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We studied the effects of grazing by Black Brant (Branta bernicla nigricans) geese (hereafter Brant) on plant community zonation and gosling growth between 1987 and 2000 at a nesting colony in southwestern Alaska. The preferred forage of Brant, Carex subspathacea, is only found as a grazing lawn. An alternate forage species, C. ramenskii, exists primarily as meadow but also forms grazing lawns when heavily grazed. We mowed plots of ungrazed C. ramenskii meadows to create swards that Brant could select and maintain as grazing lawns. Fecal counts were higher on mowed plots than on control plots in the year after plots were mowed. Both nutritional quality and aboveground biomass of C. ramenskii in mowed plots were similar to that of C. subspathacea grazing lawns. The areal extent of grazing lawns depends in part on the population size of Brant. High Brant populations can increase the areal extent of grazing lawns, which favors the growth of goslings. Grazing lawns increased from 3% to 8% of surface area as the areal extent of C. ramenskii meadows declined between 1991 and 1999. Gosling mass was lower early in this time period due to density dependent effects. As the goose population stabilized, and area of grazing lawns increased, gosling mass increased between 1993 and 1999. Because larger goslings have increased survival, higher probability of breeding, and higher fecundity, herbivore-mediated changes in the distribution grazing lawn extent may result in a numerical increase of the population within the next two decades. [ABSTRACT FROM AUTHOR]

Presents a study that estimated adult survival rates for adult female black brant using capture-recapture methods. Reason for the importance of the variation in adult survival rates on other life-history traits; Estimation of the annual survival for brant from the colonies; Evidence for a difference in survival between brant nesting on the Yukon-Kuskokwim Delta, Alaska and those nesting in the Arctic.

Analyzes the variation in growth of black brant goslings in relation to the variation in grazing pressure and food abundance. Why growing geese are susceptible to nutrient limitation during growth; Importance of growth in geese; How to measure the growth rates of goslings; Analysis of the variation in the growth of goslings.

Summary 1.We estimated age-specific probability of breeding for black brant (Branta bernicla nigricans Lawrence) (hereafter brant) at the Tutakoke River Colony, Alaska, during a series of years in which local breeding density and juvenile mortality both increased. We use these analyses to examine demographic responses to increased population density. 2.Estimates of breeding probability were based on Kendall & Nichols (1995) full-likelihood modification of Pollock’s (1982) robust design applied to observations of uniquely colour-banded brant. 3.Breeding probability varied with female age but not across years, indicating lack of response to increased population density. Annual probability of breeding increased from 0·67 ± 0·042 for 2-year-old females to 0·90 ± 0·024 for females 5 years old or older. 4.Annual breeding probability of males ≥ 5 years old was 0·78 ± 0·03. Lower breeding probability of males compared to females probably reflects dispersal of males whose mates died. 5.Lower juvenile survival appears to be a general response to increased density in large herbivorous birds and mammals, while changes in adult survival and reproductive investment may be more variable. [ABSTRACT FROM AUTHOR]

Summary 1 Field studies on effects of geese on arrowgrass (Triglochin palustris) on the Yukon-Kuskokwim Delta (SW Alaska) have demonstrated that Pacific black brant geese (Brant bernicla nigricans) can have both positive and negative effects on arrowgrass populations, but cannot predict unambiguously the effects of increased goose numbers on arrowgrass demography. 2 A cellular automata model was used to predict effects of changes in goose grazing intensity on small-scale (within-patch) arrowgrass dynamics. We examined effects of making some of the plant competitors edible to geese, of goose faeces increasing arrowgrass reproduction but reducing size of ungrazed arrowgrass, and of the presence of other species protecting arrowgrass from grazing. We also compared the effects of a random vs. patchy distribution of geese, and of incorporating threshold numbers of arrowgrass below which grazing ceased. 3 The results indicate that arrowgrass populations are likely to be highest at medium to high levels of grazing. Inclusion of edible competitors and positive effects of faecal deposition resulted in greater changes in arrowgrass population dynamics than did inclusion of associative refuges. 4 For a given grazing intensity, models generally resulted in lower arrowgrass populations with increased aggregation if distributions of geese were patchy, suggesting that decreased colonization may result from lower dispersal. 5 Inclusion of a feedback effect (grazing only above a certain plant population) caused arrowgrass populations to persist for much longer. Temporal variability in whether plots were grazed (unrelated to arrowgrass numbers) could not account for this result. 6 The model results suggest that knowledge of both small-scale and large-scale foraging behaviour is needed to predict the long-term effects of goose grazing on arrowgrass. Small-scale effects on the population may be particularly important where dispersal distances are short. The ability of plant... [ABSTRACT FROM AUTHOR]

