Deep-diving by narwhals Monodon monoceros: differences in foraging behavior between wintering areas?

Laidre, Kristin L.; Heide‐Jørgensen, Mads Peter; Dietz, Runé; Hobbs, Roderick C.; Jørgensen, Ole A

doi:10.3354/meps261269

Cited by 101 publications

(85 citation statements)

References 23 publications

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“…Studies investigating dive behavior in narwhal sexes have been limited by sample size and perhaps, as a result, have documented conflicting results. It has been shown that female narwhals have significantly lower dive rates than males (Heide-Jørgensen and Dietz 1995) and they typically make dives ,400 m (Laidre et al 2004b), but another study reported no difference in diving performance between female narwhals and their male counterparts (Laidre et al 2003). Further evidence is required to support differences in dive behavior between males and females, but given the sexual size dimorphism (Garde et al 2007), males are likely capable of making deeper dives and therefore capable of foraging in the benthos even in deep waters.…”

Section: Values and The Highest Dmentioning

confidence: 99%

How adaptable are narwhal? A comparison of foraging patterns among the world's three narwhal populations

2013

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Abstract. How organisms will fare in the face of climate change depends on their behavioral adaptability to changing conditions. Adaptability in foraging behavior will be particularly critical as food web changes are already occurring in Arctic regions. Stomach contents from narwhals (Monodon monoceros) in the Baffin Bay (BB) population have suggested that narwhals are dietary specialists with little behavioral flexibility, but there are two other narwhal populations in the world, the Northern Hudson Bay (NHB) and East Greenland (EG) populations, of which very little is known about diet. We investigated whether plasticity in foraging behaviors existed among the world's narwhal populations and between sexes by comparing their stable isotope values and niches, and running stable isotope mixing models to determine primary prey. were similar between males and females in each population, and between NHB and BB, but EG narwhals had a significantly larger niche, suggesting they either forage across a larger geographical expanse, or whales within the population employ individual dietary specialization. This is the first study to use stable isotopes to evaluate and compare diet in all three narwhal populations, which is vital for understanding how they will fare in the face of changing climate. We discuss how narwhal are adaptable in their preferred prey and how there is potential for narwhal to adjust foraging behavior in the face of the dramatic ecosystem shifts occurring with climate warming.

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Section: Values and The Highest Dmentioning

confidence: 99%

How adaptable are narwhal? A comparison of foraging patterns among the world's three narwhal populations

2013

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“…Heide-Jørgensen and Bloch, 2002;Laidre et al, 2003;Schorr et al, 2014;Tyack et al 2006). Based on an allometric regression among odontocetes (Schreer and Kovacs, 1997), even a 6,000 kg killer whale would be capable of diving to 885 m and dive durations up to 43 min.…”

Section: Diving Behaviourmentioning

confidence: 99%

Movement and diving of killer whales ( Orcinus orca ) at a Southern Ocean archipelago

Reisinger

Keith

Andrews

et al. 2015

Journal of Experimental Marine Biology and Ecology

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Eleven satellite tags were deployed on 9 killer whales at the Prince Edwards Islands in the Southern Ocean. State-space switching models were used to generate position estimates from Argos location data, while two behavioural modes were estimated from the data. Individuals were tracked for 5.6-53.2 days, during which time they moved 416-4,470 km (mean 82.7 km day -1 ) but 69% of position estimates were within the 1000 m depth contour around the islands (<35 km from the tagging site). Killer whales showed restricted behaviour close to the islands, particularly inshore where they can effectively hunt seals and penguins, and at seamounts to the north of the islands.Generalized linear mixed effect models were used to explore the relationship between environmental variables and behavioural mode. The best model included depth, sea surface temperature, latitude, sea surface height anomaly and bottom slope, but killer whales did not clearly target features such as fronts and apparent mesoscale eddies. Killer whales showed restricted behaviour in shallow water, at high latitudes and low sea surface temperature -the conditions characterising the archipelago.Dive data from two individuals largely revealed shallow dives (7.5-50 m deep), but deeper dive bouts to around 368 m were also recorded. Dives were significantly deeper during the day and maximum dive depths were 767.5 and 499.5 m, respectively. This suggests that killer whales might also prey on vertically migrating cephalopods and perhaps Patagonian toothfish.Three individuals made rapid and directed long-distance movements northwards of the islands, the reasons for which are speculative.

