scholarly journals Are Abdominal Profiles Useful to Assess Body Condition of Spring Staging Greater Snow Geese?

The Condor ◽  
2005 ◽  
Vol 107 (3) ◽  
pp. 694-702 ◽  
Author(s):  
Matthieu Féret ◽  
Joël Bêty ◽  
Gilles Gauthier ◽  
Jean-François Giroux ◽  
Gérald Picard
Keyword(s):  
Body Mass ◽  
Body Condition ◽  
Abdominal Fat ◽  
Chen Caerulescens ◽  
Individual Level ◽  
Snow Geese ◽  
Profile Score ◽  
Negative Effect ◽  
Chen Caerulescens Atlantica ◽  
The Individual

AbstractAbdominal profile indices were developed to evaluate body condition in birds without capturing or handling them. We assessed the reliability of abdominal profile indices in predicting condition of spring staging Greater Snow Geese (Chen caerulescens atlantica). We first calibrated profile scores assigned to females against two direct measures of nutrient stores, abdominal fat and body mass corrected for body size. Abdominal profile indices were linearly and significantly related to both abdominal fat and body mass but the variance was high for individuals assigned to the same profile score (R2 = 0.08 and R2 = 0.09, respectively, n = 230). On average, an increase of one profile score corresponded to an increase of 100 g in body mass. Abdominal profiles were better predictors of average abdominal fat and body mass of birds assigned to the same profile category. To assess the usefulness of abdominal profiles in the field, we also examined if the technique could detect the negative effect of a spring hunt on nutrient storage by staging geese, an effect previously detected with internal measures of nutrient reserves. We monitored seasonal changes in abdominal profile indices of staging geese in years without (1997 and 1998) and with the spring hunt (1999 and 2000). In two out of three regions, abdominal profiles revealed that condition increased at a higher rate in nonhunting than in hunting years. The lack of a negative effect of hunting in the other region was likely due to variability among observers in abdominal profile scoring. We conclude that abdominal profile indices can be useful to assess body condition of spring staging Greater Snow Geese although the technique has serious limitations at the individual level, especially without proper training of observers.¿Son los Perfiles Abdominales Útiles para Determinar la Condición Corporal de Chen caerulescens atlantica durante Escalas Migratorias de Primavera?Resumen. Los índices de perfil abdominal fueron desarrollados para evaluar la condición corporal de las aves sin tener que capturarlas o manipularlas. En este estudio examinamos la confiabilidad de dichos índices para predecir la condición corporal de gansos Chen caerulescens atlantica durante la época de escalas migratorias de primavera. Inicialmente, calibramos los puntajes de los perfiles asignados a un grupo de hembras con respecto a dos medidas directas de reservas nutritivas, la grasa abdominal y la masa corregida por el tamaño corporal. Los índices de perfil abdominal estuvieron lineal y significativamente relacionados con la grasa abdominal y la masa corporal (R2 = 0.08 y R2 = 0.09, respectivamente, n = 230), pero la varianza entre individuos asignados al mismo puntaje del perfil fue alta. En promedio, un incremento de un punto en el perfil correspondió a un incremento de 100 g en la masa corporal. Los perfiles abdominales predijeron de mejor manera los promedios de grasa abdominal y masa corporal de aves asignadas a la misma categoría del perfil. Para evaluar la utilidad de los perfiles abdominales en el campo, también examinamos si la técnica podía detectar el efecto negativo de la cacería de primavera sobre el almacenamiento de nutrientes en gansos que estaban haciendo escalas migratorias, un efecto previamente detectado por medio de medidas internas de las reservas nutritivas. Monitoreamos los cambios estacionales en los índices de perfil abdominal de gansos en años que estuvieron (1997 y 1998) y no estuvieron (1999 y 2000) expuestos a cacería en la primavera. En dos de las tres regiones, los perfiles abdominales indicaron que la condición corporal se incrementó a una tasa mayor en los años sin cacería. La ausencia de un efecto negativo de la cacería en la otra región probablemente fue debida a la variabilidad entre distintos observadores al establecer los valores del perfil abdominal. Concluimos que los índices de perfil abdominal pueden ser útiles para evaluar la condición corporal de estos gansos durante la época de escalas migratorias, pero la técnica tiene limitaciones serias a nivel individual, especialmente cuando los observadores no han sido entrenados adecuadamente.

scholarly journals Survival of Young Greater Snow Geese (Chen Caerulescens Atlantica) During Fall Migration

