Patterns Of Microhabitat Use Research Articles

All about being old and shooting hairs: clade age and urticating hair explain the patterns of diversification in tarantulas.

The extreme asymmetry of species richness distribution across the tree of life has always intrigued evolutionary biologists. Two competing explanations have been proposed to explain this pattern-the clade age hypothesis and diversification rate variation. While these two scenarios may not be mutually exclusive, to what extent time and diversification rates interact to explain species richness patterns remains understudied. Here, we investigate the relative influence of these two scenarios using tarantulas (Family: Theraphosidae) as a model. Tarantulas represent a speciose group of spiders found worldwide but exceptionally diverse in South America. These spiders show two distinct patterns of microhabitat use (ground-dwelling or arboreal) and defense strategies (presence or absence of urticating hairs). Using various trait-independent and dependent diversification models, we test the clade age hypothesis, the role of microhabitat, antipredator defense strategy, and geography in influencing diversification rates. Our results suggest that clade age is the primary predictor of species richness distribution across the tarantula subfamilies. However, the presence of urticating hair probably disrupted this pattern in some clades by increasing the net diversification rates, not by increasing the speciation rate but by reducing the extinction rate.

Predatory and competitive interaction in Anopheles gambiae sensu lato larval breeding habitats in selected villages of central Uganda

BackgroundMalaria is often persistent in communities surrounded by mosquito breeding habitats. Anopheles gambiae sensu lato exploit a variety of aquatic habitats, but the biotic determinants of its preferences are poorly understood. This study aimed to identify and quantify macroinvertebrates in different habitat types with determined water physico-chemical parameters to establish those preferred by An. gambiae s.l. larvae as well as their predators and competitors.MethodsA field survey was conducted in Kibuye and Kayonjo villages located in the vicinity of the River Sezibwa, north-eastern Uganda to identify Anopheline larval habitats shared by aquatic insects. Habitats were geo-recorded and as streams, ponds, temporary pools and roadside ditches. From October to December 2017, random microhabitats/quadrats were selected from each habitat type, their water physico-chemical parameters (electrical conductivity, total dissolved solids, temperature and pH) were measured, and they were sampled for macroinvertebrates using standard dippers. All collected arthropod macroinvertebrates were then morphologically identified to family level and enumerated.ResultsPrincipal component analysis showed that the four larval habitat types were characterized by distinct physico-chemical parameter profiles. Ponds and streams had the highest number and diversity of macroinvertebrate insect taxa and sustained few An. gambiae s.l. larvae. Anopheles gambiae s.l. were more common in roadside ditches and particularly abundant in temporary pools which it commonly shared with Dytiscidae (predaceous diving beetles) and Culex spp. Cluster correlation analysis conducted on the abundance of these taxa within quadrats suggested that An. gambiae s.l. and Dytiscidae have the most similar patterns of microhabitat use, followed by Cybaeidae (water spiders). Whilst Culex spp. co-occurred with An. gambiae s.l. in some habitats, there was only partial niche overlap and no clear evidence of competition between the two mosquito taxa.ConclusionsPonds and streams are habitats that host the largest diversity and abundance of aquatic insect taxa. Anopheles gambiae s.l. larvae distinctively preferred temporary pools and roadside ditches, where they were exposed to few predators and no apparent competition by Culex spp. Further studies should aim to test the impact of Dytiscidae and Cybaeidae on An. gambiae s.l. dynamics experimentally.Graphical

