scholarly journals Ecological Specialization and Overlap of Brachyramphus Murrelets in Prince William Sound, Alaska

The Auk ◽  
2003 ◽  
Vol 120 (3) ◽  
pp. 680-699
Author(s):  
Robert H. Day ◽  
Alexander K. Prichard ◽  
Debora A. Nigro
Keyword(s):  
Habitat Use ◽  
Habitat Type ◽  
Late Summer ◽  
Niche Overlap ◽  
Water Clarity ◽  
Turbid Water ◽  
Prince William Sound ◽  
Ecological Specialization ◽  
Marbled Murrelet ◽  
Marbled Murrelets

Abstract We compared habitat use and niche overlap in the closely related seabirds Kittlitz’s (Brachyramphus brevirostris) and Marbled (B. marmoratus) Murrelets in nearshore waters of Prince William Sound, Alaska, in 1996–1998, and examined the relationship between near shore habitat use and morphology of those two species. Within bays, the distribution of Kittlitz’s Murrelet groups diverged the most from randomness for the variables habitat type (preferring [i.e. using significantly more than what is available] glacial-affected and glacial-stream-affected habitats), distance to shore (preferring areas 51–100 m from shore), and water clarity (preferring highly turbid water), whereas the distribution of Marbled Murrelet groups diverged the most from randomness for the variables habitat type (preferring glacial-unaffected habitats), ice cover (preferring areas of no ice), and sea-surface temperature (SST) (preferring temperatures = 6°C). The probability of a group of birds being Kittlitz’s Murrelets was determined most strongly by water clarity. Kittlitz’s Murrelet groups were more common in the more heavily glaciated College and Harriman fjords than in the other two bays and more common in early and midsummer than in late summer; the reverse was true for Marbled Murrelet groups. Marbled Murrelet groups had the least niche overlap with Kittlitz’s Murrelet groups in water clarity, SST, and site, whereas Kittlitz’s Murrelets had the least overlap with Marbled Murrelets in habitat type and water clarity. Similarly, Kittlitz’s Murrelet groups occurred in water significantly more turbid than did Marbled Murrelet groups in two of four habitat types. Kittlitz’s Murrelets had eyes (as indicated by orbit diameter) that were significantly larger in proportional size than Marbled Murrelets. We propose that these two species are specialized for foraging in different water types, with specialization of the Kittlitz’s Murrelet for turbid water of glacial origin leading to optical specialization.

Intraspecific Resource Partitioning by Yellow Perch (Perca flavescens) in a Stratified Lake

1984 ◽  
Vol 41 (12) ◽  
pp. 1745-1752 ◽  
Author(s):  
Mark B. Sandheinrich ◽  
Wayne A. Hubert
Keyword(s):  
Resource Use ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Habitat Type ◽  
Late Summer ◽  
Niche Overlap ◽  
Size Classes ◽  
Use Patterns ◽  
Different Depths ◽  
Food Partitioning

Summer habitat use and relative abundances of different size classes of yellow perch (Perca flavescens) were determined using gill nets set in the main basin, deep bays, and shallow bays of a lake. Niche overlap indices were used to quantify resource use patterns. Size classes spatially segregated into different habitats, but not different depths within a habitat type. Segregation of sexes at different depths was observed with females occupying warm, shallow areas, whereas males were more common in cool, deep water. Formation of an anoxic hypolimnion restricted perch to the epilimnion in late summer, but patterns of habitat segregation observed prior to thermocline formation were maintained. Food partitioning was relatively unimportant in reducing niche overlap. Spatial segregation of perch size classes and sexes may compensate for high diet overlap between conspecifics and reinforces the importance of habitat partitioning in structuring fish communities.

Overwinter thermal habitat use in lakes by anadromous Arctic char

2018 ◽  
Vol 75 (12) ◽  
pp. 2343-2353 ◽  
Author(s):  
Ingeborg M. Mulder ◽  
Corey J. Morris ◽  
J. Brian Dempson ◽  
Ian A. Fleming ◽  
Michael Power
Keyword(s):  
Habitat Use ◽  
Water Column ◽  
Prey Capture ◽  
Salvelinus Alpinus ◽  
Late Summer ◽  
Arctic Char ◽  
Foraging Efficiency ◽  
Thermal Habitat ◽  
Metabolic Costs ◽  
Seaward Migration

