Mating Habits of New Zealand Dusky Dolphins

Markowitz, Tim M.; Markowitz, Wendy J.; Morton, Lindsay M.

doi:10.1016/b978-0-12-373723-6.00008-4

Cited by 22 publications

(60 citation statements)

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“…All dolphins in mating chases spent most of their time (>91%) at the surface of the water where they could be observed. The lack of observed aggression among male dusky dolphins in this study and rare observations of agonistic interactions in other studies (e.g., Markowitz et al 2010;Orbach et al 2015) support this hypothesis.…”

Section: Discussionsupporting

confidence: 76%

“…Orbach et al (2014) observed that males were positioned directly beneath and in close proximity to a copulating pair, and engaged in immediate copulations with the female when the initial copulating male stopped mating. Markowitz et al (2010) observed the longest copulation duration and highest copulation rate in a small group of dusky dolphins with synchronous male behaviors. They hypothesized that males form long-term cooperative alliances, as has been observed with some Indo-Pacific bottlenose dolphins (Connor et al , 2000b.…”

Section: Introductionmentioning

confidence: 94%

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Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchusobscurus)

2015

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Males in polygamous species often engage in intrasexual competition for mates. If females actively evade mating attempts, it may benefit males to cooperate to restrict female movement, as has been found in some mammals. We tested if male dusky dolphins (Lagenorhynchus obscurus (Gray, 1828)) cooperate or compete during group mating chases. If they cooperate, then the per-male probability of copulating should increase with group size; if they compete, then the probability should decrease. We followed mating groups by boat during the breeding season (October 2013 -January 2014) off Kaikoura, New Zealand. The copulation rate per male decreased with increasing group size and with the number of noncopulating males in proximity to a copulating female. Male dusky dolphins have multiple mates and appear to use sperm and exploitative scramble competition. Males may remain in mating groups despite competition because there are alliances within the groups, they are unable to exclude rivals from joining a group, the time and energy costs of searching for unescorted females exceed the costs of reduced mating opportunities in a group, they receive other direct or indirect benefits that offset the costs of reduced mating opportunities, or they are in the group largely for social learning rather than procreation.Résumé : Les mâles d'espèces polygames se font souvent concurrence pour les femelles. Si les femelles évitent activement les tentatives d'accouplement, il pourrait être avantageux pour les mâles de coopérer pour restreindre les déplacements des femelles, un comportement observé chez certains mammifères. Nous avons vérifié si les lagénorhynques obscurs (Lagenorhynchus obscurus (Gray, 1828)) mâles coopèrent ou se font concurrence durant les poursuites nuptiales en groupe. S'ils coopèrent, la probabilité de copulation par individu mâle devrait augmenter parallèlement à la taille du groupe; s'ils se font concurrence, cette probabilité devrait diminuer. Nous avons suivi par bateau des groupes reproducteurs durant la saison de reproduction (octobre 2013 à janvier 2014) au large de Kaikoura (Nouvelle-Zélande). Plus le groupe était grand et plus le nombre de mâles non copulateurs à proximité d'une femelle copulatrice était élevé, plus le taux de copulation par mâle était faible. Les lagéno-rhynques obscurs mâles ont de multiples partenaires et semblent utiliser la concurrence spermatique et en mêlée. Les mâles peuvent demeurer dans des groupes de reproducteurs malgré la concurrence parce qu'il y a des alliances au sein de ces groupes, qu'ils ne peuvent exclure des rivaux d'un groupe, que les coûts en temps et en énergie de la quête d'une femelle non escortée dépassent les coûts associés à la réduction des possibilités d'accouplement dans le groupe, qu'ils en tirent d'autres avantages directs ou indirects qui compensent les coûts de la réduction des possibilités d'accouplement ou qu'ils sont dans le groupe principalement à des fins d'apprentissage social plutôt que de procréation. [Traduit par la Rédaction]

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Section: Discussionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 94%

Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchusobscurus)

2015

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“…) and social mating strategies (Markowitz et al . ), and the social complexity described in this paper.…”

Section: Discussionmentioning

confidence: 95%

“…Off Kaikoura, bait‐ball foraging seldom occurs, and social bonding is instead likely to function in securing mates via coordinated mating strategies (Markowitz et al . ), calf‐rearing (Weir et al . , ), and predator avoidance and defense (Srinivasan and Markowitz ).…”

