Wild mouse lemurs revisit artificial feeding platforms: implications for field experiments on sensory and cognitive abilities in small primates

Dealing effectively with space to find important resources in a natural environment is a fundamental ability necessary for survival. Evidence has already been provided that wild gray mouse lemurs revisit stationary feeding sites regularly. In this study, we explore to what extent two sympatric mouse lemur species, Microcebus murinus and M. ravelobensis, revisited artificial feeding sites during a period of food scarcity. As the tested populations are marked with individual transponders, we built up artificial feeding platforms equipped with a transponder reader at nine different locations where mouse lemurs had been previously caught. We baited them with a liquid reward and recorded the visitors' ID, the time and frequency of their visits, as well as all encounters that occurred on the platforms. Only mouse lemurs visited platforms and a total of sixteen individuals across both species were identified. Mouse lemurs visited a platform with a frequency of 2.02 (+/-0.95, range: 1-3.4) times in a night and they revisited it on several consecutive nights following their first visit (percentage of revisits 90.6%+/-11.7, range: 73.3-100%). First visits on a platform occurred on average 44 min (+/-35; range: 13-131) after sunset. We identified encounters between mouse lemurs on platforms: all of them were agonistic and within a species. Within a dyad, chasers were significantly heavier than chasees (N=7 dyads). Our design of platform experiments offers the advantage of observing wild individually known small primates in their natural environment and of setting up controlled experiments to gain insight into their sensory and cognitive abilities.     

Do solitary foraging nocturnal mammals plan their routes?

Large-brained diurnal mammals with complex social systems are known to plan where and how to reach a resource, as shown by a systematic movement pattern analysis. We examined for the first time large-scale movement patterns of a solitary-ranging and small-brained mammal, the mouse lemur (Microcebus murinus), by using the change-point test and a heuristic random travel model to get insight into foraging strategies and potential route-planning abilities. Mouse lemurs are small nocturnal primates inhabiting the seasonal dry deciduous forest in Madagascar. During the lean season with limited food availability, these lemurs rely on few stationary food resources. We radio-tracked seven lemurs and analysed their foraging patterns. First change-points coincided with out-of-sight keystone food resources. Travel paths were more efficient in detecting these resources than a heuristic random travel model within limits of estimated detection distance. Findings suggest that even nocturnal, solitary-ranging mammals with small brains plan their route to an out-of-sight target. Thus, similar ecological pressures may lead to comparable spatial cognitive skills irrespective of the degree of sociality or relative brain size.     

Responding to a Variable Environment: Home Range, Foraging Behavior, and Nest Relocation in the Costa Rican Rainforest Ant Aphaenogaster araneoides

We studied how the tropical wet forest ant Aphaenogaster araneoides adjusted its home range and foraging behavior in response to changes in the leaf litter and food environments. We decoupled litter abundance and food availability by creating a factorial treatment design including litter removal and food supplementation. Leaf litter removal caused a decrease in the number of foraging trips but an increase in their duration. Over a 2-week experimental period, about half of the colonies relocated their nests. We found a strong effect of nearest neighbor distance upon the home range areas of colonies after they relocated their nests. In summary, short-term manipulations of resources resulted in changes in home range area and foraging behaviors that differed depending upon nest relocation and the competitive environment.     

Sensory Basis of Food Detection in Wild <Emphasis Type="BoldItalic">Microcebus murinus</Emphasis>

Very little is known about how nocturnal primates find their food. Here we studied the sensory basis of food perception in wild-caught gray mouse lemurs (Microcebus murinus) in Madagascar. Mouse lemurs feed primarily on fruit and arthropods. We established a set of behavioral experiments to assess food detection in wild-born, field-experienced mouse lemurs in short-term captivity. Specifically, we investigated whether they use visual, auditory, and motion cues to find and to localize prey arthropods and further whether olfactory cues are sufficient for finding fruit. Visual cues from motionless arthropod dummies were not sufficient to allow reliable detection of prey in choice experiments, nor did they trigger prey capture behavior when presented on the feeding platform. In contrast, visual motion cues from moving prey dummies attracted their attention. Behavioral observations and experiments with live and recorded insect rustling sounds indicated that the lemurs make use of prey-generated acoustic cues for foraging. Both visual motion cues and acoustic prey stimuli on their own were sufficient to trigger approach and capture behavior in the mouse lemurs. For the detection of fruit, choice experiments showed that olfactory information was sufficient for mouse lemurs to find a piece of banana. Our study provides the first experimental data on the sensory ecology of food detection in mouse lemurs. Further research is necessary to address the role of sensory ecology for food selection and possibly for niche differentiation between sympatric Microcebus species.     

