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Demographic models, which are a natural extension of capture-recapture (CR) methodology, are a powerful tool to guide decisions when managing wildlife populations. We compare three different modelling approaches to evaluate the effect of increased harvest on the population growth of Greater Snow Geese (Chen caerulescens atlantica). Our first approach is a traditional matrix model where survival was reduced to simulate increased harvest. We included environmental stochasticity in the matrix projection model by simulating good, average, and bad years to account for the large inter-annual variation in fecundity and first-year survival, a common feature of birds nesting in the Arctic. Our second approach is based on the elasticity (or relative sensitivity) of population growth rate (lambda) to changes in survival as simple functions of generation time. Generation time was obtained from the mean transition matrix based on the observed proportion of good, average and bad years between 1985 and 1998. If we assume that hunting mortality is additive to natural mortality, then a simple formula predicts changes in lambda as a function of changes in harvest rate. This second approach can be viewed as a simplification of the matrix model because it uses formal sensitivity results derived from population projection. Our third, and potentially more powerful approach, uses the Kalman Filter to combine information on demographic parameters, i.e. the population mechanisms summarized in a transition matrix model, and the census information (i.e. annual survey) within an overall Gaussian likelihood. The advantage of this approach is that it minimizes process and measured uncertainties associated with both the census and demographic parameters based on the variance of each estimate. This third approach, in contrast to the second, can be viewed as an extension of the matrix model, by combining its results with the independent census information.

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

Isolation and cohesion are two key network features, often used to predict outcomes like mental health and deviance. More cohesive settings tend to have better outcomes, while isolates tend to fare worse than their more integrated peers. A common assumption of past work is that the effect of cohesion is universal, so that all actors get the same benefits of being in a socially cohesive environment. Here, we suggest that the effect of cohesion is universal only for specific types of outcomes. For other outcomes, experiencing the benefits of cohesion depends on an individual’s position in the network, such as whether or not an individual has any social ties. Network processes thus operate at both the individual and contextual level, and we employ hierarchical linear models to analyze these jointly to arrive at a full picture of how networks matter. We explore these ideas using the case of adolescents in schools (using Add Health data), focusing on the effect of isolation and cohesion on two outcomes, school attachment and academic engagement. We find that cohesion has a uniform effect in the case of engagement but not attachment. Only non-isolates experience stronger feelings of attachment as cohesion increases, while all students, both isolates and non-isolates, are more strongly engaged in high cohesion settings. Overall, the results show the importance of taking a systematic, multi-level approach, with important implications for studies of health and deviance.

Feet and talons are the most specialized predatory attributes of raptor morphology. As such, the hindlimb morphology of owls should reflect their dietary specialization. Owls' diet varies widely between species with only a subset of owl species preying predominantly on small mammals. We hypothesize that different owl species have varied hindlimb morphology, adapted to their main prey types, and that only dietary specialists will be distinguishable based on talon morphology (e.g. toe length, talon curvature and thickness, etc.). We used a sample of 63 specimens from 15 owl species to obtain a variety of measurements of hindlimb morphology. We then used a discriminant function analysis to investigate the degree of variation between species and diet groups in terms of their morphological measurements. Our results indicate that talon morphology is linked to prey type in the owl species studied. Insect specialists and small mammal specialists were characterized by a low talon curvature, whereas generalists presented a pronounced talon curvature. Fish specialists presented particularly thick and robust talons, and insect specialists showed lower digit strength than other owl species. These findings could help determine the diet of other owl species, particularly endangered species for which data on diet is often scarce. This study will also be very useful in future studies of the ecology of sympatric species, resource partitioning between species, or between sexes of the same species, and more generally to the evolution of owls. [ABSTRACT FROM AUTHOR]

Presents an authoring model and a system for curriculum development in intelligent tutoring systems. Explains CREAM (Curriculum Representation and Acquisition Model) which allows for the creation and organization of the curriculum according to three models concerning the domain, the pedagogy, and the didactic aspects. (Author/LRW)

Presents an authoring environment dedicated to the development of curriculum and course material that can be handled by an Intelligent Tutoring System (ITS). The adopted curriculum model is Curriculum Representation and Acquisition Model (CREAM) which represents subject-matter content from the domain, the pedagogical, and the didactic points of view. (Author/AEF)

Assessment of social processes underlying anticipation for recovery-related support from family in the event of a substance problem. We drew from literature on social support, substance use, and social networks to develop a path model connecting emotionally close family relationships, closeness among members in the wider family network (density), previous emotional support exchanges, and anticipated support. We used a sample from the 2019 Nebraska Annual Social Indicators Survey (284 adults; 57% female; 94% white; 46.26% living in rural areas) and employed generalized structural equation modeling with logistic regression equations for our binary dependent variable (anticipated support). Denser family networks were associated with individuals' close relations with family (b =.18, p <.001), close family relations were associated with support received by (b =.25, p <.05) and given to (b =.47, p <.001) family, and only support given to family increased the odds of anticipated support (IRR = 4.32, CI = 1.13, 16.48). Family-wide dynamics are important for understanding how support exchange relates to anticipated support. Prioritizing efforts to strengthen family relationships and improve the likelihood that at-risk individuals, especially in rural areas, can overcome substance problems is important. [ABSTRACT FROM AUTHOR]