Niche relations in a small world: Epizoic algae on an intertidal gastropod

AbstractThe patterns of microhabitat use were investigated in three coexisting epizoic algae on an intertidal gastropod, Lunella correensis in an attempt to enhance understanding of the niche relations among ecologically similar species in a space‐limited environment. Our analysis of field‐derived data showed clear spatiotemporal partitioning of shell microhabitats by epizoic algae with different degrees of resource specialization. As a substrate‐specializing, obligate epizoic alga, Pseudocladophora conchopheria occupied wider micro‐niches on the host of different sizes than facultative epizoic algae (encrusting rhodophytes, crustose Corallina and Gelidium). While Pseudocladophora demonstrated uniform use of all shell microhabitats on hosts of all sizes, crustose Corallina and Gelidium showed more varied microhabitat use with shifting positions on hosts of different sizes. Furthermore, in addition to slight differences in microhabitat use, crustose Corallina and Gelidium demonstrated differences in their interspecific relationship with Pseudocladophora. Our generalized linear models (GLM) analyses indicated that the occurrence/abundance of crustose Corallina was negatively affected by Pseudocladophora but that of Gelidium was positively affected, while Pseudocladophora appeared to be competitively inferior to both rhodophytes when they co‐occurred on hosts of relatively large sizes. The present study, therefore, points to variable niche partitioning among algae even on a small spatial scale, which may result from complex interactions between spatio‐temporal substrate heterogeneity on a live host and interspecific interactions.

Uso y selección de microhábitat en un ensamble de anuros del Chaco Serrano de Argentina

Introduction: Research on spatial resource usage and partition strategies is important to understand the mechanisms of coexistence in sympatric amphibian species, even more when there are temporal variations in habitat availability. Objective: To learn about the patterns of microhabitat use, its seasonal variations and the possible influence of phylogeny on an anuran assembly of the Chaco Serrano in Argentina. Methods: Samplings were carried out in the Valle Fértil Natural Park protected area, Valle Fértil Department, San Juan, between 2012 and 2017. In the field, we recorded the microhabitat where each specimen was found, and we also measured site variables. In addition, microhabitats availability was determined. Data were analyzed using Manly’s selectivity index. Generalized linear models (GLM) were used to assess temporal variations in microhabitat use. Results: The species evaluated were: Rhinella arenarum arenarum, Leptodactylus latrans, Pleurodema tucumanum and Odontophrynus occidentalis. All species showed differences in usage frequencies: R. a. arenarum showed preferences for rocky and aquatic sites, P. tucumanum showed preferences towards bare soil and rocky sites, L. latrans and O. occidentalis showed greater preferences for rocky and aquatic sites. All species but Odontophrynus exhibited seasonal variations in microhabitat selection and usage. Odontophrynus occidentalis showed differences in usage proportions among microhabitats. Conclusions: This study shows plasticity in microhabitat usage as an important determinant of anuran spatial distribution, without apparent restrictions imposed by space competition or phylogeny. When species activity is coincident, the space resource may be distributed in a way that species overlap is reduced.

Microhabitat use by Rhipidomys mastacalis and Marmosops incanus (Mammalia) in a restinga areas in north‐eastern Brazil

AbstractDifferences in the patterns of microhabitat use by small mammals have been largely related to the coexistence process of the species. The present study analyses how the marsupial Marmosops incanus and the rodent Rhipidomys mastacalis use the microhabitat in a areas of arboreal restinga in the Brazilian north‐east. Through capture‐marking‐recapture, sampling was performed monthly from September 2017 to August 2018 using Sherman traps and pitfall. Six microhabitat variables were measured at all capture stations. The use of vertical strata (ground and understory) was compared using a chi‐square test, and associations of species abundances with microhabitat characteristics were explored using redundancy analysis. The results indicate that the species use the vertical strata at different frequencies, with R. mastacalis found exclusively in the understory and M. incanus found more in the understory than in the ground. The variation in the abundance of the species was associated with the density of the understory, with an increase in M. incanus abundance and a decrease in R. mastacalis. Differences in the patterns found for these species in other environments indicate plasticity in relation to the use of vertical strata and the approaches used suggest that the differential use of the arboreal stratum can be a facilitator in the process of coexistence in areas of restinga.Abstract in Portuguese is available with online material.

