What is whale breaching

This is, perhaps, why we do tend to see breaching more regularly in rough weather. But what are they trying to say? Well, no one knows for sure. I like to make an analogy however and say that it is similar to shouting in humans.

Imagine if aliens came down to Earth and asked you why people shout. You might have trouble answering that question decisively because people shout for all kinds of reasons. In other words, people shout for lots of reasons and the reason someone is shouting depends on the context in which it is done. I think the same could be said for breaching in whales. But if we could translate what a whale was saying with a breach it would be typed in all caps and have an exclamation point after it!

In conclusion: No one knows why whales exhibit this spectacular behavior. Some of the main theories include: 1. A feeding Humpback Whale. How Do Whales Sleep? Whales are air breathing mammals just like us. They must surface to breathe. So how do. Record numbers of humpback calves spotted. There were no humpbacks off southwest B. Killer Whales and Haida Culture. I was. Humpback whales: why are they so lumpy and bumpy?

Pectoral fins, head, throat and tail, all covered in bumps! What Do Whales Eat? What do whales eat? Whales can be classified by whether they have teeth or baleen.

This determines how and what. How long can a whale hold its breath? Rorqual whales feed by rapidly accelerating, opening their mouths, and engulfing large volumes of prey-laden water. Although the trajectories used for feeding lunges are highly variable Cade et al. For each of the five humpback whales, the cost of breaching was higher than the cost of accelerating to perform their highest-speed lunge. A The mass-specific energy expenditure required to perform high-emergence breaches blue and high-performance lunges red is shown for five humpback whales of different sizes.

Both the model and the data show that the mass-specific cost of breaching increases with body size. B This pattern is largely driven by the higher speeds that larger whales need to emerge from the water. C To attain the higher speeds required to emerge from the water, larger whales need to generate higher mass-specific mechanical power outputs or extend the duration of their trajectories green numbers. Relative to daily Field Metabolic Rate FMR daily , the cost of breaching increased with increasing mass and was always higher than the cost of accelerating for a high-speed feeding lunge Supplementary file 1A.

This pattern held regardless of which equation was used for predicting FMR daily of large whales. However, the Williams and Maresh equation for scaling of FMR daily resulted in a higher cost of breaching Equation 28 ; range: 0. In this study we first examined the underwater trajectories that large cetaceans use for breaching to determine if historical hypotheses about underwater movement were correct. Next, we used a hydrodynamic model to estimate the energetic costs of breaching and how it scales with body size.

It has been hypothesized that extended breaching sequences can serve as an honest signal of fitness Whitehead, b ; however, this depends on whether breaching is an energetically expensive behavior. Finally, we test the hypothesis that energetic or physical constraints impose fundamental limits on the breaching behaviors of the largest whales.

It is possible that for large whales the energetic cost of breaching is prohibitively high. Alternatively, it may be hypothesized that physical limitations of muscle contractile properties and hydrodynamics constrain the effectiveness of breaching in the largest of animals.

The underwater trajectories that allow whales to leap out of the water have been the subject of much speculation, largely because the bio-logging equipment that makes the quantitative study of underwater locomotor performance possible has only recently been developed and widely adopted Goldbogen et al.

Our data show that the underwater breaching trajectories are variable, even within species. Whitehead Whitehead, b described humpback whale breaching trajectories as having a shallow horizontal approach before pitching-up and leaving the water, and Payne described similar trajectories for right whales see Waters and Whitehead, We did find many examples of this trajectory in humpback and right whales, and we also found this trajectory used by minke and gray whales.

In addition, it has been suggested that sperm whales require long ascents to breach 70— m; Whitehead, p. We also found that humpbacks, minkes, sperm, and right whales used other types of trajectories while breaching: starting at the surface and diving, holding station, and ascending to the starting depth before beginning the breaching ascent. Our video data suggest a mechanism for this pattern: adult humpback whales appear to incorporate less long-axis angular velocity into their breaching trajectories.

Instead, they often emerge right-side up or pitch upwards, past vertical and emerge upside-down. In contrast, juvenile humpback whales often leave the water with a distinct rolling velocity, which results in a more unpredictable roll angle as they emerge Figure 5D.

Since both adults and juveniles often rotate their flippers contra-laterally before emerging, it is not clear whether the difference is behavioral or the result of the larger adults having to overcome their higher rotational inertia.

Breaching events can uniquely shed light on maximal locomotor performance of large animals, at the extremes of body size, which is a topic that has remained elusive Gough et al. For most of the species examined in this study, our ability to discuss maximal performance is influenced by low sample sizes. However, for humpback whales we measured large numbers of breaches from many individuals 28 , and data from our fastest breaches match well with previous observations and theoretical predictions.

Most data on the maximal swimming speeds of rorquals have been anecdotal Hirt et al. Lockyer reported that humpback whales could swim up to 7. Using speeds calculated from photographs of humpback whales breaching, Whitehead a reported a top speed of 8. Our examination of humpback whales with known body lengths and calculated body masses registered accelerations ranging from 0. In absolute terms, the amount of energy required for a large whale to leap out of the water is extraordinary.