The Auk ◽  
2005 ◽  
Vol 122 (2) ◽  
pp. 479-496 ◽  
Author(s):  
Stéphane Menu ◽  
Gilles Gauthier ◽  
Austin Reed
Keyword(s):  
Body Mass ◽  
High Arctic ◽  
Climatic Conditions ◽  
Factors Affecting ◽  
Chen Caerulescens ◽  
Migratory Flight ◽  
Snow Geese ◽  
Before And After ◽  
Chen Caerulescens Atlantica ◽  
Similar Survival

Abstract The many hazards that await birds along their migratory routes may negatively affect their survival, especially among newly fledged young. We estimated survival of young Greater Snow Geese (Chen caerulescens atlantica) during fall migration from the High Arctic to temperate areas and examined factors affecting their survival over a five-year period, using two approaches. First, each year (1993–1997), we banded fledglings and adults in mid-August, just before their departure from Bylot Island in the High Arctic (Nunavut, Canada), and again at an important staging area 3,000 km to the south at the Cap Tourmente National Wildlife Area (Québec, Canada) in October; recovery data from those two banding periods allowed estimation of survival during fall migration. Second, we visually determined brood size of neck-banded females before and after the main portion of the migratory flight, to estimate survival of young. The two approaches yielded similar survival estimates and showed the same interannual variation, thus suggesting that estimates were reliable. Mortality of young shortly after fledging and during the fall migration was high, compared with that of adults (monthly survival 0.662 in young vs. 0.989 in adults). However, mortality of young after migration was similar to that of adults (monthly survival 0.969 in young vs. 0.972 in adults). Migration survival of young varied considerably among annual cohorts (range of 0.119–0.707 over five years), and most of the mortality appeared to be natural. Survival was especially low in years when (1) temperatures at time of fledging and start of migration were low (i.e. near or below freezing), (2) mean body mass of goslings near fledging was low, or (3) mean fledging date was late. Our results suggest that migration survival of young is affected by a combination of several factors (climatic conditions, body mass, and fledging date) and that survival is reduced when one of those factors intervenes.

scholarly journals Are Body Condition and Reproductive Effort of Laying Greater Snow Geese Affected by the Spring Hunt?

The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Julien Mainguy ◽  
Joël Bêty ◽  
Gilles Gauthier ◽  
Jean-François Giroux
Keyword(s):  
Clutch Size ◽  
Body Condition ◽  
Reproductive Effort ◽  
Lower Proportion ◽  
The Body ◽  
Nutrient Storage ◽  
Chen Caerulescens ◽  
Snow Geese ◽  
Chen Caerulescens Atlantica

Abstract A spring hunt was implemented on the staging areas of Greater Snow Geese (Chen caerulescens atlantica) in Quebec in 1999 and 2000. We evaluated whether this activity, which occurred during the period of spring nutrient storage, may have affected the body condition and reproductive effort of laying geese. We collected laying females in years with a spring hunt (1999–2000, n = 34) and compared them with birds collected in years without a hunt (1989–1990, n = 10). All indices of body condition and clutch size were significantly lower in years with a hunt than in years without, and laying dates were delayed. Tracking of radio-marked females on the staging and breeding areas showed that a lower proportion of females reached the nesting areas in years with a hunt (28% in 1999–2000, n = 80) than in years without (85% in 1997–1998, n = 80) and that fewer females nested (9% vs. 56%, respectively). Our results suggest that the spring hunt negatively affected nesting geese. ¿Son Afectadas por la Cacería de Primavera la Condición Física y el Esfuerzo Reproductivo de Chen caerulescens atlantica? Resumen. La cacería de primavera fue implementada en áreas de escala de Chen caerulescens atlantica en Quebec en 1999 y 2000. Evaluamos si la cacería, que se llevó a cabo durante el período primaveral de acumulación de nutrientes, pudo haber afectado la condición fisica y el esfuerzo reproductivo de los gansos. Colectamos hembras que estuvieran poniendo huevos en años con cacería de primavera (1999–2000, n = 34) y las comparamos con aves colectadas en años sin cacería (1989–1990, n = 10). Todos los índices de la condición física y del tamaño de la nidada fueron significativamente menores en años con cacería que en años sin cacería, y se retrasaron las fechas de puesta. El seguimiento de hembras marcadas con radio en áreas de escala y cría mostró que una menor proporción llegó a las áreas de nidificación en años con cacería (28% en 1999–2000, n = 80) que en años sin cacería (85% en 1997–1998, n = 80), y que menos hembras nidificaron (9% vs. 56%, respectivamente). Nuestros resultados sugieren que la cacería de primavera afecta negativamente a los gansos nidificantes.

