Join us for episode 18 (SEASON FINALE) of Cetacean Sessions: The Challenges of Being a Baby Dolphin. In this episode, we will discuss two studies reporting alloparental care (caring for the baby of another species) and infanticides in various dolphin species, with two special guests: Danielle Conry & Leanne Rosser.

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Danielle is a marine mammologist from South Africa with over 15 years of experience in various roles within the marine mammal field. She holds an MSc in Zoology from Nelson Mandela University, which focused on the abundance and habitat use of the Indian Ocean humpback dolphin along South Africa’s Garden Route. As a member of South Africa’s SOUSA Consortium, she continued monitoring Indian Ocean humpback dolphins in Plettenberg Bay after the completion of her studies as part of a collaborative project until leaving to join the 78th Overwintering Expedition to remote subantarctic Marion Island to collect data on killer whales and pinnipeds for the Marion Island Marine Mammal Programme. She is now working as a photo ID specialist at Bay Cetology in Alert Bay after a recent move to Canada.

In her recent paper, they report on observations of interspecific adoption in Indian Ocean humpback dolphins (Sousa plumbea) along South Africa’s Garden Route coastline. The events involve an identifiable humpback dolphin female adopting an Indo-Pacific bottlenose (Tursiops aduncus) and common (Delphinus delphis) dolphin calf during two separate events while already rearing her own biological calf in each case. These observations are significant as only a few accounts of interspecific adoption have been reported in mammals thus far and this is the first detailed account for Indian Ocean humpback dolphins. While the proximate causes of interspecific adoptions remain debatable, observations of such novel behavior are important to understand the mechanisms driving this non-adaptive behavior.

After living in Japan for almost six years working with Mutsu Bay Dolphin Research, Leanne has returned to the UK to complete her MSc in Marine Biology at Bangor University, where her thesis focuses on Risso’s dolphins. Her research in Japan looks at the behavior and ecology of Pacific white-sided dolphins, which she hopes to continue next year for her PhD. Last year with her team in Japan, she published a paper on a unique observation of PWSD calf-directed aggression as a potential infanticide attempt.

On an annual survey of Mutsu Bay, a 75-minute-long persistent attack on a neonate was performed by 10 Pacific white-sided dolphins that left the neonate with visible injuries. Only one individual was recorded for the entirety of the event and was regarded as the possible mother, displaying protective behaviors towards the neonate as well as being the target of coercive guarding and sexual behaviors by the attackers. The observation featured a distinct group composition change in which, after 50 minutes, the attack was taken over by new attackers. This second group continued the attack with significantly increased aggression and a greater array of behavioral types than the first, often dividing into two subgroups—one that herded the suspected mother and another that focused on attacking the neonate.

The group change observed is absent from the literature on conspecific calf-directed attacks in other cetacean species and provides new insight into the behavior of Pacific white-sided dolphins. Little is known about this species' social structure, and Leanne wants to uncover more with her work in Japan on these understudied cetaceans.

Cetacean Sessions is a bi-weekly seasonal webinar series where we discuss impactful recently published scientific research on cetaceans with those conducting it around the world. Season 3 is focused exclusively on early-career researchers' publications. Cetacean Sessions is informal, educational, interactive, and geared towards those working with or interested in cetaceans. You can register for sessions and follow our channel for free with no account creation necessary.

Whale Scientists is a science communication platform created by two PhD students, Anaïs Remili and Naomi Mathew. It aims to share scientific knowledge with the public in a fun, entertaining way, to share tips with aspiring marine mammalogists on how to become whale scientists, and to share the incredible journeys of early-career researchers. You can find more info at: https://whalescientists.com/

Bay Cetology enables conservation and understanding of cetacean populations that are data deficient or threatened by climate change and human development. Our marine biologists and research technicians use various expertise to conduct field studies, analyze data, and communicate findings. Bay Cetology was founded by Jared Towers in 2017 and is based out of Alert Bay (Home of the Killer Whale) in the unceded traditional territory of the ‘Namgis First Nation, British Columbia, Canada. See more about our previous work and current projects at https://baycetology.org

Cetacean Sessions #18