Abstract
Abstract: The population of humpback whales from breeding stock A is increasing, and little is known about the routes used by humpbacks that move north of the main calving area of Brazil, the Abrolhos Bank. The aim of this study was to describe the movements of humpback whales in a reoccupation wintering area (Serra Grande, Bahia state, Brazil) based on land-based surveys to test if movement patterns change during the season and between years, due to group composition, behavioral state, and distance to the coast. The mean leg speed of the groups sighted was 6.88 (±2.92) km/h, and leg speed was positively correlated with distance to the coast. There was an increase in leg speed and distance to the coast with increasing number of escorts in the groups with calves. The mean linearity value for group trajectory was 0.81 (±0.19) and the mean reorientation rate was 25.72 (±19.09) º/min. We observed a predominance of trajectories heading south throughout the study. Groups exhibiting more erratic movements early in the season, and groups moving south showed more linear trajectories than groups moving north, indicating the beginning of their migration back to the feeding grounds. Energy conserving strategies and social context affect the movements of humpback whales in Serra Grande, resulting in the observed patterns of the reoccupation of available and suitable habitat north of Abrolhos. Thereby, special attention should be given managing activities with the potential to disturb or displace whales using the region to calve and breed.
Highlights
Humpback whales (Megaptera novaeangliae Borowski, 1781) are migratory except for the Arabian Sea population (Mikhalev 1997), reproducing in warmer waters (Rasmussen et al 2007) of low latitudes during the winter and feeding in cooler waters during the summer (Dawbin 1966; Clapham 2000)
Dalla Rosa et al (2008) suggested that variation in speed of humpback whales may occur due to individual behavioral patterns than to common patterns that differ among the areas or life stages
This study showed that the movement of the groups from breeding stock A (BSA) that were observed in Serra Grande, representing similar geomorphological characteristics with the Brazilian coast northern of Abrolhos, are influenced by the orientation of the coast which guides most trajectories parallel to it
Summary
Humpback whales (Megaptera novaeangliae Borowski, 1781) are migratory except for the Arabian Sea population (Mikhalev 1997), reproducing in warmer waters (Rasmussen et al 2007) of low latitudes during the winter and feeding in cooler waters during the summer (Dawbin 1966; Clapham 2000). Humpbacks have different movement patterns depending on their location and the phase of their life cycle (breeding, migrating or feeding). They tend to move at a lower speed in both feeding and breeding areas than in migratory corridors, even for mother and calf groups (Lagerquist et al 2008; Kennedy et al 2014), and more erratically in feeding areas than in migratory corridors (Zerbini et al 2006). This may be related to search/encounter patterns when mating or feeding. Coastline orientation seems to be a key factor that influences the trajectories of humpback whales at least for same populations (Dawbin 1956; Findlay et al 2011), where whales move following its orientation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
