Horizontal Habitat Use Research Articles

Horizontal habitat preference of three sympatric Paradoxurinae civet species in a small area in Sabah, Malaysian Borneo

We investigated the horizontal habitat use of three sympatric Paradoxurinae species, the common palm civet Paradoxurus hermaphroditus, the small-toothed palm civet Arctogalidia trivirgata and the binturong Arctictis binturong, occurring within a small area in a lowland dipterocarp rainforest in Sabah, Malaysian Borneo. We evaluated their preference for forests near open-canopy areas (forest edge habitat) or more mature interior forests (interior-forest habitat) by tracking radio-collared civets in their activity and inactivity periods. We demonstrated that all three Paradoxurinae species occurred in the same area, and extensive range overlap indicated lack of interspecific territoriality. The binturong preferred neither forest edge nor interior-forest habitats. Meanwhile, both the common palm civet and the small-toothed palm civet showed a similar preference for forest edge habitats. Food distribution may affect their habitat use. We could not find clear habitat segregation among the three sympatric Paradoxurinae species, but vertical habitat use may also affect their coexistence. Further effort is needed to elucidate both the horizontal and vertical habitat segregation of sympatric Paradoxurinae species.

Importance of multi‐dimensional analyses of resource partitioning in highly mobile species assemblages

AbstractResource partitioning is an essential mechanism enabling species coexistence. The resources that are used by an animal are linked to its morphology and ecology. Therefore, similar species should use similar resources. The ecological niche of an individual summarizes all used resources and is therefore composed of several dimensions. Many methods are established to study different dimensions of an animal's niche. The aim of this study was to demonstrate that a combination of suitable methods is needed to study spatial and dietary resource partitioning of sympatric species in detail. We hypothesized that, while each individual method might identify differences between species, the combined results of several methods will lead to a more complete picture of spatial and dietary resource partitioning. As model organisms we chose the sympatric insectivorous bat species Myotis bechsteinii, M. nattereri, and P. auritus. We examined horizontal habitat use by telemetry, vertical habitat use by measuring δ13C, trophic position by measuring δ15N in wing membrane, and diet composition by molecular fecal analysis. Our results show that each method is able to provide information about spatial/dietary resource partitioning. However, considering further dimensions by combining several methods allows a more comprehensive assessment of dietary and spatial resource partitioning in bats.

Vertical and horizontal habitat use by white marlin Kajikia albida (Poey, 1860) in the western North Atlantic Ocean

Abstract Pop-up satellite archival tags were deployed on 40 white marlin Kajika albida (synonym: Tetrapturus albidus) off the coasts of Maryland and North Carolina (United States), and the island nation of Aruba in the Caribbean. Useful data were available for analysing vertical and horizontal habitat use from 28 individuals. Time at liberty ranged from 10 to 181 d (mean 115, SD 53.3). Seasonal southerly fall migration routes were documented for fish released off the northeastern United States, while those released off Aruba remained in the Caribbean basin. Horizontal movements ranged from 228 to 8084 km (19–100 km d−1) based on light-level geolocation estimates using a sea surface temperature and bathymetry-corrected Kalman filter. Analyses included an evaluation of vertical movements using ΔT, the time spent at temperature relative to the uniform temperature surface layer. Movements included exploration of depths as great as 387 m and ambient temperatures as low as 7.8°C. However, the greatest proportion of time was spent in the upper 20 m of the water column for both day (50.8%) and night (81.6%), and time spent in water colder than 7°C below the uniform temperature surface layer was negligible. Overall, this group showed less variability in vertical movement, and less tolerance to colder temperatures compared with similar studies for blue marlin Makaira nigricans and sailfish Istiophorus platypterus. Values for ΔT are presented in tabular format to allow direct input into habitat standardization models used to estimate vertical distribution and population abundance. The large spatial dispersion and disparate tracks illustrated in the present study serve to underscore the complexity of white marlin behaviour and habitat use, and further emphasize the many challenges facing the management and conservation of this overexploited species.

Frontal zones, temperature gradient and depth characterize the foraging habitat of king penguins at South Georgia

Investigating the responses of marine predators to oceanographic structures is of key importance for understanding their foraging behaviour and reproductive success. Using Global Positioning System (GPS) and Time-Depth-Temperature-Recorder (TDR) tags, we investigated how king penguins breeding at South Georgia explore their foraging area over the summer sea- son in both the horizontal and vertical dimensions. We determined how horizontal habitat use may relate to different Antarctic Circumpolar Current (ACC) frontal zones and associated thermal structuring of the water column. To study the penguins' use of the water column, we examined for- aging niches defined by temperature, temperature gradient and depth, and explored the impor- tance of these thermal properties for prey pursuit. King penguins foraged within the Polar Front (PF) and its southern edges during incubation, and the Antarctic Zone (AAZ) and Southern ACC Front (SACCF) during brooding. Foraging niches became more distinct with the advancing sum- mer season, defined by strong thermal gradients at shallow depths in the AAZ, and weak gradi- ents at greater depths in the SACCF. These niches indicate foraging in the sub-thermocline Winter Water (WW) in the AAZ, and in deep WW and Circumpolar Deep Water (CDW) at the SACCF. The influence of different ACC frontal zones in the area to the north of South Georgia appears to provide for a horizontally and vertically segregated environment. The presence of optional foraging areas and niches close to the colony clearly play an important role in these king penguins' foraging success.

Resource Partitioning in Summer by Salmonids in South-Central Lake Ontario

Abstract During the summers of 1981 and 1982, we studied resource partitioning by stocked lake trout Salvelinus namaycush, brown trout Salmo trutta, and chinook salmon Oncorhynchus tshawytscha by fishing vertical gill nets at six distances from shore in south-central Lake Ontario. The nets were set at depths of approximately 15–45 m (nearshore stations, <4 km offshore) and more than 55 m (offshore stations, 4–24 km offshore). Salmonids were concentrated near shore, where they partitioned available habitat and, thus, food resources. Horizontal habitat was partitioned with respect to distance from shore; vertical habitat was partitioned in relation to temperature and the thermocline. Salmonids foraged for the most available prey items within their habitat. Overlaps in both food use and horizontal habitat use were inversely related to overlap in use of vertical habitat. There was increased habitat separation between sexes for those species caught farther from shore, At the salmonid stocking and prey density ...