Flexible Habitat Research Articles

Importance of seagrass-mangrove continuum as feeding grounds for juvenile pink ear emperor Lethrinus lentjan in Setiu Lagoon, Malaysia: Stable isotope approach

The commercially important pink ear emperor fish, Lethrinus lentjan, often occurs as a juvenile in subtropical and tropical interlinked mangrove and seagrass ecosystems, but little is known about its feeding habits and habitat use. Here, we used gut contents and stable isotopic (δ13C and δ15N) ratios to determine temporal changes in food sources and foraging habits of juvenile and sub-adult fish collected in mangrove forests and seagrass beds in the Setiu Lagoon. Gut content examination identified the main food sources as crustaceans, gastropods, bivalves, and annelids. Stable isotope analysis of food sources showed marked differences between the mangroves (δ13C = −26.8 ± 2.0‰; δ15N = 4.3 ± 1.7‰) and the seagrasses (mean ± S.D. δ13C = −20.5 ± 5.5‰; δ15N = 5.8 ± 1.2‰). The isotopic composition of L. lentjan revealed that it mainly utilized seagrass-based food sources. Rainfall and the semi-diurnal tidal regimes may affect the foraging habitats of fish in the lagoon. A significant depletion of 13C related to body size was observed, suggesting that mangroves provided some benefits to sub-adult fish. In contrast, trophic position increased with fish growth, although this increase was negligible. A stable isotope mixing model confirmed that the seagrass bed constituted the main carbon source for the fish, but with an increasing contribution of mangrove prey, such as sesarmid crabs, related to fish growth. This study provided novel information on seasonal variations in feeding areas and flexible habitat use in L. lentjan in the Setiu Lagoon, which will help optimize management strategies for sustainable use and wildlife conservation.

Flexible habitat selection paves the way for a recovery of otter populations in the European Alps

Carnivores are threatened worldwide through habitat loss and persecution. Habitat destruction is a major threat for the Eurasian otter. Its populations declined drastically in Europe but are now expanding again, including into the Alps. Here, flood prevention and hydropower have massively altered the riverine landscapes.We evaluated the recovery potential of otters by testing the impact of major factors of habitat transformation and human disturbance on multiple spatial scales. In a hierarchical approach, we investigated spatial use and foraging habitat selection of nine otters in a long-term radiotracking study in the eastern Central Alps. We combined fine scale habitat selection analysis with individual movements by applying a step-selection function approach to the linear river system in a novel way.At home range scale, otters preferred the main riverbeds to abstracted water and tributaries, whereas at fine scale, there was no significant preference for pristine sections within the watercourses. Otters selected for reservoirs in streams with a width smaller than 12m and otherwise preferred foraging in residual waters and stretches with main discharge.At this stage of recovery, otters show a surprising flexibility in their habitat selection. This is promising for the species' future expansion into former abandoned areas. However, given that the traditional fish stocking regime might contribute to this recovery by providing profitable hunting grounds after stocking events, there is an increased risk of human-wildlife conflicts. Our results demonstrate a high adaptability of a threatened carnivore to altered landscapes and show how this flexible behaviour opens opportunities for recovery.

Linking Dynamic Habitat Selection with Wading Bird Foraging Distributions across Resource Gradients.

Species distribution models (SDM) link species occurrence with a suite of environmental predictors and provide an estimate of habitat quality when the variable set captures the biological requirements of the species. SDMs are inherently more complex when they include components of a species’ ecology such as conspecific attraction and behavioral flexibility to exploit resources that vary across time and space. Wading birds are highly mobile, demonstrate flexible habitat selection, and respond quickly to changes in habitat quality; thus serving as important indicator species for wetland systems. We developed a spatio-temporal, multi-SDM framework using Great Egret (Ardea alba), White Ibis (Eudocimus albus), and Wood Stork (Mycteria Americana) distributions over a decadal gradient of environmental conditions to predict species-specific abundance across space and locations used on the landscape over time. In models of temporal dynamics, species demonstrated conditional preferences for resources based on resource levels linked to differing temporal scales. Wading bird abundance was highest when prey production from optimal periods of inundation was concentrated in shallow depths. Similar responses were observed in models predicting locations used over time, accounting for spatial autocorrelation. Species clustered in response to differing habitat conditions, indicating that social attraction can co-vary with foraging strategy, water-level changes, and habitat quality. This modeling framework can be applied to evaluate the multi-annual resource pulses occurring in real-time, climate change scenarios, or restorative hydrological regimes by tracking changing seasonal and annual distribution and abundance of high quality foraging patches.

