Habitat use by squirrel monkeys (Saimiri oerstedi) in Costa Rica

This paper analyses movement patterns, habitat preferences, activity schedules, and dispersion of troop members in squirrel monkeys (Saimiri oerstedi) in relation to seasonal changes in food abundance in a Costa Rican tropical wet forest. Secondary forest was the preferred habitat and use of primary forest and late successional forest was limited primarily to seasons when food availability was low. Range area differed between seasons, varying from 79 to 110 ha, and totaling 176 ha over 11 months. The number of hectares used, hourly rate of group movement, and proportion of time spent foraging each season were all negatively related to relative food abundance. There was a tendency to spend less time in foraging activities in the middle of the day and to spend more time exclusively in travel at dawn and dusk. In all seasons dispersion was least when the troop was travelling and it was generally greatest during seasons of low food abundance. Measures of the allocation of time by the troop to food-related activities and the extent of troop dispersion each season were consistent with estimates based on behavior sampling of individuals.     

Momentary maximizing and optimal foraging theories of performance on concurrent VR schedules

Optimal foraging theory proposes that animals obtain the highest rate of reinforcers for the least effort and momentary maximizing theory proposes that animals make the response that at that instant is most likely to be reinforced. While each theory may account for matching on concurrent schedules, the data supporting each theory are weak. Two experiments assessed these theories by considering concurrent choice as consisting of two pairs of stay and switch schedules. Symmetrical arrangements, which are equivalent to standard concurrent schedules, maintained behavior described by the generalized matching law. Weighted arrangements, in which the programmed rate of earning reinforcers was always greater at one alternative, maintained behavior that was biased towards the weighted alternative, yet the bias was less than that predicted by optimal foraging theory. Asymmetrical arrangements, in which the stay and switch schedules operating at an alternative are the same, maintained behavior that favored one alternative, even though momentary maximizing predicted indifference. The generalized matching law poorly described each rat's pooled data from all conditions but these data were described by an equation based on the stay and switch reinforcers earned per-visit and included elements of optimal foraging and momentary maximizing theories of choice.     

An Assessment of Fixed Interval Timing in Free-Flying Honey Bees (Apis mellifera ligustica): An Analysis of Individual Performance

Interval timing is a key element of foraging theory, models of predator avoidance, and competitive interactions. Although interval timing is well documented in vertebrate species, it is virtually unstudied in invertebrates. In the present experiment, we used free-flying honey bees (Apis mellifera ligustica) as a model for timing behaviors. Subjects were trained to enter a hole in an automated artificial flower to receive a nectar reinforcer (i.e. reward). Responses were continuously reinforced prior to exposure to either a fixed interval (FI) 15-sec, FI 30-sec, FI 60-sec, or FI 120-sec reinforcement schedule. We measured response rate and post-reinforcement pause within each fixed interval trial between reinforcers. Honey bees responded at higher frequencies earlier in the fixed interval suggesting subject responding did not come under traditional forms of temporal control. Response rates were lower during FI conditions compared to performance on continuous reinforcement schedules, and responding was more resistant to extinction when previously reinforced on FI schedules. However, no “scalloped” or “break-and-run” patterns of group or individual responses reinforced on FI schedules were observed; no traditional evidence of temporal control was found. Finally, longer FI schedules eventually caused all subjects to cease returning to the operant chamber indicating subjects did not tolerate the longer FI schedules.     

Spatio-temporal organization of the bird communities in two Mediterranean montane forests

Seasonal changes of bird communities and use of foraging substrates by the birds were studied in two forests with contrasting vegetation structure in montane and subalpine levels of central Spanish mountains throughout complete annual cycles. Common factors contributing most to foraging segregation among species were found to be the foraging on the ground vs that on vegetation and use of proximal vs distal tree parts. A complete dissimilarity exists between the composition of the respective foliage-gleaning guilds, the converse being true for the trunk-searchers.
Temporal distribution of bird species is to a great extent determined by their use of space, thus existing a gradient of seasonality with maxima for ground-searchers, minima for trunk-gleaners and intermediate positions for foliage-gleaners. A close relationship among temporal variability, mean annual density and niche breadth is found for the subalpine pinewood community, but not for that from the montane oakwood, this being related with their contrasting migratory patterns and the structural stability of vegetation in each wood. The pattern of covariation in community parameters mirrors the summed response of individual bird species to the changing environmental conditions. Increases in community richness, density and diversity are related to temporal invasion by ground and foliage-gleaners of these highly seasonal Mediterranean habitats.     

