Fishing in the Dark: A Pursuit-Diving Seabird Modifies Foraging Behaviour in Response to Nocturnal Light Levels

Regular, Paul M.; Hedd, April; Montevecchi, William A.

doi:10.1371/journal.pone.0026763

Cited by 97 publications

(72 citation statements)

References 36 publications

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“…Since the indicators of nocturnal activity vary in opposite directions, we hypothesize that the increase in flight activity represents a higher searching effort, but a lower efficiency around full-moon (Phalan et al 2007, Mackley et al 2011). This could be explained by the reduced feeding opportunities during moonlit nights, given that DVM prey tend to occur deeper in the water column during full moons (Horning & Trillmich 1999, Hernández-Leon et al 2001, Benoit-Bird et al 2009, Regular et al 2011.…”

Section: Discussionmentioning

confidence: 99%

Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitat

Dias

Granadeiro²,

Catry³

2012

Mar. Ecol. Prog. Ser.

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The diel vertical migration of zooplankton and many other organisms is likely to affect the foraging behaviour of marine predators. Among these, shallow divers, such as many seabirds, are particularly constrained by the surface availability of prey items. We analysed the atsea activity of a surface predator of epipelagic and mesopelagic prey, Cory's shearwater Calonectris diomedea, on its several wintering areas (spread throughout the temperate Atlantic Ocean and the Agulhas Current). Individual shearwaters were mainly diurnal when wintering in warmer and shallower waters of the Benguela, Agulhas and Brazilian Currents, and comparatively more nocturnal in colder and deeper waters of the Central South Atlantic and the Northwest Atlantic. Nocturnality also correlated positively with bathymetry and negatively with sea-surface temperature within a single wintering area. This is possibly related to the relative availability of epipelagic and mesopelagic prey in different oceanic sectors, and constitutes the first evidence of such flexibility in the daily routines of a top marine predator across broad spatial scales, with clear expression at population and individual levels.

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Section: Discussionmentioning

confidence: 99%

Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitat

Dias

Granadeiro²,

Catry³

2012

Mar. Ecol. Prog. Ser.

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“…This could explain the observed decrease in the frequency of shallow dives in LW (Figure 4) and the corresponding increase in daylight dives (with fewer crepuscular and nocturnal dives). Consequently, murres facing high-energy demands in LW spend more time foraging in deeper waters where capture efficiency of prey is limited by light availability (Hedd et al, 2009;Regular et al, 2011), resulting in a shorter foraging day ( Figure 6B). We suggest that murres operating under severe time (short days) and energy (high DEE, deep diving) constraints in LW push the limits of their diving capabilities to maximize their total net daily energy gain (i.e., rate maximizing behavior; Houston, 1987;Ydenberg et al, 1994).…”

Section: Optimal Foraging Strategies In a Marginal Winter Environmentmentioning

confidence: 99%

“…Diving seabirds, that are primarily visual predators (c.f. Regular et al, 2011;Berge et al, 2015) also face additional constraints on foraging time during the shorter days of winter and correspondingly longer periods of nocturnal fasting (Grémillet et al, 2005a,b;Daunt et al, 2007). This conflict between resource demand and availability in winter raises the critical, but poorly resolved question of how diving seabirds meet the energy demands of survival.…”

Section: Introductionmentioning

confidence: 99%

Taking the Bite Out of Winter: Common Murres (Uria aalge) Push Their Dive Limits to Surmount Energy Constraints

Burke

Montevecchi

2018

Front. Mar. Sci.