Roe deer at risk: teasing apart habitat selection and landscape constraints in risk exposure at multiple scales

Non‐consumptive effects of predators result from the cost of responses to perceived risk. Prey modulate risk exposure through flexible habitat selection at multiple scales which, in interaction with landscape constraints, determines their use of risky habitats. Identifying the relative contributions of landscape constraints and habitat selection to risk exposure is a critical first step towards a mechanistic understanding of non‐consumptive effects.Here, we provide an integrative multi‐scale study of roe deer spatial responses to variable hunting pressure along a landscape gradient of open habitats and dispersed refuges. Between low‐risk and high‐risk periods, we investigated shifts in 1) home‐range location, 2) probability of using risky habitats (between‐habitat scale) and 3) distance to the nearest refuge (within‐habitat scale). For 2) and 3), we disentangled the contributions of landscape constraints and habitat selection to risky habitat use.We found that when risk was high, roe deer did not shift their home‐range, but generally decreased their use of risky habitats, and sometimes reduced their distance to cover (particularly older animals). There was a functional response in between‐habitat selection, with animals living in more open landscapes responding more than those living in landscapes with more refuges. However, individuals living in more open landscapes avoided open risky habitat less. Finally, we found that among‐individual variation in risk exposure was generally, but not always, minimized by habitat selection across gradients of landscape constraints.To our knowledge, this is the first study simultaneously documenting prey responses to risk at the within‐habitat, between‐habitat and home‐range scales. Our results support the view that between‐habitat selection acts at a higher hierarchical level than within‐habitat selection, and provide a framework for disentangling the contributions of habitat selection and landscape constraints to risk exposure. Selection cannot always compensate for landscape constraints, indicating a need for further investigation of the processes underlying habitat selection.

Body size distribution demonstrates flexible habitat shift of green turtle (Chelonia mydas)

Green turtles (Chelonia mydas), listed as Endangered on the IUCN redlist, have a broad migration area and undergo a habitat shift from the pelagic (hatchling) to neritic (growth) zones. We studied habitat utilisation of the coastal feeding grounds around Okinawajima Island, Japan, in 103 green turtles. The western and eastern turtle aggregations off Okinawa had homogeneous genetic compositions, but different body size distributions. The western coastal feeding ground supported larger individuals than the eastern coastal feeding ground. Thus, green turtles appear to prefer different feeding grounds during their growth, and have a flexible habitat shift including a secondary habitat shift from east to west around Okinawajima Island after they are recruited to the coastal habitats. This study suggests maintaining coastal habitat diversity is important for green turtle conservation.

Flexible habitat selection by cougars in response to anthropogenic development

Large carnivore populations are imperiled worldwide through habitat loss, insufficient prey, and intolerance by people, promoting concerns that their populations will persist only in protected areas and remote regions. This assumption is challenged by recent colonization of areas with high human use in the former ranges of several carnivore species, including cougars (Puma concolor). We hypothesized that cougars adjust their behavior to accommodate anthropogenic development, facilitating successful use of modified habitats. We tested this hypothesis using resource selection functions for 42 individual cougars maintaining home ranges across a gradient of anthropogenic development. We evaluated variation in selection among individual cougars by time of day, home-range location (i.e., rural vs. wilderness cougars), and using functional response curves. Cougars stayed further away from both roads and buildings during the day than they did at night, and wilderness cougars showed stronger avoidance of anthropogenic features than did their rural counterparts. Selection patterns of individual cougars varied greatly, and some of this variation was explained by the functional response. For example, cougars decreased their avoidance of some anthropogenic features as those features became more prevalent on the landscape. Failure to account for potential functional responses in habitat selection could lead to overestimation of negative impacts of development for adaptable large carnivores. Given high adaptability to anthropogenic habitat modification displayed by cougars, cougar persistence in increasingly developed landscapes may depend more on human tolerance than on maintaining large tracts of pristine wilderness.