Urban gulls adapt foraging schedule to human‐activity patterns

Numerous animals are able to adapt to temporal patterns in natural food availability, but whether species living in relatively novel environments such as cities can adapt to anthropogenic activity cycles is less well understood. We aimed to assess the extent to which urban gulls have adapted their foraging schedule to anthropogenic food source fluctuations related to human activity by combining field observations at three distinct urban feeding grounds (park, school and waste centre) with global positioning system (GPS) tracking data of gulls visiting similar types of feeding grounds throughout the same city. We found that the birds' foraging patterns closely matched the timing of school breaks and the opening and closing times of the waste centre, but gull activity in the park appeared to correspond to the availability of natural food sources. Overall, this suggests that gulls may have the behavioural flexibility to adapt their foraging behaviour to human time schedules when beneficial and that this trait could potentially enable them to thrive in cities.     

Spatial and Temporal Variations in the Occurrence and Foraging Activity of Coastal Dolphins in Menai Bay,Zanzibar, Tanzania

Understanding temporal patterns in distribution, occurrence and behaviour is vital for the effective conservation of cetaceans. This study used cetacean click detectors (C-PODs) to investigate spatial and temporal variation in occurrence and foraging activity of the Indo-Pacific bottlenose (Tursiops aduncus) and Indian Ocean humpback (Sousa plumbea) dolphins resident in the Menai Bay Conservation Area (MBCA), Zanzibar, Tanzania. Occurrence was measured using detection positive minutes. Inter-click intervals were used to identify terminal buzz vocalisations, allowing for analysis of foraging activity. Data were analysed in relation to spatial (location) and temporal (monsoon season, diel phase and tidal phase) variables. Results showed significantly increased occurrence and foraging activity of dolphins in southern areas and during hours of darkness. Higher occurrence at night was not explained by diel variation in echolocation rate and so were considered representative of occurrence patterns. Both tidal phase and monsoon season influenced occurrence but results varied among sites, with no general patterns found. Foraging activity was greatest during hours of darkness, High water and Flood tidal phases. Comparisons of echolocation data among sites suggested differences in the broadband click spectra of MBCA dolphins, possibly indicative of species differences. These dolphin populations are threatened by unsustainable fisheries bycatch and tourism activities. The spatial and temporal patterns identified in this study have implications for future conservation and management actions with regards to these two threats. Further, the results indicate future potential for using passive acoustics to identify and monitor the occurrence of these two species in areas where they co-exist.     

Energy budget versus temporal discounting as determinants of preference in risky choice

Four pigeons and three ringneck doves responded on an operant simulation of natural foraging. After satisfying a schedule of reinforcement associated with search time, subjects could "accept" or "reject" another schedule of reinforcement associated with handling time. Two schedules of reinforcement were available, a variable interval, and a fixed interval with the same mean value. Food available in the session (a variable related to the energy budget) was manipulated in the different conditions either by increases of the value of the search state schedule of reinforcement, or by increases in the mean value of the handling state schedules. The results indicate that the amount of food available in the session did not affect the preference for variable schedules of reinforcement, as would be predicted by an influential theory of risk sensitive foraging. Instead, the preference for variability depended on the relationship between the time spent in the search and the handling states, as is predicted by a family of models of choice that are based on the temporal proximity to the reinforcer.     