Feeding Ecology of Sympatric Mouse Lemur Species in Northwestern Madagascar

We performed a comparative pilot study on vertical space use and feeding ecology of 2 closely related sympatric mouse lemur species in northwestern Madagascar. We recorded feeding behavior and the use of vertical forest strata for 6 gray and 4 golden-brown mouse lemur females that we followed for 120 h. We carried out feeding experiments and analyzed fecal samples for food remains. Both species showed no significant difference in use of forest strata. They had a similar overall diet, with insect secretions and gum as main plant food resources; arthropod remains occurred in about half of all fecal samples. Both lemurs used in common >50% of the plant species that each consumed, which accounts for ≥70% of all individual plants used. However, both species used >40% of their feeding plant species exclusively and seemed to differ in their degree of specialization on certain plant species.     

Sight or scent: lemur sensory reliance in detecting food quality varies with feeding ecology

Visual and olfactory cues provide important information to foragers, yet we know little about species differences in sensory reliance during food selection. In a series of experimental foraging studies, we examined the relative reliance on vision versus olfaction in three diurnal, primate species with diverse feeding ecologies, including folivorous Coquerel's sifakas (Propithecus coquereli), frugivorous ruffed lemurs (Varecia variegata spp), and generalist ring-tailed lemurs (Lemur catta). We used animals with known color-vision status and foods for which different maturation stages (and hence quality) produce distinct visual and olfactory cues (the latter determined chemically). We first showed that lemurs preferentially selected high-quality foods over low-quality foods when visual and olfactory cues were simultaneously available for both food types. Next, using a novel apparatus in a series of discrimination trials, we either manipulated food quality (while holding sensory cues constant) or manipulated sensory cues (while holding food quality constant). Among our study subjects that showed relatively strong preferences for high-quality foods, folivores required both sensory cues combined to reliably identify their preferred foods, whereas generalists could identify their preferred foods using either cue alone, and frugivores could identify their preferred foods using olfactory, but not visual, cues alone. Moreover, when only high-quality foods were available, folivores and generalists used visual rather than olfactory cues to select food, whereas frugivores used both cue types equally. Lastly, individuals in all three of the study species predominantly relied on sight when choosing between low-quality foods, but species differed in the strength of their sensory biases. Our results generally emphasize visual over olfactory reliance in foraging lemurs, but we suggest that the relative sensory reliance of animals may vary with their feeding ecology.     

饥饿和食物单宁酸对东方田鼠(Microtus fortis)食物摄入量和觅食行为的影响

实验室条件下,测定饥饿和食物单宁酸对东方田鼠食物摄入量和觅食行为的影响。结果表明,饥饿使实验个体的食物总摄入量增加,食物摄入率及口量大小随饥饿强度的增大而增加,而觅食频次则无显著改变,实验个体每取食回合的觅食时间呈缓慢增加的趋势,与对照组比较,觅食时间差异不显著。东方田鼠优先选择0%单宁酸食物,次为3%单宁酸食物,而对6%单宁酸食物的摄入量最少。在饥饿条件下,东方田鼠食物摄入率的增加主要源于其口量大小,觅食频次和觅摄食时间对食物摄入量增加的贡献不显著。在饥饿条件下,植食性小哺乳动物并未通过延长觅食时间,降低用于防卫、繁殖活动时间来增加食物摄入量,而是通过增加口量大小,提高其食物摄入率来满足其营养需要。验证了饥饿与植物次生化合物共同作用引起田鼠类动物生理的改变,能影响其食物摄入量及觅食行为的假设。     

Feeding ecology of rooks (Corvus frugilegus) on the Heretaunga Plains,Hawke's Bay,New Zealand

