Noriyuki M. Yamaguchi

Spring Migration Routes of Mallards (Anas platyrhynchos) that Winter in Japan, Determined from Satellite Telemetry

Abstract Wild birds, in particular waterfowl, are common reservoirs of low pathogenic avian influenza viruses, and infected individuals could spread the viruses during migrations. We used satellite telemetry to track the spring migration of the mallard ducks (Anas platyrhynchos) that winter in Japan. We studied their migration routes, distribution of stopover and breeding sites, and timing of migration movements. We tracked 23 mallards from four different wintering sites. Nine of the 23 mallards reached presumable breeding sites, where migration terminated. The migration routes of the birds greatly differed not only among the wintering sites but also within the same wintering site, although the general feature of the routes was shared among birds within the same wintering site. The mallards used several stopover sites, and they typically stayed for a long period (about one to four weeks) at a site between migration intervals of two to three days. Stopover sites were located in northeast Japan, the eastern coastline of South Korea and North Korea, and the interior of Far Eastern Russia. Mallards from three different wintering sites used a stopover area near the middle part of the Ussuri river in Russia. The terminal sites, which were presumably also breeding sites, were distributed widely over northeast Asia and Far Eastern Russia. These results suggest that mallards that winter in Japan originate from breeding areas widely distributed across eastern Asia. Mallards could potentially transmit avian influenza viruses between Japan and a broad region of northeastern Asia.

EXTREMELY LOW NESTING SUCCESS AND CHARACTERISTICS OF LIFE HISTORY TRAITS IN AN INSULAR POPULATION OF PARUS VARIUS NAMIYEI

Abstract Differing intensities of predation pressure can affect the evolution of life history traits in island and mainland populations. We found extremely low nesting success in an insular subspecies of the Varied Tit (Parus varius namiyei; Kozushima Island), and we compared certain life history traits among three subspecies of P. varius experiencing different predation pressures. The nesting success of P. v. namiyei was extremely low as a result of significant nest predation and nest abandonment; 83% of active nests failed due to snake predation. The proportion of depredated nests was significantly greater on Kozushima Island than on Miyakejima Island (P. v. owstoni) or on the mainland (P. v. varius). Of the three subspecies, P. v. namiyei had the longest incubation period, shortest nestling period, an intermediate clutch size, and a small brood size. There were no differences in the date of egg laying among the three populations. The short nestling period for P. v. namiyei may be an adaptive response, as the predation risk during the nestling period on Kozushima was extremely high.

The effects of atmospheric currents on the migratory behavior of soaring birds: a review

Abstract Atmospheric currents influence the choice of migratory routes and flight characteristics of birds as well as their decisions regarding migration onset and stopovers. Among long distance avian migrants, soaring birds are particularly dependent on wind and updrafts to help them complete their journeys. This review focuses on the behavioral adaptations of migratory soaring birds at various scales with regard to these atmospheric phenomena. Soaring landbirds and soaring seabirds have evolved morphological characteristics that make them specialists in soaring flight, thus enabling them to reduce the costs of migration significantly. We introduce the flight strategies of each group and discuss how migratory routes, flight characteristics, and onset and stopover decisions are all adjusted in relation to atmospheric conditions best suited for soaring. In addition, we discuss briefly how this strong dependence on atmospheric conditions makes soaring birds vulnerable to anthropogenic threats, such as wind energy development and climate change.

Raptor migration in an oceanic flyway: Wind and geography shape the migratory route of grey-faced buzzards in East Asia

Flapping flight is relatively costly for soaring birds such as raptors. To avoid costly flight, migrating raptors generally avoid flying over water. As a result, all but one of the global raptor migration flyways are largely over land. The East Asian oceanic flyway for raptors is the exception. Raptor species using this flyway migrate by island-hopping, flying over open ocean for distances of up to 300 km between islands. We used satellite telemetry data for grey-faced buzzards Butastur indicus, a species that dominates the southern part of the flyway, to investigate the geographical and atmospheric factors responsible for the suitability of this flyway for raptor migration. Using a combination of least-cost path analysis and a step selection function, we found that the occurrence of numerous islands and also suitable wind support along the oceanic flyway are responsible for route selection in grey-faced buzzards. These results confirm the role of islands, but also wind, in shaping the East Asian oceanic flyway of long-distance raptor migration.

