Mass stranding of Baird's beaked whales at San Jose Island, Gulf of California, Mexico

R., J. Urbán; Cárdenas-Hinojosa, Gustavo; U., A. Gómez-Gallardo; González-Peral, Úrsula; Toro-Orozco, W. Del; Brownell, Robert L.

doi:10.5597/lajam00111

Cited by 3 publications

(1 citation statement)

References 2 publications

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“…Eight Stejneger's beaked whales ( M. stejnegeri ) that stranded at Adak Island, in the Aleutian Islands, Alaska, in August 2018, were adult females, and 10 Baird's beaked whales that stranded on an island in the Gulf of California, Mexico, in 2006 were all mature males (Urbán et al . ). The prevalence and adaptive significance of sexual segregation among beaked whales is unknown, but it could be fairly common and widespread.…”

Section: Sightingsmentioning

confidence: 97%

Long in the tooth: Biological observations from at‐sea sightings of strap‐toothed beaked whales (Mesoplodon layardii)

Pitman

Totterdell²,

Wellard

et al. 2019

Marine Mammal Science

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Section: Sightingsmentioning

confidence: 97%

Long in the tooth: Biological observations from at‐sea sightings of strap‐toothed beaked whales (Mesoplodon layardii)

Pitman

Totterdell²,

Wellard

et al. 2019

Marine Mammal Science

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Beaked Whale Sexual Dimorphism, Mating Strategies, and Diversification

Alves,

Mesnick,

Rosso

et al. 2023

Sex in Cetaceans

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Beaked whales (Ziphiidae), with 24 currently recognized species, are arguably the least known large animals on the planet, despite being widespread and at times abundant. Mesoplodon, with 16 currently recognized species, is by far the most speciose cetacean genus. Recent technological and taxonomic advances, long-term photographic-identification studies, and historical whaling data have allowed new insights into their social and mating strategies and how these may have driven diversification within the family. In most beaked whales, only adult males have exposed teeth—a single “tusk” erupts from each lower jaw and is used in contests to determine access to breeding females. How forcefully males of different species engage conspecifics varies widely based mainly on differences in tooth size/placement and jaw structure. We compiled data on key dimorphic traits including beak modification, tooth size and location, and prevalence of scarring in adults, for all beaked whales. More detailed information is given for the four best-studied species—northern bottlenose whale and Baird’s, Cuvier’s, and Blainville’s beaked whales. We then compared these traits with what is known about their social organization and reproductive anatomy to make inferences about mating strategies. More aggressive species tend to occur in small groups with only one dominant adult male present and have small testes relative to body size, suggesting that male reproductive success is largely determined by precopulatory contest competition and female defense polygyny. Less aggressive species tend to occur (at least at times) in larger, mixed-sex groups with multiple adult males present, and females may mate with multiple males, which favors postcopulatory sperm competition and polygynandry. We further discuss how conflicting pressures arising from males using their beaks for both feeding and fighting could have sparked an adaptive radiation in tooth development and beak morphology among beaked whales, especially within Mesoplodon, which would have had implications for male-male competition, social structure, sexual strategies, and, perhaps ultimately, evolutionary divergence and speciation within this group.

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Genetic structure of the beaked whale genusBerardiusin the North Pacific, with genetic evidence for a new species

Morin

Baker

Brewer

et al. 2016

Marine Mammal Science

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There are two recognized species in the genus Berardius, Baird's and Arnoux's beaked whales. In Japan, whalers have traditionally recognized two forms of Baird's beaked whales, the common “slate‐gray” form and a smaller, rare “black” form. Previous comparison of mtDNA control region sequences from three black specimens to gray specimens around Japan indicated that the two forms comprise different stocks and potentially different species. We have expanded sampling to include control region haplotypes of 178 Baird's beaked whales from across their range in the North Pacific. We identified five additional specimens of the black form from the Aleutian Islands and Bering Sea, for a total of eight “black” specimens. The divergence between mtDNA haplotypes of the black and gray forms of Baird's beaked whale was greater than their divergence from the congeneric Arnoux's beaked whale found in the Southern Ocean, and similar to that observed among other congeneric beaked whale species. Taken together, genetic evidence from specimens in Japan and across the North Pacific, combined with evidence of smaller adult body size, indicate presence of an unnamed species of Berardius in the North Pacific.

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Mass stranding of Baird's beaked whales at San Jose Island, Gulf of California, Mexico

Cited by 3 publications

References 2 publications

Long in the tooth: Biological observations from at‐sea sightings of strap‐toothed beaked whales (Mesoplodon layardii)

Long in the tooth: Biological observations from at‐sea sightings of strap‐toothed beaked whales (Mesoplodon layardii)

Beaked Whale Sexual Dimorphism, Mating Strategies, and Diversification

Genetic structure of the beaked whale genusBerardiusin the North Pacific, with genetic evidence for a new species

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