Abstract

The food resources of rooks were measured and related to changes in the birds' feeding behaviour during 1968-1970. In all, 381 birds were individually marked with wing tags and colour-coded leg bands and released; their activities were recorded for set periods. Rooks preferred to eat invertebrates and walnuts, but also took seed of cereals, pulses, and stock feeds. They spent at least 40% of their feeding time (75-80% in spring) eating invertebrates, 30-60% finding or hiding walnuts and sometimes acorns in autumn and winter, and 45% eating seed during hot, dry weather in summer. Up to 6% of feeding time was spent eating newly sown or ripening seed. Throughout winter rooks frequently searched for hidden nuts, which they ate or moved to new positions. The proportion of time they spent feeding and the kind of food taken varied seasonally and, in summer and winter, hourly; there were only slight differences between morning, mid-day, and afternoon periods. Rooks spent 65% of the time feeding in autumn, but only 25-30% in spring. Conversely, they spent longer at nest sites from late autumn, peaking at 60% in spring, then less time at nests as they spent longer searching for food. The size of flocks altered with the food being eaten and therefore with season and time of day. Small flocks were widespread where favoured food was plentiful in autumn, winter, and spring, but flocks were larger where food was unevenly abundant in summer and sometimes in winter. During early autumn each bird usually ate and stored walnuts in a selected area of 1-2 km3, returning there later in the season to recover stored nuts. The areas formed only part of the total range used by the study population, and were usually shared with other birds. Tests in aviaries showed that rooks preferred earthworms and walnuts to acorns, maize, and wheat (in that order), and field tests confirmed that rooks preferred walnuts to maize. The numbers of each food item required to sustain a rook for a daylight hour were estimated. Summer is the most difficult season for rooks to find food.     

Habitat shifting by the common brown lemur (Eulemur fulvus fulvus): a response to food scarcity

During periods of food scarcity, most primates display behavioral responses, such as dietary switching or adjustment of traveling and foraging efforts, within home ranges. In rare cases, several primate species leave their home ranges for other remote habitats to seek alternative resources; this migration-like behavior is termed “habitat shifting.” Reports of habitat shifting have concentrated on platyrrhines, but this behavior has rarely been observed among prosimians. During 1 year of observation of a troop of common brown lemurs (Eulemur fulvus fulvus) in Ankarafantsika National Park, northwestern Madagascar, habitat shifting occurred twice. To understand the causes of this behavior, I examined the seasonal availability of fruit resources in the range continuously used by the troop during the year (defined as the annual range) and compared feeding activities and vegetation types between the annual range and new areas. The troop usually stayed within a 38.7-ha annual range, defined by a 95 % fixed kernel analysis based on GPS location data collected at 5-min intervals. In April 2007, the lemurs suddenly moved to a habitat 1.0–1.5 km south of their annual range and concentrated on the consumption of Grewia triflora fruits for 2 weeks. In November 2007, they visited a habitat 0.8–1.7 km southeast of the annual range and exploited fruits of Landolphia myrtifolia. These new areas were open habitats with high densities of the respective fruit species. The density of fruiting trees was low in the annual range during these periods; thus, habitat shifting to areas with different phenological productivity appeared to be an effective response to fruit scarcity. Brown lemurs are generally categorized as a nonterritorial species, and the lemurs observed here showed no agonistic behavior in intergroup encounters during range shifting. Such nonterritoriality may allow brown lemurs to shift habitats, a behavior resulting in long-term absence from their annual range.     

Causes of obesity in captive cynomolgus macaques: influence of body condition, social and management factors on behaviour around feeding

Similar to other primate species, captive cynomolgus macaques (Macaca fascicularis) are prone to becoming overweight. The relationship between body condition and feeding behaviour in group-housed animals has not been reported. This study evaluated the effect of daily feeding routines on behaviour patterns in cynomolgus macaques to determine whether overweight macaques displayed different behaviours and activity levels. In this prospective observational study, 16 macaques (m = 4, f = 12) from four separate troops (n = 4 per troop) were selected from a colony of 165 animals. Observational data were collected over six months during morning and afternoon feedings by scan sampling. Behaviours of interest included foraging, eating, aggressive and positive social interactions, inactivity and physical activities. Multivariable mixed logistic regression modelling was used for data analysis. Results indicated that overweight animals were more likely to be inactive, dominant animals had increased probabilities of eating compared with non-dominants, and aggressive behaviours were more likely to occur in the morning and before feeding, suggesting feeding anticipation. Positive social interaction before feeding was seen and may be a strategy used to avoid aggressive encounters around food resources. Individual animal caregivers had an unintentional impact on behaviour, as decreased eating and an increase in inactivity were noted when certain individuals fed animals. These findings illustrate the complexities of feeding group-housed cynomolgus macaques to avoid overweight body condition. Feeding routines may require more care and attention to distribute food in a way that ensures equitable food intake among troop animals, while not disturbing group cohesion.     

