Estimation of carcass fat and protein in northern pintails (Anas acuta) during spring migration

Foraging in stopover areas influences nutritional condition of birds during spring migration. Our purpose was to determine if body mass, percent carcass water, and serum biochemistry would predict energy reserves (carcass fat and protein) in northern pintails (Anas acuta) at a spring staging area, Lake St. Pierre in Québec, Canada (46 degrees 11 'N, 73 degrees 08 'W). Northern pintails were collected during spring 1997 (14 April-9 May). In this staging area, body mass and percent body water successfully estimated carcass protein and fat in male northern pintails, but only carcass protein in females. None of the seven blood parameters we used accurately estimated nutritional reserves in staging northern pintails. These findings suggest that investigators must use direct estimates of carcass reserves to examine nutrient reserve requirements for egg production, migration, or body maintenance during spring migration.     

Adaptive significance of winter pair bond in male pintail, Anas acuta

To test the female-advantage hypothesis that has been proposed to explain the adaptive significance of winter pair bonds in ducks, we examined the feeding and social behaviors of the northern pintail, Anas acuta. The female-advantage hypothesis assumes that male attendance offers paired females the benefits of increased social status and access to food, as well as less harassment from conspecifics, allowing them to spend more time feeding. Paired females dominated unpaired females, but neither time budgets of feeding nor frequency of feeding was significantly different between unpaired and paired females. The female-advantage hypothesis predicts that paired males spend less time feeding because they must closely guard their partners from harassment by male conspecifics. Paired males defended their mates by chasing and pecking the unpaired males. However, both time budgets of feeding and frequency of feeding were significantly higher in paired males than in unpaired males. Unpaired males frequently approached females while swimming. They performed courtship displays, mostly toward unpaired females. Paired males spent more time feeding by saving time and energy in courtship. We consider that the advantage of winter pairing for males comes from having a mate plus having an increase in feeding frequency. Received: February 20, 2000 / Accepted: May 22, 2000     

Landscape-dependent distribution of northern forest birds in winter

We evaluated the effects of landscape structure, along a broad gradient of deforestation (forest cover 8–88%, 500-m radius), on the spatial distribution of forest birds exposed to winter climatic conditions, in Quebec, Canada. Concurrently, we conducted an experiment to determine if these effects would persist if an unlimited source of energy, provided by food-supplementation, became available. We analyzed these effects at the population level, using count data of black-capped chickadees Poecile atricapillus , but also at the community level, referring to species richness. In one of the two years of the study, before food-supplementation began (November), forest integrity (a composite of forest cover and edge density) was positively associated with chickadee abundance and species richness. Each year, forest integrity was also positively associated with chickadee abundance and species richness in landscapes that were supplemented (December–February). However, in control landscapes, during the food-supplementation period, chickadee abundance and species richness tended to decrease with an increase in forest integrity. We argue that the more forested control landscapes facilitated winter emigration of juveniles and transient birds. Conversely, our results further suggest that, in the highly deforested and fragmented control landscapes, birds became gap-locked when rigorous winter climatic conditions exacerbated already existing movement constraints.     

Effects of winter and early spring grazing by Wigeon Anas penelope on their food supply

Wigeon Anas penelope selectively grazed small patches of grassland near water. Their grazing activity affected the vegetation on which they fed, resulting in a 52% increase in leaf production over the winter and, at the end of winter, 4.75% higher protein levels compared with plants which were ungrazed. These responses of the plants were caused by defoliation, which stimulated growth, and not a fertiliser effect from the birds' droppings. We suggest that repeated feeding on the same areas is a deliberate strategy used by Wigeon which causes an improvement in their dietary quality in late winter and early spring.     

Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta)

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.     

Timing of spring migration in birds: long-term trends, North Atlantic Oscillation and the significance of different migration routes

We studied long-term trends and the yearly variation in mean spring passage time in 36 passerine bird species trapped at Ottenby Bird Observatory in south-eastern Sweden. Between the years 1952–2002, data were available for 22–45 years depending on species. Most long-distance migrant species passed progressively earlier over the study period (range: 2.5 days earlier to 0.7 days later per 10 years, with an average of 0.9 days earlier per 10 years). The annual variation in timing of migration in most species, regardless of migration distance, correlated negatively with the winter index of the North Atlantic Oscillation (NAO), a large-scale climate phenomenon influencing the climate in the North Atlantic region. Birds passed earlier after mild and humid winters, corresponding to the high phase of the NAO. This corroborates the pattern found at a nearby migration site with a comparable dataset (Helgoland, 600 km WSW of Ottenby). However, short/medium-distance migrant species at Ottenby, in contrast to the situation at Helgoland, have shown no general trend of earlier passage in recent years. This was probably a consequence of the shorter study period at Ottenby, which included only the last 22–32 years (41 years at Helgoland), when the NAO showed no significant trend. At the species-specific level, the long-term trends in passage time were similar at the two sites, and there was some congruence to the extent that a given species was affected by NAO. Long-distance migrants wintering south and south-east of the breeding grounds showed some of the strongest changes in long-term trends (passing progressively earlier) at Ottenby, and for some of these species passage time varied negatively with NAO. Obviously, and contrary to previous suggestions, variations in NAO also influence birds migrating through eastern Europe, although the direct or indirect mechanisms through which this is achieved are unknown.     