For a 7. Furthermore, because breaches happen so quickly, the mechanical power required to breach is also extremely high. The second largest humpback whale in this study The energetic expenditure of this breach was also roughly equivalent to the energetic cost of the largest blue whale in our database performing its fastest lunge Thus a breach is much more energetically expensive than a high-speed predatory lunge. In relative terms, the cost of breaching is less clear. If the relationship between body mass and field metabolic rate proposed by Williams and Maresh holds for larger cetaceans, then increased size comes with high metabolic efficiency and the daily field metabolic rate is low.

This, in turn, makes breaching relatively expensive: humpback whales may spend between 0. For juvenile humpback whales the cost of performing a single breach represents a smaller percentage of their average daily energy budget 0. However, for large adults 46, kg the cost of a single breach increases to 2. On the other hand, if the scaling relationship between body mass and FMR daily is closer to that of terrestrial animals e.

In both scaling scenarios the cost of breaching increases with body mass and this relationship is mostly driven by the increased metabolic efficiency that comes with larger size Nagy, ; Williams and Maresh, , but it is also partially a result of the increased speed and momentum required for larger animals to emerge from the water Figure 6B.

Notably, the relative cost of performing a breach is much lower for humpback whales 0. Because the physics of breaching remains similar across similarly sized organisms, the low FMR daily that comes with being ectothermic makes breaching relatively much more expensive for sharks. Thus, for basking sharks or white sharks which use fast, vertical ascents to target prey near the surface; Semmens et al. Many of the individual whales we tracked performed multiple, sequential breaches.

One juvenile humpback performed at least 69 breaches and a series of other aerial behaviors over the course of two days 17 during a 6. In many animals, the energetic cost of performing even trivial, but frequently repeated behaviors can be substantial Dudley and Milton, Regardless of which scaling regime is used to calculate metabolic rates, the cost of repeated breaching represents a significant energetic expenditure for whales.

While at their calving grounds, capital breeding females in a fasting state maintain low metabolic rates in order to devote most of their energy to nursing their calves Bejder et al. In spite of this, repeated breaching is commonly observed, often with the mothers and calves breaching side-by-side. Thus, the energy expended breaching cannot be put towards lactation for mothers or storing blubber for the calves. Unlike feeding lunges, which are relatively less expensive but are also used to acquire energy, the cost of breaching on the breeding grounds will not be recouped until the whales return to their feeding grounds, several months later Christiansen et al.

This suggests that repeated breaching has a social purpose important enough to warrant the high energetic expense, perhaps serving a developmental function for juveniles or an honest signal of fitness for adults. On a mass-specific basis, the cost of breaching also increases with body size Figure 6A and this increase is largely driven by the higher speeds required to emerge from the water Figure 6B.

In turn, the locomotor muscles must generate higher power outputs to accelerate to these higher speeds Figure 6C , even though maximum mass-specific force production decreases with body size Arthur et al.

This suggests that there may be an upper size limit to breaching ability based on the limitations of muscle power-generating capabilities. Although little is known about power-generating capabilities of cetacean muscles, this value is near the limits muscle performance in other vertebrate taxa Jackson and Dial, ; Marden, Since power is time dependent, a large whale could decrease its power requirements by extending the length of its breaching trajectory, which explains some of the variation in Figure 6C.

The largest whale in this analysis took a long time However, this strategy likely has its limits, since the duration of a trajectory may be constrained by the onset of muscle fatigue. Our model blue line, Figure 6A—C suggests that the largest of whales would require even higher speeds to emerge from the water, but that their muscles may not be able to generate enough power or sustain a swimming trajectory long enough to attain these speeds. Why do larger whales require higher speeds to breach?

This is similar to how a projectile thrown upwards reaches its maximum height based solely on its initial velocity, regardless of its weight. Therefore, if our large blue whale It is not clear whether blue whales can even reach this speed Gough et al. The relationship between length and emergence may also explain why large, rotund species like right, bowhead, and humpback whales breach more often than large slender species, like fin and blue whales Whitehead, b.

Right whales and bowhead whales attain large masses due to their rotund shape but are similar in length to humpback whales. In 59 tag deployments on fin whales, we recorded one breach which caused the tag to slip before the whale exited the water , while in 14 tag deployments on male sperm whales and in tag deployments on blue whales we recorded no breaches. The physical and behavioral limitations on breaching performance are likely more complex and nuanced than the first approximations presented here.

On an inter-specific level, variation in the scaling of propulsive surfaces Woodward et al. Additionally, differences in body-composition and buoyancy may make it easier for certain species to breach i. Intra-specific factors such as body-condition Miller et al. Even on an individual level, the amount of air stored in the lungs and the resulting changes in buoyancy Miller et al.

Meanwhile, the physical ability to breach efficiently combined with a complex social structure and high levels of innate maneuverability may have predisposed certain species, such as humpback whales, to incorporate breaching as a form of communication.

In conclusion, our results suggest an underlying biomechanical explanation for the factors that limit intra-specific and inter-specific breaching ability in large whales. We found that breaching whales use variable underwater trajectories, and that high-emergence breaches feature speeds approaching the upper limits of locomotor performance.

