No abstract

This study examined the use of urban and rural habitats by woodland bird species in winter in the vicinity of Athens, Georgia, USA. Population densities of most species on urban sites were either comparable to or greater than those on rural sites, and most species were flexible in their habitat use patterns. On urban sites, only the golden‐crowned kinglet consistently avoided vegetation that had been opened either by felling trees or clearing undergrowth. Nuthatches and chickadees flocked together less often at urban than at rural sites.

Tropical cyclone best track data in the Atlantic from 1950 to 2009 were analysed to determine whether tendency to rapidly intensify varied among geographical sub-regions, 15-d intervals within the season, or when the storm displayed different characteristics of age, strength, or time of day. Wind speed increases of 7.7 m s −1 (15 kt)/24 h and 15.4 m s −1 (30 kt)/24 h were used to define intensification events; these ended up showing similar patterns.Cyclones were most likely to begin intensifying in the Gulf of Mexico and least likely in the northeast Atlantic. Likelihood did not peak during the early September peak of cyclone occurrence; cyclones were most likely to begin intensification on their initial observations, and at that time were most likely to do so if their wind speed was 18.0 m s −1 (35 kt). Older cyclones showed peaks of intensification onset at 15.4 m s −1 (30 kt) and 36.0 m s −1 (70 kt). Intensification rarely began immediately after wind speed had declined over the previous 6 h; when winds had been unchanged, intensification most often occurred when central pressure had dropped by 1 or 2 mb. Intensification onset was more likely when winds were slower than average relative to the storm's central pressure. In three time zones, onset of intensification (7.7 m s −1 [15 kt]/24 h) appeared to be most likely shortly after midnight local time, and least likely shortly before midnight. Cyclogenesis was least frequent around local midnight, and most likely in the diurnal morning hours.

No abstract

Landfalling tropical cyclones have been extensively researched, especially their degradation upon coming ashore and the hazardous weather they create along coastlines and farther inland. Many of the factors that weaken storms over land could begin to act when they are still at sea, yet prelandfall intensity change remains poorly documented. This study examined the consistency of prelandfall changes in tropical cyclone intensity throughout the North Atlantic Ocean from 1950 to present. On average, cyclones intensified by 3 m s 21 less in their final 12 h before landfall than in the 12 h preceding those, on both mainland shores and in the Greater Antilles, while smaller islands showed no such change. Contributions of increasing storm age and poleward movement to this reduction were negligible. Two possible contributing factors to declining intensification before landfall were examined. The presence of a spring-neap tidal pattern of ;2 m s 21 in the prelandfall decline is consistent with tidal mixing influencing ocean temperature on the continental shelf. The tendency for the decline to be greater at night suggested the possible influence of solar heating on tropical cyclones near shore.