The large-scale detoured migration route and the shifting pattern of migration in Oriental honey-buzzards breeding in Japan

We describe the detoured migration route of the Oriental honey-buzzard Pernis ptilorhyncus , showing differences between autumn and spring migration, using data from 10 adult individuals marked with satellite transmitters. In autumn, the migration routes were very similar from Japan to the south end of the Malay Peninsula. The wintering sites were distributed within the Philippines, Borneo and the Malay Archipelago. During autumn, migration of the birds had few long-term stopover sites, instead, sometimes decidedly slowing their migration rate while proceeding in a consistent direction. During spring migration, the honey-buzzards penetrated into southern China, moving north to the base of the Korean Peninsula. The birds then went south through the Korean Peninsula to reach Japan. Before travelling to China, all spring migrants stopped for several weeks in south-east Asia. The slow rate of travel in the autumn suggests that migrants were foraging and replenishing their energy reserves. Instead of a migration strategy that uses only a few long-term stopover sites, honey-buzzards may adopt a strategy based on a number of short-term stay sites.     

Variation in climate warming along the migration route uncouples arrival and breeding dates

Migratory species are of special concern in the face of global climate change, since they may be affected by changes in the wintering area, along the migration route and at the breeding grounds. Here we show that migration and breeding times of a trans‐Saharan migrant, the pied flycatcher Ficedula hypoleuca, closely follow local temperatures along the migration route and at the breeding grounds. Because of differences in long‐term temperature trends of short within‐spring periods, the migration period and the time interval between migration and breeding dates of this species have extended in SW Finland. Temperatures in northern parts of Central Europe have risen at the time when the first migrants arrive there, facilitating their migration northward. Temperatures later in the spring have not changed, and the last individuals arrive at the same time as before. The timing of breeding has not advanced because temperatures at the breeding site after arrival have not changed. These results show that the pied flycatchers can speed up their migration in response to rising temperatures along the migration route. Our results strongly indicate that the effects of climate change have to be studied at the appropriate time and geographical scales for each species and population concerned.     

The winter migration of Adelie penguins breeding in the Ross Sea sector of Antarctica

Satellite telemetry was used to monitor the migratory movements of a single Adelie penguin (Pygoscelis adeliae) from Cape Hallett (72.31°S, 170.21°E) following the 1997/1998 breeding season. Locations were obtained using the ARGOS satellite system and compared with the migratory paths taken by two penguins from the Northern Colony at Cape Bird, Ross Island (77.22°S, 166.48°E) following the 1990/1991 breeding season. Although the sample sizes are small, if representative they would indicate that: (1) Adelie penguins breeding in the Ross Sea follow a common migratory path, (2) Adelie penguins breeding in the Ross Sea may travel to a common over-winter feeding ground west and north of the Balleny Islands, and (3) Adelie penguins breeding at 77°S on Ross Island travel nearly twice the distance during their over-winter migration as do those penguins breeding at Cape Hallett and colonies further north. While the Cape Hallett penguin was tracked successfully for 172 days, a record for Adelie penguins, the problem of long-term attachment of transmitters to penguins remains.     

Associations between body composition and helminths of lesser snow geese during winter and spring migration

Costs of parasitism are predicted to be higher with greater parasite intensities and higher inter-parasite competition (diversity). We tested whether greater helminth intensities and diversity were associated with poorer body composition (whole-body fat, protein, mineral and true body mass) in lesser snow geese, Chen caerulescens caerulescens. As part of a larger study on nutritional ecology, 828 wintering or migrating geese were shot between January and May 1983 in 27 different date-locations (samples) during their northward migration through mid-continental North America. A large proportion of overall variation in body composition and parasite communities was among samples, so we analyzed data within each of the 27 samples, controlling for structural body size (the first principal component of 10 body size measurements), sex and the age of geese. There was no compelling evidence that cestodes, trematodes or helminth diversity were associated with variation in body composition but nematodes had several negative associations with fat reserves. However, negative associations between fat reserves and nematodes occurred most often in geese collected between March and May when nematode prevalences and intensities were relatively low. This suggests several possibilities: that the most common nematodes (Heterakis dispar and Trichostrongylus tenuis) were more virulent at this time, that infected individuals had been chronically infected and suffered cumulative nutrient deficits that lasted until late in the spring migration, or that geese became more vulnerable to the effects of parasites at this time of year, possibly because they redirected resources away from immunity toward fat storage in preparation for reproduction.     

