Patterns Of Foraging Activity Research Articles

Foraging and homing behaviour of the limpet, Patella vulgata: a geographical comparison

As yet few generalizations have been formulated, concerning the tuning, distance and direction of foraging behaviour of Patella vulgata (Linnaeus, 1758). This limpet has previously been reported to be active during daytime high tides and during emersion at nighttime.' Various authors have investigated local factors affecting foraging activity patterns in P vulgata*' but little attempt appears to have been made to make geographical comparisons of populations of this species as proposed in a previous study. This aimed to investigate the foraging patterns and homing behaviour of the limpet Patella vulgata at two widely separated geographical sites within the British Isles. The two localities chosen, in North Wales and in Cornwall, permitted comparisons to be made, using identical observing techniques of limpets in similar positions on the shore, at two latitudes and in localities showing marked differences in the timing during the day of high spring tides. Limpets were observed at Menai Bndge (53°13'15N, 4°09'50*W), on the Isle of Anglesey, and at Porthoustock (50°03'10*N, 503'30rW) on the Lizard peninsula. The sites were sheltered and in each locality limpets were studied on a vertical wall constructed of granite blocks. Twenty limpets of similar size at the mid-shore level were observed at each site (Menai Bridge mean limpet shell length = 43.2 ± s.d. 8-33 mm; Porthoustock = 42.6 ± s.d. 8.6 mm, ttest for size differences gives p = 0.84). At Menai Bridge, the area used for study was located directly beneath the Menai Bridge pier. The wall faced in an East-south-easterly direction, its flora dominated by the macroalga Ascophyllum nodosum Le. Jol. and its fauna by P. vulgata. Semibalanus balanoides (L.) was present, covering less than 30% of the study area. The tidal range at Menai Bridge is 6.7 m on mean spring tides, and 3.6 m on mean neap tides,' with highest spring' tides phased around 0200 and 1400 h. At Porthoustock the study site was part of the 'West of England Pier*, an abandoned quarry with a sheltered West-south-westerly facing wall. Macroalgae were absent on the wall and the fauna was dominated by Semtbalanus balanoides and P vulgata. Barnacle coverage of the wall surface was estimated

Foraging by the stoplight parrotfish Sparisoma viride II. Intake and assimilation of food, protein and energy

Daily food intake by the herbivorous parrotfish Sparisoma viride, as well as assimilation efficiencies of algal food, protein and energy, were quantified through a combination of laboratory feeding trials and field observations. The intake of algal ash-free dry wt (AFDW) per bite increases linearly with fish wet wt (FWW, g) and algal biomass (mg AFDW CM-2), and is further determined by the skeletal density of the limestone substrate. Low-density substrates yield higher amounts of AFDW per bite than do high-density substrates. The percentage of the total food intake that is derived from endolithic and crustose coralline algae increases with the size of the fish, and can be > 70 % depending on the biomass of epilithic algae. The daily pattern of foraging activity is positively correlated with diurnal changes in food quality, while seasonal daylength variations result in 13 % variation in total daily bites taken. Daily number of bites of S. viride in the field decreases with fish size, and is further dependent on life phase and foraging depth. In experiments, fish attained an assimilation efficiency of ca 20 % from a natural diet of low algal biomass and high-density dead coral substrates that predominates in the shallow reef. Assimilation efficiency was ca 70 % from a diet of high algal biomass and low-density substrates that predominates on the deeper reef parts. In spite of lower daily foraging effort, territorial fish, living in deeper parts of the reef, ingest and assimilate higher amounts of AFDW, protein and energy per day than non-territorial fish foraging on the shallow reef. The difference is caused by increased availability of high-yield food and substrate types inside territories compared to the situation on the shallow reef. Daily assimilated energy (kJ d-1) is 0.85 x FWW 0.773 for fish foraging in the shallow reef zone, and 1.22 x FWW0.854 for S. viride foraging inside territories on the deeper reef.