High plasticity in habitat use of Lycengraulis grossidens (Clupeiformes, Engraulididae)

In this study, we analyzed the Sr:Ca and Ba:Ca ratios of the otoliths of 139 Lycengraulis grossidens individuals sampled along the southwestern Atlantic Ocean, including two freshwater areas, to describe patterns of habitat use and their latitudinal organization. Otolith sections were analyzed by laser ablation inductively coupled plasma mass spectrometry along core-to-edge transects. Otolith edge analysis revealed significant differences in Sr:Ca and Ba:Ca ratios between fish from freshwater habitats and those from estuarine/marine habitats, indicating that these ratios may be used to describe habitat use patterns. Lifetime transects of Sr:Ca and Ba:Ca indicate at least four distinct habitat use patterns: freshwater residents, estuarine/marine residents, and two distinct diadromous/nomadic types. Most individuals (88.6%) sampled at northern latitudes in sheltered marine bays and the coastal ocean were estuarine/marine residents, whereas at southern latitudes, most individuals were diadromous (72.5%). We also identified landlocked populations in the Uruguay River and in Mirim Lagoon. These results suggest that L. grossidens exhibits flexible habitat use strategies and may use freshwater, estuarine and marine environments throughout their lifetime.

Stand structure and small mammals in intensively managed forests: Scale, time, and testing extremes

Stand thinning and fertilization have the potential to create a diversity of forest habitat conditions to meet the goals of biodiversity conservation while sustaining wood and biomass production. Three factors are crucial to a better scientific understanding of how wildlife habitats develop in managed forests: real-world scale of treatments using adaptive management, several decades of time to monitor responses, and the testing of extreme treatments. Communities of arboreal and forest-floor small mammals occupy young coniferous stands and may serve as indicators of change in forest structure and function, and hence biodiversity. We tested the hypotheses (H) that, when compared with unmanaged (unthinned and old-growth) stands, large-scale pre-commercial thinning (PCT) and PCT with repeated fertilization, up to 16–21years after the onset of treatments, would enhance (H1) stand structure, (H2) abundance of southern red-backed voles (Myodes gapperi) and species diversity of forest-floor small mammals, and (H3) abundance of northern flying squirrels (Glaucomys sabrinus), in young lodgepole pine (Pinus contorta) stands in the south-central interior of British Columbia, Canada.Mean diameters and heights of crop trees in thinned stands were less than those in old-growth stands, but the low-density stands did have greater mean diameters than those in unthinned stands. Mean crown volume of pine crop trees was significantly greater in the low- and medium-density stands than in the high-density, unthinned, or old-growth stands. Mean density of overstory (range of 1010–1590 stems/ha) and understory conifers were similar in the thinned and old-growth stands. Mean species and structural diversity of total conifers were significantly higher in the heavily thinned (⩽1000stems/ha) than other stands. For vascular plants, mean abundance of understory herbs and total structural diversity were higher in heavily thinned and fertilized stands. Thus, some aspects of stand structure supported H1 while others did not.Mean abundance of M. gapperi was higher in old-growth forest than the younger managed and unthinned stands, except in years of low numbers, and hence did not support H2 that these treatments over a longer time-frame would enhance abundance of this species. Fluctuations in numbers, drier forest ecosystems, and slow development of forest-floor habitat with decaying woody debris and fungi may contribute to flexible habitat occupancy for M. gapperi. The second part of H2, that mean species diversity of forest-floor small mammals would be enhanced in heavily thinned and fertilized stands tended to be supported, particularly in the period prior to canopy closure. H3, that abundance of G. sabrinus would be maintained at levels recorded in old-growth forests by PCT of young stands, was supported for medium- and high-density stands.A sustained flow of wood products and structural features with their habitats for wildlife and biodiversity should be achievable with a wide range of stand densities from PCT and variable regimes of nutrient additions in intensively managed forests. Essential key elements include large-scale (operational-size) treatment units and long-term monitoring of installations over decades, preferably at 5- to 10-year intervals.