Seasonal dynamics of guild structure in a bird assemblage of the central Monte desert

Most studies of ecological guilds consider guild membership as a fixed attribute of species, and the guild structure as a fixed attribute of a community. Consequently, almost no study tackled the examination of temporal changes in the guild structure of a particular assemblage. We used data on foraging patterns of central Monte desert birds to assess seasonal differences in resource use by resident species, and to examine seasonal changes in the guild structure of the assemblage. From 1993 until 1999, we quantified the use of foraging substrates, manoeuvres, and height strata, and the utilisation of plants by 18 bird species. Resident species showed different kinds of seasonal dynamics, from no noticeable to drastic changes in their foraging patterns. Seasonal changes in guild structure were remarkable. Only two guilds were present all year round (ground foragers and foliage foragers), although they suffered important species turnover. Three other guilds had a seasonal occurrence: graminivores (during the non-breeding season), arboreal herbivores, and aerial feeders (during the breeding season). Two species changed from one guild to another between seasons. Both presence–absence of migrant species, and changes in the feeding ecology of resident species had an influence on the temporal dynamics of guild structure. These factors appeared to be related with changing resource availability, especially with the birds’ ability for facing lean conditions through migration and with the opportunistic use of seasonally superabundant resources. Our results undermine the trust in studies in which guild structure was assessed irrespective of temporal variations. We show also that guild membership is not a fixed attribute of a species: we should rather evaluate the individuals’ resource use in a given moment to assign them to a guild, instead of obtaining a single measure purporting to represent a species’ fixed attribute.     

Reduced-impact Logging has Little Effect on Temporal Activity of Frugivorous Bats (Chiroptera) in Lowland Amazonia

Reduced-impact logging (RIL) represents a viable option for sustainable use of Neotropical lowland forests while minimizing negative effects on local biodiversity. Many Neotropical bats of the family Phyllostomidae provide ecosystem services associated with pollination and seed dispersal that promote the regeneration of disturbed areas; therefore, effects of RIL on these species is of particular concern. We determined patterns of temporal activity, degree of temporal overlap of activity, and dispersion in peaks of activity for seven abundant species of frugivorous bat in Tapajós National Forest, Pará, Brazil. In addition, we evaluated the effects of RIL at a harvest level of 18.7 m³/ha and habitat physiognomy on temporal patterns of activity for these species. Bats were surveyed for four nights at each of 96 sites for a total sampling effort of 64,512 net-m-h. Sites were distributed among four experimental blocks, two blocks of unlogged forest and two blocks of forest subjected to RIL. Half of the sites in each management type were in forest gaps and half were in closed-canopy forest. In general, species exhibited similar patterns of activity, and greater than expected temporal overlap in activity among species. RIL and forest physiognomy had little effect on activity patterns of species. RIL in Amazonia removes fewer trees than do naturally occurring treefalls and such changes in habitat structure do not alter activity patterns of frugivorous bats. Evidence suggests that RIL does not have an appreciable adverse effect on frugivorous bats in Amazonia.     

Seasonal patterns of diet and ranging in two species of tamarin monkeys: Stability versus variability

From June through December, data were collected on the diet and ranging patterns of moustached (Saguinus mystax) and saddle-back (Saguinus fuscicollis) tamarin monkeys in the Amazon Basin of northeastern Peru. During this 7-month period, insects and nonleguminous fruits accounted for 83% of tamarin feeding and foraging time. Despite marked seasonal variation in rainfall and forest productivity, patterns of habitat utilization, day range, dietary diversity, resource exploitation, and activity budget remained relatively stable throughout the year. Moustached and saddle-back tamarins appear to solve problems of food acquisition and exploit patchily distributed feeding sites using a relatively limited set of foraging patterns. In general, these primates concentrate their daily feeding efforts on several trees from a small number of target plant species. These feeding sites are uncommon, produce only a small amount of ripe fruit each day, and are characterized by a high degree of intraspecific fruiting and flowering synchrony. Trees of the same species are frequently visited in succession, and individual feeding sites are revisited several times over the course of 1–2 weeks. This type of foraging pattern occurred during both dry and wet seasons and when exploiting fruit, nectar, legume, and exudate resources. Seasonal variation in the percentage of feeding and foraging time devoted to insectivory was also limited. In this investigation, there was no consistent evidence that temporal changes in overall forest fruit production had a major impact on the feeding, foraging, or ranging behavior of either tamarin species.     