First nest description of the Iberá Seedeater (Sporophila iberaensis)

ABSTRACT The southern capuchino seedeaters constitute a rapid radiation of finch-like birds that inhabit Neotropical grasslands in continental South America. While capuchinos are highly sympatric, the mechanisms allowing them to breed in sympatry, such as patterns of microhabitat use, remain largely unknown. We provide the first nesting account of the Ibera Seedeater (Sporophila iberaensis), a recently discovered capuchino species that breeds exclusively in the Ibera wetlands of northeastern Argentina, and compare its nesting habits to those of other members of the capuchino radiation. From November 2016 to January 2017, we located and monitored 25 Ibera Seedeater nests. The Ibera Seedeater constructs open-cup nests in clumps of grass on the margins of flooded habitat and lays an average of 2 eggs per clutch. Like other capuchino species, females participate in nest construction and incubation, while both sexes provision offspring. Despite similarities in nest architecture, the Ibera Seedeater differs in ...

Predictors and benefits of microhabitat selection for offspring deposition in golden rocket frogs

AbstractIn many tropical frogs, offspring development and survival potentially depend on microhabitat features associated with sites that parents select for oviposition and tadpole rearing. We investigated the importance of microhabitat features in the selection of oviposition sites versus tadpole rearing sites, as well as in determining offspring survival, in the golden rocket frog, Anomaloglossus beebei. Endemic to Guyana, this species exhibits biparental care and exclusively uses phytotelmata in bromeliads for oviposition and tadpole rearing. We used model‐based inference to evaluate evidence that parents prioritize different microhabitat features in selecting phytotelmata suitable for oviposition versus tadpole rearing and that microhabitat selection can adaptively promote offspring survival. For phytotelmata in 132 bromeliads, we quantified bromeliad size, phytotelm height, leaf angle (indicative of location within the bromeliad), water volume, water temperature, dissolved oxygen concentration, and the presence/absence of potential predators and nearby conspecifics. Compared to tadpole rearing sites, oviposition sites were found in phytotelmata associated with leaves at lower angles within bromeliads, smaller water volumes, lower water temperatures, higher dissolved oxygen concentrations, and more predatory crabs. Compared with unsuccessful egg clutches, successful clutches were found in phytotelmata with lower water temperatures, higher dissolved oxygen concentrations, fewer crabs, more dragonfly larvae, and more nearby conspecifics. We conclude that the nonrandom patterns of microhabitat use for oviposition sites and tadpole rearing sites in golden rocket frogs are associated with specific environmental factors that promote offspring survival through a critical stage of the animals’ complex life cycle.

Microhabitat use during brumation in the Japanese treefrog, Dryophytes japonicus

Abstract Although amphibians undergo drastic changes in physiology and behaviour before hibernation, this phase of their life cycle (i.e., brumation) is the least understood. We investigated the patterns of microhabitat use by Dryophytes japonicus during brumation using a Harmonic Direction Finder to track 27 adults in October 2013. Most frogs used chestnut trees throughout their diel cycle. The species was most active within the “leafy vegetation” microhabitat, moving about 2 m within 72 h on average, and mostly circa 10 AM. Frogs moved less in the four other microhabitats, with individuals moving between 1 m and 50 cm, typically during the early afternoon. Around 3 pm, the microhabitat mostly used was “on bark”, with displacements almost totally halted. The use of microhabitats and shelters, as well as movements in relation to time of day, suggests that D. japonicus displays behavioural thermoregulation during brumation. This research is the first providing insights in the brumation ecology of a non-freeze-resistant Palearctic anuran.

Predicting Variation in Microhabitat Utilization of Terrestrial Salamanders

Understanding patterns of microhabitat use among terrestrial salamanders is important for predicting their responses to natural and anthropogenic disturbances. The dependence of terrestrial salamanders on cutaneous respiration limits their spatial distribution to moist, humid areas. Although many studies have shown negative effects of canopy removal on terrestrial salamander abundance, some have shown potential ameliorating effects of retaining coarse woody debris (CWD) as moist refugia (critical resources in the landscape). Because cover objects like CWD retain moisture longer than fine debris, terrestrial salamanders are often more locally abundant in areas of dense cover. Temporally variable environmental conditions could affect microhabitat quality and influence the fine-scale spatial distributions of salamanders. Spatial and temporal variability in microhabitat use greatly influence individual detectability, which is always a challenge for terrestrial salamanders. We conducted repeated area-constrained surveys to examine variation in salamander microhabitat use of terrestrial salamanders in relation to season, year, and weather conditions. We found that time since rain (TSR) was the best predictor of relative salamander microhabitat use, but the strength of this relationship varied among years. In addition, TSR was also the best predictor of salamander surface activity. We captured most salamanders within leaf litter, but the proportion of leaf litter captures varied with TSR. Our results illustrate the importance of accounting for variable detectability when sampling for terrestrial salamanders. Disturbances which affect leaf litter depth and decomposition rates could influence the availability and quality of microhabitats and potentially increase competition among individuals for natural cover objects.

