Distribution and behaviour of humpback whale mother–calf pairs during the breeding season off Ecuador

Abstract

Data on distribution and behaviour of mother-calf pairs of humpback whales Megaptera novaeangliae obtained during the breeding season (June to October) off Ecuador were analysed. The study was carried out between 2001 and 2009 aboard whale-watching boats. A total of 187 groups containing mother-calf pairs were recorded: 124 pairs alone (MC), 44 with an escort whale (MCE) and 18 with 2 or more whales (MC + n). Five environmental variables were used to assess mother-calf distribution with a principal component analysis (PCA). Two variables, depth and time of day, were sufficient to explain heterogeneity. Average depths increased significantly with group size from MC to MC + n groups (p < 0.001), showing that mother-calf social condition would be a function of the depth at which they moved. MC groups were distributed in shallower waters during afternoon hours (p = 0.035), indicating a preference for shelter areas when sea conditions worsened. The proportion of the 3 female-calf group classes remained fairly constant during the season. In 2 MCE groups, the same escort accompanied the pair after 1 and 4 d, indicating some level of stability and/or guarding behaviour. Twenty resightings of 14 different mother-calf groups were recorded, 90% of resightings occurred within 10 d, showing low site fidelity. In coastal waters, a lower proportion of mother-calf pairs was associated with competitive groups than in other breeding areas located in oceanic archipelagos. This is probably because whales breeding in continental shores do not have to enter oceanic waters when moving between sites within the breeding area. Coastal distribution exposes mother-calf pairs to a greater extent than other age classes to anthropogenic activities in coastal waters, which must be taken into account when considering coastal management.

Identification of humpback whale breeding and calving habitat in the Great Barrier Reef

“…It is important to note, however, that it was not possible to separately model mating and calving areas; therefore, the depth ranges presented represent wintering habitat in general for humpback whales during the breeding season. If there were proportionally fewer groups containing a calf in the sighting data, then it is possible that the model has underestimated the use of shallower waters, considering that females with calves prefer shallow waters (Craig & Herman 2000, Ersts & Rosenbaum 2003, Félix & Botero-Acosta 2011.…”

“…Depending on the social organization and reproductive status of whales, there also appears to be differential utilisation of habitat (Craig & Herman 2000, Ersts & Rosenbaum 2003. Specifically, females with calves show strong preference for areas of shallow, sheltered water close to the coastline (Ersts & Rosenbaum 2003, Félix & Botero-Acosta 2011. It is possible that factors such as water temperature influence the distribution of humpback whales at a broad scale, whereas the availability of suitable repro ductive habitat can influence it at a local scale (Rasmussen et al 2007).…”

Movements and Timing of Humpback Whales (Megaptera novaeangliae) Within the Breeding Region of the Eastern South Pacific

“…This change to a coastal distribution is more evident in females with calves (Félix & Botero-Acosta, 2011;Guidino et al, 2014), a behavior that is maintained by migrating females after leaving the breeding area (Félix & Guzmán, 2014). Recently generated information on movements of whales that were satellite-tagged in Panama and Ecuador supports stratification in this population at breeding grounds (Guzmán & Félix, 2017) as well as the low number of matches in a large sample as in our study.…”

“…Recently generated information on movements of whales that were satellite-tagged in Panama and Ecuador supports stratification in this population at breeding grounds (Guzmán & Félix, 2017) as well as the low number of matches in a large sample as in our study. We are aware that migration is a complex process with different timing and overlapping stages (Dawbin, 1966;Craig et al, 2003), and spatial segregation according to the whale's age/class (Félix & Haase, 2005;Félix & Botero-Acosta, 2011;Rasmussen et al, 2012;Guidino et al, 2014), which increases uncertainty and precludes reaching definitive conclusions from the available data. In the same line, we suggest caution with between-years matching results.…”

Spatial Distribution and Habitat Use Patterns of Humpback Whales in Okinawa, Japan

“…Mating activities and aggression between male and female humpbacks tend to occur in deeper offshore waters (Smultea 1994;Ersts and Rosenbaum 2003;Felix and Botero-Acosta 2011). The singing behavior of male humpback whales is considered to be a part of the male's mating display and intrasexual competition among males (Winn et al 1973;Winn and Winn 1978;Glockner 1983).…”