scholarly journals Foraging segregation of two congeneric diving seabird species (common and thick-billed murres) breeding on St. George Island, Bering Sea

2015 ◽  
Vol 12 (21) ◽  
pp. 18151-18183 ◽  
Author(s):  
N. Kokubun ◽  
T Yamamoto ◽  
N. Sato ◽  
Y. Watanuki ◽  
A. Will ◽  
...  
Keyword(s):  
Foraging Behavior ◽  
Bering Sea ◽  
Environmental Changes ◽  
Dive Depth ◽  
Bottom Phase ◽  
Flight Duration ◽  
Seabird Species ◽  
Top Predators ◽  
Data Loggers ◽  
Two Peaks

Abstract. Sub-arctic environmental changes are expected to affect the ecology of marine top predators. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabirds, common (Uria aalge: hereafter COMU) and thick-billed (U. lomvia: hereafter TBMU) murres breeding on St. George Island located in the seasonal sea-ice region of the Bering Sea. We investigated their flight duration, diel patterns of dive depth, and underwater wing strokes, along with morphology and blood stable isotopes. Acceleration-temperature-depth data loggers were attached to chick-guarding birds, and behavioral data were obtained from 7 COMU and 12 TBMU. Both species showed similar trip duration (13.21 ± 4.79 h for COMU and 10.45 ± 7.09 h for TBMU) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, dive depths of COMU had two peaks in shallow (18.1 ± 6.0 m) and deep (74.2 ± 8.7 m) depths, while those of TBMU were 20.2 ± 7.4 m and 59.7 ± 7.9 m. COMU showed more frequent wing strokes during the bottom phase of dives (1.90 ± 0.11 s−1) than TBMU (1.66 ± 0.15 s−1). Fishes occurred with higher proportion in the bill-loads brought back to chicks in COMU (85 %) than in TBMU (56 %). δ15N value of blood was significantly higher in COMU (14.47 ± 0.27 ‰) than in TBMU (13.14 ± 0.36 ‰). Relatively small wing area (0.053 ± 0.007 m2) of COMU compared to TBMU (0.067 ± 0.007 m2) may make them more agile underwater and thus enable them to target more mobile prey including larger fishes that inhabit deeper depths. These differences in foraging behavior between COMU and TBMU might explain the differences in their responses to long-term marine environmental changes.

scholarly journals Foraging segregation of two congeneric diving seabird species breeding on St. George Island, Bering Sea

2016 ◽  
Vol 13 (8) ◽  
pp. 2579-2591 ◽  
Author(s):  
Nobuo Kokubun ◽  
Takashi Yamamoto ◽  
Nobuhiko Sato ◽  
Yutaka Watanuki ◽  
Alexis Will ◽  
...  
Keyword(s):  
Bering Sea ◽  
Environmental Changes ◽  
Foraging Ecology ◽  
Stress Hormones ◽  
Food Resource ◽  
Dive Depth ◽  
Bottom Phase ◽  
Seabird Species ◽  
Top Predators ◽  
The Bering Sea

Abstract. Subarctic environmental changes are expected to affect the foraging ecology of marine top predators, but the response to such changes may vary among species if they use food resources differently. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabird: common (Uria aalge: hereafter COMUs) and thick-billed (U. lomvia: hereafter TBMUs) murres breeding on St. George Island, located in the seasonal sea-ice region of the Bering Sea. We investigated their foraging trip and flight durations, diel patterns of dive depth, and underwater wing strokes, along with wing morphology and blood stable isotope signatures and stress hormones. Acceleration–temperature–depth loggers were attached to chick-guarding birds, and data were obtained from 7 COMUs and 12 TBMUs. Both species showed similar mean trip duration (13.2 h for COMUs and 10.5 h for TBMUs) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, the dive depths of COMUs had two peaks in shallow (18.1 m) and deep (74.2 m) depths, while those of TBMUs were 20.2 m and 59.7 m. COMUs showed more frequent wing strokes during the bottom phase of dives (1.90 s−1) than TBMUs (1.66 s−1). Fish occurred more frequently in the bill loads of COMUs (85 %) than those of TBMUs (56 %). The δ15N value of blood was significantly higher in COMUs (14.5 ‰) than in TBMUs (13.1 ‰). The relatively small wing area (0.053 m2) of COMUs compared to TBMUs (0.067 m2) may facilitate their increased agility while foraging and allow them to capture more mobile prey such as larger fishes that inhabit deeper depths. These differences in food resource use may lead to the differential responses of the two murre species to marine environmental changes in the Bering Sea.