Whether migrating birds compensate for wind drift or not has been discussed frequently during the last decades. Observed behaviours seem to differ between species and situations. Even though complete compensation allows a bird to fly the shortest distance during its migration, this is not necessarily the optimal solution in all cases. There are certain situations when drifting with the wind, and thus getting higher groundspeed, will be more beneficial, i.e. adaptive drift. In this article, I analyse flight directions of spring migrating barnacle and brent geese, tracked by radar and optical range finder, and compare these with prevailing winds to see if these birds compensate or drift with the wind. I also use wind data from the days when the trackings were made to construct expected flight paths to see whether wind drift or compensation would be the most beneficial behaviour. The geese were found to drift partially with the wind. The drift effect was concluded to be true partial drift, i.e. not pseudodrift or drift forced by strong winds. The drift was not found to be of any obvious adaptive value, as the geese drifted irrespective of the strategy that would have been most beneficial to them. None of the situations in which drift is predicted to be adaptive was applicable to the birds and migration days in this study. A possible explanation for the observed pattern is that since these birds usually have access to favourable winds during their spring migration, selection pressures for adaptive drift or compensation behaviours might be weak. [ABSTRACT FROM AUTHOR]

Presents information on a study that compared different analytical approaches for estimating repeatability of egg size of Black Brant. Methodology of the study; Results and discussion on the study.

Presents information on a study which examined behavioral responses of Pacific brant and Canada geese to experimental overflights during fall staging at Izembek Lagoon, Alaska. Study area; Methods used; Results and discussion; Management implications.

1 We investigated the effects of grazing by black brant geese on Carex subspathacea lawns on the Yukon-Kuskokwim delta, Alaska. 2 We compared variation in growth and forage quality in both grazed and temporarily exclosed sites to determine responses of C. subspathacea to grazing at landscape scales within two nesting colonies that had experienced different population dynamics over recent decades. 3 Landscapes differed in forage quality, grazing patterns, and in the effect grazing had on C. subspathacea forage characteristics. We found no effect of grazing on net above-ground primary productivity (NAPP) over a wide range of natural grazing intensities at the landscape scale. 4 No differences in forage quality, NAPP, or response of C. subspathacea growth rates to grazing pressures could be detected between colonies. This suggests that goose grazing does not have deleterious effects on C. subspathacea in this ecosystem. 5 It has been suggested that gosling growth rates are sensitive to seasonal declines in forage availability and quality. Spatial variation in forage quality and availability per sampled area exceeded seasonal variation in these characteristics and is likely to have dramatic effects on gosling growth and recruitment rates. [ABSTRACT FROM AUTHOR]

Studies the migration patterns of black brant in Boundary Bay, British Columbia. Data analysis; Methodology and study area; Findings of the study.

Examines concerns of biologists on the number of captured waterfowls in banding drives during the adult remigial molt, while analyzing the results of research on the ultrastructure approach in program SURVIV. Information pertaining to the female black brant which is also known as the Branta bernicla nigricans; Methodology used in the study; Description of data collected.

Presents information as it relates to the reducing mid-winter counts of Pacific brant which is known as Branta bernicla nigricans, and reduces the number of nesting birds on their breeding grounds. Analysis of data conducted on the nesting birds; Methodology used in research; Details on the results of the research.

Examines the effects nest visits and placing of markers near nest sites have on the population of black brant and lesser snow geese at Anderson River, Canada. Years when study was conducted; Corporations which provided funding; Information on previous studies; Reasons for placing markers near nest sites; Location of study area; Description of study area; Why ornithologists believe their activities reduce nest population.

Estimates survival of black brant goslings during the summers between 1987-1989 on the Yukon-Kuskokwim Delta, Alaska. Survival as a component of waterfowl productivity; Timing and magnitude of gosling mortality; Comparison of methods of estimated gosling survival; Estimates of gosling survival during brood rearing; Survival estimates on the basis of age ratios of birds.

Investigates the effects of harness-attached transmitters on premigration and reproduction of brant. Migration schedules at a fall staging area; Return rates to nesting grounds; Nesting rates of returning female brants in subsequent breeding seasons.

Describes the two methods used to evaluate the effect of visiting black brant nests on the survival of whole nests and eggs in a single colony in Alaska. Regression of surviving nests or eggs over time interval; Nest visits before and after return of nesting pairs of black brants; Results.

Reports on a study on the relationships between body size of female Black Brant goslings late in their growth period and first year survival. Statistical analyses; Early growth and life history traits; Acknowledgments.

Reports on the evaluation of breeding black brant at Tutakoke River, Alaska. Fidelity of nesting sites; Estimations of fidelity; Methods used; Result; References.

Examines how estimates of survival rates are affected by dependency in survival probability among the black brant (Branta bernicla nigricans). Use of models; Analysis of simulated data; References.