Predatory Foraging Behaviour and Activity Patterns of Larvae of Two Species of Limnephilid Cased Caddis

Temporal feeding behaviour, locomotory activity patterns and functional responses of larvae of two species of cased caddis were investigated in the laboratory. The temporal pattern of locomotory activity of both Potamophylax cingulatus (Stephen) and Halesus radiatus (Curtis) was examined under constant conditions of 12 h light/12 h darkness, continuous light and continuous darkness. Larvae of both showed a similar endogenous rhythm of activity consistent with the species being nocturnal and were most active at night during a 4 h period (2000-2400 h). They also demonstrated a greater consumption of prey at night and under the continuous darkness conditions. This feeding activity pattern appears to be based primarily on intrinsic predator activity patterns rather than generated as a response to prey activity

Temperature and the pollinating activity of social bees

Abstract. Thermal constraints on flight acivity limit the pollinating effectiveness of bees. Each species of social bee has a microclimatic ‘window’ within which foraging flight can be sustained. To predict whether a given species of social bee is worth testing as a pollinator in a given climate, it is useful to know at least the lower limits of that microclimatic ‘window’. We consider how information from a series of bee counts through a day can be used to characterize a bee species in terms of activity/microclimate relations as a basis for predicting the diel pattern of foraging activity of a bee introduced into a new climate as a pollinator. We discuss the relative merits of bee counts at a foraging patch and counts based on hive traffic as indices of the proportion of bees active. We suggest that the activity/microclimate relations of a species be expressed in terms of the lower threshold black globe temperature for flight activity. Black globe temperature, Tg, is easily measured with inexpensive equipment, and can substitute for measurements of ambient temperature and radiation as a predictor of diel patterns of bee activity. We use examples of field data to explore the relationship between microclimate and activity for the honeybee Apis mellifera and several species of bumblebee, Bombus. Regression analysis is used to relate activity to Tg and to identify the lower temperature threshold for activity from field bee counts. In field studies analysed here, the bumblebees Bombus terrestrisllucorum, B.pascuorum and B.hortorum began foraging at lower temperatures than honey‐bees or B.lapidarius.

Spatial and temporal patterns of granivorous ant seed predation in patchy cereal crop areas of central Spain.

Patterns of granivorous ant seed predation in extensive cereal croplands of central Spain were investigated by measuring seed removal rates on artificial seed patches. Sampling was designed to cope with the seasonal and daily foraging cycle of ant colonies. Simultaneously with removal rates, I measured seed availability, habitat physiognomy at two spatial scales (landscape and microhabitat), weather variables (temperature and rainfall), and distance to the nearest ant nest. Ant seed predation was concentrated on shrublands, and associated with places with high covers of shrubs, chamaephytes and stones. These results were in close agreement with those obtained by analyzing the spatial distribution of granivorous ant nests (Díaz 1991). Moreover, there was a close relationship between seed removal rates and distance to the nearest ant nest, that fitted the predictions of the optimal foraging model developed by Reyes-López (1987). Seasonal and daily patterns of ant foraging activity seemed to depend more on endogenous factors than on environmental variation. I conclude that ants were not able to track the spatial and temporal variation of their food resources in these man-modified habitats, so that their potential to interact with other members of the granivore system is greatly reduced by human activities.

Seasonal patterns of foraging activity in colonies of the African honey bee,Apis mellifera scutellata, in Africa

Seasonal foraging patterns were investigated using six observation colonies maintained in the Okavango Delta, Botswana. Pollen collection, flight from the hive, and recruitment for pollen and nectar sources occurred throughout the 11 months of the study. However, the distribution of foraging activity throughout the day changed seasonally. Colonies emphasized recruitment for pollen sites throughout most of the year. Brood production occurred in all months except May, and there was a significant, positive correlation between the proportion of recruitment activity devoted to pollen sources and the amount of brood comb in the colonies. The seasonal foraging patterns ofscutellata in the Okavango were similar to those of Africanized honey bees in the neotropics. The extended foraging season and emphasis on pollen collection may be associated with the high swarming rates and migrational movements of tropical honey bees.

Summer Activity Patterns of Insectivorous Bats and Their Prey in Tasmania

Nightly activity patterns of seven species of bats (Eptesicus vulturnus, E. regulus, E. sagittula, Nyctophilus geoffroyi, N. timoriensis, Chalinolobus morio and FalsistreNus tasmaniensis) and their volant insect prey were studied during late spring and summer at four sites in Tasmania. Activity of bats was assessed from trapping results. Bats exhibited a biomodal pattern of foraging activity being most active in the first hours after dark, declining to low levels in the middle part of the night and rising again to a secondary peak in the three hours before dawn. These patterns of activity in bats closely reflected the patterns of insect activity. The insectivorous bats thus appear to have adjusted their nightly activities to match those of their prey, thereby maximising foraging success and energy gains.