The instability of an iso-dense non-Brownian suspension of polystyrene beads of diameter 40 μm dispersed in a water-glycerol mixture submitted to a periodic square wave oscillating flow in a Hele-Shaw cell is studied experimentally. The instability gives rise to stationary bead concentration waves transverse to the flow. It has been observed for average particle volume fractions between 0.25 and 0.4, for periods of the square wave flow variation between 0.4 and 10 s and in finite intervals of the amplitude of the fluid displacement. The study shows that the wavelength λ increases roughly linearly with the amplitude of the oscillatory flow; on the other hand, λ is independent of the particle concentration and of the period of oscillation of the flow although the minimum threshold amplitude for observing the instability increases with the period.

Indigenous clients in need of residential care for substance use disorders (SUD) often present with the diagnosis of substance use disorder (SUD) combined with intergenerational trauma (IGT) or both. SUD is exceedingly prevalent amongst Indigenous peoples due to the health impacts of colonisation, residential school trauma, and IGT on this population’s health. We evaluated the effectiveness of a Two-Eyed Seeing approach in a four-week harm reduction residential treatment programme for clients with a history of SUD and IGT. This treatment approach blended Indigenous Healing practices with Seeking Safety based on Dr. Teresa Marsh’s research work known as Indigenous Healing and Seeking Safety (IHSS). The data presented in this study was drawn from a larger trial. This qualitative study was undertaken in collaboration with the Benbowopka Treatment Centre in Blind River, Northern Ontario, Canada. Patient characteristic data were collected from records for 157 patients who had enrolled in the study from April 2018 to February 2020. Data was collected from the Client Quality Assurance Survey tool. We used the qualitative thematic analysis method to analyse participants’ descriptive feedback about the study. Four themes were identified: (1) Motivation to attend treatment; (2) Understanding Benbowopka’s treatment programme and needs to be met; (3) Satisfaction with all interventions; and (4) Moving forward. We utilised a conceptualised descriptive framework for the four core themes depicted in the medicine wheel. This qualitative study affirmed that cultural elements and the SS Western model were highly valued by all participants. The impact of the harm reduction approach, coupled with traditional healing methods, further enhanced the outcome. [ABSTRACT FROM AUTHOR]

Analysis of carbon ([sup.13]C/[sup.12]C) and nitrogen ([sup.15]N/[sup.14]N) stable isotope ratios (hereafter [delta][sup.13]C and [delta][sup.15]N, respectively) in animal tissues is a powerful tool in food-web studies. However, isotopic ratios of prey are not transmitted directly to a consumer, as a diet-tissue discrimination factor (denoted A) occurs between sources and consumer's tissues. An accurate assessment of the diet of a consumer with stable isotopes thus requires that the [DELTA][sup.13]C and [DELTA][sup.15]N of the studied species are known. Our aim was to establish [DELTA][sup.13]C and [DELTA][sup.15]N values in the Snowy Owl (Bubo scandiacus (L., 1758)). Moreover, we assessed the potential effect of ethanol preservation of blood samples on [delta][sup.13]C and [delta][sup.15]N values. We kept four captive adult Snowy Owls on a pure diet of mice for [greater than or equal to] 6 weeks. We then collected mouse muscle and blood samples from the owls and analyzed their [delta][sup.13]C and [delta][sup.15]N values. [DELTA][sup.13]C and [DELTA][sup.15]N values (mean [+ or -] SE) for owl blood were +0.3 [per thousand] [+ or -] 0.2 [per thousand] and +1.9 [per thousand] [+ or -] 0.1 [per thousand], respectively. These values are the first discrimination factors ever reported in Strigiformes and are lower, for [DELTA][sup.15]N, than those obtained in terrestrial carnivores and other bird species, including falcons. Preservation in ethanol did not significantly affect [delta][sup.13]C and [delta][sup.15]N values. L'analyse des ratios isotopiques de carbone ([sup.13]C/[sup.12]C) et d'azote ([sup.15]N/[sup.14]N) (symbolises par [delta][sup.13]C et [delta][sup.15]N respectivement) dans les tissus animaux est un outil puissant pour l' etude des reseaux trophiques. Cependant, les ratios isotopiques des proies ne sont pas transmis directement au consommateur et un facteur de discrimination (note [DELTA]) est observe entre les ratios des sources et ceux du consommateur. La determination exacte du regime alimentaire d'un consommateur a l'aide des isotopes stables demande donc une connaissance des [DELTA][sup.13]C et [DELTA][sup.15]N chez l'espece a l'etude. Notre objectif etait de determiner les valeurs de [DELTA][sup.13]C et [DELTA][sup.15]N chez le harfang des neiges (Bubo scandiacus (L., 1758)). De plus, nous voulions determiner l'impact potentiel de la conservation d'echantillons sanguins dans une solution d'ethanol 70 % sur les valeurs de [delta][sup.13]Cet [delta][sup.15]N. Nous avons garde quatre harfangs des neiges en captivite, nourris exclusivement de souris pendant [greater than or equal to] 6 semaines. Nous avons ensuite recolte des echantillons sanguins des oiseaux et des muscles de souris et nous avons determine leur signature de [delta][sup.13]C et de [delta][sup.15]N. Les valeurs de [DELTA][sup.13]C et [DELTA][sup.15]N (moyenne [+ or -] ES) du sang chez le harfang des neiges sont de +0,3 [per thousand] [+ or -] 0,2 [per thousand] et +1,9 [per thousand] [+ or -] 0,1 [per thousand], respectivement. Ces valeurs de discrimination sont les premieres rapportees a ce jour chez les strigiformes et elles sont plus faibles, pour l'azote, que celles observees chez les carnivores terrestres et d'autres especes d'oiseaux, incluant les faucons. La conservation des echantillons sanguins dans une solution d'ethanol 70 % n'as pas affecte significativement les valeurs de [delta][sup.13]C et de [delta][sup.15]N., Introduction Naturally occurring stable isotopes of carbon ([sup.13]C, [sup.12]C) and nitrogen ([sup.15]N, [sup.14]N) are present in every living organism and they occur under specific ratios (denoted [delta][sup.13]C and [delta][sup.15]N, respectively) [...]

