Behavioral responses of humpback whales to biopsy sampling on a breeding ground: the influence of age‐class, reproductive status, social context, and repeated sampling

AbstractSocial context is critical in shaping behavioral responses to stimuli and can alter an individual’s behavioral type, which would otherwise be fixed in social isolation. For monogamous biparental vertebrates, social context is critical as interactions are frequent and consistent, involving high interindividual dependence and cooperation that can lead to large fitness impacts. We demonstrate that in the strictly monogamous and highly territorial California mouse, individuals alter approach response to an aggressive conspecific playback stimulus, barks, to become more similar to their partner during early bonding prior to pup birth; an effect distinct from assortative mating. Additionally, sustained vocalizations, an affiliative ultrasonic vocalization when used between pair members, correlate with increased behavioral convergence following pair formation suggesting a role for vocal communication in emergent pair behavior. We identified the neuropeptide oxytocin as sufficient to promote behavioral convergence in approach behavior of paired individuals who differed in their initial behavioral type. Social context, specifically pair-bonding, appears vital for behavioral responses to aggressive signals. While non-bonded animals maintained stable responses, pair-bonding led to an emergent property: convergence in behavioral responses. This convergence can be driven by oxytocin revealing a significant expansion in oxytocin’s effects on behavioral coordination.

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First Description of Migratory Behavior of Humpback Whales From an Antarctic Feeding Ground to a Tropical Breeding Ground

10.21203/rs.3.rs-224086/v1 ◽

2021 ◽

Author(s):

Michelle Modest ◽

Ladd Irvine ◽

Virginia Andrews-Goff ◽

William Gough ◽

David Johnston ◽

...

Keyword(s):

Linear Regression ◽

Feeding Behavior ◽

State Space ◽

Humpback Whale ◽

Humpback Whales ◽

Migratory Behavior ◽

Migration Speed ◽

Breeding Ground ◽

Feeding Ground ◽

Departure Date

Abstract Background: Despite exhibiting one of the longest migrations in the world, half of the humpback whale migratory cycle has remained unexamined; until this point, no study has provided a continuous description of humpback whale migratory behavior from a feeding ground to a breeding ground. We present new information on the satellite derived offshore migratory movements of 16 humpback whales from Antarctic feeding grounds to South American breeding grounds. Satellite locations were used to demonstrate migratory corridors, while the impact of departure date on migration speed was assessed using a linear regression, and a Bayesian hierarchical state-space animal movement model was utilized to investigate the presence of feeding behavior en route. Results: 35,642 Argos locations from 16 tagged whales from 2012-2017 were collected. The 16 whales were tracked for an average of 38.5 days of migration (range 10-151 days). The length of individually derived tracks ranged from 645–6,381 km. Humpbacks were widely dispersed geographically during the initial and middle stages of their migration but convened in two bottleneck regions near the southernmost point of Chile as well as Peru’s Illescas Peninsula. The state space model found almost no instances of ARS, a proxy for feeding behavior, along the migratory route. The linear regression assessing whether departure date affected migration speed found suggestive but inconclusive support for a positive trend between the two variables. No clear stratification by sex or reproductive status, either in migration speed, departure date, or route choice, was found.Conclusions: Southern hemisphere humpback whale populations are recovering quickly from intense commercial whaling and, around the Antarctic Peninsula, are doing so in the face of a rapidly changing environment. The current lack of scientific knowledge on marine mammal migration is a major barrier to cetacean conservation. This multi-year study sets a baseline against which the effects of climate change on humpback whales can be studied across years and conditions and provides an excellent starting point for the investigation into humpback whale migration.

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