PolydomousCrematogaster pilosa(Hymenoptera: Formicidae) Colonies Prefer Highly Connected Habitats in a Tidal Salt Marsh

High productivity in salt marshes creates an attractive resource base for terrestrial consumers, but regular tidal inundation creates a harsh environment. numerous terrestrial organisms have adapted to living in salt marshes by timing activity cycles and vertical movements to tidal cycles, while others exhibit physiological adaptations, increasing their tolerance to submersion (Foster 1983; Vaughn & Fisher 1992; petillon et al. 2009). one of the species able to withstand these harsh conditions is the ant Crematogaster pilosa (emery) (Hymenoptera: Formicidae), which has been reported to nest in hollow stems of salt marsh vegetation ranging from Florida to north carolina (davis & gray 1966; mccoy & rey 1987), as well as in trees in mesic forests and within stems of upland plants (teal 1962; Johnson 1988; morgan 2010). little is known about C. pilosa (synonymous with C. clara; Johnson 1988) with the exception of its flexible habitat requirements. the objective of this study was to examine the basic colony attributes and habitat preferences of C. pilosa in a saltmarsh cordgrass [Spartina alterniflora loisel (poales: poaceae)] dominated salt marsh on sapelo island, georgia. connectivity in the S. alterniflora canopy, dead and living stem densities, and maximum stem height were evaluated to examine the influence of habitat structure on ant densities. in october 2011, two marsh transects stretching from the forest edge to the bank of a large tidal creek were demarcated and divided into fourteen 10 × 2 m sections. ant density was sampled in 4 randomly selected 2 m2 quadrats per section by sweep netting for 15 seconds. percent vegetation cover was estimated from photographs taken from ground level and converted to binary sky/ vegetation images using imageJ software. living and dead stem density and tallest stem height were measured in 4 haphazardly placed quadrats (0.25 m2) within a subset of 9 sections. Workers from 15 nests were enumerated, and the presence of eggs or pupae was recorded. to evaluate tidal inundation relative to nest height, 5 fence posts with cups attached at 5 cm intervals covering the lower range of observed nest heights were deployed. Flooded cups were recorded daily for 4 days, which included some of the highest local tides of 2011. the spatial extent and number of colonies examined in this study are small, limiting the potential for generalization to other colonies and habitats. square-root transformed ant densities showed a positive correlation with percent vegetation cover (Fig. 1) when data were averaged over 20 m2 transect sections (r2 = 0.50, p = 0.003). no relationship was found between ant density and living stem density (r2 = 0.21, p = 0.22), dead stem density (r2 = 0.06, p = 0.53), or tallest stem height (r2 = 0.10, p = 0.42). mean nesting stem and entrance heights were 44.6 cm (sd = 14.4) and 35.3 cm (sd = 10.6), respectively. the maximum observed tidal height from substrate was less than 20 cm, and minimum nest entrance height was 21 cm (Fig. 2). nests averaged 242 workers (range: 53-1106, sd = 276), which is conservative because some workers were foraging at the time of collection. eggs and pupae were found in 87% and 46% of the nests, respectively. Workers were observed traveling and carrying eggs among 21 nests within

Releasing Stored Solar Energy within Pond Scum: Biodiesel from Algal Lipids

Microalgae have emerged as an attractive feedstock for the mass production of renewable transportation fuels due to their fast growth rate, flexible habitat preferences, and substantial oil yields. As an educational tool, a laboratory was developed that mimics emerging algal biofuel technology, including the extraction of algal lipids and transesterification into biodiesel. First, students were introduced to algae as an energy feedstock and taught how to cultivate and harvest algal biomass. Next, students learned how to convert algal biomass to a transportation fuel using transesterification and extraction, including an experimental comparison of base- and acid-catalyzed transesterification methods. The energy content of homemade algae biodiesel was determined and compared to soybean biodiesel and petroleum diesel using a homemade calorimeter.

