Habitat edges are considered to have an important role in determining the abundance of deer in forest landscapes, but to our knowledge there are few lines of evidence indicating that forest edge enhances the vital rate of deer. We examined pregnancy of female sika deer in Boso peninsula, central Japan, and explored how forest edges, food availability in forests, and local population density influence the pregnancy rate of sika deer. Local deer density was estimated by the number of fecal pellets, and food availability in forests was estimated by combining GIS data of vegetation distribution and the relationship between vegetation biomass and local deer density. Forest edge length was also determined by GIS data. Model selection was performed with multiple logistic regression analyses using the AIC to find the best model for accounting for the observed variation in pregnancy rates of the deer. Multiple logistic regression analysis showed that the length of forest edge had a positive effect on the pregnancy rate of females, whereas food availability in forests and local deer density had little effect. This forest edge effect was detected in a 100-200-m radius from deer captured locations, indicating that deer pregnancy is primarily determined by habitat quality within a 10-ha area. This result was confirmed by tracking females with GPS telemetry, which found that the core areas of the home range were less than 12 ha. The positive effect of edges and the lack of density dependence could be a result of high plant productivity in open environments that produces forages not depleted by high deer densities. Our results support the view that land management is the cause of the current problem of deer overabundance.

One important challenge of spatial ecology is to generate models linking individual behavior to population‐level phenomena. Although animals often face great uncertainty regarding foraging patch quality, earlier models explaining the aggregation of animals have rarely specified how stable outcomes are achieved through individual decisions, especially under realistic assumptions for incompletely informed foragers. We developed a new foraging model that assumed a realistic decision‐making rule for incompletely informed group foragers, and we tested its performance against existing models with different assumptions by comparing how well they reproduce the patterns observed in foraging White‐fronted Geese (Anser albifrons). The assumptions in each of the four compared models were: (1) incompletely informed foraging with benefits of group foraging, which uses the expected gain rates for making decisions on diet choice, patch departure, and flock joining; (2) incompletely informed foraging without benefits of group foraging, which uses the expected gain rates to determine the timing of patch departure but selects a new patch randomly; (3) completely informed foraging without benefits of group foraging, which simply selects the most profitable patches; and (4) completely informed foraging with benefits of group foraging, which selects the most profitable patches, considering benefits from the presence of conspecifics. The model that assumed incompletely informed foragers with benefits of group foraging was best in agreement with the observed patterns in all of the five spatial distribution and fat deposition parameters. The models that assumed no benefits of group foraging could not reproduce the observed seasonal variation in flock sizes, whereas the models with completely informed foragers overestimated the flock size as well as usage by the geese of alternative food and the fields near the roost. These results supported the idea that the geese can be assumed to use the expected gain rates for decision‐making on diet choice, patch departure, and flock joining. Further, the incompletely informed foragers showed greater disparity in foraging performance among individuals. We discuss the necessity of assuming, when appropriate, that foragers have incomplete information on patch quality in models explaining spatial distribution and foraging success. We also make some references to the applicability of the presented model in other studies.

Satellite‐tracking of 15 White‐naped Cranes (Grus vipio) from their Japanese wintering grounds through the Korean Peninsula shows that there are four important regions for conserving migrant cranes: the Three Rivers Plain, the People’s Republic of China; Lake Khanka, Russia; Kumya, North Korea; and—most importantly—the demilitarized zone of the Korean Peninsula. Two sites along the Korean demilitarized zone, Panmunch’om and Ch’olwon, were the most heavily used stopover sites, and they present complex international conservation challenges. Cranes stopped at these sites for up to 87.1% of their total migration time; cranes migrating to Zhalong Nature Reserve, China, made it their only lengthy stop. We report the migration routes and the importance of the identified stopover sites, and we outline conservation issues at those sites.

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.

We investigated the application of satellite tracking to the conservation of cranes and other waterbirds and the necessity of international cooperation in the conservation of migratory species. Using satellite tracking, we followed 11 White-naped Cranes (Grus vipio) on migration from their breeding grounds in eastern Russia to their wintering grounds in China and Japan. From 1991 to 1993, we captured cranes with the aid of helicopters and attached satellite transmitters (platform transmitter terminals) to captured birds via a harness system. We tracked cranes for 156 days on average, across 2558 km, and obtained an average of 339 locations per crane. Cranes migrated over 8-90 days. During migration, birds spent 1-30 days at 4-12 rest sites. Cranes wintered at two main sites: Poyang Lake, China, and Izumi, Japan. All seven cranes migrating to the Poyang Lake area rested at the Yellow River delta-Bohai Bay, China, and all three traveling to Izumi rested in the Demilitarized Zone on the Korean Peninsula. Other important rest sites were marshes around the Wulagai River, Huainan, Hu-Lun Lake, Linyi, Tangshan, the Three Rivers (Sanjiang) Plain, Tianjin, and the Xar Moron River, all in China, and Lake Khanka-Xinghai at the border of China and Russia. The habitats resting cranes used most frequently were plains, including upland areas, marshes, and rivers. Although nature reserves exist at the two main wintering sites of Poyang Lake and Izumi, rest sites used by cranes were poorly protected. Even when areas used by cranes for resting or wintering were included in nature reserves, reserves were threatened by human encroachment and development. To ensure that cranes can continue to migrate successfully, it is crucial that the establishment of reserves continues at important rest areas and that the areas covered by reserves at wintering sites be extended to include more of the areas utilized by cranes. Also, development and human disturbance should be minimized in reserve areas. Because long-distance migrant birds, including cranes, range over such large areas, conservation of these organisms and their habitats necessitates multinational communication and cooperation. Resumen: Investigamos la aplicación del rastreo por satélite a la conservación de grullas y otras aves acuáticas y la necesidad de cooperación internacional en la conservación de especies migratorias. Utilizando el rastreo por satélite, seguimos la migración de 11 grullas de nuca blanca (Grus vipio), desde susáreas de reproducción en Rusia oriental hasta suárea de hibernación en China y Japón. De 1991 a 1993 capturamos grullas con la ayuda de helicópteros y les colocamos transmisores de satélite (terminales de transmisor de plataforma) mediante un sistema de arnés. Rastreamos a las grullas por 156 días en promedio, a lo largo de 2558 km, y obtuvimos un promedio de 339 localidades por grulla. Las grullas migraron por 8-90 días. Durante la migración, las aves estuvieron de 1-30 días en 4-12 sitios de descanso. Las grullas invernaron en dos sitios principales: L...