Predation of Juvenile Pacific Salmon by the Common Merganser (Mergus merganser) on Eastern Vancouver Island. I: Predation during the Seaward Migration

Predation of juvenile salmonids by the common merganser (Mergus merganser) was investigated during the period of seaward migration in two streams where fish populations are enhanced by spawning channels and hatcheries. Observation of foraging behaviour and crop-gullet contents indicated that, during this period, mergansers foraging on freshwater reaches of the streams ate juvenile salmonids almost exclusively whereas those foraging on tidal waters rarely ate salmonids. Maximum rates of salmonid mortality were estimated by assessing merganser abundance and the pattern of foraging activity on fresh versus tidal waters. Maximum mortality rate declined as fish abundance increased (i.e. mortality was depensatory) in all cases where the effects of prey size-selection could be ignored owing to an overwhelming abundance of one prey species. Bounds on maximum mortality rate by species for the entire migration period were computed under different hypotheses about the prey size-selection habits of mergansers; maximum mortality rate did not exceed 10% for any salmonid species over the entire seaward migration.

Foraging activity patterns in the goosander (Mergus merganser) and the red-breasted merganser (M. serrator) in relation to patterns of activity in their major prey species.

Diel and seasonal foraging activity patterns of goosanders (Mergus merganser L.) and red-breasted mergansers (M. serrator L.) were studied during the breeding season on the Rickleå River in northern Sweden (64°05'N). In addition, the locomotor activity patterns of their most important prey species, the river lamprey (Lampetra fluviatilis (L.)) and the three-spined stickleback (Gasterosteus aculeatus L.), were recorded.During spring, as mergansers arrived in the breeding area, both species exhibited a bimodal, diurnal pattern of activity with morning and evening peaks. By June (the spawning period for the river lamprey and the migratory period for the three-spined stickleback), goosander activity had shifted to late in the evening. This new activity peak correlated well with the main activity period in the river lamprey. Red-breasted mergansers remained predominantly diurnal throughout the observation period. Their diurnal activity correlated with the activity of their major prey, the three-spined stickleback.Both merganser species utilize a specialized foraging technique, i.e. probing the river-bottom with the bill, to catch hiding fish more or less at random. This behaviour probably helps them to forage during the relatively bright summer nights and thus prey upon the abundant nocturnal river lamprey. The goosander preys upon the river lamprey to a greater extent than does the red-breasted merganser, thus leading to a temporal segregation in food resource utilization between the two duck species.

Patterns of foraging activity in the limpet Patellavulgata L. — A preliminary study

Activity of limpets was studied at Lough Ine, Co. Cork, Ireland. The small tidal range allowed long periods of continuous observation over consecutive tidal cycles. All activity was associated with the time of low water, but showed varying relations to it depending on vertical height on the shore and on the time in the spring/neap cycle. Low-water limpets were predominantly active in the day, but also showed a minor activity peak on the low water at night. Limpets higher on the shore were active only at night. It is possible that these differences reflect different behaviour in relation to the effects of desiccation and predation at different levels on the shore. The activity periods were shown to be exclusively concerned with feeding: radula rasping was almost continuous while the limpets were away from the home scar. Limpets at different levels had, however, different behaviour patterns in terms of the areas that they used for grazing.

Species diversity and temporal distribution of ants in the semi‐arid mallee region of northwestern Victoria

AbstractThe ant communities of two adjacent sites bearing markedly different vegetation (heath and mallee) were studied using quadrat counts and pitfall traps in semi‐arid northwestern Victoria. The ants were extremely abundant and rich in species (86 species from 27 genera were recorded from two 50 m × 25 m plots within 25 m of each other) and were dominated by species ofMonomorium and Iridomyrmex. Pronounced site differences in species composition were found, with 73% of the most abundant species showing a strong site preference. The ants exhibited marked seasonality: activity was highest in summer and lowest in winter and this was accompanied by a high turnover of species in time, resulting in pronounced seasonal differences in species composition. Most foraging was nocturnal during summer but was almost exclusively diurnal during winter, and individual species displayed distinctive patterns of diet foraging activity. Although the overall temporal distribution of the communities were apparently controlled by temperature, interspecific competition may also be an important factor influencing the seasonal and diel distributions of individual species, resulting in their high degree of temporal separation. The overall consequence is that although the study area contains many abundant species with similar ecological requirements, few of these are active in the same place at the same time.

