Feeding preferences and the relationships between food choice and assimilation efficiency in the herbivorous marine snail Lithopoma undosum (Turbinidae)

Preference rankings for 13 macrophytes were established for the subtidal herbivorous snail Lithopoma undosum using two-choice laboratory experiments and consumption rates. L. undosum did not discriminate among three kelp foods (Egregia menziesii, Eisenia arborea and Macrocystis pyrifera) but ate kelp preferentially and more rapidly over all but Ulva spp. among tested macrophytes. Secondary preferences were established for the red alga Pterocladiella capillacea, followed by the coralline Lithothrix aspergillum, whereas the brown seaweeds Zonaria farlowii and Halidrys dioica and the seagrass Phyllospadix torreyi were the least preferred macrophytes. Fastest consumption rates (1.91 g day⁻¹) were measured in trials consisting only of kelp foods. These results indicate that L. undosum exhibits clear feeding preferences even when given less-preferred, non-kelp macrophytes. Using an ash-marker technique, we determined total organic, carbon, and nitrogen assimilation efficiencies (AE%) for six macroalgae used in preference trials. Tested macrophytes were assimilated at different efficiencies but a pattern was not detected between AE (%) and a macrophyte’s position in L. undosum’s preference hierarchy. Highest total organic AEs were found for P. capillacea (61.2%) and H. dioica (59.4%); lowest AEs were detected for E. menziesii (34.9%), a preferred dietary item. Nitrogen was assimilated from red algae with higher efficiencies (74.9–84.3%) than from brown or green algae. These data suggest that the digestive capabilities of L. undosum are better suited for assimilating organic material and nitrogen from less-preferred, non-kelp foods. This supports the hypothesis that factors besides nutritional composition and digestive optimization have played a role in the evolution of feeding preferences in L. undosum and probably other herbivorous snails associated with northeastern Pacific kelp beds.     

Influence of season,ontogeny and tide on the diet of the temperate marine herbivorous fish Odax pullus (Odacidae)

The diet of the temperate marine herbivorous fish Odax pullus (Pisces: Odacidae) was examined using gut-content analysis followed by principal-component analysis and analysis of variance. Fish were collected near Leigh, on the northeast coast of New Zealand, from February 1983 to September 1984. The data were categorised by size of fish, season, and state of tide. A major ontogenetic shift in diet was observed. Juveniles fed on animal material (crustaceans and gastropods), epiphytic rhodophytes, and some phaeophyte material. Adults fed almost exclusively on two phaeophyte taxa, the laminarian Ecklonia radiata and the fucoid Carpophyllum spp. Dietary selection was evident at the level of particular plant components; the diet of larger fish in spring samples was dominated by fucoid reproductive receptacles. There was no direct evidence of a tidal influence on diet composition of O. pullus, although the relative proportions of E. radiata and Carpophyllum spp. ingested by adult fish appeared to vary with tidal state. The volume of gut contents varied seasonally for all size classes, although the timing of peak annual food intake varied among size classes. Tidal state did not influence the volume of the gut contents. The ontogenetic and seasonal trends evident in the diet of O. pullus appeared to be related to a number of factors including relative gut length, gonad development, ontogenetic changes in feeding anatomy and seasonal changes in algal composition.     

Extractable atrazine and its metabolites in agricultural soils from the temperate humid zone

Extractable atrazine and its metabolites (hydroxyatrazine, deethylatrazine and deisopropylatrazine) were evaluated in agricultural soils from the temperate humid zone (Galicia, NW Spain) under laboratory conditions. The experiment was performed with five soils with different properties (organic C, soil texture and atrazine application history), both unamended and treated with atrazine at field application rate. Measurements of the atrazine compounds were made at different time intervals (1, 3, 6, 9 and 12 weeks) during a 3-month incubation period. Results showed that only hydroxyatrazine was detected in the extractable fraction of the unamended soils, with values remaining relatively constant throughout the incubation period. Atrazine addition notably increased the concentration of the parent compound and its degradation products; deisopropylatrazine and hydroxyatrazine were the main metabolites detected in the extractable fraction of the treated soils, whereas deethylatrazine was not detected. After 7 days incubation, values of total extractable residues, expressed as percentage of initially added atrazine, ranged from 75 to 86% (25–68% of atrazine, 7–11% of hydroxyatrazine and 9–57% of deisopropylatrazine). The values decreased rapidly during the first 3 weeks of incubation, showing values of 2–8% in soils with higher atrazine application and from 28 to 30% in soils with lower application history. At the end of the incubation, 2–8% of total extractable residues were still detected (0–4% of atrazine, 2–3% of hydroxyatrazine and 0–2% of deisopropylatrazine), indicating a residual effect of atrazine addition. These variations in the extractable fraction indicated that most added atrazine was rapidly degraded, especially in soils with higher application history.     

