Fruit tracking,frugivore satiation,and their consequences for seed dispersal

Vertebrate frugivore communities are easily satiated by abundant fruit supplies and, contrary to abiotic dispersal agents, typically disperse only part of the available seed pool. This frugivore satiation is likely to be a widespread phenomenon and should be an influential predictor of plants’ ability to disperse their offspring to suitable establishment sites; yet it has never been systematically quantified. Here I investigate patterns of fruit abundance, frugivore activity and frugivore satiation, and their consequences for seed dispersal in the fleshy-fruited tree Frangula alnus. Based on constant-effort seed trapping conducted over 3 years, I assess densities of total and frugivore-consumed seedfall across two spatial (within/between populations) and two temporal (within/between ripening seasons) scales. Furthermore, I examine relationships between fruit abundance and the amount of seeds that are actually dispersed away from fruiting trees. Frugivore activity tightly matched fruit abundance, although some differences existed between scales. This marked fruit tracking did not prevent a significant frugivore satiation, however, and only 53% of the available fruit crops were actually consumed. The extent of satiation varied most at the within-population level, likely due to the territorial behaviour of important frugivore species. In contrast, levels of satiation remained remarkably invariable through time, suggesting that frugivores behave as opportunists and closely adjust the composition of their diet to the available food supply. Overall, greater fruit abundance resulted in a higher proportion of seeds falling beneath fruiting trees, but it also helped increase the (absolute) number of seeds dispersed. This study shows that frugivore satiation can be an important phenomenon even when frugivores tightly track fruit abundance. Its negative effects on recruitment may be attenuated, however, if greater fruit crops help increase population-wide frugivore activity and the amount of seeds being dispersed to suitable establishment sites.     

Irregular fruiting in Fraxinus excelsior

Abstract. Data of fruit-set and fruit production of Fraxinus excelsior (ash) at two sites in the archipelago of Stockholm, Sweden, were recorded over six years (1980-85), with particular emphasis on the fruiting tendency of individual trees. The aim was to determine the grounds for the irregularity of fruiting. There was no support for the assumption that irregular fruiting originates as a consequence of the fruiting tendency being resource limited. The probability of fruiting in a certain year was neither negatively related to previous fruiting years, nor positively related to climatically favourable years. Seeds were infested by the monophagous moth larva Pseudar-gyrotoza conwagana. An increased seed survival was noted in times of large seed crops, indicating seed predator satiation. Date of leafing the preceding year determined whether individual trees fruited or not. This relationship may have significance in synchronizing the fruit production of ash trees.     

Opposing survivorship and fecundity effects of host phenology on the gall-forming aphid Hormaphis hamamelidis

Abstract  1. This study examined the synchronisation and roles of host and insect phenology for fundatrices of the gall-forming aphid Hormaphis hamamelidis , which forms galls on the leaves of the understorey tree Hamamelis virginiana .
2. Host and insect phenologies varied widely among years and individual host trees.
3. Most winter eggs (≈ 85%) hatched before budbreak and galls could be initiated but in 2 years there was no inherent risk for earlier hatching fundatrices in terms of greater mortality. Egg hatch was not synchronised tightly with host trees but instead seemed to occur well in advance of budbreak as a conservative, bet-hedging strategy to ensure the opportunity to form galls.
4. Fundatrices that formed galls later had higher fecundity, contrary to typical patterns for insects that feed on the first flush of leaves in temperate forests, where later herbivores have lower fecundity. Also, unlike many other systems, trees that had later budbreak had greater densities of galls.     

Carabid populations in field beans and their effect on the population dynamics of Sitona lineatus (L.)

The abundance and diversity of potential carabid predators of Sitona lineatus (L.) in field beans were monitored between 1980 and 1983. The absolute abundance of the large predatory species was determined in mark-recapture experiments and a radio-labelling technique was used to estimate the level of predation in the field. Using previously published population data for S. lineatus, the importance of predation in the population dynamics of the weevil was estimated. The mortality of weevil larvae due to predation varied from 0.6%– 10.5% while that of adult weevils varied from 2.6%– 23.8%. It appeared that carabids played a significant role in the population dynamics of S. lineatus and, in years when abundant, could reduce the population of larvae and overwintering adults by more than 30%.     

Phenology of fleshy fruits in a wet sclerophyll forest in southeastern Australia: are birds an important influence?

Summary The hypothesis that seasonality in the production of fleshy fruits in temperate regions is the result of selection by avian seed dispersal agents or avian seed predators was tested in a temperate wet sclerophyll forest in south-eastern Australia. I determined whether ten common fleshy-fruited species produced fruits when potential avian seed dispersers were most abundant or avian seed predators were least abundant. The season of fruit production was not correlated with avian disperser abundance nor with seasonal changes in avian seed predators. Peak fruiting occurred during autumn but fruit-eating birds were equally abundant from spring through to autumn. Avian seed predators (parrots) did not show any seasonal variation in abundance. If dispersers are influencing fruiting seasonality in wet sclerophyll forest, it is likely that changes in social behaviour and feeding patterns of dispersers during autumn, rather than increases in abundance, will be an important influence on fruiting patterns in wet sclerophyll forest. However, environmental and life history factors may also influence phenology.     