Clearcutting forestry and Eurasian boreal forest grouse: Long-term monitoring of sympatric capercaillie Tetrao urogallus and black grouse T. tetrix reveals unexpected effects on their population performances

Along the succession gradient of the boreal forest ecosystem, black grouse Tetrao tetrix inhabits the early and capercaillie Tetrao urogallus the latest stages. When converting old forest to clearcuts and plantations, commercial forestry has therefore been assumed to affect capercaillie negatively and to be favourable to black grouse. During a 30-year period (1979–2008) we monitored sympatric populations of the two species in a forest in southeast Norway based on annual spring and autumn censuses and radio-marked birds. During this period, the proportion of old, semi-natural forest was halved and clearcuts and young plantations increased accordingly. The grouse populations did not change as predicted. While the trend in August numbers of adult black grouse declined, males more than females, abundance of adult capercaillie remained unchanged. Number of males at leks showed similar patterns. Equally surprising, breeding success (number of chicks per female in August) of both species increased, thus indicating that the populations were regulated more by variation in adult survivorship than by recruitment of young birds. No correlations were found with changing climatic factors (precipitation and temperatures in winter and spring, snow depth and time of snow melt), except that year-to-year breeding success was positively correlated with minimum temperatures during 2 weeks posthatch. The results are explained by a combination of more flexible habitat selection than previously assumed and a changing predator regime: In the early period, nearly all capercaillie leks were located in old, semi-natural forest, but as plantations grew older (>30 years), new leks were established there. Similarly, while young capercaillie broods used old semi-natural forest almost exclusively when the study started, they frequently used middle-aged plantations, especially those with a ground cover of bilberry Vaccinium myrtillus, when these became common in later years. The increasing breeding success could largely be explained by more females rearing chicks successfully, presumably due to a marked decline in the main nest predator, the red fox Vulpes vulpes. A practice of thinning of the old, semi-natural forest some years prior to final harvesting probably facilitated predation of black grouse by goshawks Accipiter gentilis. Contrary to many beliefs, our results indicate that both capercaillie and black grouse are quite tolerant to changes in forest management regimes. In our study, numerical and functional responses of predators (mainly red fox and goshawk) apparently played a more important role in regulating grouse numbers than habitat factors per se.

Habitat use and habitat transitions in the tropical eel, Anguilla bicolor bicolor

Recently, the migratory history of temperate species of anguillid eels has been intensively studied using analytical microchemical techniques to determine the ratios of strontium to calcium (Sr:Ca) in the otoliths. However, there have been few studies of this nature on tropical anguillid eel species. To elucidate the migration ecology of the freshwater eel genus Anguilla, as well as its life history and habitat use, we examined the otolith Sr and Ca concentrations of a tropical anguillid eel Anguilla bicolor bicolor collected in Indonesian waters. In A. bicolor bicolor collected in a lagoon area, the change in Sr:Ca ratios outside the high Sr:Ca core showed two patterns of habitat use, (1) constantly living in either brackish or sea waters with no freshwater life (residents, 37%), and (2) habitat shift from freshwater to brackish or sea waters (migrants, 63%). For migrant fishes, most fish shifted their residence between 520 and 950 μm (mean: 740 μm) from the otolith core. These transitions suggest that these specimens moved to a higher salinity environment. The wide range of otolith Sr:Ca ratios (0.02 × 10−3 to 12.79 × 10−3 in all analytical points outside of 150 μm from the core of all otoliths) in A. bicolor bicolor indicated that the habitat use of the tropical eel was facultative among fresh, brackish and marine waters during their growth phases after recruitment to the coastal areas. This flexible habitat use was the same as that of temperate eels. Thus, the migrations of anguillid eels into freshwater is clearly not an obligatory behavior.