Effects of wave-induced lightflecks in the intertidal zone on photosynthesis in the macroalgae Postelsia palmaeformis and Hedophyllum sessile (Phaeophyceae)

Intertidal algae are exposed to a highly variable photic regime because of crashing waves. We measured photosynthetic rate of whole fronds of the seaweeds Postelsia palmaeformis (Ruprecht) (at Bodega Marine Laboratory, 1991) and Hedophyllum sessile (Setchell) (Phaeophyceae) (at Friday Harbor Laboratories, 1990) in flashing and steady-state photosynthetically active radiation (PAR) of equal irradiance, using a recirculating metabolism chamber designed to minimize the thickness of diffusional boundary layers on the surfaces of algal tissues. The dimensionless ratio of photosynthetic rate under flecking PAR (P_fleck) and the sum of photosynthetic rate under steady state PAR (P_s) of high and low irradiance was computed for lightfleck periods from 0.2 to 100 s. P_fleck:P_s is a measure of the light-flash utilization-efficiency in flashing light, and was greater than unity at periods between lighflecks of 2 to 30 s, with a peak at 10 s. We used a novel optical fiber irradiance meter to measure PAR incident on fronds of P. palmaeformis as they were washed about by waves breaking in the intertidal zone, and compared the light records to that obtained by a stationary sensor under the canopy. PAR flashing period was closely correlated with the period of breaking waves in stands of P. palmaeformis. We estimated the seasonal spectrum of period between light flashes in stands of this species by examining the spectral density of ocean waves at Bodega Marine Laboratory, Bodega Bay, California. The wave spectrum peaks at a period (10 s) where light-flashes may theoretically enhance the light-flash utilization-efficiency of seaweeds. We calculate that the enhanced light-flash utilization-efficiency wrought by wave-induced light-flashes may contribute to significant gains in primary productivity of these macroalgae under some conditions.     

Spatial and temporal variability in the assemblage structure of fishes associated with mangroves (<Emphasis Type="Italic">Avicennia marina</Emphasis>) and intertidal mudflats in temperate Australian embayments

Fishes using mangrove (Avicennia marina) and mudflat habitat were sampled using three different types of gear (seine, fyke, and gill nets) at three sites within each of two large embayments through time (quarterly) between January 2002 and November 2002. At least 41 species of fish were sampled, of which 78% were marine, 17% were estuarine, and 5% were freshwater. Juveniles were sampled in 41% of the species, and 5 and 6 species occurred exclusively in mangrove and mudflat habitats, respectively. The assemblage structure of fishes varied significantly between habitats (for both fyke and seine catches) and between spring and summer (seine catches), but only in one bay. Most of the variability between habitats and times of the year could be explained by differences in abundances of atherinids, mugulids, gobiids, tetraodontids, pleuronectids, and clupeids. Fyke nets sampled mainly juvenile and smaller species of fish. Fish abundance was always greater in mangroves than mudflats (but significantly so at four of the six study sites) and varied significantly between times of the year at one site, while the number of species varied significantly between times of the year at three sites. Gill nets sampled mostly adult/subadult fishes and abundances were greater in mudflats than mangroves at two sites, and in mangroves over mudflats at one site, while species abundance varied between times of the year at two sites. The seine net sampled mainly early post-settlement and small (<20 mm) fishes, more species of which were sampled in mudflat than mangrove during winter and spring, whereas the opposite pattern occurred in summer and autumn. The number of fish sampled with the seine net only varied significantly between habitats in one embayment during summer and spring, when they were larger and smaller, respectively, in mangroves than mudflats. Mangrove habitat in temperate Australian waters supports a richer juvenile fish assemblage than adjacent mudflats, but there is little difference between habitats for the subadult/adult assemblage. Ultimately, the value of mangrove habitats to fishes depends strongly on when and where (bays and sites within bays) the study is done.Communicated by M.S. Johnson, Crawley     