The provision of winter bird food by the English Environmental Stewardship scheme

Environmental Stewardship (ES) is the main mechanism for reversing the decline in farmland birds in England, and includes a range of options designed to provide winter foraging for seed‐eating species. We estimated granivorous songbird densities on ES options designed to provide winter food, on farms within the Entry Level (ELS) or Higher Level (HLS) strata of ES. ES Wild Bird Mixtures (WBMs) hosted higher densities and a wider range of granivores than non‐ES game covers, although in East Anglia the enhanced HLS WBM was used no more than the basic ELS WBM. In the West Midlands there were low densities of granivores on all WBMs and game covers. The widespread ELS WBM appeared to provide little food for buntings but supported finches, partially through greater weed burdens. There was a weak, non‐significant trend for Skylarks Alauda arvensis to make greater use of ELS cereal stubbles than non‐ES stubbles, possibly because of post‐harvest herbicide restrictions allowing overwinter weed growth. At the field scale, this work demonstrates that although some ES options provide winter food resources for birds, there is limited evidence for additional benefits of Higher Level vs. Entry Level Stewardship to wintering farmland songbirds.     

Relocation, reproduction and remaining alive in the orb-web spider

When mortality is high, animals run a risk if they wait to accumulate resources for improved reproduction so they may trade-off the time of reproduction with number and size of offspring. Animals may attempt to improve food acquisition by relocation, even in 'sit and wait' predators. We examine these factors in an isolated population of an orb-web spider Zygiella x-notata . The population was monitored for 200 days from first egg laying until all adults had died. Large females produced their first clutch earlier than did small females and there was a positive correlation between female size and the number and size of eggs produced. Many females, presumably without eggs, abandoned their web site and relocated their web position. This is presumed because female Zygiella typically guard their eggs. In total, c . 25% of females reproduced but those that relocated were less likely to do so, and if they did, they produced the clutch at a later date than those that remained. When the date of lay was controlled there was no effect of relocation on egg number but relocated females produced smaller eggs. The data are consistent with the idea that females in resource-poor sites are more likely to relocate. Relocation seems to be a gamble to find a more productive site but one that achieves only a late clutch of small eggs and few achieve that.     

High Energy or Protein Concentrations in Food as Possible Offsets for Cyanide Consumption by Specialized Bamboo Lemurs in Madagascar

Plants producing toxic plant secondary metabolites (PSMs) deter folivores from feeding on them. Animals that can cope with noxious PSMs have a niche with a competitive advantage over other species. However, the ability to cope with toxic PSMs incurs the costs of detoxification. To assess possible compensations for the ingestion of toxic PSMs, we compare the chemical quality of plants consumed by bamboo lemurs (genera Hapalemur and Prolemur; strepsirrhine primates of Madagascar) in areas with and without bamboo. Some bamboo lemurs consume bamboo containing concentrations of cyanogenic substances 10–50 times above the average lethal dosage for mammals, and we postulate that animals consuming cyanogenic substances need supplementary protein or readily available energy for detoxification. We compared the chemical composition of food consumed by three species of bamboo lemurs that feed mainly (>80% of their time) on bamboo in the evergreen rainforest of Ranomafana (Madagascar) with published data of the diets of bamboo lemurs at two sites without highly cyanogenic plants (reed beds of Lac Alaotra and the evergreen littoral forest of Mandena) and with food of sympatric folivorous lemur species that do not feed on bamboo. Lemurs feeding on bamboo consumed up to twice as much protein as bamboo lemurs in areas without bamboo and sympatric lemur species that feed on leaves of trees. Concentrations of nonstructural carbohydrates (a source of energy) showed the opposite trend. This result supports the hypothesis that feeding on cyanogenic plants is linked to high protein intake, either as a source of protein or for sulfur-containing amino acids that can be used for detoxification. Owing to the high protein concentrations in bamboo, however, we cannot distinguish between the hypothesis that lemurs that eat bamboo target additional food items with higher protein from the hypothesis that lemurs feeding on bamboo unavoidably obtain higher concentrations of protein than animals feeding on leaves of trees, without an added nutritional benefit.     