Food-caching by arctic foxes (Vulpes lagopus (L., 1758)) is a behavioural adaptation thought to increase winter survival, especially in bird colonies where a large number of eggs can be cached during a short nesting season. In this paper, we measured the energy content of greater snow goose (Chen caerulescens atlantica Kennard, 1927) eggs and evaluated their perishability when cached in tundra soil for a whole summer. We estimated that eggs lost only ~8% of their dry mass over 60 days of storage in the ground. We used published estimates on digestibility of nutrients by arctic foxes to estimate that fresh and stored goose eggs contained 816 and 730 kJ of metabolizable energy, respectively, a difference of 11%. Using information on arctic fox energetics, we evaluated that 145 stored eggs were required to sustain the growth of one pup from the age of 1 to 3 months (nutritional independence). Moreover, 23 stored eggs were energetically equivalent to the average fat deposit of an arctic fox during winter. Finally, we calculated that an adult arctic fox would need to recover 160-220 stored eggs to survive 6 months in resting conditions during cold winter temperatures. This value increased to 480 when considering activity cost. Based on egg acquisition and caching rates observed in many goose colonies, we conclude that cached eggs represent an important source of energy relative to the needs of an arctic fox during winter, and have thus a high fitness value. La mise en reserve de nourriture chez le renard arctique (Vulpes lagopus (L., 1758)) est une adaptation comportementale largement soupconnee d'augmenter la survie durant l'hiver, plus particulierement dans les colonies d'oiseaux ou un grand nombre d'oeufs peuvent etre caches durant la courte saison de nidification. Nous avons mesure le contenu energetique des oeufs de la grande oie des neiges (Chen caerulescens atlantica Kennard, 1927) et evalue leur perissabilite lors que entreposes dans le sol de la toundra durant tout un ete. Les neufs ont perdu seulement ~8 % de leur masse seche durant 60 jours d'entreposage dans le sol. En utilisant des estimations de la digestibilite des nutriments par le renard arctique tirees de la litterature, nous avons evalue que les neufs d'oies frais et entreposes contiennent respectivement 816 et 730 kJ d'energie metabolisable, une difference de 11 %. A l'aide de donnees sur le metabolisme du renard arctique, nous avons evalue que 145 oeufs entreposes seraient requis pour soutenir la croissance d'un jeune renard entre l'age de 1 et 3 mois (l'independance alimentaire). De plus, 23 neufs entreposes contiennent autant d'energie que les reserves de gras moyennes d'un renard durant l'hiver. Finalement, nous avons calcule que 160 A 220 oeufs entreposes seraient necessaires A la survie d'un renard pendant 6 mois aux temperatures froides d'hiver en condition de repos. Cette valeur augmente A 480 lorsqu'on considere les couts de l'activite. A la lumiere des taux d'acquisition et d'entreposage d'oeufs observes dans plusieurs colonies d'oies, nous concluons que les oeufs entreposes representent une source d'energie importante pour un renard en hiver, compte tenu de ses besoins. Le comportement d'entreposage a donc une grande importance pour l'aptitude phenotypique des individus. [Traduit par la Redaction], Introduction Surviving winter is a great challenge for terrestrial home-otherms living at high latitudes or altitudes because extensive heat loss owing to low temperatures is often associated with food scarcity. [...]

Abstract: 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 [...]