in habitat influenced by geese. We document spatial and temporal changes in sedge meadow habitat and lateral concealment relating to goose influence. The availability of sedge meadow habitat and the degree of lateral concealment declined with increasing goose influence, and also declined at two sites over the 11 years of the study. Densities of both cover‐ and open‐nesting shorebirds were highest where goose influence was lowest. At sites with Low goose influence, cover‐nesting shorebirds selected nest sites with more sedge meadow and concealment than at sites with Moderate and High goose influence, presumably because these high‐quality sites were more available. Synthesis and applications. Intensive foraging by a colony of hyperabundant geese is limiting the availability of preferred nesting habitat and densities of sympatric‐nesting shorebirds. Where goose‐induced habitat alteration is pronounced shorebird species that select concealed nest sites are nesting in areas with lower concealment and less sedge meadow. Studies examining the degree to which these effects scale up to impact the population sizes of declining shorebirds should be considered a future research priority. Moreover, management strategies for geese should incorporate the habitat needs of sympatric species and reinvigorate efforts for goose population reduction in order to achieve the population targets articulated by management agencies. Intensive foraging by a colony of hyperabundant geese is limiting the availability of preferred nesting habitat and densities of sympatric‐nesting shorebirds. Where goose‐induced habitat alteration is pronounced shorebird species that select concealed nest sites are nesting in areas with lower concealment and less sedge meadow. Studies examining the degree to which these effects scale up to impact the population sizes of declining shorebirds should be considered a future research priority. Moreover, management strategies for geese should incorporate the habitat needs of sympatric species and reinvigorate efforts for goose population reduction in order to achieve the population targets articulated by management agencies.

Expanding populations of North American midcontinent lesser snow geese (Anser caerulescens caerulescens) have potential to alter ecosystems throughout the Arctic and subarctic where they breed. Efforts to understand origins of harvested lesser snow geese to better inform management decisions have traditionally required mark-recapture approaches, while aerial photographic surveys have typically been used to identify breeding distributions. As a potential alternative, isotopic patterns that are metabolically fixed within newly grown flight feathers following summer molting could provide inferences regarding geographic breeding origin of individuals, without the need for prior capture. Our objective was to assess potential to use four stable isotopes ([delta].sup.13 C, [delta].sup.15 N, [delta].sup.34 S, [delta].sup.2 H) from feather material to determine breeding origins. We obtained newly grown flight feathers from individuals during summer banding at three Arctic and two subarctic breeding colonies in 2014 (n = 56) and 2016 (n = 45). We used linear discriminant analyses to predict breeding origins from models using combinations of stable isotopes as predictors and evaluated model accuracy when predicting colony, subregion, or subpopulation levels. We found a strong inverse relationship between [delta].sup.2 H values and increasing latitude (R.sup.2 = 0.83), resulting in differences (F.sub.4, 51 = 90.41, P < 0.0001) among sampled colonies. No differences in [delta].sup.13 C or [delta].sup.15 N were detected among colonies, although [delta].sup.34 S in Akimiski Island, Baffin Island, and Karrak Lake were more enriched (F.sub.4, 51 = 11.25, P < 0.0001). Using [delta].sup.2 H values as a predictor, discriminant analyses improved accuracy in classification level as precision decreased [model accuracy = 67% (colony), 88% (subregion), 94% (subpopulation)]. Application of the isotopic methods we describe could be used to provide an alternative monitoring method of population metrics, such as overall breeding population distribution, region-specific productivity and migratory connectivity that are informative to management decision makers and provide insight into cross-seasonal effects that may influence migratory behavior.

Migratory animals can serve as ecological links between geographically distant ecosystems. Moreover, when seasonally linked ecosystems differ in carrying capacity of migrant species, those with high capacity may support population growth with consequences to shared ecosystems with lower capacity through trophic cascades. Agricultural production has increased carrying capacity of lesser snow (Anser caerulescens caerulescens) and Ross's geese (Anser rossii, collectively, “light geese”) in southern agricultural landscapes where these species winter and stage during migration to and from northern breeding areas, resulting in population increase. In subarctic and arctic ecosystems where carrying capacity for geese is lower, high abundance and densities of light geese have caused trophic cascades during summer breeding. This has raised concern for resilience of northern ecosystems to withstand cumulative and intense pressures of above‐ and belowground herbivory and nest construction. We investigated the empirical relationship between intensity of vegetation disturbance by multidecadal foraging and nest construction by up to ~1.3 million geese and shifts in (1) plant community composition and (2) taxon richness of freshwater plant communities near Karrak Lake, in Canada's central arctic. Intense use by nesting light geese caused shifts from lowland communities dominated by grasses and sedges (collectively, graminoids), Sphagnum spp., and willows (Salix spp.) to those comprised of exposed peat, non‐Sphagnum mosses, marsh ragwort (Tephroseris palustris), mare's tail (Hippuris vulgaris), and particularly birch (Betula glandulosa). Community change was less apparent in upland regions that were naturally less vegetated even in the absence of avian herbivores, but fruticose lichens, crowberry (Empetrum nigrum), and white heather (Cassiope tetragona) dominated undisturbed plant communities, whereas crustose lichens and bearberry (Arctostaphylos spp.) comprised disturbed communities. We did not find evidence for dominance by a limited number of species with long‐term occupancy by light geese, as taxon richness was equivocal between disturbed and undisturbed plant communities. Cessation of foraging and nesting pressure increased taxon richness and reestablishment of locally eradicated plant species. Overall, herbivory and nesting effects were not uniform across this widespread nesting colony and, together with underlying influence from abiotic gradients, increased heterogeneity in the mosaic of vegetation communities.