Invasive rainbow trout affect habitat use, feeding efficiency, and spatial organization of warpaint shiners

Rainbow trout have been introduced to six of the seven continents and currently are widely stocked for sport fishing. Despite their broad distribution, outside of New Zealand, little is known about the effects of rainbow trout on native species, especially fishes. We conducted experiments in an artificial stream to assess hypotheses that stocked rainbow trout significantly affected: (1) mesohabitat use, (2) foraging success, (3) social behavior, and (4) spatial organization of warpaint shiners (Luxilus coccogenis) a common native minnow found in southern Appalachian streams, with similar patterns of microhabitat use to rainbow trout. We replicated experiments at high and low natural densities (two and five warpaint shiners) and spring/fall (12 °C) and summer (17 °C) temperatures. Treatments included: (1) a control (five warpaint shiners), (2) trout (five warpaint shiners and one rainbow trout), (3) large fish control (five warpaint shiners and one river chub) and (4) density control (six warpaint shiners). The presence of rainbow trout produced a shift by warpaint shiners from pool mesohabitats to shallower, higher velocity habitats with more variable substrata, as well as reduced prey capture success, feeding efficiency, and distance from the front of the tank (i.e., warpaint shiners moved closer to food release points), and increased the distance to the additional fish (i.e., avoidance of the rainbow trout). Negative effects on foraging behaviors were stronger in 12 °C treatments. In a realistic stream flume the presence of rainbow trout produced effects that likely influenced individual fitness of warpaint shiners. The potential effects of stocking rainbow trout on native non-game fishes, such as warpaint shiners should be assessed when implementing or evaluating stocking programs.

Spatial niche variation in two sympatric species of Bokermannohyla (Anura: Hylidae) in southeastern Brazil

We studied patterns of microhabitat use by adults of two sympatric Bokermannohyla species at the Reserva Particular do Patrimônio Natural Santuário do Caraça, southeastern Brazil. We selected three streams, one where both species occurred in syntopy and the other two where each one occurred alone. We sampled 150-m transects in each stream throughout 1 year, recording microhabitat features for each frog located (substrate type, height and distance from water). Microhabitat availability varied between dry and wet seasons in all streams, and overall microhabitat diversity changed in two streams. Bokermannohyla nanuzae seemed to have a niche contraction in the presence of Bokermannohyla martinsi, but this only happened during the dry season. Microhabitat requirements during the wet season may be closely linked to similar reproductive needs that probably represent a strong selective pressure, forcing niche overlap.

Acoustic characteristics of a native anuran (Amphibia) assemblage in a palustrine herbaceous wetland from Puerto Rico

Abstract: We documented patterns of microhabitat use, relative species abundance, and acoustic characteristics of a Puerto Rican native anuran assemblage from a palustrine herbaceous wetland. We found significant interspecific differences in the spatial distribution of calling males among microhabitat types, which differed in percent cover, height, and physical structure. The spectrogram revealed no acoustic interspecific overlap of calls above 3.0 kHz and a significant inverse relationship between body size and frequency of call. Most calls were between 4.0 kHz and 8.5 kHz range, indicative of a small-sized species assemblage. Diel calling activity patterns showed considerable interspecific overlap with most calling activity starting at approximately 16:30 hrs and decreasing after 23:30 hrs. In general, acoustic communication seems enhanced by interactions between abiotic (e.g., microhabitat/vegetation type used for calling) and biotic factors (e.g., calling behavior) that reduce acoustic attenuation in this wetland environment even though calling males can be within interspecific hearing range. Key Words: acoustic partitioning, anurans, Caribbean, Coqui Llanero, Eleutherodactylus, herbaceous wetland, Leptodactylus