scholarly journals Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

2015 ◽  
Vol 12 (21) ◽  
pp. 17693-17720 ◽  
Author(s):  
T. Yamamoto ◽  
N. Kokubun ◽  
D. M. Kikuchi ◽  
N. Sato ◽  
A. Takahashi ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Bering Sea ◽  
Physiological Stress ◽  
Ocean Basin ◽  
Ecosystem Dynamics ◽  
Seabird Species ◽  
Oceanic Basin ◽  
Top Predators ◽  
Differential Responses ◽  
Year 2013

Abstract. Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to the inter-annual change in environmental conditions. Between the study years, winter ice retreated earlier and summer water temperatures were warmer in 2014 compared to those in 2013. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf, but showed a relatively higher use of the shelf break and oceanic basin in the colder year, 2013. The foraging distances from the colony peaked at 250–300 km in 2013 and, bimodally, at 150–250 and 300–350 km in 2014 for RLKI, and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between years in RLKI, but differed in TBMU, showing higher levels of physiological stress incurred by murres during the colder year, 2013. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU, while δ13C (a proxy of prey origin) were lower in 2014 than in 2013 in both species, suggesting possible differences in influx of oceanic prey items into foraging areas. These results suggest that the response of ecosystem dynamics to climate variability in the southeast Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those habitats for foraging.

Diving behavior of an epipelagically feeding alcid, the Rhinoceros Auklet (Cerorhinca monocerata)

2003 ◽  
Vol 81 (7) ◽  
pp. 1249-1256 ◽  
Author(s):  
Maki Kuroki ◽  
Akiko Kato ◽  
Yutaka Watanuki ◽  
Yasuaki Niizuma ◽  
Akinori Takahashi ◽  
...  
Keyword(s):  
Feeding Habits ◽  
Dive Depth ◽  
Diving Behavior ◽  
Bottom Phase ◽  
Cerorhinca Monocerata ◽  
The Hours ◽  
Small Bird ◽  
Rhinoceros Auklet ◽  
Ascent Phase ◽  
Horizontal Bottom

The diving behavior of Rhinoceros Auklets (Cerorhinca monocerata) breeding at Teuri Island, Hokkaido, Japan, was studied using small bird-borne time–depth dataloggers. The eight auklets made dives without an obvious horizontal bottom phase to a median depth of 14.0 ± 1.8 (mean ± SD) m (maximum 57 m) for 53 ± 8 s (maximum 148 s) between the hours of 0300 and 2000. They made undulations (rapid depth changes), considered to represent prey pursuit, in 35% of the dives. Of the undulations, 57% occurred during the deep (>80% of maximum depth) parts of the dives and 26% during the ascent phase. The auklets performed 26 ± 31 dives continuously during dive bouts of 32 ± 34 min. Dive bouts at the end of the day were twice as long as in the morning and at midday. During dive bouts, the auklets showed consistent trends in dive depth, decreasing (23% of bouts), increasing (32%), or stable (19%), but sometimes they showed hectic depth changes (26%). V-shaped dives (with no horizontal bottom phase), potential prey pursuit in both the deep parts and ascent phases of the dives, and variable depth changes within dive bouts indicate the auklets' epipelagic feeding habits.

scholarly journals The relationship between pink salmon biomass and the body condition of short-tailed shearwaters in the Bering Sea: can fish compete with seabirds?