Retrieval of granular bait by the Argentine ant (Hymenoptera: Formicidae): effect of clumped versus scattered dispersion patterns

Argentine ants, Linepithema humile (Mayr), use mass recruitment foraging, with clumped prey items being retrieved more efficiently than dispersed prey. However, in prior field experiments, granular baits, whether dispensed in containers or broadly scattered, had a similar impact on Argentine ant populations. In laboratory experiments, granular insecticide bait was encountered faster by Argentine ant workers and more granules were initially returned to the colony when the granules were scattered versus clumped. After 2 h, granules from both dispersion patterns were retrieved equally. Our results suggest that Argentine ant colonies adjust their foraging patterns to resources of different quality (prey versus bait). Also, foraging activity patterns for bait in the laboratory are consistent with prior field results demonstrating no efficacy advantages to discrete granular bait placements.     

Fear factor: do dugongs (<Emphasis Type="Italic">Dugong dugon</Emphasis>) trade food for safety from tiger sharks (<Emphasis Type="Italic">Galeocerdo cuvier</Emphasis>)?

Predators can influence plants indirectly by altering spatial patterns of herbivory, so studies assessing the relationship between perceived predation risk and habitat use by herbivores may improve our understanding of community organization. In marine systems, the effects of predation danger on space use by large herbivores have received little attention, despite the possibility that predator-mediated alterations in patterns of grazing by these animals influence benthic community structure. We evaluated the relationship between habitat use by foraging dugongs (Dugong dugon) and the threat of tiger shark predation in an Australian embayment (Shark Bay) between 1997 and 2004. Dugong densities were quantified in shallow (putatively dangerous) and deep (putatively safe) habitats (seven survey zones allocated to each habitat), and predation hazard was indexed using catch rates of tiger sharks (Galeocerdo cuvier); seagrass volume provided a measure of food biomass within each zone. Overall, dugongs selected shallow habitats, where their food is concentrated. Foragers used shallow and deep habitats in proportion to food availability (input matching) when large tiger sharks were scarce and overused deep habitats when sharks were common. Furthermore, strong synchrony existed between daily measures of shark abundance and the extent to which deep habitats were overused. Thus, dugongs appear to adaptively manage their risk of death by allocating time to safe but impoverished foraging patches in proportion to the likelihood of encountering predators in profitable but more dangerous areas. This apparent food-safety trade-off has important implications for seagrass community structure in Shark Bay, as it may result in marked temporal variability in grazing pressure. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Structure and Dynamics of Minke Whale Surfacing Patterns in the Gulf of St. Lawrence,Canada

Animal behavioral patterns can help us understand physiological and ecological constraints on animals and its influence on fitness. The surfacing patterns of aquatic air-breathing mammals constitute a behavioral pattern that has evolved as a trade-off between the need to replenish oxygen stores at the surface and the need to conduct other activities underwater. This study aims to better understand the surfacing pattern of a marine top predator, the minke whale (Balaenoptera acutorostrata), by investigating how their dive duration and surfacing pattern changes across their activity range. Activities were classified into resting, traveling, surface feeding and foraging at depth. For each activity, we classified dives into short and long dives and then estimated the temporal dependence between dive types. We found that minke whales modified their surfacing pattern in an activity-specific manner, both by changing the expression of their dives (i.e. density distribution) and the temporal dependence (transition probability) between dive types. As the depth of the prey layer increased between activities, the surfacing pattern of foraging whales became increasingly structured, going from a pattern dominated by long dives, when feeding at the surface, to a pattern where isolated long dives were followed by an increasing number of breaths (i.e. short dives), when the whale was foraging at depth. A similar shift in surfacing pattern occurred when prey handling time (inferred from surface corralling maneuvers) increased for surface feeding whales. The surfacing pattern also differed between feeding and non-feeding whales. Resting whales did not structure their surfacing pattern, while traveling whales did, possibly as a way to minimize cost of transport. Our results also suggest that minke whales might balance their oxygen level over multiple, rather than single, dive cycles.     

