Distinct habitat use strategies of sympatric rorqual whales within a fjord system

Keen, Eric M.; Wray, Janie; Pilkington, James F.; Thompson, Kim-Ly; Picard, Chris R.

doi:10.1016/j.marenvres.2018.06.014

Cited by 15 publications

(24 citation statements)

References 41 publications

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“…[4766]-28 fjords of British Columbia, Canada, were associated with low surface salinity and strong stratification (Keen, Wray, Pilkington, Thompson, & Picard, 2018). However, outside the fjords in British Columbia a similar pattern to that detected in this study is seen with salinity only associated with whale foraging in shallow waters (Gregr & Trites, 2001).…”

Section: Salinitysupporting

confidence: 79%

A Southern Ocean archipelago enhances feeding opportunities for a krill predator

Harrison

Goetz

Cox

et al. 2019

Marine Mammal Science

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Section: Salinitysupporting

confidence: 79%

A Southern Ocean archipelago enhances feeding opportunities for a krill predator

Harrison

Goetz

Cox

et al. 2019

Marine Mammal Science

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“…). A preliminary study in 2013, with a 500‐m backscatter range, did not detect any euphausiid‐like backscatter below 250 m (Keen ). Details of echosounder data collection and processing are provided in Keen et al.…”

Section: Methodsmentioning

confidence: 99%

“…), nested within the Great Bear Rainforest, a segment of the largest temperate coastal rainforest in the world (Thompson ). Marine habitat in the KFS is shaped by processes typical of fjord oceanography: estuarine circulation (forced by freshwater discharge), wind forcing (e.g., katabatic outflows), and dramatic tides (reviewed in Keen ).…”

Section: Methodsmentioning

confidence: 99%

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Aggregative and feeding thresholds of sympatric rorqual whales within a fjord system

Keen

2017

Ecosphere

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Citation: Keen, E. M. 2017. Aggregative and feeding thresholds of sympatric rorqual whales within a fjord system. Ecosphere 8(3):e01702. 10. 1002/ecs2.1702 Abstract. Rorqual whales (f. Balaenopteridae) supposedly respond to increases in prey supply according to both aggregative and feeding thresholds. With the former, they gather in areas above a minimum prey density set by their basal metabolic needs. With the latter, feeding occurs only above a prey density set by the energetic cost of lunge feeding. To compare prey preferences and the two threshold types in sympatric rorquals, I conducted systematic transect surveys and behavioral observations of humpback whales (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) in a British Columbia fjord system. While multiple prey features were found to influence whale aggregation and feeding, both threshold types were observed in each species' response to krill volume. Humpback response to prey features was less predictable and influenced by more factors than that of fin whales, which appeared to be exclusively euphausivorous and interested in the deepest high-volume krill patches within the deepest channels. Compared with fin whales, humpbacks found higher-volume krill patches and had higher aggregative thresholds, but had lower feeding thresholds. Findings aligned overall with the expectations that aggregative behavior is responsive to local prey supply, while feeding thresholds are governed by less mutable energetic constraints imposed by body size and feeding mode. Both aggregative and feeding threshold responses appeared to be a function of local conditions: As total krill-like backscatter increased, feeding thresholds stabilized (became more nonlinear and more nonrandom), while aggregative thresholds destabilized. All results emphasized the importance of incorporating observations of feeding effort in studies of prey preference and habitat use.

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“…1). Swimming distance describes the shortest possible route around islands between two points within the KFS (R package 'bangarang', [83]; this metric has been used in Keen et al [84] and Keen et al [85]). Small values for average fjord position correspond to whales that are commonly seen deep within the fjord system, whereas large values correspond to whales commonly seen in the outer channels near the continental shelf.…”

Section: Data Preparationmentioning

confidence: 99%

Social survival: humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

Wray¹,

Keen

O’Mahony

2020

Preprint

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Animal culture and social bonds are relevant to wildlife conservation because they influence patterns of geography, behavior, and strategies of survival. Numerous examples of socially-driven habitat partitioning and ecological-niche specialization can be found among vertebrates, including toothed whales. But such social-ecological dynamics, described here as ‘social niche partitioning’, are not known among baleen whales, whose societies -- particularly on foraging grounds -- are largely perceived as unstructured and incidental to matters of habitat use and conservation. However, through 16 years of behavioral and photo-identification observations of humpback whales (Megaptera novaeangliae) feeding within a fjord system in British Columbia, Canada, we have documented long-term pair bonds (lasting up to 12 years) as well as a complex societal structure, which corresponds closely to persistent patterns in feeding strategy, long-term site fidelity (extended seasonal occupancy and annual rate of return up to 75%), specific geographic preferences within the fjord system, and other forms of habitat use. Randomization tests of network congruency and clustering algorithms were used to test for overlap in patterns of social structure and habitat use, which confirmed the occurrence of social niche partitioning on the feeding grounds of this baleen whale. In addition, we document the extensive practice of group bubble net feeding in Pacific Canada. This coordinated feeding behavior was found to strongly mediate the social structure and habitat use within this humpback whale society. Additionally, during our 2004 – 2019 study, we observed a shift in social network structure in 2010 – 2012, which corresponded with environmental and demographic shifts including a sudden decline in the population’s calving rate. Our findings indicate that the social lives of humpback whales, and perhaps baleen whales generally, are more complex than previously supposed and should be a primary consideration in the assessment of potential impacts to important habitat.

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Distinct habitat use strategies of sympatric rorqual whales within a fjord system

Cited by 15 publications

References 41 publications

A Southern Ocean archipelago enhances feeding opportunities for a krill predator

A Southern Ocean archipelago enhances feeding opportunities for a krill predator

Aggregative and feeding thresholds of sympatric rorqual whales within a fjord system

Social survival: humpback whales (Megaptera novaeangliae) use social structure to partition ecological niches within proposed critical habitat

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