Anadromous Arctic char (Salvelinus alpinus) migrate back to fresh water in late summer to spawn and (or) overwinter. Upon freshwater entry, feeding is reduced or absent, and movement activity is restricted. While the physiological responses to low temperatures (e.g., growth, metabolism) are understood, specifics of the use of thermal habitat for overwintering remains poorly characterized. This study used acoustic and archival telemetry data from two lakes in southern Labrador, Canada, to study thermal habitat use during the ice-covered period. Results showed that lake-dwelling anadromous Arctic char predominantly occupied a narrow range of temperatures (0.5–2 °C) and used cooler temperatures available within the middle and upper water column. Use of the selected temperatures is likely a strategy that lowers metabolic costs and minimizes energy expenditure, preserving stored lipids for overwinter survival and the energetic costs of preparation for seaward migration. As Arctic char are visual feeders, use of the upper water column is also thought to aid foraging efficiency by increasing the likelihood of prey capture.

scholarly journals Habitat use by mountain nyala Tragelaphus buxtoni determined using stem bite diameters at point of browse, bite rates, and time budgets in the Bale Mountains National Park, Ethiopia

2013 ◽  
Vol 59 (6) ◽  
pp. 707-717 ◽  
Author(s):  
Solomon A. Tadesse ◽  
Burt P. Kotler
Keyword(s):  
Habitat Use ◽  
National Park ◽  
Habitat Type ◽  
Time Budgets ◽  
Non Invasive ◽  
Wildlife Species ◽  
Focal Animal ◽  
Northern Edge ◽  
Browse Species ◽  
Invasive Techniques

Abstract We studied the habitat use of mountain nyala Tragelaphus buxtoni in the northern edge of the Bale Mountains National Park, Ethiopia. The aims of this study were to: (1) measure and quantify habitat-specific stem bite diameters of mountain nyala foraging on common natural plant species in two major habitat types (i.e. grasslands versus woodlands), and (2) quantify the bite rates (number of bites per minute) and the activity time budgets of mountain nyala as functions of habitat type and sex-age category. We randomly laid out three transects in each habitat type. Following each transect, through focal animal observations, we assessed and quantified stem diameters at point of browse (dpb), bite rates, and time budgets of mountain nyala in grasslands versus woodlands. Stem dpb provide a measure of natural giving-up densities (GUDs) and can be used to assess foraging costs and efficiencies, with greater stem dpb corresponding to lower costs and greater efficiencies. The results showed that stem dpb, bite rates, induced vigilance, and proportion of time spent in feeding differed between habitats. In particular, mountain nyala had greater stem dpb, higher bite rates, and spent a greater proportion of their time in feeding and less in induced vigilance in the grasslands. In addition, adult females had the highest bite rates, and the browse species Solanum marginatum had the greatest stem dpb. Generally, grasslands provide the mountain nyala with several advantages over the woodlands, including offering lower foraging costs, greater safety, and more time for foraging. The study advocates how behavioural indicators and natural GUDs are used to examine the habitat use of the endangered mountain nyala through applying non-invasive techniques. We conclude that the resulting measures are helpful for guiding conservation and management efforts and could be applicable to a number of endangered wildlife species including the mountain nyala.

scholarly journals Ready for bed: pre-hibernation movements and habitat use by Fowler’s Toads (Anaxyrus fowleri)

2018 ◽  
Vol 132 (1) ◽  
pp. 46-52
Author(s):  
David M. Green ◽  
Katharine T. Yagi
Keyword(s):  
Habitat Use ◽  
Global Positioning System ◽  
Late Summer ◽  
The Body ◽  
Positioning System ◽  
Radio Tracking ◽  
Water Line ◽  
Global Positioning ◽  
Radio Transmitters ◽  
Early Fall

We used radio-tracking to investigate movement patterns and habitat use of Fowler’s Toads (Anaxyrus fowleri) during late summer and early fall in a relatively undisturbed lakeshore dune and beach habitat at Long Point, Ontario. Small radio transmitters were fitted to 11 adult toads with an external harness made from fine surgical plastic tubing wrapped around the body behind the front limbs. We located radio-tagged toads morning and evening, for a maximum of 9 days, recording their locations using Global Positioning System units. Initially, the toads were located on the upper beach or in the fore-dunes during the day, either dug in under the sand or hiding beneath debris; in the evening, they were generally active on the lower beach close to the water line. After a storm and the onset of cooler autumn weather, the toads tended to move further from the water line. They also curtailed their nightly activity and retreated deeper into the sand. As this sort of behaviour was not observed during the summer, we interpret it as pre-hibernation movement to more stable sites away from the beach where the animals can burrow deeply into the sand to lie dormant during the winter.