2011 ◽  
Vol 278 (1718) ◽  
pp. 2584-2590 ◽  
Author(s):  
Kanako Toge ◽  
Rei Yamashita ◽  
Kentaro Kazama ◽  
Masaaki Fukuwaka ◽  
Orio Yamamura ◽  
...  
Keyword(s):  
Body Condition ◽  
Bering Sea ◽  
Pink Salmon ◽  
The Body ◽  
Oncorhynchus Gorbuscha ◽  
Catch Per Unit Effort ◽  
Study Region ◽  
Top Predators ◽  
The Relationship ◽  
The Bering Sea

Seabirds and large fishes are important top predators in marine ecosystems, but few studies have explored the potential for competition between these groups. This study investigates the relationship between an observed biennial change of pink salmon ( Oncorhynchus gorbuscha ) biomass in the central Bering Sea (23 times greater in odd-numbered than in even-numbered years) and the body condition and diet of the short-tailed shearwater ( Puffinus tenuirostris ) that spends the post-breeding season there. Samples were collected with research gill nets over seven summers. Both species feed on krill, small fishes and squid. Although the mean pink salmon catch per unit effort (in mass) over the study region was not related significantly with shearwater's stomach content mass or prey composition, the pink salmon biomass showed a negative and significant relationship with the shearwater's body mass and liver mass (proxies of energy reserve). We interpret these results as evidence that fishes can negatively affect mean prey intake of seabirds if they feed on a shared prey in the pelagic ecosystem.

scholarly journals DISTRIBUTION AND POPULATION STRUCTURE OF THE INVASIVE AMPHIPOD GMELINOIDES FASCIATUS (STEBBING) IN LAKE ONEGO

2017 ◽  
Vol 1 ◽  
pp. 259
Author(s):  
Anastasiia Sidorova ◽  
Lidia Belicheva
Keyword(s):  
Alien Species ◽  
Environmental Changes ◽  
Vegetation Period ◽  
Amphipod Species ◽  
Gmelinoides Fasciatus ◽  
Artificial Ecosystems ◽  
Littoral Biotopes ◽  
One Year ◽  
Invasive Amphipod ◽  
Two Peaks

Since the middle of the ХХ century, the rapid spread of exotic species and their successful penetration in natural and artificial ecosystems has led to significant environmental changes all over the world [1, 2]. As it was pointed out by many researchers, biological invasion by alien species is one of the main threats to biodiversity [3, 4, 5, 6, 7]. Gmelinoides fasciatus (Stebbing 1899) attracts special attention due to the fact that it is the most successful alien species among other invaders in aquatic ecosystems in Eurasia. This invasive amphipod of Baikalian origin was first recorded in Lake Onego in 2001 by Berezina and Panov [8]. The results of the present study indicate that the invader significantly expanded its areal in Lake Onego during the last 15 years. At present amphipod G. fasciatus is dominant on the biomass among macrozoobenthos community in littoral biotopes of some islands and east part of the Lake. In Lake Onego the invader has a one-year life cycle with the generations of the previous and current year. Seasonal dynamics of the amphipod abundance in Lake Onego has two peaks during the vegetation period. According to our data G. fasciatus successfully reproduces in the new environment and shows stable sexual structure with sex ratio of approximately 1:1. Female fecundity of the amphipod in the Lake varied from 3 to 22 eggs per female, the average variation of fertility is 9 eggs per female. Revealed data of G. fasciatus abundance and biomass in Lake Onego are comparable with those for other water bodies where this amphipod species was successfully established earlier.

scholarly journals Essential Physiological Differences Characterize Short- and Long-Lived Strains of Drosophila melanogaster

2018 ◽  
Vol 74 (12) ◽  
pp. 1835-1843 ◽  
Author(s):  
Nina Gubina ◽  
Alba Naudi ◽  
Rhoda Stefanatos ◽  
Mariona Jove ◽  
Filippo Scialo ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life Span ◽  
Foraging Behavior ◽  
Animal Species ◽  
Environmental Changes ◽  
Mitochondrial Gene ◽  
Genetic Component ◽  
Wild Type ◽  
Aging Research ◽  
Type Strains

Abstract Aging is a multifactorial process which affects all animals. Aging as a result of damage accumulation is the most accepted explanation but the proximal causes remain to be elucidated. There is also evidence indicating that aging has an important genetic component. Animal species age at different rates and specific signaling pathways, such as insulin/insulin-like growth factor, can regulate life span of individuals within a species by reprogramming cells in response to environmental changes. Here, we use an unbiased approach to identify novel factors that regulate life span in Drosophila melanogaster. We compare the transcriptome and metabolome of two wild-type strains used widely in aging research: short-lived Dahomey and long-lived Oregon R flies. We found that Dahomey flies carry several traits associated with short-lived individuals and species such as increased lipoxidative stress, decreased mitochondrial gene expression, and increased Target of Rapamycin signaling. Dahomey flies also have upregulated octopamine signaling known to stimulate foraging behavior. Accordingly, we present evidence that increased foraging behavior, under laboratory conditions where nutrients are in excess increases damage generation and accelerates aging. In summary, we have identified several new pathways, which influence longevity highlighting the contribution and importance of the genetic component of aging.