scholarly journals Ecological and Physiological Factors Affecting Brood Patch Area and Prolactin Levels in Arctic-Nesting Geese

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 405-418 ◽  
Author(s):  
Jón Einar Jónsson ◽  
Alan D. Afton ◽  
Ray T. Alisauskas ◽  
Cynthia K. Bluhm ◽  
Mohamed E. El Halawani
Keyword(s):  
Body Condition ◽  
The Body ◽  
Nest Size ◽  
Patch Area ◽  
Physiological Factors ◽  
Factors Affecting ◽  
Chen Caerulescens ◽  
Brood Patch ◽  
Snow Geese ◽  
Ross's Geese

AbstractWe investigated effects of ecological and physiological factors on brood patch area and prolactin levels in free-ranging Lesser Snow Geese (Chen caerulescens caerulescens; hereafter “Snow Geese”) and Ross's Geese (C. rossii). On the basis of the body-size hypothesis, we predicted that the relationships between prolactin levels, brood patch area, and body condition would be stronger in Ross's Geese than in the larger Snow Geese. We found that brood patch area was positively related to clutch volume and inversely related to prolactin levels in Ross's Geese, but not in Snow Geese. Nest size, nest habitat, and first egg date did not affect brood patch area in either species. Prolactin levels increased as incubation progressed in female Snow Geese, but this relationship was not significant in Ross's Geese. Prolactin levels and body condition (as indexed by size-adjusted body mass) were inversely related in Ross's Geese, but not in Snow Geese. Our findings are consistent with the prediction that relationships between prolactin levels, brood patch area, and body condition are relatively stronger in Ross's Geese, because they mobilize endogenous reserves at faster rates than Snow Geese.Factores Ecológicos y Fisiológicos que Afectan el Área del Parche de Incubación y los Niveles de Prolactina en Gansos Nidificantes del Ártico

scholarly journals Migration and Wage Effects of Taxing Top Earners: Evidence from the Foreigners’ Tax Scheme in Denmark *

2013 ◽  
Vol 129 (1) ◽  
pp. 333-378 ◽  
Author(s):  
Henrik Jacobsen Kleven ◽  
Camille Landais ◽  
Emmanuel Saez ◽  
Esben Schultz
Keyword(s):  
Wage Bargaining ◽  
Income Taxation ◽  
Tax Rate ◽  
Flat Rate ◽  
Individual Level ◽  
New Immigrants ◽  
Wage Effects ◽  
Matching Frictions ◽  
Negative Effect ◽  
The Individual

Abstract This article analyzes the effects of income taxation on the international migration and earnings of top earners using a Danish preferential foreigner tax scheme and population-wide Danish administrative data. This scheme, introduced in 1991, allows new immigrants with high earnings to be taxed at a preferential flat rate for a duration of three years. We obtain two main results. First, the scheme has doubled the number of highly paid foreigners in Denmark relative to slightly less paid—and therefore ineligible—foreigners. This translates into a very large elasticity of migration with respect to 1 minus the average tax rate on foreigners, between 1.5 and 2. Second, we find compelling evidence of a negative effect of the scheme-induced reduction in the average tax rate on pretax earnings of foreign migrants at the individual level. This finding can be rationalized by a matching frictions model with wage bargaining where there is a gap between pay and marginal productivity.

scholarly journals Isolated individuals and groups show opposite preferences toward humidity

2018 ◽  
Author(s):  
Mariano Calvo Martín ◽  
Stamatios C. Nicolis ◽  
Isaac Planas-Sitjà ◽  
Jean-Christophe de Biseau ◽  
Jean-Louis Deneubourg
Keyword(s):  
Relative Humidity ◽  
Environmental Conditions ◽  
Group Level ◽  
Individual Level ◽  
Negative Effect ◽  
Multi Level ◽  
The Individual ◽  
Shed Light ◽  
Selection Of

AbstractCockroaches, like most social arthropods, are led to choose collectively among different alternative resting places. These decisions are modulated by different factors, such as environmental conditions (temperature, relative humidity) and sociality (groups size, nature of communications). The aim of this study is to establish the interplay between environmental conditions and the modulation of the interactions between individuals within a group leading to an inversion of preferences. We show that the preferences of isolated cockroaches and groups of 16 individuals, on the selection of the relative humidity of a shelter are inversed and shed light on the mechanisms involved. We suggest that the relative humidity has a multi-level influence on cockroaches, manifested as an attractant effect at the individual level and as a negative effect at the group level, modulating the interactions.