Microhabitat use in an Assemblage of Native and Introduced Fishes in a Hawaiian Stream

Abstract: Ecological aspects of the relatively diverse fish assemblages found in the terminal reaches of streams in Hawai'i are largely unknown. This study described patterns of microhabitat use in an assemblage of native and introduced stream fishes living in the terminal reach of Wailoa Stream on the island of Hawai'i. Multivariate analyses of data collected through underwater visual surveys indicated that differences in microhabitat use were an important factor in structure of this assemblage. In riffle habitats, native fishes selected distinct microhabitats based on water velocity, substrate size, and position in the water column. In run habitats, a benthic guild (native gobies) and a water-column guild (introduced poeciliids and the endemic Kuhlia xenura) were identified. Strong differences in three-dimensional microhabitat use patterns appear to allow native gobioids to resist being displaced by introduced poeciliids in Wailoa Stream. However, high overlap in the microhabitat use patterns of juvenil...

Habitat Use and Separation among Congeneric Darter Species

AbstractFive darter species (Greenside Darter Etheostoma blennioides, Rainbow Darter E. caeruleum, Fantail Darter E. flabellare, Johnny Darter E. nigrum, and Orangethroat Darter E. spectabile) were collected from seven streams and rivers in two Indiana watersheds to determine patterns of microhabitat selection with respect to depth, water velocity (flow), and substrate size. Heterogeneous habitats create a variety of niche dimensions, promoting the coexistence of congeneric species. Greenside and Rainbow darters were most commonly found among intermediate substrate sizes (cobble + boulder) and in locations with higher velocities and deeper water. Fantail and Orangethroat darters associated with intermediate to large substrate sizes (cobble + bedrock) were found in shallower water with lower velocities. Fantail Darters were only observed in the Whitewater River watershed. In contrast, Johnny Darters were observed only within the White River watershed among small substrate sizes (silt + sand), moderate velocities, and deeper water. Based on nonmetric multidimensional scaling and multinomial logistic regression, substrate size was the most important variable in characterizing microhabitat selection. Ultimately, habitats produced patterns of segregation and coexistence among these five darters in Indiana streams. Although ecological patterns of microhabitat use are additionally influenced by competition, morphology, and life history traits, heterogeneous habitat features within ecosystems appear to be structuring fish assemblages.

Invasion of the shelter snatchers: behavioural plasticity in invasive red swamp crayfish, Procambarus clarkii

Summary1. In many freshwater systems, competition for shelter plays an important role in determining the persistence of both native and alien species. The red swamp crayfish, Procambarus clarkii, is currently invading the native habitat of the signal crayfish, Pacifastacus leniusculus, in southern Oregon, and interspecific competition for shelter may be driving the species replacement in this region.2. We designed a 2 × 3 factorial mesocosm experiment, with shelter density and species combination as factors, to investigate shelter occupancy and resource competition. Contrary to our predictions, the two crayfish species are equal competitors for shelter. Further, the invasive P. clarkii modified its shelter occupancy behaviour in the presence of the native P. leniusculus and has broader microhabitat preferences.3. Specifically, we found that P. clarkii alters shelter occupancy and space use patterns when the two species occurred together, such that shelter use was identical between P. clarkii and P. leniusculus in mixed‐species treatments. In such treatments, both species increased their use of shelters when shelter density increased. When P. clarkii was alone, however, individuals did not alter shelter use as a function of shelter density, whereas P. leniusculus exhibited similar density‐dependent behaviour in both mixed‐ and single‐species treatments.4. In a complementary field survey, we employed an ‘epicentre‐based’ design to sample two field sites. We observed patterns of microhabitat use and breadth for each species similar to those in our mesocosm experiment: the invasive P. clarkii was more abundant across different habitats and used a broader range of microhabitats than the native P. leniusculus. As such, we found that P. clarkii was more abundant across both field sites than the P. leniusculus, occupying microhabitats within and beyond the preferred range of P. leniusculus. Both field sites were affected by urban development and agriculture.5. The use of microhabitats by both species was similar in the laboratory and the field. This study confirms that P. clarkii individuals can, and do, successfully occupy microhabitats preferred by P. leniusculus in the Willamette Valley. The results from our study may be relevant to other freshwater systems inhabited by P. clarkii and contribute to the understanding of ‘niche opportunity’, a concept which defines the environmental conditions that promote biological invasions.

