| Summary: | Humpback whales arrive to Colombian Pacific Ocean for breeding and rearing its calves; from 20 m high shore platforms, 115 groups were observed during 44.8 effective sample hours during the 2006 breeding season. Using the group-follow method and incidental sampling were evaluated the group structure, displacement patterns and surface behavior frequency (flippering, lobtailing, breaching, arching, surface turns and spy hoping). Results showed that 26.1% of the groups were formed mainly by one adult, following by groups formed by two adults (22.6%), female, its calf and one escort (21.7%), female and its calf (20%), female, its calf and more than one escort (7%), by three adults (1.7%), and by two females, two calves and two escorts (0.9%). Whales swam with an average speed of 7.3 km/h, and there were not significant differences in speed between the groups (H6=4.9, p=0.5). 69.6% of the whales swam north, 27.8% south, and the rest did not show a clear course; the average time diving was about 4.9 min. Surface behaviors were short, it occurred during 2.5% of the registered time, and the group formed by two adults was the most active (H6=19.9, p=0.02). Humpback whales passing by Bahia Solano, in July and August, principally alone and in groups with one calf, course north, with a moderate speed, with diving intervals about 5 minutes; and that the aerial behavior is not frequent. Las ballenas jorobadas llegan al océano Pacífico colombiano para la reproducción y la crianza; desde plataformas marinas de 20 m de altura, se observaron 115 grupos durante 44.8 horas de muestreos efectivos, durante la temporada de cría 2006. Utilizando el método de muestreo de seguimiento grupal- incidental, se evaluó la estructura grupal, los patrones de desplazamiento y la frecuencia de la conduc- ta sobre la superficie marina (aleteos, coletazos, exhalaciones, arqueos, saltos y espionajes). Los resultados mostraron que el 26.1% de los grupos estuvieron formados principalmente por un adulto, seguidos por grupos de dos adultos (22.6%), ...
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