A 28-years-long monitoring study suggests heavy decline and habitat shifts in three populations of a Mediterranean tortoise species

2020 ◽  
Vol 71 (1) ◽  
pp. 21-35
Author(s):  
Lorenzo Rugiero ◽  
Massimo Capula ◽  
Daniele Dendi ◽  
Fabio Petrozzi ◽  
Massimiliano Di Vittorio ◽  
...  
Keyword(s):  
Habitat Use ◽  
Linear Models ◽  
Central Italy ◽  
Habitat Type ◽  
Thermal Ecology ◽  
Ecological Studies ◽  
Monitoring Study ◽  
Testudo Hermanni ◽  
Selection Of

Abstract Long-term ecological studies are important for understanding wild populations’ dynamics and processes and the actual factors that can determine their decline. Here, we report the results of a 28-years-long (1992–2019) monitoring of three distinct populations of a tortoise, Testudo hermanni, in Central Italy, with an emphasis on their population abundance trends and on the eventual variation in their habitat use across years and among the study areas. Samplings were conducted by Visual Encounter Survey (VES) methodology, and using a suite of statistical analyses including correlations and Generalized Linear Models analyses. Our data showed a statistically significant decline in tortoise sightings through time, and concurrently also a variation in habitat use by tortoises. In all the three study areas, we observed a significant increase of tortoise sighting frequency in the habitat type characterized by high (>taller than 200 cm) shrubby and wooded vegetation. Since our analyses revealed no significant change in the habitat type availability by year in each study area, we suggest that T. hermanni was increasingly selecting closed vegetation spots throughout the years. We hypothesize that this observed trend of shift in habitat selection could be due to lowering their body temperatures to prevent overheating. So, the selection of more covered spots would be a thermal ecology adaptive consequence of the ongoing global warming.

Habitat selection and home-range dynamics of the Gaspé caribou: a hierarchical analysis

2003 ◽  
Vol 81 (7) ◽  
pp. 1174-1184 ◽  
Author(s):  
Arnaud Mosnier ◽  
Jean-Pierre Ouellet ◽  
Luc Sirois ◽  
Nelson Fournier
Keyword(s):  
Home Range ◽  
Habitat Use ◽  
Rangifer Tarandus ◽  
Large Diameter ◽  
Habitat Type ◽  
Spatial And Temporal Scales ◽  
Management Plans ◽  
Forested Areas ◽  
Range Dynamics ◽  
Snow Conditions

We used several spatial and temporal scales to determine space and habitat use of the caribou (Rangifer tarandus caribou) of the Gaspé Peninsula. Thirty-five radio-collared caribou were followed from November 1998 to April 2001. Habitat use was studied by superimposing radiolocations on ecoforestry maps using five predefined habitat types (deciduous, immature, mature spruce, mature fir, and barren). At a finer scale, we tracked caribou in forested areas during winter 2000 and 2001 in order to describe physical and biological characteristics of foraging tracks and used stands. Our results indicated that the distribution of caribou extended beyond the limits of Gaspé Conservation Park. Patterns of space use showed the existence of three groups, which formed a metapopulation. These groups consisted of spatially distinct units that used space and habitat differently. At the home-range level, caribou preferred barren areas found in alpine and subalpine zones at all times of the year. The most frequently used forested habitat type was the mature fir. At the finer scale of foraging tracks, caribou selected fir stands characterized by dense snow conditions and large diameter trees bearing greater quantities of lichen. Our results demonstrated the importance of protecting areas outside the park that are likely to become used or reused by caribou, and of managing these areas to increase settlement by caribou. Lastly, management plans must be adapted to each of the three groups forming this metapopulation.

scholarly journals Activity Patterns of Marbled Murrelets in Douglas-Fir Old-Growth Forests of the Oregon Coast Range

The Condor ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 275-285 ◽  
Author(s):  
Patrick G. R. Jodice ◽  
Michael W. Collopy
Keyword(s):  
Daily Activity ◽  
Spatial Scales ◽  
Activity Patterns ◽  
Daily Basis ◽  
Data Sets ◽  
Coast Range ◽  
Oregon Coast Range ◽  
Oregon Coast ◽  
Marbled Murrelet ◽  
Marbled Murrelets

Abstract We monitored activity patterns of Marbled Murrelets (Brachyramphus marmoratus) on a near-daily basis using audio-visual surveys during three breeding seasons at five forest stands in the Oregon Coast Range. Three measures of activity were recorded: number of daily detections, number of daily vocalizations, and duration of daily activity. Each measure was highly variable within and among stands and years, and we recorded greater variability than has been previously reported for this species. The three measures of activity were strongly correlated within a day at each survey station, but correlative relationships at temporal and spatial scales greater than this were inconsistent. Activity varied greatly from one day to the next during all portions of the breeding season, and we did not identify any month when variability in activity was consistently higher or lower than any other month. Multivariate analyses revealed that weather and date variates explained little of the variability in daily activity. Given the extreme levels of variability in Marbled Murrelet activity and our lack of understanding as to which factors drive that variability, it is critical that conclusions about activity or behavior not be drawn from data sets not specifically designed to answer the questions of interest.