Species and size matter: An experimental study of microhabitat use under the influence of competitive interactions in intertidal gobiids

Patterns of microhabitat use and biotic interactions were examined under experimental conditions using three intertidal gobies, Bathygobius fuscus, Chaenogobius annularis and C. gulosus. A series of microhabitat choice experiment was conducted to document microhabitat utilisation, spatial use overlap and occurrence of agonistic behaviour in single-individual and mixed-individual setups using two size-categories of the three species. Patterns of habitat utilisation as observed under single-individual conditions were significantly modified in the presence of another individual, depending on species identity, body size and time of day. Chaenogobius species showed marked changes especially when paired with a large individual, occurring more frequently outside the shelter and using those substrates that were infrequently used by the paired individual. In contrast, B. fuscus did not show marked changes. Observed (realised) overlap in spatial use under mixed-individual conditions was significantly smaller than the expected overlap based on single-individual conditions (i.e. without any biotic interactions). Marked departures from expected patterns were detected for intra- and inter-specific combinations of Chaenogobius species: there were effects of biotic interactions. C. gulosus rarely showed direct aggression, in contrast to other species, though it exerted an apparent influence on the microhabitat use of a paired species/individual. The occurrence of aggression was different among species pairs and times of day. Body size differences affected the outcome of a contest, but not the occurrence of behaviour itself. The pattern also varied depending upon species combinations and times of day. Fish activity was also influenced by the presence of a paired individual in some cases. The present study revealed that species identity and body sizes are important elements of biotic interactions that affect the patterns of habitat utilisation in these fishes. Such diverse and subtle manners of interaction and habitat use may contribute to species coexistence in tidepool fish assemblages.

Seasonal variation of tadpole spatial niches in permanent streams: The roles of predation risk and microhabitat availability

AbstractPhenotypic plasticity can improve fitness in unstable environments and can be expressed in many traits, such as life history attributes, growth and behavioural features. Microhabitat choice can have important consequences for development and survival of aquatic organisms and is expected to vary in response to stimuli, such as predation risk, food availability and temperature. At seasonal sites, microhabitat availability and associated benefits may change from season to season, which might lead to altered patterns of microhabitat use by tadpoles. We investigated this hypothesis in 17 streams from two localities in south‐eastern Brazil. We tested whether water level drops significantly during the dry season, whether lower water level results in altered microhabitat availability and whether predation risk changes between seasons, based on predator density. We then tested whether tadpoles change their pattern of microhabitat use, their spatial niche breadth (given by diversity of used microhabitats) and spatial niche overlap (in the case of co‐occurring species). We were able to include in our analyses tadpoles of four species of Hylidae, that occurred throughout both seasons. Stream depth decreased in the dry season, but microhabitat availability remained relatively stable in many streams, and predator density did not change significantly. Tadpoles of three out of the four species studied were more abundant during the dry season, which may be an adaptation to adjust time of metamorphosis to the rainy season. Tadpoles changed their patterns of microhabitat use between seasons, although the potential causing factors investigated did not seem to be responsible. Tadpole plasticity in microhabitat use may indicate the existence of selective pressures that vary through time and space and are still not well understood.