Heart rates of northern elephant seals diving at sea and resting on the beach.

1997 ◽  
Vol 200 (15) ◽  
pp. 2083-2095 ◽  
Author(s):  
R D Andrews ◽  
D R Jones ◽  
J D Williams ◽  
P H Thorson ◽  
G W Oliver ◽  
...  
Keyword(s):  
Heart Rate ◽  
Dive Depth ◽  
Dive Duration ◽  
Cardiac Response ◽  
Elephant Seals ◽  
Heart Rates ◽  
Data Loggers ◽  
Long Duration ◽  
Northern Elephant Seals ◽  
Instantaneous Heart Rate

Heart rates of northern elephant seals diving at sea and during apnoea on land were monitored to test whether a cardiac response to submergence is an important factor in their ability to make repetitive, long-duration dives. Seven juvenile northern elephant seals were captured at Año Nuevo, CA, instrumented and translocated to release sites around Monterey Bay. Heart rate and dive depth were recorded using custom-designed data loggers and analogue tape monitors during the seals' return to Año Nuevo. Heart rates during apnoea and eupnoea were recorded from four of the seals after they hauled out on the beach. Diving patterns were very similar to those of naturally migrating juveniles. The heart rate response to apnoea at sea and on land was a prompt bradycardia, but only at sea was there an anticipatory tachycardia before breathing commenced. Heart rate at sea declined by 64% from the surface rate of 107 +/- 3 beats min-1 (mean +/- S.D.), while heart rate on land declined by 31% from the eupnoeic rate of 65 +/- 8 beats min-1. Diving heart rate was inversely related to dive duration in a non-linear fashion best described by a continuous, curvilinear model, while heart rate during apnoea on land was independent of the duration of apnoea. Occasionally, instantaneous heart rate fell as low as 3 beats min-1 during diving. Although bradycardia occurs in response to apnoea both at sea and on land, only at sea is heart rate apparently regulated to minimise eupnoeic time and to ration oxygen stores to ensure adequate supplies for the heart and brain not only as the dive progresses normally but also when a dive is abnormally extended.

scholarly journals Seabirds as samplers of the marine environment – a case study of northern gannets

Ocean Science ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 337-347 ◽  
Author(s):  
Stefan Garthe ◽  
Verena Peschko ◽  
Ulrike Kubetzki ◽  
Anna-Marie Corman
Keyword(s):  
Wind Farms ◽  
Distribution Patterns ◽  
Dive Depth ◽  
Sea Surface ◽  
Breeding Colony ◽  
Data Loggers ◽  
Interdisciplinary Approaches ◽  
Different Types ◽  
Daylight Period

Abstract. Understanding distribution patterns, activities, and foraging behaviours of seabirds requires interdisciplinary approaches. In this paper, we provide examples of the data and analytical procedures from a new study in the German Bight (North Sea) tracking northern gannets (Morus bassanus) at their breeding colony on the island of Heligoland. Individual adult northern gannets were equipped with different types of data loggers for several weeks, measuring geographic positions and other parameters mostly at 3–5 min intervals. Birds flew in all directions from the island to search for food, but most flights targeted areas to the (N)NW (north–northwest) of Heligoland. Foraging trips were remarkably variable in duration and distance; most trips lasted 1–15 h and extended from 3 to 80 km from the breeding colony on Heligoland. Dives of gannets were generally shallow, with more than half of the dives only reaching depths of 1–3 m. The maximum dive depth was 11.4 m. Gannets showed a clear diurnal rhythm in their diving activity, with dives being almost completely restricted to the daylight period. Most flight activity at sea occurred at an altitude between the sea surface and 40 m. Gannets mostly stayed away from the wind farms and passed around them much more frequently than flying through them. Detailed information on individual animals may provide important insights into processes that are not detectable at a community level.

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