Detecting predators and locating competitors while foraging: an experimental study of a medium-sized herbivore in an African savanna

Vigilance allows individuals to escape from predators, but it also reduces time for other activities which determine fitness, in particular resource acquisition. The principles determining how prey trade time between the detection of predators and food acquisition are not fully understood, particularly in herbivores because of many potential confounding factors (such as group size), and the ability of these animals to be vigilant while handling food. We designed a fertilization experiment to manipulate the quality of resources, and compared awareness (distinguishing apprehensive foraging and vigilance) of wild impalas (Aepyceros melampus) foraging on patches of different grass height and quality in a wilderness area with a full community of predators. While handling food, these animals can allocate time to other functions. The impalas were aware of their environment less often when on good food patches and when the grass was short. The animals spent more time in apprehensive foraging when grass was tall, and no other variable affected apprehensive behavior. The probability of exhibiting a vigilance posture decreased with group size. The interaction between grass height and patch enrichment also affected the time spent in vigilance, suggesting that resource quality was the main driver when visibility is good, and the risk of predation the main driver when the risk is high. We discuss various possible mechanisms underlying the perception of predation risk: foraging strategy, opportunities for scrounging, and inter-individual interference. Overall, this experiment shows that improving patch quality modifies the trade-off between vigilance and foraging in favor of feeding, but vigilance remains ultimately driven by the visibility of predators by foragers within their feeding patches.     

Mother-Young Feeding Synchrony and Early Food Selection Differences in Eulemur fulvus

I tested the hypothesis that mother-young cofeeding correlates with a systematic similar food selection in wild Mayotte brown lemurs (Eulemur fulvus). I simultaneously recorded the feeding behavior of 4 maternal dyad members, from infant birth to weaning, and 10–12 mo of juvenile age, during 10-min focal periods, each separated by 5-min intervals over 10 mo. I recorded the solid food items selected for each feeding behavior at the level of specific plant part, along with the distance between the 2 individuals. I considered feeding behaviors simultaneous (between the young lemurs and their mothers) when the young began to eat a food item while the mother was already eating, regardless of the separation distance. During their first year, most of the feeding events of the young brown lemurs were initiated by their mothers. However, infants also selected different food items from those chosen by their mothers in almost one-third of cases, and the food selection dissimilarity was not attributable to an increase in the distance of separation. For juveniles, dissimilar food selection was significantly lower and linked to an increase in mother-juvenile separation distance. Thus, the substantial proportion of dissimilarity in solid foods selected by the infant during the synchronized feeding behaviors strongly suggests that social influences were not food-specific and might instead drive the acquisition of group feeding activity rhythm rather than food selection habits.     

Diet, Nutritional Ecology, and Birth Season of Eulemur macaco in an Anthropogenic Forest in Madagascar

We investigated the feeding ecology of Eulemur macaco macaco in an old coastal secondary forest of northwestern Madagascar. We analyzed whether the local combination of introduced and native plant species could provide viable anthropic conditions for sustaining the black lemurs. Fruits (79 spp.) dominated the annual diet (>104 species from 50 families via observations ad libitum and use of a feeding frequency methods). Records from the early dry (mating) and late dry (birth) seasons show that a few major fruit species are staples in conjunction with a variety of other plant items in much lower proportions. We further estimated daily food intake and analyzed nutrient/antinutrient content in the diet during the birth season to evaluate the possibility that black lemurs undergo nutritional stress. They exhibited a high-energy input/low energy output foraging strategy then and had limited use of alternative resources such as leaves throughout the study period. We conclude that the potential for feeding flexibility is low because specialization on fruit results in protein requirements being achieved probably by a narrow margin. We hypothesize that patchy distribution of preferred cash-crop plants and indigenous species currently has a major limiting effect on population size through feeding competition.     