Intra‐seasonal changes in distribution and habitat associations of a multi‐brooded bird species: implications for conservation planning

AbstractIntra‐seasonal changes of the ecological needs and the distribution patterns of multi‐brooded bird species are a poorly studied but potentially important topic in avian conservation planning. In this study of a passerine species of conservation concern, the woodlark Lullula arborea, we highlight the conservation implications of spatial shifts of breeding territories and changes of habitat requirements during the course of the breeding season. We described the factors affecting the distribution and habitat selection of this species in the Trebbia river valley (northern Apennines, Italy), where we mapped woodlark territories during the average time of first and second clutches. A strong shift of territories towards higher altitudes with the progression of the season was observed. The habitat models predicting woodlark occurrence varied between the early and the late period. Specifically, fodder cover positively predicted occurrence early in the season, whereas late in the season occurrence was positively influenced by shrub cover, length of woodland edge, alfalfa cover and rocky areas. Accordingly, territories that were occupied throughout the entire season had greater fodder, shrub and rocky cover compared with those that were occupied only early in the season, suggesting that these variables were important in determining territory quality for woodlarks. Therefore, changing ecological needs of multi‐brooded bird species during the breeding season have to be taken into account for defining appropriate conservation strategies. This was demonstrated by showing that the habitat variables predicting woodlark occurrence early in the season poorly predicted occurrence late in the season and vice versa. In conclusion, this study provides the first detailed assessment of habitat factors affecting the occurrence of breeding woodlarks in an important portion of the species' range, and represents the first explicit attempt to model seasonally changing ecological requirements of bird species for conservation purposes. Our findings suggest that complex data and flexible habitat management strategies are required to account for temporal changes in habitat suitability in multi‐brooded bird species.

QUANTIFYING THE SENSITIVITY OF ARCTIC MARINE MAMMALS TO CLIMATE-INDUCED HABITAT CHANGE

We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential (R(max)). The index suggests three types of sensitivity based on: (1) narrowness of distribution and specialization in feeding, (2) seasonal dependence on ice, and (3) reliance on sea ice as a structure for access to prey and predator avoidance. Based on the index, the hooded seal, the polar bear, and the narwhal appear to be the three most sensitive Arctic marine mammal species, primarily due to reliance on sea ice and specialized feeding. The least sensitive species were the ringed seal and bearded seal, primarily due to large circumpolar distributions, large population sizes, and flexible habitat requirements. The index provides an objective framework for ranking species and focusing future research on the effects of climate change on Arctic marine mammals. Finally, we distinguish between highly sensitive species and good indicator species and discuss regional variation and species-specific ecology that confounds Arctic-wide generalization regarding the effects of climate change.

Movements of, and habitat utilisation by, threespot tilapia Oreochromis andersonii (Teleostei: Cichlidae) in the Upper Zambezi River, Namibia

Movements of and habitat utilisation by radio-tagged threespot tilapia (body length 25–50cm) were studied in the Upper Zambezi River between 23 November 2000 and 8 May 2001. Although utilising a relatively large stretch of river (average 5.4km) during the study period, the fish mainly stayed within defined home ranges, with an average 95% utility distribution of 0.3km2. The individual variation was large, with the largest home range being 28 times larger than the smallest. A broad spectrum of habitats was used, with 39% of the 'fixes' lying in the main stream of the river, 26% in backwaters, 0.5% in the mouths of backwaters, 12% in channels, 16% in permanent swamps, and 7% on the floodplain. Mean width of the waterbody where the fish were positioned was 493m. Mean distance to the nearest shore was 158m, constituting 31% of the total river width. On average, 51% of the fixes were at vegetation, 39% away from vegetation, and 11% near vegetation. Mean water depth where the fish were recorded was 3.4m. Hence, adult threespot tilapia did not appear to be habitat specialists, but displayed flexible movement behaviour and habitat utilisation, with a large degree of individual variation.