Simulating an Incentive Framework for Scientific Production by Means of Adaptive Agents

2014 ◽  
pp. 221-238
Author(s):  
Gabriel Franklin ◽  
Tibérius O. Bonates
Keyword(s):  
Incentive Mechanism ◽  
Scientific Production ◽  
Agent Based Simulation ◽  
Adaptive Agents ◽  
Scientific Publications ◽  
Agent Based ◽  
Individual Level ◽  
Original Target ◽  
Negative Effect ◽  
The Individual

This chapter describes an agent-based simulation of an incentive mechanism for scientific production. In the proposed framework, a central agency is responsible for devising and enforcing a policy consisting of performance-based incentives in an attempt to induce a global positive behavior of a group of researchers, in terms of number and type of scientific publications. The macro-level incentive mechanism triggers micro-level actions that, once intensified by social interactions, lead to certain patterns of behavior from individual agents (researchers). Positive reinforcement from receiving incentives (as well as negative reinforcement from not receiving them) shape the behavior of agents in the course of the simulation. The authors show, by means of computational experiments, that a policy devised to act at the individual level might induce a single global behavior that can, depending on the values of certain parameters, be distinct from the original target and have an overall negative effect. The agent-based simulation provides an objective way of assessing the quantitative effect that different policies might induce on the behavior of individual researchers when it comes to their preferences regarding scientific publications.

Trust, Ethnicity and Integrity in East Africa: Experimental Evidence from Kenya and Tanzania

2017 ◽  
Vol 2 (1) ◽  
pp. 88-123 ◽  
Author(s):  
Dominic Burbidge ◽  
Nic Cheeseman
Keyword(s):  
Ethnic Diversity ◽  
Negative Impact ◽  
Common Knowledge ◽  
Individual Level ◽  
Trust Games ◽  
Negative Effect ◽  
Experimental Games ◽  
The Individual ◽  
The Impact ◽  
First Time

AbstractPolitical economy comparisons of Kenya and Tanzania have often found the political salience of ethnicity to be far higher in the former than the latter, with a negative impact on intercommunal trust. This difference has tended to be explained on the basis of the different kinds of leadership that the two countries experienced after independence. However, these findings have typically been demonstrated using aggregate or survey data. This paper assesses the salience of ethnicity at the individual level for the first time, deploying monetized two-round trust games in urban Kenya and Tanzania. The experimental games isolate the comparative impact of common knowledge of ethnicity and integrity among a quasi-random selection of 486 citizens. Verifying previous findings, we observe higher levels of trust and trustworthiness in Tanzania as compared with Kenya. Further, in comparison with Kenya, any shared knowledge of ethnic identities in Tanzania leads players to transfer fewer resources, while common knowledge that both players are “honest” led to higher transfers there than in Kenya. These results provide robust evidence of higher levels of trust in Tanzania, and of the negative effect in that country of common knowledge of ethnicity on levels of cooperation. The findings demonstrate the way in which political context can shape the impact of ethnic diversity, and encourage further experimental research that looks at the intersubjective dynamics of social cooperation.

scholarly journals Gosling Growth and Survival in Relation to Brood Movements in Greater Snow Geese (Chen Caerulescens Atlantica)

The Auk ◽  
2006 ◽  
Vol 123 (4) ◽  
pp. 1077-1089 ◽  
Author(s):  
Julien Mainguy ◽  
Gilles Gauthier ◽  
Jean-François Giroux ◽  
Joël Bêty
Keyword(s):  
Selective Advantage ◽  
Nest Site Selection ◽  
High Quality ◽  
Growth And Survival ◽  
Chen Caerulescens ◽  
Brood Rearing ◽  
Snow Geese ◽  
Movement Distance ◽  
Chen Caerulescens Atlantica ◽  
Precocial Birds

Abstract 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 radio-marked 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. Croissance et Survie des Oisons en Relation avec les Déplacements des Familles chez Chen caerulescens atlantica

Habitat use and behaviour of Greater Snow Geese during movements from nesting to brood-rearing areas

2006 ◽  
Vol 84 (8) ◽  
pp. 1096-1103 ◽  
Author(s):  
J. Mainguy ◽  
G. Gauthier ◽  
J.-F. Giroux ◽  
I. Duclos
Keyword(s):  
Habitat Use ◽  
Long Distance ◽  
High Quality ◽  
Chen Caerulescens ◽  
Brood Rearing ◽  
Snow Geese ◽  
Greater Snow Goose ◽  
Chen Caerulescens Atlantica ◽  
Precocial Birds ◽  
Aerial Tracking

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.

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