Lion-tailed macaques (Macaca silenus) in a disturbed forest fragment: Activity patterns and time budget

We describe the activity patterns and time budget of a feral group of lion-tailed macaques that were confined to a disturbed forest fragment of 65 ha and compare the results with those obtained for groups in protected forests. The degraded nature of the study site was reflected in low tree densities, low specific diversity, gaps in the girth distribution of trees, and frequent disturbance by humans. The study group of 43 subjects was twice as large as lion-tailed macaque groups in protected habitats. They spent the most time ranging (34.0%), followed by foraging (23.7%), feeding (17.9%), resting (16.0%), and other activities such as social interactions (8.4%). Monthly variations are significant for all activity categories except ranging. Times spent resting and foraging are negatively correlated (r = −0.5) and show significant seasonal differences. Foraging time was highest from September to November, when key food sources such asCullenia andArtocarpus were absent or marginally available. The study group spent most time (40.4%) at canopy levels between 21 and 30 m. They spent more time each day ranging than resting or feeding and more time terrestrially compared with groups in protected forests. Large group size, poor habitat quality, and seasonal variation in food availability were the major variables affecting their time budget, and these variables accounted for differences from the time budgets of groups in protected forests.     

Foraging behavior adjustments related to changes in nectar sugar concentration in phyllostomid bats

Nectar-feeding bats regulate their food ingestion in response to changes in sugar concentration as a way to achieve a constant energy intake. However, their digestive capability to assimilate sugars can limit their total energy intake, particularly when sugar concentration in nectar is low. Our experimental study evaluated the effect that changes in sugar concentration of nectar have on the foraging behavior of the nectar-feeding bats Glossophaga soricina and Leptonycteris yerbabuenae in captivity. We measured foraging behavior and food intake when bats fed at different concentrations of sucrose (5, 15, 25 and 35%wt/vol.). To compensate for low-energy intake, both bat species reduced their flight time, and increased feeding time when sugar concentration decreased. Our results suggest that nectar-feeding bats in nature confront two scenarios with complementary ecological effects: 1) bats feeding on dilute nectars (i.e. ≤15%wt/vol.) should increase the number of flowers visited per night enhancing pollination, and 2) bats feeding on concentrated nectars could spend more time flying, including long- and short-distance-flights increasing food patch exploration for use during subsequent nights, and thus enhancing plant gene flow. Further studies on foraging behavior of nectarivorous bats under natural conditions are necessary to corroborate these hypotheses.     

Contrafreeloading in grizzly bears: implications for captive foraging enrichment

Although traditional feeding regimens for captive animals were focused on meeting physiological needs to assure good health, more recently emphasis has also been placed on non‐nutritive aspects of feeding. The provision of foraging materials to diversify feeding behavior is a common practice in zoos but selective consumption of foraging enrichment items over more balanced “chow” diets could lead to nutrient imbalance. One alternative is to provide balanced diets in a contrafreeloading paradigm. Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. To investigate contrafreeloading and its potential as a theoretical foundation for foraging enrichment, we conducted two experiments with captive grizzly bears (Ursus arctos horribilis). In Experiment 1, bears were presented with five foraging choices simultaneously: apples, apples in ice, salmon, salmon in ice, and plain ice under two levels of food restriction. Two measures of contrafreeloading were considered: weight of earned food consumed and time spent working for earned food. More free than earned food was eaten, with only two bears consuming food extracted from ice, but all bears spent more time manipulating ice containing salmon or apples than plain ice regardless of level of food restriction. In Experiment 2, food‐restricted bears were presented with three foraging choices simultaneously: apples, apples inside a box, and an empty box. Although they ate more free than earned food, five bears consumed food from boxes and all spent more time manipulating boxes containing apples than empty boxes. Our findings support the provision of contrafreeloading opportunities as a foraging enrichment strategy for captive wildlife. Zoo Biol 29:484–502, 2010. © 2009 Wiley‐Liss, Inc.     

Eating yourself sick: transmission of disease as a function of foraging ecology

Species interactions may profoundly influence disease outbreaks. However, disease ecology has only begun to integrate interactions between hosts and their food resources (foraging ecology) despite that hosts often encounter their parasites while feeding. A zooplankton–fungal system illustrated this central connection between foraging and transmission. Using experiments that varied food density for Daphnia hosts, density of fungal spores and body size of Daphnia , we produced mechanistic yet general models for disease transmission rate based on broadly applicable components of feeding biology. Best performing models could explain why prevalence of infection declined at high food density and rose sharply as host size increased (a pattern echoed in nature). In comparison, the classic mass-action model for transmission performed quite poorly. These foraging-based models should broadly apply to systems in which hosts encounter parasites while eating, and they will catalyse future integration of the roles of Daphnia as grazer and host.