Gut length and mass in herbivorous and carnivorous prickleback fishes (Teleostei: Stichaeidae): ontogenetic, dietary, and phylogenetic effects

Relative gut length, Zihler’s index, and relative gut mass were measured in four species of prickleback fishes and the effects of ontogeny, diet, and phylogeny on these gut dimensions were determined. Of the four species, Cebidichthys violaceus and Xiphister mucosus shift to herbivory with growth (>45 mm SL), whereas X. atropurpureus and Anoplarchus purpurescens remain carnivores. A. purpurescens belongs to a carnivorous clade, and the three other species belong to an adjacent, herbivorous clade. Gut dimensions were compared in three feeding categories of the four species: (1) small, wild-caught juveniles representing the carnivorous condition before two species shift to herbivory; (2) larger, wild-caught juveniles representing the natural diet condition of the two carnivores and the two species that have shifted to herbivory; and (3) larger, laboratory-raised juveniles produced by feeding a high-protein artificial diet to small juveniles until they have reached the size of the larger, wild-caught juveniles. Comparisons of gut dimensions in categories (1) versus (2) tested for an ontogenetic effect, in (2) versus (3) for a dietary effect, and within each category for a phylogenetic effect. C. violaceus and X. mucosus increased gut dimensions with increase in body size and did not change ontogenetic trajectory in gut dimensions on the high-protein artificial diet, suggesting that they are genetically programmed to develop relatively large guts associated with herbivory. X. atropurpureus increased its gut dimensions with increase in size similar to its sister taxon, X. mucosus, suggesting a phylogenetic influence, but decreased gut dimensions on the high-protein artificial diet, suggesting phenotypic plasticity. Nevertheless, X. atropurpureus displayed a larger gut than A. purpurescens, further evidence that it evolved in an herbivorous clade. A. purpurescens possessed a relatively small gut that was little affected by ontogeny or diet. Ontogeny and phylogeny more than diet appear to influence gut dimensions in the four species, thus favoring genetic adaptation over phenotypic plasticity as the major force acting on digestive system features in the two prickleback clades.     

Photosynthesis in air and in water of Acanthophora najadiformis growing within a narrow zone of the intertidal

In this work, we investigated photosynthetic gas exchange responses of the red alga Acanthophora najadiformis (collected in 1991 from a shore near Netanya, Israel) to heating, light, inorganic carbon and desiccation of the thalli. This was done to elucidate some of the contributing causes for its particular restricted vertical distribution within the lower intertidal zone of the Israeli Mediterranean rocky shore. In contrast to other common intertidal species, the photosynthetic performance of A. najadiformis was very sensitive to desiccation and to high temperature, and these factors may thus prevent the alga from growing above the surge zone. On the other hand, this species photosynthesized five times faster in air than in water (provided it was kept highly hydrated), and this may be the reason why it does not succeed in competing with other algae in the subtidal which use HCO ₃ ^- more efficiently.This paper is in partial fulfillment of a Ph.D. study by R. Einav in cooperation with the Department of Ecology, University of Bielefeld (under supervision of Prof. Dr. S. W. Breckle), under a cooperative arrangement between Tel Aviv and Bielefeld Universities     

Sexual signalling and viability in a wolf spider (Hygrolycosa rubrofasciata): measurements under laboratory and field conditions