Seasonal Movements of Japanese Murrelets Revealed by Geolocators

Abstract The Japanese Murrelet Synthliboramphus wumizusume is listed as a vulnerable species by IUCN, but little information is available on its movements during the non-breeding season. We tracked three murrelets during the non-breeding season using light-level geolocators in 2012–2014. Birds from Eboshijima in Kyushu and Koujima in Shikoku were each tracked for one year, and one bird from Birojima in Kyusyu was tracked for two years. All three moved northward in the Pacific Ocean off Shikoku and Honshu in the spring then to the Pacific and the Sea of Japan off Hokkaido and off Sakhalin. In the fall and early winter two movement patterns were observed: (1) southwestward along the coast of Primorskii, the Peoples Democratic Republic of Korea, and the Republic of Korea; (2) southwestward movement along the east and south coasts of Honshu and Shikoku. In winter, two stayed in the southwestern part of the Sea of Japan, while the third moved southward into the Pacific Ocean.

Climate change alters the optimal wind-dependent flight routes of an avian migrant

Migratory birds can be adversely affected by climate change as they encounter its geographically uneven impacts in various stages of their life cycle. While a wealth of research is devoted to the impacts of climate change on distribution range and phenology of migratory birds, the indirect effects of climate change on optimal migratory routes and flyways, through changes in air movements, are poorly understood. Here, we predict the influence of climate change on the migratory route of a long-distant migrant using an ensemble of correlative modelling approaches, and present and future atmospheric data obtained from a regional climate model. We show that changes in wind conditions by mid-century will result in a slight shift and reduction in the suitable areas for migration of the study species, the Oriental honey-buzzard, over a critical section of its autumn journey, followed by a complete loss of this section of the traditional route by late century. Our results highlight the need for investigating the consequences of climate change-induced disturbance in wind support for long-distance migratory birds, particularly species that depend on the wind to cross ecological barriers, and those that will be exposed to longer journeys due to future range shifts.

The effects of weather conditions on avian movements

The capacity for flight lends birds great mobility. They are capable of traveling great distances, sometimes at the global spatial scale, and use various resources over land, water, and in the air. During their journeys, their flight (or travel) direction, the timing of their departure, and their destinations may be affected by various weather conditions including rain, snow, horizontal wind direction and strength, and thermals. Birds also exhibit the capacity to make active use of such conditions for efficient, energy saving flight. To fully understand the spatiotemporal movement patterns of birds, it is essential to consider how weather conditions affect avian movements. Observing the movements of free-ranging birds has its limitations, thus in the past it has been challenging to obtain information on the spatio-temporal movements of subject species. However, recent advances in technology have allowed ornithologists to track birds with great accuracy by using animal-borne devices such as global positioning system data-loggers and Argos Platform Transmitter Terminals. Furthermore, various institutes now provide numerical and graphical weather data (sometimes for free). The time is ripe, therefore, for ornithologists to consider engaging in this area of study. Recent global climate change has been reported to alter atmospheric and weather conditions; in turn these changes will likely influence ongoing changes and/or affect the distribution and movement patterns of birds. From environmental and ecological perspectives, it is important to understand the current relationship between the effects of weather conditions and bird movements, allowing us to provide projections of the potential impacts of climate change on birds. The first paper, by Nourani et al., reviews the behavioral characteristics of migratory soaring birds at various spatial scales with regard to horizontal and vertical air movements. The authors discuss different aspects of the migratory behavior of soaring birds, addressing separately land birds and seabirds. In the second paper, Yamamoto et al. examine how wind conditions affected the foraging trip durations of tropical Brown Booby fledglings by direct observation of nest attendance and by monitoring their flight behavior at sea by means of attached video camera loggers. They found that the Brown Booby’s aerodynamic performance is impaired by strong wind conditions. The third paper by Matsumoto et al. examined the sex-related differences in foraging behavior of a sexually size-dimorphic seabird, Streaked Shearwaters, and the effect of a windy strait confining their foraging movement. Their results imply there may be a trade-off between the cost of traveling with unfavorable winds and the energy intake at the studied sea area. The forth paper, by Yamaguchi et al., describes how the movement patterns of Rough-legged Buzzards in winter and spring match the spatial distribution of snow cover. In the fifth paper, Manda et al. introduce user-friendly atmospheric data for ornithological studies. This review should be extremely helpful for ornithologists just beginning research into this subject. We hope that this special feature will stimulate future research in the field of avian movement ecology especially among Asian ornithologists.