Experimental analysis of recruitment patterns of coral reef fishes in seagrass beds: Effects of substrate type, shape, and rigidity

Habitat choice of reef fish larvae at settlement is one of the mechanisms proposed to explain spatial patterns in the distribution of fishes and the corresponding spatial structure of communities. Field experiments using Pomacentridae were conducted at Iriomote Island, southern Japan, in order to determine if rare recruitment of coral reef fishes in seagrass beds is due to larval settlement preference. When three types of natural patch treatments (branching coral patch, seagrass patch, and control without patches) were established in cleared seagrass squares in the center of a seagrass bed, four pomacentrid species, Amblyglyphidodon curacao, Dischistodus prosopotaenia, Cheiloprion labiatus, and Dascyllus aruanus, recruited exclusively onto the coral patches, indicating that larvae distributed in the seagrass bed may have preferred a coral rather than seagrass substrate as a settlement habitat. The effects of differences in physical shape (grid structure for branching coral vs. vertical structure for seagrass leaves) and rigidity (rigid substrate for coral vs. flexible substrate for seagrass) between coral and seagrass substrates on such recruitment patterns were investigated using artificial coral and seagrass units. When artificial habitat units with predator exclusion cages were established in the cleared seagrass squares as above, high densities of A. curacao and D. prosopotaenia recruits were observed on the rigid rather than flexible habitat units (both unit types having similar shape), whereas differences in recruit numbers of the two species were unclear in differently shaped units. These results demonstrated that even though pomacentrid larvae are distributed in the seagrass bed, they do not settle on the seagrass substrate owing to their habitat choice being partially based on a preference for substrate rigidity. Moreover, non-recruitment of C. labiatus and D. aruanus on artificial habitat units suggested that the presence of living coral substrates rather than physical shape/rigidity of substrates are an important cue for habitat choice of these fishes.

Distribution, abundance, and individual strategies: a multi‐scale analysis of dasyurid marsupials in arid central Australia

We investigated the effects of different environmental factors on the distribution and abundance of 6 species of dasyurid marsupials using a multiple‐scale analysis. Data collected in the spinifex dunefields of the Simpson Desert, Australia, were analysed at 3 spatial scales spanning more than 5 orders of magnitude: “metasite” (covering an area of 1000–2000 km2), site (2–12 km2) and grid (0.01 km2). Temporal variability was also investigated, using data collected in March, April, and May in 4 consecutive years from 1997 to 2000. Both abiotic and biotic factors influenced the capture rates of different species at different times and spatial scales. At the coarsest spatial scale, Dasycercus cristicauda (mulgara) was consistently limited in its distribution by the intensity of rainfall, probably as an indirect result of increased grazing pressure from pastoral activity and a higher density of feral predators in high rainfall areas. However, at the finest spatial scale, this partly carnivorous species was scarce in areas of dense spinifex, perhaps because such habitats yield lowest returns during foraging, and was more common in areas where small invertebrate prey were abundant. Factors affecting the distribution of the most abundant dasyurid species in the study area, Sminthopsis youngsoni (lesser hairy‐footed dunnart), could not be identified at any scale; we conclude that this reflects the opportunistic foraging strategies and flexible habitat requirements of this insectivorous species. Both Ningaui ridei (wongai ningaui) and Sminthopsis hirtipes (hairy‐footed dunnart) were less abundant throughout the study region. For N. ridei, a spinifex specialist, predictors of occurrence could be identified only at the finest scale of analysis; at the grid level, a close positive association was detected in 2 of the 4 study years between capture rate and spinifex cover. For S. hirtipes, all 3 levels of spatial analysis revealed a negative association between capture rate and both rainfall and spinifex density. For the rarely‐caught S. crassicaudata (fat‐tailed dunnart) and Planigale tenuirostris (narrow‐nosed planigale), no clear results were obtained at any spatial scale, and we interpret this to indicate that the study region represents sub‐optimal habitat for these species.Given that different factors affected the distribution and abundance of dasyurids at different spatial scales over time, we conclude that a multiple‐scale approach to population and community analysis is vital to accurately identify which environmental processes shape population and community dynamics. Understanding the interplay between regional and local processes will be crucial for management of existing species populations and for prediction of their distributions and abundances in future.