This study examined the crucial prediction of the conditional-handicap theory, the relationship between male sexual trait size and male viability, in the wolf spider Hygrolycosa rubrofasciata. In this species, males court females by drumming dry leaves with their abdomen, and males with the highest drumming rate enjoy highest mating success. We determined male drumming rate, body mass, and mobility, which reflects mate-searching activity, in relation to male survival. Because it is often difficult to know how results obtained from laboratory studies reflect the natural world, particularly when the measured variable is survival, we repeated our study in both laboratory and field conditions. Males drumming at the highest rate survived better than males drumming at a lower rate in both laboratory and field conditions. These results are in accordance with the predictions of conditional-handicap models of sexual selection. Survival was independent of male body mass and there was no significant correlation between male drumming activity and body mass. However, large males moved further than smaller males, and males moving longer distances lost less mass than those moving shorter distances. These results suggest that, moving, and consequently mate-searching activity, may be a condition-dependent trait and that there may be a advantage for large males in mate searching. Received: 22 October 1998 / Received in revised form: 28 January 1999 / Accepted: 14 February 1999     

Transmission of food preferences in spiny mice (Acomys cahirinus) via nose-mouth interaction between mothers and weanlings

Summary Two laboratory experiments assessed the role of nose-to-head and nose-mouth investigation in the transmission of food preferences from Acomys cahirinus mothers to their offspring. Pups spent more time nosing and licking the nose-mouth area of mothers who ate a novel food (fresh potato or carrot) than of mothers who ate no novel food. A greater amount of the less-preferred novel food (potato) was subsequently eaten by pups whose mothers had eaten potato than pups whose mothers had eaten either carrot or familiar laboratory chow only. Mothers maintained a stereotypic posture during nose-mouth investigation, holding still with mouth slightly open, providing both a source of specific food cues and a context in which pups could become familiar with them. These data suggest an active role by Acomys mothers in the development of offspring food preferences.     

Interactions between sea urchins (Strongylocentrotus droebachiensis) and their predators in field and laboratory experiments

Field observations and manipulative experiments in a nearshore cobble bed (2 to 3 m below mean low water) at Eagle Head, Nova Scotia, Canada, between 1984 and 1986, showed that small juveniles ofStrongylocentrotus droebachiensis (3 to 6 mm diam) sheltering beneath cobbles had a refuge from predators such as rock crabs, small lobsters, and fish. Sea urchins gradually outgrew these refuges and small adults (25 to 30 mm) required larger rocks as shelter from predators, particularly large cancrid crabs. Small juveniles were usually solitary and well dispersed beneath cobbles, whereas small adults tended to aggregate on the undersides and in the interstices of boulders. These aggregations may develop passively as sea urchins accumulate in suitablysized refuges. Chemotaxis experiments indicate that juvenileS. droebachiensis are repelled by waterborne stimuli from conspecifics. In a factorial experiment, effects of the presence of potential predators (rock crabs and lobsters) and/or food (kelp) on the behaviour of large juvenile (10 to 15 mm) and small adult sea urchins were examined in flowing seawater tanks. Both size classes formed exposed feeding aggregations when kelp was provided as food, irrespective of the presence or absence of predators. In the absence of kelp, each size class responded differently to the presence of a predator: juveniles became more cryptic, whereas adults aggregated on the tank sides. Increased movement to the sides of a tank in the presence of a predator may reflect a flight response, since chemotaxis experiments indicated thatS. droebachiensis is repelled by waterborne chemical stimuli from predators. Observational and experimental data suggest that predation at the late juvenile and early adult stages may influence population structure, distribution and abundance ofS. droebachiensis.     

Relation of particle-size spectrum and food abundance to particle selectivity in the mud snail Hydrobia totteni (Prosobranchia: Hydrobiidae)

We studied the relationship between particle-size selectivity and variable particle-size distribution in the American mud snail Hydrobia totteni Morrison (Prosobranchia: Hydrobiidae) collected in the summer of 1979 and 1982, from saltmarsh mudflats at Flax Pond, Old Field, New York, USA. Using individual size fractions of native sediment, snails fed fastest on intermediate-sized particles (41 to 63 m); this pattern was related to diatom abundance, which was similarly greatest on the intermediate particle-size classes. These results conform to another study, which found a quite different relationship between feeding rate and particle size, but a similarly strong correlation between particle size and diatom abundance. Snails were fed a range of particle-size distributions of glass beads. As median particle size increased, preference shifted towards smaller particles. This shift cannot be explained by feeding rates determined from individual particle-size classes. The most reasonable alternative model is a shift towards feeding on fine particles that occur among the coarser particles that are not ingested. Our data suggest that diatom growth on certain particle sizes is as important to particle selectivity as the particle sizes themselves. Particle size preference cannot be extrapolated from studies of feeding rates on individual size classes since selectivity is qualitatively different in mixtures of various size classes.     

Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India

This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes (Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (As^V ranges from 0.16 to 0.50 mg kg^?1) or arsenite (As^III ranges from 0.10 to 0.41 mg kg^?1) (30–53 % as inorganic As) and dimethylarsinic acid (DMA^V <1–25 %). Arsenobetaine (AB < 16 %), and PO₄-arsenoriboside (8–48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MA^V) was not detected in any of the polychaetes. The highest total As (14.7 mg kg^?1 dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kg^?1 dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kg^?1 of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands.     

Discussion of methods of investigating the food of fishes,with reference to a preliminary study of the prey of Gobiusculus flavescens (Gobiidae)

The validity, reliability and practicability of different methods for the investigation of stomach contents of a small, plankton-eating fish are discussed. Tests demonstrated the problems related to mass and volume measurements of planktonic food. Several nutrition indices, particularly Hynes's frequency of occurrence are criticized. A logarithmic version of Shorigin's index is proposed as a replacement for Ivlev's food selection index. A preliminary study on the food of Gobiusculus flavescens (Fabricius), sampled in July, 1975 at Helgoland, provides some numerical information on the composition of its stomach contents and food preference.     

Impact of Arenicola marina (Polychaeta) on the microbial assemblages and meiobenthos in a marine intertidal flat

The benthic microbial food web can be responsible for a large proportion of benthic carbon cycling yet there are few data on the trophic interactions between this food web and macrobenthos. A large-scale field experiment was conducted to investigate effects of eliminating the polychaete Arenicola marina on benthic microbes (prokaryotes, heterotrophic and autotrophic protists) and metazoan meiofauna in a marine intertidal flat of the North Sea, Germany. Over a period of 2 years, quantity and composition of micro- and meiobenthos from unmanipulated sites were compared to those from sites deplete of lugworms. These grazer treatments were cross-classified with different sediment characteristics (low- and mid-intertidal areas). Lugworm removal resulted in an initial increase in abundance of prokaryotes and nanoflagellates, which became less pronounced in the second year. Ciliates were not affected quantitatively, but in the absence of lugworms, diversity and the proportion of carnivorous forms increased. Meiobenthos (nematodes, ostracods and copepods) were affected only moderately. The observed changes are probably due to a combination of release from grazing/predation pressure, changes in the species composition of higher trophic levels (namely large polychaetes) and altered environmental conditions (such as depth of the oxygenated layer and sediment grain size). Spatial differences between sites of different tidal exposure/grain size appeared to be as large as temporal differences during the 2 years following the manipulation of the system. We conclude that in intertidal sediments, indirect effects due to habitat transformation are as important as direct biological interactions (grazing pressure and competition) for the dynamics of the benthic microbial food web.     

Occurence of intersexuality in a laboratory culture of the copepod Eurytemora affinis from the Seine estuary (France)

We show in this study that intersexuality can occur in the estuarine copepod Eurytemora affinis, and we reported the presence of three intersexual copepod individuals from a laboratory culture of this species from the Seine estuary conducted at low temperature (7°C). These individuals presented both female and male characteristics. The prosome size and antennules of intersex individuals were similar to those of normal females, but all the other morphological details were more similar to normal males. The appearance of the three intersex individuals in the culture at low temperature coincided with a decrease in food quality due to a feeding with Rhodomonas marina at its stationary phase. This induced a significant decrease in the mean clutch size and skewed sex-ratio in favor of males. The reduction in food quality in addition to low temperature of 7°C (which induced slow development) is suspected to be responsible of the appearance of intersex individuals. This stressful situation seems to propagate to the following two generations at low temperature in contrast to the case of the experiment at higher temperature 20°C where no intersex individual was observed. These results confirmed the role of food quality in sex determination of copepods. Moreover, the role of early developmental stages and also the consequences of stressful conditions throughout different generations were discussed.     

