Masayuki Senzaki

Traffic noise reduces foraging efficiency in wild owls.

Anthropogenic noise has been increasing globally. Laboratory experiments suggest that noise disrupts foraging behavior across a range of species, but to reveal the full impacts of noise, we must examine the impacts of noise on foraging behavior among species in the wild. Owls are widespread nocturnal top predators and use prey rustling sounds for localizing prey when hunting. We conducted field experiments to examine the effect of traffic noise on owls’ ability to detect prey. Results suggest that foraging efficiency declines with increasing traffic noise levels due to acoustic masking and/or distraction and aversion to traffic noise. Moreover, we estimate that effects of traffic noise on owls’ ability to detect prey reach >120 m from a road, which is larger than the distance estimated from captive studies with bats. Our study provides the first evidence that noise reduces foraging efficiency in wild animals, and highlights the possible pervasive impacts of noise.

Surrogate species versus landscape metric: does presence of a raptor species explains diversity of multiple taxa more than patch area?

Prioritizing conservation areas is a central theme in conservation biology. The use of surrogate species and landscape metrics to identify areas with high conservation value is common. However, few studies have examined the relative efficacy of these two surrogates. In this study, we compared the efficacy of the presence/absence (PA) of a top predator (Eastern Marsh Harrier, Circus spilonotus) and wetland patch area on species richness, total abundance, and community composition of birds, plants, and small mammals, but species richness and community composition only for plants, in a fragmented wetland landscape. Although harrier PA was an effective indicator of the distribution of birds, it had no significant efficacy on the distributions of plants and small mammals. Patch area was more effective indicator of the distributions of plants and small mammals. These results suggest that surrogate species can be more effective indicators than landscape surrogates when there are ecological linkages between surrogate species and the focal taxa (e.g., similarity of habitat requirements between surrogate species and focal taxa or hetero-specific attraction). On the other hand, landscape surrogates would be useful when ecological knowledge about the relationships is limited.

Foraging Tactics and Success of Inter- and Intra-Specific Kleptoparasites on Rhinoceros Auklets Cerorhinca monocerata

Abstract Diurnal gulls and skuas, which depend mostly on visual cues during kleptoparasitic attacks, experience reduced predation success when low light conditions or dense vegetation impair prey visibility. Rhinoceros Auklets Cerorhinca monocerata lose prey to kleptoparasitic conspecifics and kleptoparasitic gulls. The return of adult auklets to their colony was observed and incidences of inter- and intra-specific kleptoparasitism were recorded in five study sites with high and low vegetation coverage under variable conditions of illumination. Whereas gulls (Black-tailed Larus crassirostris and Slaty-backed L. schistisagus) mainly attacked auklets in flight in the early evening and from distances exceeding five metres, auklets attacked later in the evening after auklet numbers on the ground had increased, and only when closer than two metres. Intra-specific kleptoparasitism occurred less frequently in sites with dense vegetation and where the visible range was short. These findings indicate that environmental factors facilitating kleptoparasitism among gulls (aerial pirates) and auklets (close-quarter terrestrial pirates) are different.

Can Charismatic Megafauna Be Surrogate Species for Biodiversity Conservation? Mechanisms and a Test Using Citizen Data and a Hierarchical Community Model

Charismatic megafauna are a conservation concern and a flagship of conservation for many other species in the practice of biodiversity conservation. However, some studies support the roles of charismatic megafauna while others do not. In this chapter, we review the ecological mechanisms of why charismatic megafauna can be surrogate species. Based on the niche theory, specialist charismatic species, such as umbrella species, are likely to be surrogate species for richness or abundance of specialist species sharing the same niche axis. Citizen data are promising for testing this hypothesis; however, they are usually collected in a spatially biased manner, which hampers their usage. Here we analyzed citizen data with a hierarchical community model accounting for sampling processes and mapped Hokkaido bird species richness at different resolutions. By overlaying these maps with the distributions of Blakiston’s fish owl and red-crowned crane breeding sites, we show that these sites had higher forest or grassland/wetland bird species richness. Furthermore, the surrogacy was scale-dependent. Conservation practices entail social costs, and continued focus on the role of surrogate species would be due to public understanding and support being prerequisites for their implementation. We advocate selecting species with charismatic features and umbrella roles or flagship-umbrella species, given the strengths and limitations of surrogate schemes, as they play prominent roles linking biodiversity conservation and society.

Mobbing call experiment suggests the enhancement of forest bird movement by tree cover in urban landscapes across seasons

Mobbing call experiment suggests the enhancement of forest bird movement by tree cover in urban landscapes across seasons Atsushi Shimazaki , Yuichi Yamaura , Masayuki Senzaki , Yuki Yabuhara 1 and Futoshi Nakamura 1 Graduate School of Agriculture, Hokkaido University, Department of Forest Vegetation, Forestry and Forest Products Research Institute, Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies

Effects of Land Use and Climate on the Distribution of the Jungle Nightjar Caprimulgus indicus in Hokkaido, Northern Japan

Abstract Although the relative importance of land use and climate to large-scale bird distributions has received great attention, it is difficult to separate the effects of land use and climate, and there are few studies on bird abundance distributions on a large scale. Here, we examined the effects of land use and climate on the abundance of the nocturnal Jungle Nightjar Caprimulgus indicus in Hokkaido, northern Japan. We chose 125 sampling sites with low correlations (|r|<0.58) between land use and climate, and combined a playback method with a hierarchical model (N-mixture model). We thereby accounted for the possibility that we could not detect all individuals during the field survey. Results show that Jungle Nightjar abundance was greater at sites within a 4—km radius of moderate forest cover (∼75%) and with high average temperatures during the breeding season. Moreover, the effects of land-use were greater than those of climate. Mapping predictions of Jungle Nightjar abundance indicated that suitable areas are distributed in southern and central Hokkaido and around the margins of montane zones. Factoring in the covariation of land use and climate, land use may be the most important driver of the distribution of the Jungle Nightjar in Hokkaido.

Status of the Spectacled Guillemot (Cepphus carbo) in Japan

Abstract. —The Spectacled Guillemot (Cepphus carbo) is a seabird endemic to northeastern Asia. It is listed as a “Vulnerable” species in Japan, though little is known of its population status. Population surveys were carried out during 2011–2014 throughout their range in northern Japan. Twenty-eight known and six suspected breeding colonies were reported in this region during 1875–2010. Fourteen known and four suspected breeding colonies were found in the 2011–2014 surveys, with 1,169 individuals and 294 nests. Based on our analysis of the two survey periods, 19 colonies have apparently disappeared, and populations have decreased in 12 of the current colonies. Our models indicated that colonies with small numbers of individuals were most likely to disappear, whereas other environmental factors (i.e., colony type, latitude, and SST trends) had relatively minimal effects on local colony extirpation. Our study shows that the population status of the Spectacled Guillemot has deteriorated in Japan.