Atmospheric Data for Ornithology: An Introduction

Abstract This paper introduces user-friendly atmospheric data, so-called objective analysis data, for ornithological studies. The data have been interpolated onto grid points distributed at a regular interval in space and time, and are suitable for analyzing using computer data analysis software. Data assimilation techniques, which are basically the application of optimization and control theories, are utilized for producing objective analysis data in order to reduce errors as much as possible and obtain the most reliable dataset. Some examples of objective analysis data are shown and their features are described. Some cautionary notes are also given in order to avoid misinterpretation of the data.

Migration Routes of Satellite-Tracked Rough-Legged Buzzards from Japan: The Relationship between Movement Patterns and Snow Cover

Abstract The Rough-legged Buzzard Buteo lagopus is a Holarctic species that breeds in the Arctic and subarctic regions and winters in a broad range from 40° to 55°N. In Japan, this species is typically a rare winter visitor, but in January 2008 there was an unprecedented influx and 350–400 individuals were observed in western and central Japan. Winter irruptions of this species are considered to be caused by low temperatures and increased snow cover. Here, we describe the distribution of snow cover in mainland Asia leading up to the irruption into Japan. We predicted that movement patterns during spring migration would also be influenced by snow cover. We satellite-tracked four Rough-legged Buzzards from Japan, to show their spring migration routes, and examined the relationship between their spring movement patterns and changes in snow cover along their route. There were two spring migration routes from Japan, which varied with wintering sites. One route led up to the Amur River basin bordering China and Russia. The other extended northwards, reaching the lowlands of the western Chukotka Autonomous Okrug in North-eastern Russia. The bird following the latter route was tracked for two consecutive years and was found using the same summering site in 2009. Shortly before the irruptive movements into Japan, most of north-eastern China and eastern Russia were covered with snow, suggesting that unusually severe weather conditions caused the irruptive movements. The northward movements of one bird tracked to Russia generally matched the northward progression of snowmelt.

Experimental evidence of local variation in the colour preferences of Great Bowerbirds for bower decorations

Abstract Previous observational studies near Darwin, Northern Territory, revealed that males of a population of the western subspecies of the Great Bowerbird (Ptilonorhynchus nuchalis nuchalis) gathered only green objects as coloured decorations for their bowers. To test whether collection of certain coloured objects by Bowerbirds was caused by the skew of availability of such colours in the environment, we conducted experiments in which glasses of various colours were placed in or near bowers. We supplied shards of coloured glass of five colours (Brown, Yellow-Green, Green, Dark Olive-Green and Dark Blue) and painted glass of six colours (Red, Yellow, Light Green, Deep Green, Light Blue and Blue). Both Green and Deep Green were favoured, whereas other colours were ignored or disfavoured, especially Red and Yellow. Males in our population showed a narrow range of colour preferences even when a wide choice of colours was available, which differs from findings for the eastern subspecies (P. n. orientalis), in which red and purple were favoured. Green objects were placed beside the avenue entrance, probably for ready access when displaying to females in the avenue. We suggest that the green was preferred because it contrasts with the lilac nuchal crest displayed to females during courtship.