Spatial distribution, habitat utilization, and social interactions of humpback whales,Megaptera novaeangliae, off Hawai'i, determined using acoustic and visual techniques

Abstract

Acoustic and visual methods were used to track and observe humpback whales off the island of Hawai'i. Sixty-two singing whales were located acoustically in water depths from 10 to 305 fathoms (mean 126 fathoms; 1 fathom = 1.828 m). This indicates that singers are not confined within the 100-fathom contour, although nearshore waters had a higher density of singers. The separation distance between singers (mean 5.1 km) was found to be significantly greater than that between nonsinging singletons (mean 2.1 km), supporting the hypothesis that song functions to maintain spacing between singers. The mean speed of singers determined from visual data was 1.79 km/h and from acoustic data 1.6 km/h. Some singers actively swam while singing. Other singers continued singing while affiliating with or being joined by other whales. The correlation between breaching and the cessation of singing suggests that the sounds of aerial behavior can convey information to other whales. These observations suggest the need to expand the traditional interpretations of the behavior of singing humpback whales obtained from visual observations alone.RCsumC : Des mCthodes acoustiques et visuelles ont semi a repdrer et a observer des Rorquals a bosse au large de l'ile d'Hawai'i. Soixante-deux rorquals chanteurs ont Ct C repCrCs par leurs cris a des profondeurs de 10 a 305 brasses (moyenne 126 brasses; 1 brasse = 1.828 m), ce qui indique que les chanteurs ne sont pas restreints aux 100 premikres brasses, mCme si les chanteurs sont gCnCralement prCsents en plus grand nombre dans les eaux cdtikres. La distance entre deux chanteurs (moyenne 5,l km) s'est avCrCe significativement plus ClevCe que la distance entre deux individus non chanteurs (moyenne 2,l km), ce qui appuie l'hypothkse selon laquelle les cris servent a assurer l'espacement entre les chanteurs. La vitesse moyenne des chanteurs a Ct C estimCe a 1,79 km/h d'aprks les donnCes visuelles et a 1,6 km/h d'aprks les donnCes acoustiques. Certains rorquals chanteurs nageaient mCme en Cmettant leurs cris. D'autres ont continud d'dmettre leurs cris tout en s'associant a d'autres rorquals ou a l'approche d'autres rorquals. La corrClation entre les sauts hors de l'eau et 1'arrCt des chants semble indiquer que les bruits reliCs aux comportements aCriens peuvent fournir de l'information aux autres rorquals. Ces observations nous enjoignent de remettre en question les interprktations traditionnelles du comportement des rorquals chanteurs ClaborCes seulement a partir d'observations visuelles. [Traduit par la RCdaction]

Underwater topography determines critical breeding habitat for humpback whales near Osa Peninsula, Costa Rica: implications for Marine Protected Areas

“…Hence humpback males could be in the whole study area, shown in the overlap with mothers and calves groups. Moreover, the pods without calves could be occurring in same the locations frequented by singers, similar to what Frankel et al (1995) reported in Hawaii.…”

“…For instance, distribution of male singers seemed to follow a similar pattern described by Whitehead and Moore (1982), they report singers in shallow isothermal water over to smooth bottom, where song propagation will be virtually bi-dimensional. However, singers elsewhere had been located on deep waters (Frankel et al 1995), where offshore locations provide different acoustics propagation conditions. Thus, the factor that determines which area is preferable may be social rather than oceanographic (Frankel et al 1995).…”

“…However, singers elsewhere had been located on deep waters (Frankel et al 1995), where offshore locations provide different acoustics propagation conditions. Thus, the factor that determines which area is preferable may be social rather than oceanographic (Frankel et al 1995). Hence humpback males could be in the whole study area, shown in the overlap with mothers and calves groups.…”

Predicting the acoustic exposure of humpback whales from cruise and tour vessel noise in Glacier Bay, Alaska, under different management strategies

“…The predominant vocalizations are short, simple 'whup' calls, likely contact calls (Wild & Gabriele 2014) that could be rendered inaudible by vessel noise in a way similar to those documented for right whale calls (Clark et al 2009, Tennessen & Parks 2016). On the humpback whale's tropical wintering grounds, male humpback whales spend copious amounts of time on song displays integral to their mating system (Frankel et al 1995, Darling et al 2006, Herman 2017. Males are known to sing in late summer and fall in Glacier Bay (Gabriele & Frankel 2002) and it is speculated that high-latitude song on or adjacent to feeding areas may also be important to the reproductive success of individual males (Charif et al 2001, Gabriele & Frankel 2002.…”

Applicability of Information Theory to the Quantification of Responses to Anthropogenic Noise by Southeast Alaskan Humpback Whales

“…Vessel noise has the potential to interfere with the complex vocal behavior of humpback whales, and thus could indirectly affect their population dynamics. Humpbacks produce a wide variety of vocalizations in many social contexts, which include the famous mating "songs" in their winter breeding grounds [4][5][6][7][8][9][10] as well as specialized "feeding calls" in their summer feeding grounds [11][12][13][14] that could serve as long-range assembly calls [2], likely coordinates group-feeding behavior and/or manipulate their prey (small schooling fish, [32]). Singing humpbacks are also known to modify their vocal behavior as a direct consequence of the vocal behavior of other humpbacks [5,8,15], most readily evidenced in the convergence of song acoustic structure among populations of males across each breeding season.…”