Biometrics,possible breeding origins and migration routes of South African Grey Plovers,Pluvialis squatarola

Data on 355 Grey Plovers, Pluvialis squatarola, ringed in South Africa in 1971–1997 were analysed. Biometrics could not identify well-defined origins in the Siberian breeding grounds, but suggested the presence of birds from east of the Gydan Peninsula. Comparisons with populations spending the non-breeding period elsewhere did not allow a clear definition of the flyways used, although ringing recoveries indicated a migration route crossing the Mediterranean/Black Sea region during both southward and northward movements. First-year birds were on average smaller than adults. Bill length increased during the first year, reaching adult length by June. First-year wing length decreased by 4% before the outermost primary was shed, adult wing length did not change with season.     

Breeding dispersal directions in the white stork (Ciconia ciconia) are affected by spring migration routes

We examined breeding dispersal directions in the white stork (Ciconia ciconia), a migratory bird breeding in large parts of Europe. We asked whether and how the direction of the major spring/autumn migration route (from south-east to north-west and vice versa) affects breeding dispersal directions. Breeding dispersal directions were clearly nonrandomly distributed and were influenced by the major spring migration direction, leading to a bias toward south-eastward and north-westward breeding dispersal.     

Variation of sterility and fertility in Utricularia australis f. australis in Hokkaido, northern Japan

Seed-production ability was studied in Utricularia australis R. Br. f. australis Komiya and Shibata through field observation, pollination experiment, pollen culture, and isozyme analysis for populations in various regions of Hokkaido, northern Japan. Utricularia australis f. australis has previously been postulated to be sterile in Japan, however, in the present study, fertile populations were found in eastern Hokkaido. Bisexual sterility and male sterility were suspected to be present in populations in the western part of Hokkaido. There was also a strain that seemed to produce no seed because of intra-clonal inbreeding depression or self-incompatibility. Isozyme analysis of three enzyme systems indicated a uniformity of multienzymatic phenotype (MEP) in each population or region. The MEP grouping of populations corresponded to the type of sterility and fertility revealed by pollination and pollen culture experiments. These experiments suggested that each regional strain had its own sterility or fertility type.     

Individuality in bird migration: routes and timing

The exploration of animal migration has entered a new era with individual-based tracking during multiple years. Here, we investigated repeated migratory journeys of a long-distance migrating bird, the marsh harrier Circus aeruginosus, in order to analyse the variation within and between individuals with respect to routes and timing. We found that there was a stronger individual repeatability in time than in space. Thus, the annual timing of migration varied much less between repeated journeys of the same individual than between different individuals, while there was considerable variation in the routes of the same individual on repeated journeys. The overall contrast in repeatability between time and space was unexpected and may be owing to strong endogenous control of timing, while short-term variation in environmental conditions (weather and habitat) might promote route flexibility. The individual variation in migration routes indicates that the birds navigate mainly by other means than detailed route recapitulation based on landmark recognition.     

Variation in egg quality and composition in the Mallard Anas platyrhynchos

Three complete Mallard Anas platyrhyncos clutches from a single site were analysed to determine intra-and inter-clutch variation within and among clutches in quality and composition. Variation between clutches was significantly greater than within clutches in all the examined criteria of egg composition, except for the percentage of water found in yolk. In addition the weight of the yolk was proportional to fresh egg weight. When log transformations were used, the slope of the regression was greater than unity, indicating the proportional contribution of yolk increased respectively with egg weight. A total of 26 eggs from four locations was analysed and no regional variation in egg composition was found but there was variation in egg quality (lipid and protein). The factors affecting the production of a 'good egg' and what in fact is a 'good egg' are discussed. In the Mallard, as in other Anseriformes, it appears that larger eggs may confer a survival advantage to the subsequent young.     

Local factors affecting winter habitat use of non-native rainbow trout in a boreal stream in northern Japan

Ichthyological Research - Despite its potential use for population control, the winter ecology of nonnative fishes is still poorly understood due to the difficulty of conducting field surveys. In...