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

The 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.     

You are what you eat: describing the foraging ecology of southern elephant seals (Mirounga leonina) using blubber fatty acids

Understanding the trophodynamics of marine ecosystems requires data on the temporal and spatial variation in predator diet but, particularly for wide-ranging species, these data are often unavailable. The southern elephant seal (Mirounga leonina) consumes large quantities of fish and squid prey in the Southern Ocean relative to other marine mammals; however, how diet varies relative to seasonal and spatial foraging behaviour is unknown. We used fatty acid (FA) signature analysis of 63 blubber cores from adult female M. leonina over three seasons (winter 1999, summer 2000 and winter 2001) to determine diet structure. We detected significant differences between seasons and between the main foraging regions (Antarctic continental shelf versus pelagic). We used the FA profiles from 53 fish, squid and krill species to construct a discriminant function that would classify each seal, from its blubber sample as having a fish- or squid-FA profile. We determined that a higher proportion of M. leonina had fish-dominated diets during the winter and when foraging around the Antarctic continental shelf, and the majority had more squid-dominated diets during the summer when foraging pelagically. Thus, we were able to measure the coarse-scale diet structure of a major marine predator using FA profiles, and estimate its associated seasonal and temporal variation.     

Acoustic monitoring reveals the times and tides of harbor porpoise (Phocoena phocoena) distribution off central Oregon,U.S.A.

Harbor porpoises (Phocoena phocoena) are commonly observed in Oregon's nearshore marine environment yet knowledge of their ecosystem use and behavior remains limited, generating concerns for potential impacts on this species from future coastal development. Passive acoustic monitoring was used to investigate spatial and temporal variations in the presence and foraging activity of harbor porpoises off the Oregon coast from May through October 2014. Digital monitoring devices (DMONs) were deployed to record acoustic data (320 kHz sample rate) in two neighboring but bathymetrically different locations off the Oregon coast: (1) a site on the 30 m isobath in close proximity (<50 m) to a rocky reef, and (2) a site on the 60 m isobath in an open sandy environment. Data were analyzed with respect to two dynamic cyclic variables: diel and tidal phase. Porpoise presence at the rocky reef site was aligned with the ebb phase of the tidal forcing, while, harbor porpoise presence and foraging at the offshore, sandy bottom site was associated with night‐time foraging. The spatial and temporal patterns identified in this study suggest harbor porpoise habitat use is modulated by specific environmental conditions particular to each site that maximize foraging efficiency.     

The effects of foraging demand on social interactions in a laboratory group of Bonnet Macaques

The relationship between foraging demand and social behavior was experimentally studied in a laboratory group of bonnet macaques. Fourteen adult animals were housed in a large outdoor enclosure containing three shallow gravelfilled circular containers that served as the foraging sites. During the experimental foraging sessions raisins were placed in the containers and the social and foraging behaviors of the group were observed for 50 min following the distribution of raisins. Three types of foraging conditions were inter-spersed with one another on different test days: (1) surface load— raisins placed on top of the gravel; (2) buried load— raisins hidden underneath the gravel; and (3) sham load— no raisins placed at the foraging sites. Three basic foraging patterns, defined along a temporal dimension, were seen. One group of animals completed 50% of their total foraging by the end of the first 15 min. A second group foraged more steadily through the session. A third group foraged late, completing 50% of their foraging during the last half of the session. The foraging patterns were similar in the buried and surface condition, although the patterns were more compressed during the surface condition. More aggression and more avoidance of other animals occurred in the buried condition than in the surface condition. Very little foraging occurred during the sham condition. There was no clear relationship between the patterns of interaction during foraging and nonforaging observation sessions. The results suggest the value of manipulative laboratory studies in examining the relationship between ecological variables and social behavior in nonhuman primates.     