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Diving seabirds that overwinter at high latitudes experience persistent cold exposure, short days and associated declines in ocean productivity that can challenge their ability to balance daily energy budgets. We used dive-immersion geo-locators to test the hypothesis that pursuit-diving Common murres (Uria aalge) will respond to the challenges of winter in the North Atlantic through increased daily energy expenditures (DEE) that will be met by increased foraging effort and adjustments in dive tactics. Largely flightless in winter (<5% of daylight hours flying), murres spent most of their time on the water (>85% resting and swimming). Accordingly, when sea surface temperatures (SST) were consistently near freezing in late winter (1.9 ± 0.8 • C), mean DEE (2463.2 ± 10.9 kJ day −1 ) exceeded the theoretical limit to sustainable energy expenditure in vertebrates (i.e., 7 X Basal Metabolic Rate or 2450 kJ day −1 for murres). Consistently deep (70% >50 m) and long dives in late winter, 38% of which exceeded their calculated aerobic dive limit indicate that targeted prey was distributed in deep (dark) waters. Consequently, foraging was largely diurnal; likely because capture efficiency of deep-water prey is poor under low light. Murres responded to these late winter time and energy constraints with a nearly two-fold increase in daily time spent diving (95.2 ± 5.6 and 178.3 ± 6.3 min day −1 during early and late winter, respectively), an increase in dive bout frequency and duration, and correspondingly less time resting between bouts. Uniquely adapted for deep-diving, pursuit-diving can push their dive limits to maximize daily energy intake when energy demands are high and prey are distributed in deep water. Our study highlights late winter as an extremely challenging phase in the annual cycle of North Atlantic murres and provides critical insights into the behavioral mechanisms underlying their winter survival.

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“…Diurnal patterns of foraging activities are typically linked with the behaviour of mobile prey (e.g. diel-vertical migration: Regular et al, 2010), changes in light-levels effecting the detection of prey (Regular et al, 2011), or commuting distances between breeding colonies and foraging areas. However, black guillemots breed locally and probably exploit sessile benthic prey items, whereas light levels would not differ greatly between morning and afternoon periods.…”

Section: Other Conditionsmentioning

confidence: 99%

Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

et al. 2016

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Tidal stream turbines could have several direct impacts upon pursuit-diving seabirds foraging within tidal stream environments (mean horizontal current speeds > 2 ms À1 ), including collisions and displacement. Understanding how foraging seabirds respond to temporally variable but predictable hydrodynamic conditions immediately around devices could identify when interactions between seabirds and devices are most likely to occur; information which would quantify the magnitude of potential impacts, and also facilitate the development of suitable mitigation measures. This study uses shore-based observational surveys and Finite Volume Community Ocean Model outputs to test whether temporally predictable hydrodynamic conditions (horizontal current speeds, water elevation, turbulence) influenced the density of foraging black guillemots Cepphus grylle and European shags Phalacrocorax aristotelis in a tidal stream environment in Orkney, United Kingdom, during the breeding season. These species are particularly vulnerable to interactions with devices due to their tendency to exploit benthic and epi-benthic prey on or near the seabed. The density of both species decreased as a function of horizontal current speeds, whereas the density of black guillemots also decreased as a function of water elevation. These relationships could be linked to higher energetic costs of dives in particularly fast horizontal current speeds (>3 ms À1 ) and deeper water. Therefore, interactions between these species and moving components seem unlikely at particularly high horizontal current speeds. Combining this information, with that on the rotation rates of moving components at lower horizontal current speeds, could be used to assess collision risk in this site during breeding seasons. It is also likely that moderating any device operation during both lowest water elevation and lowest horizontal current speeds could reduce the risk of collisions for these species in this site during this season. The approaches used in this study could have useful applications within Environmental Impact Assessments, and should be considered when assessing and mitigating negative impacts from specific devices within development sites.

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Fishing in the Dark: A Pursuit-Diving Seabird Modifies Foraging Behaviour in Response to Nocturnal Light Levels

Cited by 97 publications

References 36 publications

Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitat

Working the day or the night shift? Foraging schedules of Cory’s shearwaters vary according to marine habitat

Taking the Bite Out of Winter: Common Murres (Uria aalge) Push Their Dive Limits to Surmount Energy Constraints

Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

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