scholarly journals Habitat use and abundance of goliath grouper Epinephelus itajara in Brazil: a participative survey

2014 ◽  
Vol 12 (4) ◽  
pp. 803-810 ◽  
Author(s):  
Vinicius J. Giglio ◽  
Johnatas Adelir-Alves ◽  
Leopoldo C. Gerhardinger ◽  
Fabiano C. Grecco ◽  
Felippe A. Daros ◽  
...  
Keyword(s):  
Habitat Use ◽  
Marine Protected Areas ◽  
Habitat Type ◽  
Population Recovery ◽  
Conservation Policies ◽  
Conservation Measures ◽  
Highly Sensitive ◽  
Significant Difference ◽  
Goliath Grouper ◽  
The Relationship

Developing survey strategies for threatened species is often limited by access to sufficient individuals to acquire information needed to design appropriate conservation measures. The goliath grouper (Epinephelus itajara) is a large reef fish, globally classified as critically endangered. In Brazil, fishing has been prohibited since 2002. Herein we investigated habitat use and abundance of E. itajara in Brazil drawn from a participative survey, which engaged volunteer divers in data-collection. A total of 188 reports were recorded between 2005 to 2011 throughout 13 Brazilian states. Our results revealed that habitat type influenced the relationship between total length and depth of occurrence of E. itajara. We observed a significant difference between habitats, artificial presented a nonlinear and natural an asymptotic relationship. This study underscores the importance of developing conservation measures addressing specific habitats and locations to enhance population recovery. Artificial structures (shipwrecks and manmade reefs) are critical habitats that must be considered as highly sensitive areas to E. itajara strategic conservation policies. We suggest the creation and implementation of marine protected areas, as key strategies for E. itajaraconservation, especially for artificial habitats and aggregation sites.

scholarly journals Influence of Niche Overlap and Territoriality on Hybridization Between Hermit Warblers and Townsend's Warblers

The Auk ◽  
2000 ◽  
Vol 117 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Scott F. Pearson ◽  
David A. Manuwal
Keyword(s):  
Habitat Use ◽  
Hybrid Zone ◽  
Parental Species ◽  
Niche Overlap ◽  
Habitat Characteristics ◽  
Hybrid Zones ◽  
Parental Fitness ◽  
Habitat Transition ◽  
Habitat Variables ◽  
Washington Cascades

Abstract Hybrid zones between Townsend's Warblers (Dendroica townsendi) and Hermit Warblers (D. occidentalis) in the Pacific Northwest are narrow relative to estimated dispersal distances and appear to be moving, with Townsend's replacing Hermits. We examined whether the habitat-transition and parental-fitness asymmetry models can explain why these zones are narrow and moving by comparing habitat variables associated with warbler territories in the Washington Cascades hybrid zone. Habitat variables did not differ among phenotypes, suggesting that the habitat-transition model cannot explain the narrow and dynamic nature of this hybrid zone. Habitat characteristics of Hermit Warbler territories did not differ inside versus outside the hybrid zone, also suggesting that this zone is not associated with a region of habitat transition. The lack of difference in habitat use could be the result of comparing variables that are not important to pairing success. However, warblers tended to select territories on west-southwest aspects. South aspects in the southern Washington Cascades are dominated by Douglas fir (Pseudotsuga menziesii) and true fir, which is a habitat selected by female warblers when choosing among territories and males. The parental-fitness asymmetry model does not necessarily make predictions about habitat use within the hybrid zone but predicts the superiority of one parental species over the other. However, if significant overlap occurs in habitat use or niche (as in these warblers), then competition between parental species is likely to occur. To determine whether these species compete, we mapped 12 warbler territories and monitored an additional 94 territories throughout the breeding season and found that all males with neighbors compete for and hold exclusive territories. Thus, the pattern of habitat use and territoriality is consistent with the parental-fitness asymmetry model.

scholarly journals Foraging Success and Foraging Habitat Use by Cattle Egrets and Little Egrets in the Camargue, France

The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Katia Lombardini ◽  
Robert E. Bennetts ◽  
Christophe Tourenq
Keyword(s):  
Habitat Use ◽  
Habitat Type ◽  
Foraging Success ◽  
Foraging Habitat ◽  
Mixed Species ◽  
Habitat Types ◽  
Southern France ◽  
Bubulcus Ibis ◽  
Egretta Garzetta ◽  
Selection Of

Abstract We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.

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