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“…A variety of methods have been used, including satellite tracking (e.g. Laidre et al 2003), stomach content analysis (e.g. Spitz et al 2006), fecal analysis (e.g.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Feeding preferences of West Indian manatees in Florida, Belize, and Puerto Rico as indicated by stable isotope analysis

Alves-Stanley¹,

Worthy²,

Bonde³

2010

Mar. Ecol. Prog. Ser.

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The endangered West Indian manatee Trichechus manatus has 2 recognized subspecies: the Florida T. m. latirostris and Antillean T. m. manatus manatee, both of which are found in freshwater, estuarine, and marine habitats. A better understanding of manatee feeding preferences and habitat use is essential to establish criteria on which conservation plans can be based. Skin from manatees in Florida, Belize, and Puerto Rico, as well as aquatic vegetation from their presumed diet, were analyzed for stable carbon and nitrogen isotope ratios. This is the first application of stable isotope analysis to Antillean manatees. Stable isotope ratios for aquatic vegetation differed by plant type (freshwater, estuarine, and marine), collection location, and in one instance, season. Carbon and nitrogen isotope ratios for manatee skin differed between collection location and in one instance, season, but did not differ between sex or age class. Signatures in the skin of manatees sampled in Belize and Puerto Rico indicated a diet composed primarily of seagrasses, whereas those of Florida manatees exhibited greater regional variation. Mixing model results indicated that manatees sampled from Crystal River and Homosassa Springs (Florida, USA) ate primarily freshwater vegetation, whereas manatees sampled from Big Bend Power Plant, Ten Thousand Islands, and Warm Mineral Springs (Florida) fed primarily on seagrasses. Possible diet -tissue discrimination values for 15 N were estimated to range from 1.0 to 1.5 ‰. Stable isotope analysis can be used to interpret manatee feeding behavior over a long period of time, specifically the use of freshwater vegetation versus seagrasses, and can aid in identifying critical habitats and improving conservation efforts.KEY WORDS: Stable isotope · West Indian manatee · Seagrass · Aquatic plants · 13 C · 15 N · Feeding ecology · Mixing model Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 402: [255][256][257][258][259][260][261][262][263][264][265][266][267] 2010 many other differences in habitat, climate, and population size that have unique effects on the success of each subspecies. Both subspecies appear to require regular year-round access to a freshwater source (Lefebvre et al. 1989, Olivera-Gomez & Mellink 2005, a requirement that is likely a result of osmoregulatory constraints (Ortiz et al. 1998(Ortiz et al. , 1999. Winter habitat use by Florida manatees is primarily influenced by water temperature, whereby physiological constraints require that they aggregate at natural (springs) and/or artificial (power plant outflows) warm water sources when water temperatures drop below 20°C (Irvine 1983, Worthy et al. 2000, Bossart et al. 2003. This pattern is unnecessary for Antillean manatees since their range lies in the tropics where water temperatures are more constant. Population estimates for the Florida manatee suggest counts as high as 3807 individuals (FWC 2009), whereas Antillean manatees are thought to number fewer than 100 individuals ...

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Deep-diving by narwhals Monodon monoceros: differences in foraging behavior between wintering areas?

Cited by 101 publications

References 23 publications

How adaptable are narwhal? A comparison of foraging patterns among the world's three narwhal populations

How adaptable are narwhal? A comparison of foraging patterns among the world's three narwhal populations

Movement and diving of killer whales ( Orcinus orca ) at a Southern Ocean archipelago

Feeding preferences of West Indian manatees in Florida, Belize, and Puerto Rico as indicated by stable isotope analysis

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