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Central-place foraging seabirds increase food-loads and decrease meal frequency when they forage in areas that are distant from the breeding colony. In 2001–2002, we studied the seasonal changes in at-sea distribution, food-load mass, meal frequency, and fledging mass in rhinoceros auklets ( Cerorhinca monocerata), which forage in coastal waters during the day and feed their chicks at night. In both years, greater numbers of auklets were observed flying in northern waters that are more distant from the colony in June (65 km) and July (65–66 km) than in May (38–47 km). In July of both years, many auklets flew northward across the transect set 65–120 km north of the colony at sunrise; the birds returned south again at sunset, indicating that they foraged in waters outside the study area. This seasonal northward movement of the foraging area may reflect the migration of their main prey item, the Japanese anchovy ( Engraulis japonicus), which move with the Tsushima Warm Current flowing from the southern Sea of Japan. Food-load mass did not increase seasonally. In both years, the estimated daily meal frequency was lower in July than in May or June, partly because of the increased foraging distance in July. Late-hatched chicks also displayed lighter fledging masses than early chicks in both years. We suggest that late breeders are required to forage at great distances for longer periods, which may result in decreased meal frequency and lighter fledging mass of their chicks. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the diets of rhinoceros auklets Cerorhinca monocerata breeding in Hokkaido, Japan as well as the relationship between temporal changes in the marine ecosystems of the region. The study found that there were no differences in the diets of rhinoceros auklets between age categories. Moreover, it revealed no differences in the occurrence of Japanese sandlance Ammodytes personatus, Japanese Sea greenling Pleurogrammus azonus and Japanese anchovy Engraulis japonicus between adult and chick diets during the early chick-rearing period.

Sea-surface temperature (SST) directly and indirectly affects the distribution and abundance of prey species for seabirds, so we expect variation in SST to be associated with variation in seabird life history traits. In black-tailed gulls ( Larus crassirostris) at Teuri Island in northern Hokkaido, Japan, we investigated the diet of the gulls prior to egg laying in 2004 and 2005, and examined the influences of SST in March or April, when the gulls congregate in the colony, on egg-laying parameters using 13 years of data (1992–2004). The gulls fed on krill ( Thysanoessa inermis) and fish prior to the egg laying. Mean first egg dates and clutch sizes were significantly and quadratically related to SST anomalies in March, but were not influenced by SST anomalies in April. There was no significant effect of SSTs in either March or April on egg volume. Sea-surface temperature anomalies in March of the years of early laying (−1 to 1°C) were higher than those in 2001 (−2.2°C), but lower than those in 1992 (+1.2°C) and 2004 (+1.1°C). Thysanoessa inermis congregates to spawn at the sea surface, when SSTs rise 3−4°C. Thus, a mismatch between food availability and the timing of egg production in the gulls could have occurred in these 3 years. This study suggests that SST fluctuations prior to laying are important in breeding success of black-tailed gulls. [ABSTRACT FROM AUTHOR]

Flight and diving activity of rhinoceros auklets Cerorhinca monocerata breeding on Teuri Island, Japan, were monitored during the summers 1999 and 2000 using miniaturized time-depth and acceleration recorders. Birds made 14.5 dive bouts per day of on average 15.4 min duration, which consisted of on average 16.2 dives of 12.1 m depth and 42.7 s duration. Birds made 13.8±7.3 flight bouts per day, which lasted on average 11.5±4.5 min. Daily total flight duration was 2.7±1.7 h (range 54 s–5.1 h) and the mean potential foraging range was estimated to be 87 km (maximum 164 km). Most birds stayed at the colony or rested on the water surface during the night. Rhinoceros auklets dived more actively in early morning and in late afternoon than during mid-day. Compared to results from studies of time allocation in other alcids species, rhinoceros auklets spent longer time flying (3.3 hd[sup -1] ) and resting on water (13.1 hd[sup -1] ), and less time diving (3.1 hd[sup -1] ) and staying at the colony (4.4 hd[sup -1] ). These foraging patterns are probably related to the nest attendance pattern of rhinoceros auklets, i.e. leaving the colony early in the morning, staying at sea all the day and returning to the colony in the evening to provision their chicks. [ABSTRACT FROM AUTHOR]