Temporal patterns of foraging activity in some wood warblers in relation to the availability of insect prey

I monitored the temporal pattern of diurnal feeding activity in several wood warbler (Parulidae) species and concomitantly recorded the numbers of active (flying) insects in 2 willow habitats in the western United States. At one site the temporal relationship between the density of active and inactive (nonflying) insects was investigated. The diurnal patterns of insect and bird activity were inversely related and each pattern was significantly nonuniform throughout the day; the wood warblers were largely inactive during the middle of the day when insects were most active.

Temporal structure of an ant community in semi‐arid Australia

AbstractThe activity of five seed‐harvesting and ten non‐harvesting species of ants was examined over a 2‐year period. The ant community appeared to be stable in the long term, but there was considerable variability in the numbers and species of ants active at any one time, both on a seasonal and diel basis. Only four species were active throughout the year, with activity reduced in winter. Two species were consistently nocturnal, nine were mainly diurnal, and the remaining four species switched from diurnal to more nocturnal activity with increasing temperatures.The changes in the diurnal pattern and intensity of foraging activity were shown to be controlled by several climatic and biotic variables. These were classed as either ‘stimulatory‐inhibitory’ which determined whether activity would occur or not, or ‘regulatory’, which set the physical limits to activity and controlled foraging intensity. Factors such as forage availability and colony satiation were placed in the first category, and soil temperature, moisture stress and light intensity were placed in the second.There was no simple response to the combination of variables, and individual species responded differently to the various factors. The resulting temporal separation probably reduces competitive interactions between species.

Microhabitat Resource Use, Activity Patterns, and Episodic Catastrophe: Conus on Tropical Intertidal Reef Rock Benches

Low species richness (five to nine species) and high population density (means of 0.2—8.6 individuals per square metre) characterize Conus assemblages on intertidal benches throughout the tropical Indo—West Pacific region. Data from 16 such habitats in Hawaii, Marshall Islands, Australia, Maldives, and Seychelles indicate that similarity of microhabitats between species is equal to or greater than random expectation. Significant between—species differences in zonation pattern occur across benches at a given time and place. The peak of C. ebraeus abundance typically occurs closest to shore; C. chaldaeus and C. sponsalis are usually most distant from shore. However, we found about as man significant within—species differences between censuses made at different times on the same bench as between—species differences within censuses. Co—occurring species thus tend not to use microhabitat resources differentially. Physical environmental variables including tide level, strength of water flow and time of day determine refuging and foraging activity patterns, and all species appear to respond similarly to these factors. The data thus do not support the hypothesis of temporal resource partitioning. We found evidence neither for homing, as mark—recapture results suggested that individuals occupy any convenient refuge after foraging, nor for interference competition for protected sites among Conus. species diversity is significantly correlated with (1) substrate topographic diversity measured either independently or as the diversity of microhabitats utilized by all species together, and (2) the proportion of individuals occupying protected sites. Where refuges (potholes and crevices) comprise only 2—9% of bench surface area, an average of 63% of Conus individuals occupy them, indicating strong selection for protected microhabitats. The presence and quality of these physical refuges are less important on benches with thick mats of algal turf binding sand. The gastropods burrow in these mats during periods of stress. A catastrophic rainstorm coinciding with low tide caused high mortality in an inner bench population at Enewetak, but more C. ebraeus survived (30%) than other species (8%). Tolerance to such unpredictable physical stress may explain the observed patterns of zonation of Conus of different species and sizes across benches.

NOTES ON THE ECOLOGY OF AN AUSTRALIAN DESERT SPECIES OF CALOM YRMEX (HYMENOPTERA: FORMICIDAE)

The ecology of a formicine desert ant, Calomyrmex, was studied in an arid region of southern N.S.W. The patterns of foraging activity are noted and the nest structure is described. A nearest neighbour analysis of nest distribution found the nests to be strongly aggregated into groups. ***Observations of fighting behaviour demonstrated that certain groups of nests were compatible, suggesting that colonies are integrated as a social unit. The mandibular gland secretion released by disturbed foragers and guard ants was deep orange in colour while that released by workers tending young within the nest, was often white or yellow.