Urban Dingoes (Canis lupus dingo and Hybrids) and Human Hydatid Disease (Echinococcus granulosus) in Queensland, Australia

Author(s): Allen, Ben | Abstract: Urban dingoes are known to occur along most of the Australian eastern seaboard but are particularly common in Queensland coastal cities and towns. Urban dingoes cause significant damage to domestic pets and livestock and present four serious threats to human health and safety: attacks on humans, attacks on domestic animals, zoonotic disease transmission to humans, and the psychological and emotional trauma to affected residents. I have begun to monitor urban dingoes in three metropolitan and regional Queensland coastal cities using GPS datalogging collars to determine habitat use by dingoes in urban communities, assess their reliance on bushland areas, and evaluate their potential role in the epidemiology of zoonotic diseases, including human hydatid disease (caused by the parasitic tapeworm Echinococcus granulosus). Similar to urban predators on other continents (e.g., red foxes and coyotes), I found urban dingoes to have smaller home ranges than their rural counterparts, exhibit flexible habitat requirements in a resource-rich urban environment, and potentially have a pivotal role in the transmission of E. granulosus to humans in built-up areas. Some challenges of urban predator and zoonotic disease management are discussed.

Movements and habitat utilization of nembwe, Serranochromis robustus (Günther, 1864), in the Upper Zambezi River

Fifteen adult nembwe Serranochromis robustus (Günther, 1864) were tagged with radio transmitters in the Zambezi River, Namibia, from 4–15 November 2000 to record behaviour and outline the implications for fisheries management. The fish were tracked on average every 3.7 days until 18 May 2001. They stayed within relatively small home ranges, with a 95% probability of localization within an average area of 184 563m2. The fish utilized a mean river stretch of 1330 m (range = 24– 3787). Nembwe were recorded in a variety of habitats, and the individual variation in movements and habitat use was substantial. All the fish were recorded in the mainstream of the river, but 62% of the fish were recorded in one or more additional main habitat types. During rising and high water, 67% and 71% of the fish, respectively, were recorded in adjacent temporary flooded areas during some or all tracking surveys, but did not undertake long-distance migrations onto the floodplains. It is concluded that although staying within relatively small home ranges, nembwe appears as a species with a variable and flexible habitat utilization.

Is Atlantic salmon production limited by number of territories?

Thirty Atlantic salmon Salmo salar parr (mean 135 mm total length, LT) in the River Alta, Norway, were radio‐tagged and tracked during a 11–13 day period. The parr stayed within defined home ranges with a 95% probability of localization within an average area of 1286 m2(241–3484 m2). On average, each parr had overlapping home ranges with 7·7 other parr, and the overlap between pairs of fish covered on average 24% of their home range areas. Mean length of the river stretch used was 90 m (22–383 m). On average, during 38%(16–77%) of the tracking surveys, the fish had moved >10 m since the previous survey. Mean total distance moved during the whole study was 402 m (208–862 m). The Atlantic salmon were most often recorded in riffles, but 27% of the parr alternated between riffles and pools. The extensive movements, flexible habitat utilization and relatively large home ranges, together with the fact that all the parr had home ranges partly overlapping with other radio‐tagged parr, indicate a flexible and variable behaviour and, thereby, a more complex social structure than a rigid defence of a fixed territory. Thus, Atlantic salmon production seems not to be limited by the highest potential number of territories for large parr in a given area.