Presents a study on Black Brant species, which was conducted to estimate site fidelity to wintering and spring areas in the Boundary Bay and Parksville of British Columbia. Methods used in conducting the study; Effect of emigration and immigration on the population size of species of birds and mammals; Results of the study.

Presents a study where factors affecting duration of incubation in Black Brant during 1992 and 1993 on the Yukon-Kuskokwim Delta, Alaska was investigated. How the duration of incubation varied; Methodology used to conduct study; Results of study.

Presents a study carried out on the Black Brant (Branta bernicla nigricans), which investigated the effects of timing of spring snowmelt on nesting phenology, nest site location and clutch size. Background on the methodology used in the study; When nest initiation was most prevalent; Factors that may affect distribution of nest initiation dates; Conclusion of the study.

Examines the relationship between dispersal distance and consecutive nesting attempts of female Black Brant nesting colonially at the Tutoke River in Alaska. Relationship between dispersal distance and measures of reproductive performance; Age related movement; Effects of reproductive performance on dispersal distance.

Reports on sightings of Black Brants, Branta bernicla nigricans, from Alaska, wintering in Japan. Background on the study; Description of methods used in the study.

Describes the development of a spatial depletion model to predict the distribution and abundance of grazing brent geese (Branta bernicla) and wigeon (Anas penelope) in response to changes in the availability of their food on the intertidal mudflats of the Lindisfarne National Nature Reserve in northeastern England. Predictions in the distribution of both grazers; Calculation of the maximum number of the birds that could be supported.

Studies the use of grassland and field selection by brent geese. Time of arrival of the geese on the fields; Individual geese visitation; Grazing intensity; Field selection of the geese.

Studies the effect of the grazing of brent geese on winter wheat. Background on the feeding behavior of the species; Impact of the grazing on the level of biobass of leaves and shoots of winter wheat; Rate of ripening of grazed wheat.

Examines the nesting of the Black Brant females in the Tutakoke River colony, in reference to gosling, adult body and clutch size, during 1986 and 1995. Increase in the colony from 1,100 to 5,000 nesting pairs; Decline in gosling size; Interpretation of the effect of density on adult size between Black Brant and other geese.

Presents a study which examined the use of brood-rearing sites by female Black Brant (Branta bernicla nigricans), on the Tutakoke River, Alaska, during 1987 to 1993. Fidelity to brood-rearing sites by adult females; Observation of site-specific and annual variation in movements among sites; Results of movement among brood-rearing sites for adults.

Compares the influence of hatch date and maternal and genetic effects on the growth of Black Brant goslings. Determinant of their fitness; Explanation for the ubiquitous seasonal decline in growth rate among geese; Role of parental quality in the seasonal decline in gosling growth.

1. The effect of loss of a spring staging site on dispersal and on the fitness parameters fecundity and survival of Dark-bellied Brent Geese Branta bernicla bernicla was investigated. A group of marked birds from an embanked saltmarsh area was compared with a control group of birds from nearby, non-embanked saltmarshes for a period of 13 years after the embankment. 2. Both displaced and control birds were seen at numerous sites other than their ringing site; long-distance movements were detected more frequently in displaced birds during the first years after the habitat loss. 3. Displaced birds appeared to move more often to less preferred sites that were not filled to capacity than did control birds. 4. Significant differences in subsequent fecundity and survival of displaced and control birds could not be detected; it appears that the majority of displaced birds succeeded in finding good alternative sites. There was, however, a tendency for the displaced birds to have lower breeding success and to survive less well, which suggests that subtle effects of displacement may occur. 5. Even if habitat loss has no significant effects on displaced individuals, loss of a spring staging site increases population pressure on the remaining sites and may reduce fitness parameters of the population as a whole. In addition, invasion of previously unused sites leads to increasing conflict between Brent Geese and agricultural interests. 6. In order to predict impacts of future habitat changes on bird populations, many more empirical data on long-term effects of habitat loss, such as provided in this study, are needed. [ABSTRACT FROM AUTHOR]

En este número no se incluyeron resúmenes ni palabras clave.

A black brane solution to Gauss–Bonnet massive gravity is introduced. In the context of AdS/CFT correspondence, the viscosity to entropy ratio is found by the Green–Kubo formula. The result indicates a violation of the well-known KSS bound, as expected in a higher derivative theory. Setting mass zero gives back the known viscosity to entropy ratio dependent on the Gauss–Bonnet coupling, while without the Gauss–Bonnet term, a nonzero mass parameter does not contribute to the ratio which saturates the bound of [ABSTRACT FROM AUTHOR]

Correction to the article related to Branta bernicla nigricans and Kittiwakes Rissa tridactyla from the January 2016 issue is presented.