Estimates of demographic parameters for lesser snow geese Anser caerulescens caerulescens have become critical to understand ecosystem change in northern Canada. Exponential increase in abundance has produced hyperdensities of these herbivores that can affect Arctic ecosystem stability through intense foraging. Increased and sustained marking of individually‐identifiable lesser snow geese over their breeding distribution now permits joint estimation of local vital rates and movement probabilities among widely scattered subpopulations. We used multi‐state models, including an unobservable state, with live captures from 5 subpopulations and dead recoveries to estimate annual probabilities of 1) survival, 2) capture, 3) reported mortality and 4) movement to other subpopulations, as well as derived estimates for probabilities of site fidelity and harvest. Our dataset included 144 719 captures of 139 177 lesser snow geese marked with metal legbands, from 2006 to 2015, of which 5542 were recaptured near breeding sites and 9709 were recovered dead in North America. The best model supported variation in survival by subpopulation and age, with additive effects of subpopulation, age and sex on movement probability. Male breeding dispersal was greater than by females, and juvenile geese were more likely to move than adults. Strong northeastward geographic asymmetry in the probability of breeding movement was consistent with an eastward shift in wintering distribution observed in hunter recoveries. Mean annual survival ranged from 0.79 to 0.94 for adults, and 0.16 to 0.47 for juvenile geese, with a strong negative relationship between regional adult and juvenile survival. Harvest probabilities were all ≤ 0.03 for adult and ≤ 0.06 for juvenile geese, suggesting little influence from direct anthropogenic exploitation. Metrics for subpopulation persistence and contributions of each to the metapopulation suggested declines in all but one subpopulation, and a declining Midcontinent population overall. Our study highlights the importance of all subpopulation demographic parameters as modulators of persistence at both local and range‐wide population dynamics.

Inuit living in Nunavut have harvested light geese and lived near goose colonies for generations. Inuit knowledge includes important information about light goose ecology and management that can inform co-management and enhance scientific research and monitoring. Since the 1970s, populations of light geese (Snow and Ross’ Geese; kanguit and kangunnait in Inuktut; Chen caerulescens (Linnaeus, 1758) and Chen rossii (Cassin, 1861)) have experienced significant increases in abundance which led to habitat alteration in some portions of the central and eastern Canadian Arctic. In response to concerns expressed by Inuit and wildlife managers about light goose abundance, we conducted a collaborative research project in Arviat and Salliq (Coral Harbour), Nunavut, aiming to mobilize and document Inuit knowledge about light goose ecology and management in the Kivalliq region. Here, we explore the potential of collaborative research for mobilizing Inuit knowledge to support informed and inclusive decision-making about wildlife resources. First, we describe the participatory research methods employed to explore Inuit-identified management recommendations for light geese and engage co-management partners and research contributors to explore select management options. Then, we present these light goose management recommendations and options. Lastly, we discuss opportunities and challenges around the use of collaborative research to support wildlife co-management and Inuit self-determination. Inuit nunaqaqtut Nunavuumi angunasuksimalirmata kanguqpangnik kangurniglu nunaqarvingita sanianni araagunik unuqtunnik. Inuit qaujimaningat ilaqaqpuq aturnilingnik kanguit niqinginnik mianirijauninginniklu tusaumatitaulutik qaujisarningit mianiriyaunigillu. Taimangat 1970s atuqtilugit, kanguit unirningit (kanguit amma kanguaryuit Inuktut; Chen caerulescens (Linnaeus, 1758) amma Chen rossii (Cassin, 1861)) ayunganaqtukut pisimangmata unulialiqlutik amma niqiqatiarungnauqlutik Kanataup uqiuktaqtunngani. Tamana piblugu Inuit uumayuliriyillu isumaalulirmata kanguit unulualirninginnik, taima qaujisarnirmik pigialauqpugut Arvianni and Sallim (Coral Harbour), Nunavuumi, aulataulutik amma qaujisagaulutik Inuit kaujimajagit kangurnik Kivallirmi. Tavani atuqtuuluaqtunik qaujisarnirmut mianiqsinirmullu pitaqaqpuq Inuit nagminiq isumaliurlutik nirjutinut atugaksanullu. Sivullirmik, qaujisarniup qanuinninga isumagilugu kanguit mianirijauninginut. Amma suli, uqausirilirlugu kanguit mianirijauningat atugaujuuluaqtullu. Kingulirmik, uqausirilugu atuinnaujut amma ajurutaujut qaujisarniup iluanni nirjutinik amma Inuit nagminiq aulatuulualirninginnik.