NMFS Biological Opinion on U.S. Navy training ... - Govsupport.us

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FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 from a paddle raft when their perches were closer to the river or were closer to the ground (Steidl and Anthony 1996). One consequence of behavioral avoidance results from changing the energetics of marine mammals because of the energy required to avoid surface vessels or the sound field associated with active sonar (Frid and Dill 2002). Most animals can avoid that energetic cost by swimming away at slow speeds or those speeds that are at or near the minimum cost of transport (Miksis-Olds 2006), as has been demonstrated in Florida manatees (Hartman 1979, Miksis-Olds 2006). Those costs increase, however, when animals shift from a resting state, which is designed to conserve an animal’s energy, to an active state that consumes energy the animal would have conserved it they had not been disturbed. In the case of humpback whales, lactating females with calves should spend more time in a resting state because of high energetic costs of lactating and their inability to compensate for those costs by feeding (humpback whales generally do not feed in their calving areas). Marine mammals that have been disturbed by anthropogenic noise and vessel approaches are commonly reported to shift from restirng behavioral states to active behavioral states, which would imply that they incur an energy cost. Morete et al. (2007) reported that undisturbed humpback whale cows that were accompanied by their calves were frequently observed resting while their calves circled them (milling) and rolling interspersed with dives. When vessels approached, the amount of time cows and calves spent resting and milling, respectively declined significantly. These results are similar to those reported by Scheidat et al. (2004) for the humpback whales they observed off the coast of Ecuador. Constantine and Brunton (2001) reported that bottlenose dolphins in the Bay of Islands, New Zealand only engaged in resting behavior 5 percent of the time when vessels were within 300 meters compared with 83 percent of the time when vessels were not present. Miksis-Olds (2006) and Miksis-Olds et al. (2005) reported that Florida manatees in Sarasota Bay, Florida, reduced the amount of time they spent milling and increased the amount of time they spent feeding when background noise levels increased. Although the acute costs of these changes in behavior are not likely to exceed an animals’ ability to compensate, the chronic costs of these behavioral shifts are uncertain. Based on the evidence available, most of the endangered whales that are being considered in this <strong>Opinion</strong> are likely to avoid being exposed to the exercises or, if they are exposed, are likely to avoid continued exposure to the exercises. Blue, fin, humpback, sei, and sperm whales would probably be alerted to the start of an exercise by lowfrequency sounds produced by Navy surface vessels entering an area to begin an exercise. Because the main Hawai’ian Islands do not appear to be an important feeding area or calving area for fin, sei, and sperm whales, they seem likely to try to avoid an area in which surface vessels are moving at tactical speeds accompanied by active sonar transmissions, low-frequency sounds produced by aircraft and helicopters, sonobuoys, and submarines. The main Hawai’ian Islands are an important breeding and calving area for humpback whales, however. If breeding, adult hunpback whales try to avoid being exposed to mid-frequency active sonar and that avoidance behavior prevented them from breeding, the avoidance behavior would have reduced the fitness of any humpback whales that made this trade-off (avoiding the sonar rather than breeding). Adult humpback whales with calves do not seem likely to try to avoid continued exposure if they are accompanied by very young calves because swimming at speeds that would allow them to avoid exposures would separate them from calves that could not sustain such swimming speeds. 214
FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 Their inability to avoid further exposure, however, seems likely to produce stress responses because they would want to avoid the sonar but would their circumstances would prevent them from doing so (see Box S of Figure 3). ATTENTIONAL CAPTURE. Attention is the cognitive process of selectively concentrating on one aspect of an animal’s environment while ignoring other things (Posner 1994). Because animals (including humans) have limited cognitive resources, there is a limit to how much sensory information they can process at any time. The phenomenon called “attentional capture” occurs when a stimulus (usually a stimulus that an animal is not concentrating on or attending to) “captures” an animal’s attention. This shift in attention can occur consciously or unconsciously (for example, when an animal hears sounds that it associates with the approach of a predator) and the shift in attention can be sudden (Dukas 2002, van Rij 2007). Once a stimulus has captured an animal’s attention, the animal can respond by ignoring the stimulus, assuming a “watch and wait” posture, or treat the stimulus as a disturbance and respond accordingly, which includes scanning for the source of the stimulus or “vigilance” (Cowlishaw et al. 2004). Vigilance is normally an adaptive behavior that helps animals determine the presence or absence of predators, assess their distance from conspecifics, or to attend cues from prey (Bednekoff and Lima 1998, Treves 2000). Despite those benefits, however, vigilance has a cost of time: when animals focus their attention on specific environmental cues, it is not attending to other activities such a foraging. These costs have been documented best in foraging animals, where vigilance has been shown to substantially reduce feeding rates (Saino 1994, Beauchamp and Livoreil 1997, Fritz et al. 2002). Animals will spend more time being vigilant, which translates to less time foraging or resting, when disturbance stimuli approach them more directly, remain at closer distances, have a greater group size (for example, multiple surface vessels), or when they co-occur with times that an animal perceives increased risk (for example, when they are giving birth or accompanied by a calf). Most of the published literature, however, suggests that direct approaches will increase the amount of time animals will dedicate to being vigilant. For example, bighorn sheep and Dall’s sheep dedicated more time being vigilant, and less time resting or foraging, when aircraft made direct approaches over them (Frid 2001, Stockwell et al. 1991). Several authors have established that long-term and intense disturbance stimuli can cause population declines by reducing the body condition of individuals that have been disturbed, followed by reduced reproductive success, reduced survival, or both (Daan et al. 1996, Madsen 1994, White 1983). For example, Madsen (1994) reported that pink-footed geese (Anser brachyrhynchus) in undisturbed habitat gained body mass and had about a 46% reproductive success compared with geese in disturbed habitat (being consistently scared off the fields on which they were foraging) which did not gain mass and has a 17% reproductive success. Similar reductions in reproductive success have been reported for mule deer (Odocoileus hemionus) disturbed by all-terrain vehicles (Yarmoloy et al. 1988), caribou disturbed by seismic exploration blasts (Bradshaw et al. 1998), caribou disturbed by low-elevation military jet-fights (Luick et al. 1996), and caribou disturbed by low-elevation jet flights (Harrington and Veitch 1992). Similarly, a study of elk (Cervus elaphus) that were disturbed experimentally by pedestrians concluded that the ratio of young to mothers was inversely related to disturbance rate (Phillips and Alldredge 2000). The primary mechanism by which increased vigilance and disturbance appear to affect the fitness of individual animals is by disrupting an animal’s time budget and, as a result, reducing the time they might spend foraging and 215
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