Climate change and climate variability have been shown to affect a broad range of species worldwide. As seabirds are likely to be affected by changing climate while breeding on-land and foraging at-sea, their population status and ecological changes are monitored as indicators of ecosystem change. This paper reviews the ecological processes and population consequences of climate impacts on penguins. The review shows that climate change and climate variability are important factors driving the changes in the population size and breeding success of various penguin species (up to 13 of 18 extant species) via changes in their breeding and foraging environments. However, these factors affect penguins in a complex way. For example, the effects of a warming climate can vary from negative to positive in different parts of the distribution range of a single species, or in different life-history parameters within a single population (e.g., breeding success vs. adult survival rates). Some simulation studies have produced future population projections for Antarctic and subantarctic penguins based on multiple climate change scenarios, emphasizing the importance of climate mitigation. The results of these simulations should still be interpreted with caution, while appreciating the uncertainties associated with climate projections and penguin responses to future climate. More research on penguin foraging ecology is needed, especially during data-poor non-breeding or juvenile periods, to elucidate fully the processes of climate impacts on penguins. Finally, mitigating existing human impacts is essential to safeguard penguin species, and will help penguin populations become more resilient to existing and future climate impacts.

Penguins are considered to ingest stones and retain them in the stomach to aid in buoyancy control and digestion, or they may be accidentally ingested while feeding. In this study, we recorded the behavior of several captive Humboldt Penguin Spheniscus humboldti swallowing and regurgitating stones, and examined this behavior in relation to the timing of egg-laying. We found that only females swallowed stones, and they only did so during the egg-laying period. Furthermore, the behavior was concentrated mostly during the period of eggshell formation. These observations suggest that female penguins in captivity may swallow stones intentionally to replenish the calcium they need for eggshell formation.

I constructed a diving model for captive Tufted Duck Aythya fuligula foraging in shallow water in the manner of Little Grebe Tachybaptus ruficollis. This model was based on the assumption that part of the total oxygen uptake at the water surface is used for the bird's own metabolism during the diving interval and the remaining part stored in the lungs and air sacs is allocated to underwater diving. Oxygen utilization efficiency, η, is introduced and defined as the ratio of the oxygen used for diving to the total oxygen uptake. Here, η is formulated by using modified allometric equations relating avian respiratory variables, such as the tidal volume, V_T1, and ventilation rate, V_es, in addition to the metabolic rate during the diving interval, E_MR. On the basis of the oxygen utilization efficiency, η, thus derived, the diving interval, T_p, diving period, T_d, maximum diving period, T_dmax, and average metabolic rate during diving interval and diving period, MR_d, can be predicted. In estimating the diving period, T_d, a total energy loss per unit time during diving is assumed to be a sum of the metabolic rate during the diving interval, E_MR, and energy losses in relation to buoyancy, hydrodynamic drag, and forced convection heat transfer. Comparison of the estimated values of T_p, T_d, T_dmax, and MR_d with their respective measured values reported in literature is made to validate the modified allometric equations, the formula of η, and the assumed total energy loss per unit time during diving.

Bean Goose Anser fabalis middendorffii is one of many waterfowl species wintering in Japan. Flocks of Bean Goose frequently forage on submerged water chestnuts (Trapa species) at their wintering sites which consist of ponds and lakes. While foraging process, the birds did not always eat all of the fruit they picked and discarded many before swallowing them. We hypothesized that the geese select fruits based on their size to achieve high foraging efficiency. To test the prediction, we conducted field research at Katano-kamoike (pond), which is one of the main wintering sites of the species in Honshu. In 2009–2010, 2015–2016, 2016–2017 and 2017–2018, exclosure experiments were conducted to investigate the size of fruits that were consumed. In the exclosures, the density of small water chestnuts was higher and the average dry weight tended to be lighter, suggesting that the geese were selecting small-sized fruits. Observations of foraging behavior showed that small fruits were more frequently eaten than estimated. Additionally, the time required to consume large fruit was three times longer than that for small fruit. These results suggest that Bean Goose selects small water chestnuts for greater foraging efficiency.

We examined stomach contents of 96 Laysan Phoebastria immutabilis and 25 Black-footed Albatrosses P. nigripes caught incidentally in the western North Pacific during 2014–2018. A higher proportion of Laysan Albatross (91%) than Black-footed Albatross (48%) was found to have plastics in their stomachs as has been reported also in the central North Pacific. The mean mass and size of each plastic fragment or pellets were both greater for Laysan (0.073 g, 8.25 mm) than for Black-footed (0.031 g, 5.86 mm) albatross. The difference in the plastic loads between albatross species could not be explained by their overall distributions or diets. The plastic loads of these two albatross species in the northern North Pacific is greater than that in albatrosses caught incidentally or stranded ashore in the western South Pacific, so it is a matter of concern.

We surveyed the distribution and population of the endangered Tiger Shrike Lanius tigrinus breeding along the coast of the Sea of Japan, from the Tohoku to Hokuriku regions in Japan. One hundred and eleven adult males were found during field surveys, at a population density of 5.1 pairs/km². Based on this information, the Maxent models were performed to show the distribution area from Akita through Yamagata to Niigata prefectures. The shrike's preferred main habitat was shown to consist of a mixture of Black Pine Pinus thunbergii woodland and grassland or agricultural land. The total area occupied by the last breeding population left in Japan, was estimated to be just 31.3 km² and the number of pairs was estimated to be only 160. For the conservation of the Tiger Shrike, it is important to conserve areas that combine both Black Pine forest and grassland/agricultural land.

We conducted road-based censuses of the Crested Serpent Eagle Spilornis cheela perplexus on Iriomote Island, southern Japan, and analyzed sightings in relation to the time of day and weather conditions. Eagle numbers were highest in the morning, followed by the evening. Wind speed was negatively correlated with the number of individuals counted during both periods, but there was no relationship with humidity or temperature. As wind speed increased, the posture of perching eagles changes significantly with a greater tendency towards a forward-leaning posture. As the diet of Crested Serpent Eagle consists primarily of nocturnal amphibians and reptiles, food availability is likely increased in the morning and evening. However, windy conditions may incur an increase in energy expenditure for a sit-and-wait predator, consequently resulting in a negative effect on sightings. This study highlights the importance of considering the time and wind speed when analyzing road census results for this species.

The aim of this study was to establish a non-invasive sex identification method for wild Japanese Rock Ptarmigan Lagopus muta japonica using excreta samples. The utility of preexisting primers was evaluated using blood derived from male and female Svalbard Rock Ptarmigan, L. m. hyperboreus. 2550F/2718R were easily able to distinguish DNA fragments by agarose gel electrophoresis. Then, based on this sequence data, we established a new primer set named Lm-F/Lm-R targeting shorter regions. PCR testing was performed on 132 fecal DNA samples from wild Japanese Rock Ptarmigan, using 2550F/2718R or Lm-F/Lm-R to examine the amplified fragment patterns. 2550F/2718R determined the gender of 68 samples, whereas Lm-F/Lm-R determined 89. The concordance rate (with sexing from the bird appearance like plumage and comb at the time of the collection of these samples) was 88.2% for 2550F/2718R and 85.4% for Lm-F/Lm-R. The amplification rate of the Z-chromosome-derived band was 43.6% for 2550F/2718R and 64.4% for Lm-F/Lm-R. Therefore, the PCR amplification rate was improved by using Lm-F/Lm-R. To be shorter the target amplification region, we were able to improve sex identification.