Section: Discussionmentioning

confidence: 99%

Dusky dolphin (Lagenorhynchus obscurus) social structure characterized by social fluidity and preferred companions

Pearson

Markowitz

Weir

et al. 2016

Marine Mammal Science

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Many coastal delphinids exhibit social structures with a high degree of fission‐fusion dynamics. However, little is known about fission‐fusion dynamics in semipelagic delphinids such as dusky dolphins (Lagenorhynchus obscurus). We analyzed dusky dolphin social structure in a winter foraging habitat in New Zealand. We examined the population‐level societal attributes of preferred/avoided companions, behaviorally specific preferred/avoided companions, and simple ratio (SR) association index strength and distribution and the dyad‐level societal attribute of temporal patterning of associations. We identified 741 individuals; 99 met inclusion criteria for analysis. Long‐term and short‐term preferred/avoided companions were present in the pooled (6 yr) and annual samples. Individuals were observed to form long‐term but not short‐term preferred/avoided companions during all behavioral states. Mean and maximum SRs were 0.03 ± 0.01 SD and 0.40 ± 0.20 SD, respectively. Temporal analysis indicated that individuals associated preferentially throughout the study period. Dusky dolphins exhibited high social fluidity, as indicated by many weak and few strong associations. However, there was stability as individuals were observed to form behaviorally specific preferred/avoided companions and associate preferentially throughout the 6 yr period. Dusky dolphins thus display a dynamic social structure where overall low levels of bonding are juxtaposed against a subset of the population that forms strong bonds.

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“…Dusky dolphins live sympatrically with Hector's dolphins (Cephalorhynchus hectori) in Kaikoura waters, but observed interactions have been nonantagonistic (Heinrich et al, 2010). Small groups of common dolphins occasionally accompany dusky dolphin groups (Cipriano, 1992), and interspecific mating has been observed (Markowitz et al, 2010b). Bottlenose dolphins occasionally occur offshore, and interspecific interactions might occur during the nocturnal feeding of the dusky dolphins (Markowitz, 2004;Würsig et al, 2007).…”

Section: Intraspecific Interactionsmentioning

confidence: 96%

Sources of Notch and Scar Patterns on the Dorsal Fins of Dusky Dolphins (Lagenorhynchus obscurus)

Kügler¹

2014

Aquat Mamm

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Few studies have investigated the origins of distinctive marks on cetaceans and quantitatively evaluated the causal factors. We used photo-identification data to categorize the ecological sources of scars and notches on the dorsal fins of freeranging dusky dolphins (Lagenorhynchus obscurus) off Kaikoura, New Zealand. Dorsal fin photographs of 1,171 individuals that had marks from ecological sources were collected from October 2011 through January 2012. Photographs of scars and notches were compared to marks of known origin, cross-validated by experts, and categorized as derived from conspecifics, killer whales, sharks, vessel strikes, fishing gear, or unknown. A total of 1,019 dusky dolphins had notches, of which 419 (41%) individuals had additional scars. A smaller subset of dolphins (152 individuals) had only scars or pigmentations as marks. The marks on the majority of dusky dolphins were attributed to intraspecific interactions (notches: 84%, n = 983; scars: 30%, n = 355). Indications of predation attempts (sharks: 0.17%, n = 2; killer whales: 0.09%, n = 1; unclassified natural predators: 0.26%, n = 3) and human impact (net/line: 0.43%, n = 4; vessel: 0.17, n = 2; unclassified human impact: 0.34%, n = 4) were comparatively low. These results are consistent with previous studies and indicate that most marks on dusky dolphins are caused by conspecifics and that predation pressure and bycatch rates are low off Kaikoura. We suggest that these data indicate that current management actions regulating commercial and recreational boating activities in the area are sufficient, with no need for immediate modification.

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Mating Habits of New Zealand Dusky Dolphins

Cited by 22 publications

References 0 publications

Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchusobscurus)

Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchusobscurus)

Dusky dolphin (Lagenorhynchus obscurus) social structure characterized by social fluidity and preferred companions

Sources of Notch and Scar Patterns on the Dorsal Fins of Dusky Dolphins (Lagenorhynchus obscurus)

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