Public preferences for visual quality and management in the Kackar Mountains National Park (Turkey)

There are 37 national parks in Turkey, encompassing the most important mountain ecosystems, with high biological, natural, cultural and historical diversity. These parks also have aesthetic and recreational potential, and are valuable components within the country's nature protection programmes. Globally, a landscape can be regarded as the face of an ecosystem and constitutes a relationship between natural structure and visual features. There have been several studies on whether visual quality can provide indicators for landscape planning. Visual quality can also be assessed as a manifesto for community participation. This paper attempts to extend the understanding of visual quality assessment for national parks, using the Kackar Mountains National Park (KMNP) in north-eastern Turkey as an example. A detailed survey of visual quality preferences, landscape factors (10 main and 40 sub-factors) and semantic factors (naturalness, variety, fascination, vividness, unity, interesting and exciting) affecting these preferences was made using 30 represenative slides selected from the park. The highest preference was found to be 6.54, while the lowest was 2.30. Regression analysis enabled us to determine the relationship between visual quality and visual landscape attributes. The R2 value for naturalness was 0.482, while naturalness together with lake and fog percentage was 0.641. The assessment of preferences for the studied views in various landscape units can be evaluated and used for land-use decisions and future planning in KMNP.     

Studies on the uptake of cadmium by the crab Carcinus maenas in the laboratory. I. Accumulation from seawater and a food source

The crab Carcinus maenas (L.) was exposed to radioactively labelled cadmium dissolved in seawater at concentrations of 0.1, 1 and 10 ppm, the latter concentration being toxic to the crabs (50% mortality after 12.3 days). Net accumulation of cadmium from solution was proportional to the level and time period of cadmium exposure. Total absorbed cadmium levels reached 0.0043 and 0.0412 mg Cd g^-1 dry weight after 40 days exposure to 0.1 and 1 ppm Cd, respectively, and 0.1115 mg Cd g^-1 dry weight after 12.3 days average exposure to 10 ppm Cd. The highest tissue concentration was found in the midgut gland, reaching 0.786 mg Cd g^-1 dry weight after 12.3 days average exposure to 10 ppm Cd. The midgut gland only contained about 10% of the total cadmium absorbed from solution, while the exoskeleton contained the bulk of obsorbed cadmium (59 to 80%) probably passively adsorbed onto the surface. When cadmium was absorbed by the crabs from a food source, the midgut gland contained 16.9% of the total absorbed cadmium whereas the exoskeleton now contained only 22.2%. Ten percent of the cadmium available in the food source (Artemia salina) was accumulated by the crabs. When placed in cadmium-free seawater, crabs that had accumulated cadmium from solution lost 69% of the absorbed cadmium in 10 days, mostly from the exoskeleton which lost 78% of its original absorbed cadmium concentration.     

Density and distribution patterns of the temperate marine fish Cheilodactylus spectabilis (Cheilodactylidae) in a reef environment

Cheilodactylus spectabilis (Hutton) is common over shallow reefs in north-eastern New Zealand. Replicated transect between-area differences in density and in size frequency. C. spectabilis is not nocturnally active. The between-area differences in density and size frequency remained constant over daylight hours, demonstrating that C. spectabilis does not undergo any systematic feeding migrations. Topographic complexity was shown to have a significant positive influence on fish density. Mean size was related to water depth at 5 localities investigated, with small (<200 mm standard length, SL) individuals being restricted to shallow water. All sizes of C. spectabilis examined had fed on small invertebrates, with gammarid amphipods predominating. No evidence of size-related differentiation in feeding patterns was observed, although small individuals spent significantly more time feeding than large ones. Small (<200 mm SL) individuals occupied feeding areas and shelter sites from which they excluded other small C. spectabilis. Large individuals showed no site-associated aggression, covered a greater area during daily movements and overlapped with other large and small C. spectabilis while feeding. No evidence of dawn or dusk peaks of feeding activity or movement was collected.