Seabirds are high trophic predators in marine ecosystems and are sensitive to change in food supply and thus seabirds can be used as monitors of the marine environment. In order to study the foraging responses of Japanese cormorants Phalacrocorax filamentosus breeding at Teuri Island, Hokkaido to changes in fish availability, the diet was assessed from the regurgitations of parents and chicks, and diving behavior was measured by using time-depth recorders. Breeding performance (brood size, chick growth, breeding success) was monitored using conventional methods to study their breeding responses. Japanese cormorants changed the diet and foraging behavior over four summers. The birds fed mainly on epipelagic schooling fish when they were available and on demersal fish when pelagic fish availability was low. They tended to dive deeper and longer in a year when they fed mainly on demersal fish than the other years, reflecting the change in the depth distribution of prey fish. Chick growth rate did not differ among years, but fledging success was lower in the years of demersal fish as their meal delivery rate was low. When epipelagic schooling fish were considered scare, parents maintained chick growth by reducing brood size. High variability and unpredictability in pelagic fish abundance are key factors affecting the foraging and breeding performance of Japanese cormorants, which could potentially be used to monitor fish resources. [ABSTRACT FROM AUTHOR]

Examines the feeding rates and energy deficits of adult Japanese monkeys in cool temperate areas. Effect of energy crisis on parental survival and offspring production; Increase of energy base feeding rates with body mass; Accounts on the general pattern of age-sex differences.

We examined the effects of offspring food demand on parental regulation of food provisioning and body condition in a small long-lived seabird, Leach’s storm-petrels (Oceanodroma leucorhoa). In one experimental group, food demand of chicks on their parents was increased by removing one parent (‘single’), and in another group these food demands were decreased by supplementary feeding of chicks (‘supplement’). A further unmanipulated group provided a ‘control’. Feeding frequencies by one parent were higher in the single but lower in the supplement than in the control group, in accordance with the food demand of chicks. The size of meals appeared to be not different among the experimental groups. However, as single parents did not compensate perfectly for the increase of chick food demand by food provisioning, single chicks grew at slower rates and fledged at smaller masses than control chicks. Supplement chicks grew at similar rates and fledged at similar masses as control chicks, because parents decreased food provisioning and food processing capacity of the chicks might be limited. The body condition of parents, which was determined by body mass loss and feather regrowth rate, did not differ among the groups. These results indicate that feeding frequency was regulated by parental decision in this storm-petrel species. Parents may adjust their food provisioning to match the food demand of chicks but within a certain range so as not to deteriorate their own body condition. [ABSTRACT FROM AUTHOR]

Juvenile mortality, a key factor determining the stock sizes of salmonids, may be increased by predation both in rivers and along shores. Information on predation at sea, however, is scarce. We analysed the diet of a pelagic seabird, the rhinoceros auklet Cerorhinca monocerata, breeding on an isolated island off eastern Hokkaido, Japan, and estimated their consumption of juvenile chum salmon Oncorhynchus keta. The auklets brought juvenile chum salmon and Japanese anchovy Engraulis japonicus for their chicks and, in addition, fed on squid themselves. The fork length of most of the juvenile chum salmon was over 80 mm, indicating that they were migrating to offshore nursery area, the Sea of Okhotsk. Using a simple bioenergetics model, the consumption of juvenile chum salmon by auklets during the first half of chick-rearing period (late June to middle July) was 316.6 t in 2014 (296.4 t by adults, 20.2 t by chicks) and 11.7 t in 2015 (0 t by adults, 11.7 t by chicks). The otoliths of six out of 66 juvenile salmon found in the diet for chicks had thermal markings and indicated that these fish were released from the rivers along Pacific coast of Hokkaido. Our study first demonstrates the extent of the auklets' consumption contributing to the reduction of the survival in the open coastal area of juvenile chum salmon with the known stock origins. [ABSTRACT FROM AUTHOR]

