Feeding tactics of resident Bryde’s whales in New Zealand
Sahar Izadi, Natacha Aguilar de Soto, Rochelle Constantine, Mark Johnson
Predators typically feed on proportionally sized prey, but baleen whales take large mouthfuls of small zooplankton and fishes. Unlike most whales, Bryde’s whales live year-round in warmer waters with variable quality prey. Suction-cup tag data and drone footage of Bryde’s whales in New Zealand revealed specialized feeding tactics depending on whether they were eating zooplankton or fish. The whales use head-slaps and side-lunges to catch zooplankton, and vertical surfacing to catch fish; this probably allows them to capture more prey. Bryde’s whales’ flexible diet and ability to change their behavior may be key to successfully living in warmer waters.
Vocalization of Bryde’s whales (Balaenoptera edeni) in the Beibu Gulf, China
Zhi-Tao Wang, Peng-Xiang Duan, Mo Chen, Zhi-Gang Mei, Xiao-Dong Sun, Zhi-Wen Nong, Mei-Han Liu, Tomonari Akamatsu, Ke-Xiong Wang, Ding Wang
Bryde’s whale vocalizations were recorded in the Beibu Gulf, China. Bouts of frequency modulated repetitive and diversified calls were recorded. Repetitive calls probably functioned as contact calls. Repetitive calls were divided into biphonation downswept tonals and downswept tonals. Diversified calls were probably associated with acoustic exchanges between or among conspecifics. Diversified calls occasionally contained inflection points, frequency jumps, and break point features. Most vocalizations in the current study were different than those previously reported for this species, providing new information on the acoustic repertoire of Bryde’s whales.
Comparative electrocardiogram in two anesthetized pinnipeds, the South American fur seal (Arctocephalus australis) and the Southern sea lion (Otaria byronia), with analysis of ECG parameters allometry
Mariela Dassis,Carolina De León,Alejandro Diaz,Edgardo M. Rodríguez,Diego H. Rodríguez,Gisela V. Giardino, Eduardo F. Castro
The cardiac conduction systems of South American sea lions and fur seals were found to be evolutionarily conserved, and cardiac cycle duration was directly related to body weight. We found that atrial-ventricular coordination, which is crucial for optimal hemodynamic efficiency, remained close to expected theoretical values in anesthetized animals. For both species, body mass could be used to estimate electrocardiogram duration parameters, which is particularly useful given the difficulty of animal handling and cardiac recordings in natural colonies.
Tagging, ranging patterns, and behavior of franciscana dolphins (Pontoporia blainvillei) off Argentina and Brazil: Considerations for conservation
Randall S. Wells, Marta J. Cremer, Leonardo G. Berninsone, Diego Albareda, Krystan A. Wilkinson, M. Andrew Stamper, Renan L. Paitach, Pablo Bordino
Franciscanas are the most endangered cetaceans in the Southwestern Atlantic, where they are exposed to human activities such as artisanal gillnet fishing and coastal development. A need for information on ranging patterns and behavior led to efforts to attach satellite-linked tags to franciscanas in three bays in Argentina and Brazil during 2005-2013. Residency, with small home ranges, occurred at each site. Movements were influenced by tides. The dolphins used the entire water column, exposing them to gillnets regardless of net depth. Definable ranges facilitate relating specific geographically based threats to appropriate population units, increasing the potential for effective conservation.
Acoustic-based estimates of Cuvier’s beaked whale (Ziphius cavirostris) density and abundance along the U.S. West Coast from drifting hydrophone recorders
Jay Barlow,Jeffrey E. Moore,Jennifer L. K. McCullough,Emily T. Griffiths
The abundance of Cuvier’s beaked whales off the U.S. West Coast was estimated from an acoustic survey conducted in 2016. This is the most common species of beaked whale and has a worldwide distribution. This survey differed from all previous surveys in its use of drifting acoustic recording devices to estimate whale abundance. The estimated number of these whales in the 1 million square kilometer study area is 5,500. This number is slightly higher than the average estimate from 7 prior visual surveys but is considerably more precise.