Species Habitat (species + habitat)

Distribution by Scientific Domains


Selected Abstracts


Distribution of migratory fishes and shrimps along multivariate gradients in tropical island streams

JOURNAL OF FISH BIOLOGY, Issue 2 2001
E. Fièvet
Among the 16 species of fishes and shrimps studied at 51 sites along several small streams at Basse Terre, Guadeloupe, Lesser Antilles, more than 60% showed a spatial distribution significantly influenced by environmental conditions. These included altitude, basin size, terrestrial vegetation and land use. However, the range of the species habitat was generally high, except for three species limited to the downstream stretches (two fishes and one shrimp). The habitat characteristics of fish and shrimp species tended to differ, but the difference was not significant (P<0·05). On the contrary, the habitat characteristics of amphidromous and catadromous species clearly differed, with a lower occurrence at the most elevated sites of catadromous species than amphidromous species. [source]


Fauna habitat modelling and mapping: A review and case study in the Lower Hunter Central Coast region of NSW

AUSTRAL ECOLOGY, Issue 7 2005
BRENDAN A. WINTLE
Abstract Habitat models are now broadly used in conservation planning on public lands. If implemented correctly, habitat modelling is a transparent and repeatable technique for describing and mapping biodiversity values, and its application in peri-urban and agricultural landscape planning is likely to expand rapidly. Conservation planning in such landscapes must be robust to the scrutiny that arises when biodiversity constraints are placed on developers and private landholders. A standardized modelling and model evaluation method based on widely accepted techniques will improve the robustness of conservation plans. We review current habitat modelling and model evaluation methods and provide a habitat modelling case study in the New South Wales central coast region that we hope will serve as a methodological template for conservation planners. We make recommendations on modelling methods that are appropriate when presence-absence and presence-only survey data are available and provide methodological details and a website with data and training material for modellers. Our aim is to provide practical guidelines that preserve methodological rigour and result in defendable habitat models and maps. The case study was undertaken in a rapidly developing area with substantial biodiversity values under urbanization pressure. Habitat maps for seven priority fauna species were developed using logistic regression models of species-habitat relationships and a bootstrapping methodology was used to evaluate model predictions. The modelled species were the koala, tiger quoll, squirrel glider, yellow-bellied glider, masked owl, powerful owl and sooty owl. Models ranked sites adequately in terms of habitat suitability and provided predictions of sufficient reliability for the purpose of identifying preliminary conservation priority areas. However, they are subject to multiple uncertainties and should not be viewed as a completely accurate representation of the distribution of species habitat. We recommend the use of model prediction in an adaptive framework whereby models are iteratively updated and refined as new data become available. [source]


The use of breeding sites of Tilapia congica (Thys & van Audenaerde 1960) to delineate conservation sites in the Lake Tumba, Democratic Republic of Congo: toward the conservation of the lake ecosystem

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2010
Bila-Isia Inogwabini
Abstract To guide the zoning process in Lake Tumba, Democratic Republic of Congo, breeding sites of Tilapia congica were studied. Physical metrics measured were: nest depths, exposure to sun rays, distance from the edges, site spreads, and habitat types. Mean nest depth = 0.23 m ± 0.08 (SD), range = 0.04,2.2 m (n = 553 nests); 100% (n = 70 sites) sites were exposed to the sun and the polynomial regression analysis showed 90% sites were within the range 51,250 m from the lake shores (y = ,1.7143x2 + 10.371x, 1.8; R2 = 0.597, n = 70 sites), with 60% clumped within the range of 51,150 m, indicating a relationship between nesting sites and the distance from edges. The largest group spread group was 300 m, and among the four breeding sites identified, one was ,10 km long, meaning a zonal spatial spread , = 300 ha and a core reproduction zone ,, = 100 ha. T. congica built 87.30% of their nest in habitats where Hippo grass Vossia cuspidata (48.20%) and Water lily Nympheae stellata (39.10%) dominated. T. congica shared 41.81% of its nesting sites with other fish species, leading to the conclusion that protecting the species habitats would provide the umbrella for the conservation of other species. Résumé Pour orienter le processus de zonage au lac Tumba, en République Démocratique du Congo, nous avons étudié les sites de reproduction de Tilapia congica. Les paramètres physiques mesurés étaient : la profondeur des nids, l'exposition aux rayons du soleil, la distance par rapport à la berge, l'étendue des sites et les types d'habitat. La profondeur moyenne des nids = 0,23 m ± 0,08 (DS), le domaine vital du nid = 0,04,2,2 m (n = 553 nids); 100% des sites (n = 70) étaient exposés au soleil, et l'analyse de la régression polynomiale a montré que 90% des sites se trouvaient entre 51 et 250 m des berges du lac (y = ,1,7143x2 + 10,371x , 1,8; R2 = 0,597; n = 70 sites) et 60% d'entre eux étaient rassemblés à une distance comprise entre 51 et 150 m des berges, ce qui indique une relation entre les sites de nidification et la distance par rapport aux berges. Le groupe le plus étendu avait 300 m et, parmi les quatre sites de reproduction identifiés, un avait , 10 km de long, ce qui signifie une dispersion spatiale zonale , = 300 ha et une zone de reproduction centrale ,' = 100 ha. Les T.congica construisent 87,30% de leurs nids dans des habitats où dominent l'herbe à hippos Vossia cuspidata (48,20%) et les nénuphars Nymphea stellata (39,10%). Les T. congica partagent 41,81% de leurs sites de nidification avec d'autres espèces de poissons, d'où la conclusion que la protection des habitats de cette espèce fournirait aussi une protection à d'autres espèces. [source]