Influence of stock density and rate and temporal patterns of forage allocation on the diet mixing behavior of sheep grazing sagebrush steppe

An animal's ability to select a diet depends on forage availability, the density of herbivores, and the allocation of forage resources. We hypothesized that the temporal and spatial availability of forages in sagebrush steppe vegetation both influence food selection and may encourage lambs to learn to use sagebrush, a shrub that contains high levels of terpenes that limit food intake. We conducted a field study with three treatments of 20 lambs each. Forage resources were manipulated by restricting grazing areas. Lambs in treatment H grazed at a high stock density, whereas lambs in treatment L grazed at a low stock density; both groups were moved to fresh pasture daily. Lambs in treatment H3 had three times the area of treatment H, but they were moved every 3 days, making the total area grazed by H and H3 equal, but with a different temporal allocation of forage. Scan sampling was used to record the incidence of consumption among sagebrush and understory herbs. During 24 days of conditioning, stock density and temporal patterns of forage allocation both influenced the behavior of lambs. Lambs in H spent more time foraging on sagebrush (25%) than lambs in H3 (16%), and lambs in both H and H3 spent more time foraging on sagebrush than lambs in L (1%) (P < 0.05). For lambs in H3, foraging on sagebrush was cyclic and depended on the daily availability of herbs. Use of sagebrush, expressed as a percentage of total foraging time, was <1% for day 1, 13% for day 2, and 37% for day 3 (P < 0.0001). Importantly, use of sagebrush by H3 and H increased steadily as the trial progressed, whereas use of sagebrush by L was consistently low (P < 0.05). Following conditioning, when lambs were tested at low stock densities during preference test 1, use of sagebrush did not differ by groups, but at higher stock densities in preference test 2, their use of sagebrush varied by treatments: H > H3 > L (P < 0.005). Thus, the availability of alternative foods, manipulated through animal density and the temporal allocation of those resources, both affected how readily lambs learned to use sagebrush.     

Spatial-temporal patterns in intra-annual gray whale foraging: Characterizing interactions between predators and prey in Clayquot Sound, British Columbia, Canada

In Clayquot Sound, British Columbia, gray whales (Eschrichtius robustus) forage primarily on mysids (Family Mysideae) and also on crab larvae (Family Porcellanidae) that are constrained to specific habitat, which relate to bathymetric depths. In this paper we characterize the interactions of gray whales and their prey by analyzing fine scale spatial‐temporal patterns in foraging gray whale distribution within a season. Kernel density estimators are applied to two seasons (1998 and 2002) of high‐resolution data on foraging by gray whales. By partitioning data from each foraging season into several time periods (12 in 1998 and 11 in 2002), using a temporal autocorrelation function, and generating kernel density estimated surfaces for each time period, it is possible to identify discrete areas of increasing and declining foraging effort. Our results indicate that gray whales forage on mysids throughout a season and opportunistically forage on crab larvae. The episodic crab larvae feeding may reduce, but not eliminate, pressure to mysid populations enabling mysids to reassemble swarms and continue to support gray whale foraging in the latter part of the season. Results suggest that when managing marine environments, gray whale populations require multiple and connected habitats for summer foraging.     

Temporal polyethism in Korean yellowjacket foragers,Vespula koreensis (Hymenoptera,Vespidae)

We examined the foraging behavior of the Korean yellowjacket, Vespula koreensis, to determine whether this species displays temporal polyethism. Using video-recordings of the entrances of artificial nest boxes installed in the field, we investigated the association between the tasks performed by workers and age. We identified three foraging tasks (pulp, nectar and prey foraging). Pulp foraging was performed by younger foragers, while nectar and prey foraging were performed by older foragers. We measured the foraging time (time spent outside of the nest during a single foraging bout) and the weight of the materials that foragers brought into the nest for each task to estimate the cost of the task. Pulp foraging was less costly than nectar or prey foraging by both measures. Taken together, the results suggest that yellowjacket foragers tend to perform low-cost task in their early foraging days and high-cost task later. Our results add to a growing literature showing temporal polyethism in social insects.