The location performance of a global positioning system (GPS) collar was assessed for different habitats and geographical areas. We tested the effects of habitat features, antenna position, movement, and fix interval on location performance around Mount Fuji, a single peak surrounded by wide and flat areas. Fix rate decreased from 100% in open flat areas to 53% under sloped dense canopy. The openness (the actual available sky, i.e., the percentage of a radio collar exposed to the sky when part of the collar is blocked due to terrain and vegetation) and canopy closure affected location accuracy and most other performance parameters. All nine habitat features except for available sky (theoretical, due to terrain) influenced location time. Any combination of obstructions between collar and satellite decreased the available number of satellites, the fix rate, increased the location time, and resulted in poorer location (higher DOP, lower 3-D proportion, or greater location error). A horizontal antenna yielded poorer location performance than a vertical one in the forest but not in the open area.Location performance always decreased when moving in forest rather than in open areas. Location performance changed with fix interval. Sixty-minute intervals resulted in a longer location time and a lower DOP than 10-min intervals. Vegetation affected location performance more than topography in the Mount Fuji area. Factors that cause a longer location time will shorten battery life. We suggest that location frequency and duration employed for field research should be decided by considering the aim of the study and the effects of habitat features, animal activity, and fix interval on GPS performance and battery longevity. The strengthened effect of canopy closure during windy weather should be considered for forest-dwelling animals.

In recent times, tsunamis and typhoons have threatened Japan's coastal lands with increased flooding and salinity. Using satellite data, we monitored the effect of increased salinity on vegetation health in the coastal area of southern Japan, which was affected by flooding following Typhoon 9918 in 1999. An index of plant activity called the Normalized Difference Vegetation Index (NDVI) was evaluated before and after the typhoon, and the change in NDVI was computed as a comparison measure. The results were then correlated with electric conductivity, which is a measure of soil salinity. A strong negative correlation was found between NDVI ratio and salt concentration (r = -0.7731, n = 50, p \ 0.0001), indicating that the reduced NDVI values were attributable to increased salinity from the flooding. These results not only provide useful insight into a rapid method of assessing large-scale flood impacts using satellite data, but also validate the monitoring of NDVI as an indicator of salinity damage to vegetation. To summarise, by understanding the changes in vegetation health following natural disasters such as flooding (as revealed by NDVI), we can potentially develop improved management strategies.