Habitat selection by Ortolan Buntings Emberiza hortulana in post-fire succession in Catalonia: implications for the conservation of farmland populations

IBIS, Issue 4 2009
MYLES H. M. MENZ
The Ortolan Bunting Emberiza hortulana is a long-distance migrant that has suffered major population declines across much of its European breeding range. While northern populations are bound largely to farmland, Mediterranean populations are largely confined to habitats subject to recurrent wildfires. Habitat selection of the Ortolan Bunting was assessed in a recently burnt area in Catalonia at landscape and habitat scales. A Zero-inflated Poisson procedure was used to model the abundance of birds in relation to landscape and habitat variables. The most parsimonious landscape model predicted the highest abundance on south-facing slopes, with a gradient above 10°. The most parsimonious habitat model showed a positive quadratic effect of bare ground and regenerating oak Quercus spp., with predicted optima for abundance around 20,30% and 20% cover, respectively. There was a clear relationship between predicted abundance of the Ortolan Bunting and post-fire regenerating oak shrubs. South-facing, moderately sloping areas were favoured and bare ground was a key feature of the species' habitat. A matrix combining patches of sparse oak shrubs and patches of bare ground appears to be the optimal breeding habitat in the Mediterranean. The maintenance or provision of similar habitat features, especially patches of bare ground, may prove crucial for the conservation of rapidly declining Ortolan Bunting populations on farmland across temperate Europe. [source]


Patterns of commonness and rarity in central European birds: reliability of the core-satellite hypothesis within a large scale

ECOGRAPHY, Issue 4 2002
David Storch
The frequency distribution of species' area of occupancy is often bimodal, most species being either very rare or very common in terms of number of occupied sites. This pattern has been attributed to the nonlinearity associated with metapopulation dynamics of the species, but there are also other explanations comprising sampling artifact and frequency distribution of suitable habitats. We tested whether the bimodal frequency distribution of occupied squares in central European birds could be derived solely from the frequency distribution of species population sizes (i.e. the sampling artifact hypothesis) or from the spatial distribution of their preferred habitats. Both models predict high proportion of very common species, i.e. the right side of frequency distribution. Bimodality itself is well predicted by models based on random placement of individuals according to their abundances but neither model predicts the observed prevalence of rare species. Even the combined models that assume random placement of individuals within the squares with suitable habitat do not predict such a high proportion of rare species. The observed distribution is more aggregated, rare species occupying a smaller portion of suitable habitat than predicted on the basis of their abundance. The pattern is consistent with metapopulation processes involving local population extinctions. The involvement of these processes is supported by two further observations. First, species rarity is associated with significant population trend and/or location on the edge of their ranges within central Europe, both situations presumably associated with metapopulation processes. Second, suitable habitats seem to be either saturated or almost unoccupied, which is consistent with the predictions of the metapopulation model based on nonlinear dynamics of extinction and colonization. Although the habitat suitability is an important determinant of species distribution, the rarity of many species of birds within this scale of observation seems to be affected by other factors, including local population extinctions associated with fragmentation of species' habitats. [source]


Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitats

PLANT CELL & ENVIRONMENT, Issue 12 2001
J. Cavender-Bares
Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source]