Analysis of spatial niche structure in coexisting tidepool fishes: null models based on multi-scale experiments

1. Fundamental and realized spatial niches were investigated through a combination of laboratory and mesocosm experiments, field observations and null model analysis in three intertidal gobiid species (Bathygobius fuscus, Chaenogobius annularis and C. gulosus). Null models based on the results of single-species experiments were used to assess interspecific spatial use and coexistence on two different scales: (i) microhabitats within a tidepool ('microhabitat' scale); and (ii) distribution among a set of tidepools ('habitat-wide' scale). 2. Patterns of microhabitat use varied from single to paired treatments, depending on paired species. Realized overlap of microhabitat use was smaller than would be expected from single-individual situations for intraspecific combinations, but not for interspecific ones. 3. Patterns of tidepool occupancy (a measure of spatial niche breadth) in the mesocosm were influenced by interspecific interactions. Two Chaenogobius species, but not B. fuscus, decreased tidepool occupancy in the hetero-specific treatments compared with the mono-specific ones. For all interspecific combinations, spatial overlap (habitat-wide scale) was significantly lower than the values expected from mono-specific situations. The results also indicated a possible trade-off between competitiveness and growth efficiency in these fishes. 4. Interspecific spatial overlap in the field was similar to that in the mesocosm experiment and the pattern of coexistence of gobiids can be explained by the results of our experiments. 5. This study demonstrates that niches of intertidal fishes may experience modifications under the influence of species interactions and that null models based on controlled experiments can greatly facilitate the deciphering of such changes in niche structure.

Foraging Habitat Selection in the Last Ortolan BuntingEmberiza hortulanaPopulation in Switzerland: Final Lessons before Extinction

The Ortolan Bunting Emberiza hortulana has suffered a general decline across much of Western Europe in recent decades. In Switzerland, only one population remains in sub-Mediterranean shrub-steppe on the south-facing slopes of the Rhône Valley (Valais). We aimed to collect data on foraging ecology of the last Swiss Ortolan Buntings during reproduction. However, this population underwent a considerable decline, with no breeding confirmed in Switzerland in 2007. We investigated foraging habitat selection of four unpaired males at the habitat and microhabitat scales, and compared patterns of foraging habitat use with patterns of terrestrial invertebrate abundance. All radio-tracked birds foraged exclusively on the plain. The adjacent slope, which harboured the former breeding grounds, was used only for territorial song displays. All males showed a disproportionate use of conventional maize fields that had been treated with herbicides, while also exhibiting an avoidance of meadows and riparian vegetation. These observed patterns of habitat use may be driven by unavailability of optimal foraging habitat, with birds being forced to use the best of a poor set of options. Structurally, it was shown that birds foraged in areas with a high proportion of bare ground, as well as moderately dense overhead vegetation. These areas did not support higher arthropod abundance, suggesting that food accessibility (and/or cover) rather than food abundance dictated habitat selection. It remains to be seen whether these patterns of microhabitat use also apply to breeding Ortolan Buntings. Further work in southern European breeding grounds should be envisioned to gain crucial information about the ecological requirements of Ortolan Buntings in Mediterranean and sub-Mediterranean habitats. Additionally, effort needs to be focused on identifying factors affecting the species on the wintering grounds, which may assist in explaining the observed declines in the breeding areas.

Intertidal slope of coral sand beach as a unique habitat for fish: meiobenthic diet of the transparent sand dart, Kraemeria cunicularia (Gobiidae)

Coral sand beaches harbor gobiid sand darts (genus Kraemeria), the only fish known to live in the sand throughout their adult life. Despite the uniqueness of sand-dwelling habitat as a vertebrate, the biology of this fish remains unclear. To explore how this unique fish utilize an unusual habitat, we investigated diurnal patterns of microhabitat use and prey consumption by the transparent sand dart, Kraemeria cunicularia, at a sandy beach on Iriomote Island, the Ryukyu Archipelago, Japan. Sand darts were found in sediment in the lower intertidal zone throughout the daytime regardless of changes in tidal level, whereas at nighttime these fish were found swimming. Gut content analyses revealed that the sand dart diet was dominated by harpacticoid copepods throughout the day. Analyses of meiobenthic distribution indicated that these copepods were most abundant at lower intertidal zones where highest numbers of sand darts were found during the daytime; thus, it is possible that microhabitat use of the fish is largely determined by food availability. An extensive distributional survey throughout the Ryukyu Archipelago further indicated that sand darts prefer sandy beaches with well-sorted, coarse sand. These results provide novel insights into how sand darts respond to the tidal rhythm and highlight putative key environmental factors that determine their distribution at both regional and microhabitat scales.