Promoting the use of renewable energy and conserving biodiversity are conflicting issues that need addressing. While the development of offshore wind facilities/turbines is accelerating, many seabirds have been exposed to collisions with wind turbines. We must identify high collision areas and avoid the construction of wind turbines in these spaces to reduce these conflicts. One solution is to develop useful finer scale sensitivity maps. In this study, we created a fine-scale map of collision risk by spatial modelling using information from bird flights at sea and explored the relative importance of each geographic variable relevant to the risk. Between 2016 and 2019, we collected 3D-location data from 117 black-tailed gulls (Larus crassirostris) of three colonies in two areas and 21 slaty-backed gulls (L. schistisagus) of four colonies in one area of northern Hokkaido, Japan. The spatial models that explain the occurrence of M-zone flight, which is the flight within the heights of high collision risk (20-140 m height), were constructed at a 1 km mesh using a random forest algorithm, a machine-learning tool. The model satisfactory predicted the spatial distribution of M-zone flights using geographic variables and species (correlation coefficient: 0.57-0.94), although data had some degrees of variation between species, years, colonies, and areas. Our model can be applied to other regions, as long as we have general topological information and the locations of colonies and harbors. The distance to the breeding colony and the nearest harbors were important, and the collision risk was 6-7 times higher within 15 km from the colonies and 5 km from harbors. Black-tailed gulls used different sites for foraging and commuting between years, whereas slaty-backed gulls used relatively consistent sites. These variations between species and among years suggest that collecting bird data over multiple years is necessary and effective for creating a generally applicable sensitivity map., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Habitat use is often examined at a species or population level, but patterns likely differ within a species, as a function of the sex, breeding colony, and current breeding status of individuals. Hence, within-species differences should be considered in habitat models when analyzing and predicting species distributions, such as predicted responses to expected climate change scenarios. Also, species' distribution data obtained by different methods (vessel-survey and individual tracking) are often analyzed separately rather than integrated to improve predictions. Here, we eventually fit generalized additive models for Streaked Shearwaters Calonectris leuconelas using tracking data from two different breeding colonies in the Northwestern Pacific and visual observer data collected during a research cruise off the coast of western Japan. The tracking-based models showed differences among patterns of relative density distribution as a function of life history category (colony, sex, and breeding conditions). The integrated tracking-based and vessel-based bird count model incorporated ecological states rather than predicting a single surface for the entire species. This study highlights both the importance of including ecological and life history data and integrating multiple data types (tag-based tracking and vessel count) when examining species-environment relationships, ultimately advancing the capabilities of species distribution models.

Teuri Island, Hokkaido in Japan is an important place for seabirds breeding. We measured the concentrations of heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn, and Pb) and a metalloid (As) in rhinoceros auklet (Cerorhinca monocerata) (n = 7), thick-billed murre (Uria lomvia) (n = 2), spectacled guillemot (Cepphus carbo) (n = 6), slaty-backed gull (Larus schistisagus) (n = 15), jungle crow (Corvus macrorhynchos) (n = 3), Japanese anchovy (Engraulis japonica) (n = 6) and Atka mackerel (Pleurogrammus azonus) (n = 2). Spectacled guillemot had high As concentrations, with its source being their feeding habitat. Concentration of Hg in kidney of jungle crow was higher than other seabird species at Teuri.

In nest-bound avian offspring, food shortages typically trigger a release of the stress hormone corticosterone (CORT). Recent studies indicate that CORT is passively deposited in the tissue of growing feathers and thus may provide an integrated measure of stress incurred during development in the nest. The current hypothesis predicts that, assuming a constant rate of feather growth, elevated CORT circulating in the blood corresponds to higher levels of CORT in feather tissue, but experimental evidence for nutritionally stressed chicks is lacking. Here, we examined how food limitation affects feather CORT content in the rhinoceros auklet (Cerorhinca moncerata). We (i) used captive chicks reared on control versus restricted diets, and (ii) applied this technique to free-living chicks with unknown nutritional histories that fledged at three separate colonies. We found that (i) feather growth was not affected by experimentally induced nutritional stress; (ii) captive chicks raised on a restricted diet had higher levels of CORT in their primary feathers; (iii) feather CORT deposition is a sensitive method of detecting nutritional stress; and (iv) free-living fledglings from the colony with poor reproductive performance had higher CORT in their primary feathers. We conclude that feather CORT is a sensitive integrated measure revealing the temporal dynamics of food limitations experienced by rhinoceros auklet nestlings. The use of feather CORT may be a powerful endocrine tool in ecological and evolutionary studies of bird species with similar preferential allocation of limited resources to feather development., (© 2014. Published by The Company of Biologists Ltd.)

It is reported that seabirds accumulate high levels of metals, prompting concerns regarding poisoning. The present study investigated the accumulation patterns of metals in tissues among four species of seabirds (Fratercula corniculata, Uria lomvia, Puffinus tenuirostris, and Fulmarus glacialis). Furthermore, we focused on Slaty-backed Gulls, which accumulated high levels of cadmium and mercury, and compared the areal differences. Geographic variation of metal levels could also contribute to differences in metal accumulation levels in these bird species. Therefore, the concentrations of metals in seabirds are considered to reflect their habitat. There are differences in the accumulation pattern among the seabird species. The high accumulation of metals could affect seabirds even if they do not show any symptoms.