Diel changes in humpback whale Megaptera novaeangliae feeding behavior in response to sand lance Ammodytes spp. behavior and distribution

Abstract

Humpback whales Megaptera novaeangliae have adopted unique feeding strategies to take advantage of behavioral changes in their prey. However, logistical constraints have largely limited ecological analyses of these interactions. Our objectives were to (1) link humpback whale feeding behaviors to concurrent measurements of prey using scientific echo-sounders, and (2) quantify how sand lance behavior influences the feeding behaviors and foraging ecology of humpback whales. To measure, in fine detail, the 3-dimensional orientation and movement patterns of humpback whales underwater, we used a multi-sensor tag attached via suction cups (DTAG). We tested the specific hypothesis that the diel movement patterns of sand lance between bottom substrate and the water column correlates to changes between surface and bottom feeding strategies of humpback whales on Stellwagen Bank, MA. We collected over 96 h of both day-and nighttime data from 15 whales in 2006, and recorded 393 surface and 230 bottom feeding events. Individual whales exhibit both surface and bottom feeding behaviors, switching from one to the other in relation to changing light and prey conditions. Surface feeding behaviors were individually variable in their constitution but ubiquitously biased towards daylight hours, when prey was most abundant in the upper portion of the water column. Bottom feeding behavior occurred largely at night, coincident with when sand lance descend to seek refuge in the substrate. Our data provide novel insights into the behavioral ecology of humpback whales and their prey, indicating significant diel patterns in foraging behaviors concurrent with changes in prey behavior.

Spatial distribution and dive behavior of Gulf of Mexico Bryde’s whales: potential risk of vessel strikes and fisheries interactions

“…Similarly, several studies found that blue whales Balaenoptera musculus in pelagic waters dove deeper during the day than at night, likely while foraging on krill (Croll et al 1998, Oleson et al 2007). Additionally, a diel pattern of deep night dives and shallow daytime dives was found for 2 associated Bryde's whales likely foraging on krill in pelagic waters in the eastern North Atlantic off Madeira Island (Alves et al 2010) and for humpback whales Megaptera novaeangliae likely foraging on sand lance (Ammodytidae) along the bottom at Stellwagen Bank in the western North Atlantic (Friedlaender et al 2009). Further tagging research is needed to increase the sample size and determine whether the documented dive behavior is representative of the GoM Bryde's whale population.…”

Synchronous mother and calf foraging behaviour in humpback whales Megaptera novaeangliae: insights from multi-sensor suction cup tags

“…Prior to deployment, the time on the tags was synchronised to the GPS time to ensure the ability to synchronise data parameters (e.g. Friedlaender et al 2009). …”

Mechanics, hydrodynamics and energetics of blue whale lunge feeding: efficiency dependence on krill density

“…However, there is limited evidence that humpback whales feed at night using putative echolocation (Stimpert et al, 2007) or tactile mechanisms (Friedlaender et al, 2009). Crittercam deployments on blue whales show that daytime foraging dives often involve lunges at steep upward pitch angles [see fig.4 in Calambokidis et al ; cf.…”

“…This lunge feeding behavior occurs anywhere prey is particularly dense and abundant, from the sea surface (Friedlaender et al, 2009) to more than 500m in depth (Panigada et al, 1999). During a single lunge, rorquals accelerate to high speed towards a prey patch (Friedlaender et al, 2009;Goldbogen et al, 2008;Goldbogen et al, 2006) and open their mouths wide to approximately 80deg (Brodie, 1993;Brodie, 2001).…”

“…This lunge feeding behavior occurs anywhere prey is particularly dense and abundant, from the sea surface (Friedlaender et al, 2009) to more than 500m in depth (Panigada et al, 1999). During a single lunge, rorquals accelerate to high speed towards a prey patch (Friedlaender et al, 2009;Goldbogen et al, 2008;Goldbogen et al, 2006) and open their mouths wide to approximately 80deg (Brodie, 1993;Brodie, 2001). The dynamic pressure generated by an open mouth at high speed causes the inflation of the buccal cavity (Goldbogen et al, 2007), whereby the tongue inverts and forms a large portion of the capacious sac that envelopes the engulfed water mass (Lambertsen, 1983).…”