The speeds required to substantially emerge from the water result in high energetic costs that increase disproportionately with body size. The cost of performing extended breaching sequences certainly represents a significant energetic expenditure, supporting the hypothesis that breaching serves an important social function for some species. However, the energetic cost of performing a single, isolated breach is likely not sufficient to explain why the largest of whales do not breach.

Instead, our analysis suggests that the breaching ability of large whales may be limited by the capacity of their muscles to deliver high bursts of power or sustain high-speed trajectories for extended durations. The confluence of muscle contractile properties, hydrodynamic limitations of lunate tail propulsion, and the higher speeds required for longer whales to emerge from the water likely imposes an upper limit to the body size and effectiveness of breaching whales.

The DTAGs were deployed on sperm, right, and humpback whales. Bio-loggers were also deployed on three juvenile humpback whales: CATS tags were deployed on two smaller animals in their feeding grounds, and a DTAG was deployed using a special protocol designed to minimize disturbance, on a calf in the breeding grounds Stimpert et al.

We identified breaches Figure 1 by watching the onboard videos CATS tags, Figure 2 , Video 1 , using surface observation data, or manually examining the data for rapid ascents that were followed by sections where the depth sensors abruptly emerged from the water 0 m depth; Figure 2. We only included breaches where the suction-cups did not slip throughout the ascent, and where we could confidently estimate the orientation of the tag on the whale Johnson and Tyack, Deployments that contained breaches represented a small subset of larger datasets collected for different projects.

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Once we identified breaching events, the raw data were downsampled to 5, 10, or 25 Hz depending on the original dataset. We applied a zero-lag Butterworth filter designed to remove sampling error from the accelerometer and magnetometer data low pass, cutoff frequency: 1 Hz and calculated the orientation of the whale using the standard pitch, roll, and heading framework Johnson and Tyack, We then applied another series of zero-lag Butterworth filters to the pitch signal to separate the contribution of the body orientation low pass, cutoff frequency: 0.

For each breach we identified the start of the maneuver as the time when the body pitched upwards past horizontal and began the ascent towards the surface. In some cases, when the whale was already ascending from a dive, we defined the start of the breaching ascent by manually finding the time when the fluke strokes began or intensified.

The depth sensors clearly showed when the tag exited the water, but often the tag placement was distal enough that by the time the tag broke the surface, the whale was already falling out of the air. Therefore, to accurately measure the underwater trajectories associated with breaching, we estimated the time when whale broke the surface, using the depth sensor and the pitch angle as a guide to ensure the whale had not already started its abrupt downward, aerial trajectory.

We estimated speed using two methods. This method is only valid at high pitch angles, and was used to calculate most of the exit velocities reported in Table 1. We used a combination of both methods to calculate the velocity profiles of the humpback breaches and lunges used for the energetic analysis. The breaching trajectories were broadly classified by shape Table 2. The sinusoidal fluke strokes were not always visible in the data, particularly when the tag was placed anteriorly.

When possible breaches , we counted the number of fluke strokes upstroke to upstroke or downstroke to downstroke per breach, by using the zero-crossings of the high-pass filtered pitch signal. We did not include the last half-stroke as the whale emerged, but we did include the part of the first stroke that occurred as the breach began - expressed as a fraction. We calculated the average stroke frequency over the course of the breach. We also calculated a rough estimate of the percentage of the whale that emerged from the water, using the simple physics-based model from Whitehead a and Lang We used exit velocities and pitch angles derived from the sensor data, modeling the whales as cylinders.

The remaining behaviors were classified as partial breaches. When available, video data confirmed these emergence calculations and classification system. Although coarse, this method provides a useful separation between high-performance and low-performance breaches. To examine the relationships between kinematic variables associated with breaching we used a linear mixed effects model with nested random effects individuals nested within species.

We calculated a pseudo-R2 designed for use with Bayesian regression models: the variance of the predicted values divided by the variance of predicted values plus the variance of the errors Gelman et al.

Statistics were performed using the Statsmodels package in Python. We estimated the energetic cost of breaching using breaches from five individual humpback whales of different sizes 7.

As a comparison, for each individual we also selected the fastest lunge individuals had between 12 to lunges with a stereotypical acceleration profile also starting at low speed and rapidly accelerating; Figure 3. We measured the velocity at the end of the maneuver using orientation-corrected depth rate to avoid any accelerometer clipping that may occur during the highest accelerations.

The energetics of breaching and lunging were estimated using a two-step process. First, the mechanical work of the system was calculated by adding the work done against drag to the change in kinetic energy. Second, the metabolic energy spent by the muscles to perform the work was estimated using metabolic efficiency coefficients Blake, ; Fish, ; Fish, ; Webb, ; Webb, These calculations represent the cost of accelerating and do not include estimates of basal metabolic rate.

Using data from the bio-loggers, each breach and lunge was split into two phases: an acceleration phase where the velocity increased from the initial velocity U i to the final velocity U f over the duration of T acc seconds, and a plateau phase where the velocity stayed constant at U f for the duration of T plat seconds Supplementary file 1 - Table S1B.

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