Floristic heterogeneity between forested sites in Kibale National Park, Uganda: insights into the fine-scale determinants of density in a large-bodied frugivorous primate

1.  Despite a long history of research on the influence of fruit availability on the population density of large-bodied vertebrate frugivores, operational understanding of the factors regulating density in these taxa remains elusive. We propose that fruit resources can be distinguished from one another on the basis of their functional role for the animals in question, and that such a classification system can aid in identifying the most influential determinants of frugivore density.
2.  We compared the availability of several resource classes between two sites in Kibale National Park, Uganda separated by only 12 km yet differing threefold in density of chimpanzees ( Pan troglodytes ).
3.  We categorized plant species used for fruit by chimpanzees according to their availability relative to habitat-wide fruit productivity, and by their tendency towards inter-individual fruiting synchrony. We predicted that the site of high chimpanzee density would support a higher density of food plant species tending to produce crops during periods of high habitat-wide productivity [high fruit abundance (HFA foods)] and of those tending to fruit synchronously among individuals during times of low habitat-wide availability (sLFA foods). The first food class should provide chimpanzees with a high nutrient density (and thus promote population growth), whereas the second should provide stable subsistence during lean periods and thus a temporally consistent resource base.
4.  Counter to our prediction, only sLFA resources were more abundant at the site of high chimpanzee density than at the site of low density. We suggest that sLFA resources are most important in influencing density of large-bodied frugivores.     

Seasonal changes in a population of the nectar-feeding marsupial Tarsipes spencerae (Marsupialia: Tarsipedidae)

During 1978 and 1979 over 900 individuals of the mouse-sized marsupial nectarivore Tarsipes spencerae were pitfall trapped in Banksia thickets on the south coast of Western Australia. In both years numbers were highest in spring, when nectar was most abundant and lowest during summer months when it was scarce. The larger number of males caught probably reflects their greater activity rather than their greater abundance.     

Many to flower, few to fruit: the reproductive biology of Hamamelis virginiana (Hamamelidaceae)

Hamamelis virginiana flowers from late September to late November. In 1977, we began studying the reproductive biology of this eastern North American arborescent shrub by examining floral phenology and rewards, pollen-ovule ratios, breeding system, pollination, pollinator and resource limitation, and seed dispersal. The homogamous, self-incompatible flowers emit a faint odor, bear nectar with sucrose ratios typical of bee- and fly-pollinated flowers, and produce abundant sticky pollen. Flowers were visited infrequently by insects representing six orders. Flies were the most common floral visitors, specifically members of the genus Bradysia, but small bees also carried high percentages of Hamamelis pollen. Despite high pollen/ovule ratios (11?445 grains/ovule), bees and flies are likely pollinators, as experiments indicate wind pollination is less likely. Pollen quantity and resource availability did not appear to limit reproductive output, but pollen quality did. Tests of >40?000 flowers showed natural fruit set to be <1%. The flowering time, breeding system, and clumped distribution of plants, likely due in part to limited seed dispersal, combine to yield this remarkably low fruit set. Because all other species of Hamamelis flower from late winter to early summer, it may be that H. virginiana evolved a fall flowering phenology to avoid competition for pollinators with the closely related H. vernalis.     

The diet and impact of house mice on a sub-Antarctic island

An analysis of the stomach contents of house mice (Mus musculus L.) at three sites on Marion Island (47°S, 38°E) over a 1-year period showed that the mice feed mostly on terrestrial macroinvertebrates but that plants (mainly seed) are an important component of the diet in mid- to late summer. Larvae of a flightless moth, weevil larvae and adults and, at one of the sites, earthworms were the invertebrate items that showed the highest importance value over the year. Diet diversity was slightly lower in summer and autumn than in winter and spring. Diet variety was lowest in midsummer and highest in either autumn or winter, depending on the site. Mean stomach-content mass was significantly higher in midwinter than during the rest of the year. When offered prey of different types and sizes, mice selected moth larvae first in 92% of the trials; earthworms or weevil adults were most frequently selected second, and weevil larvae fourth. An introduced slug species was selected only once, as the last choice and only part of it was eaten. With both moth larvae and earthworms, the heaviest individual offered was almost always chosen first. Surprisingly, mice never consumed more than about half of the seed offered to them and their condition deteriorated severely during the trials with seed; in a third of the trials with two types of seed, the mice completely ignored the seed. The impact of mice predation on invertebrates was assessed at two of the sites - a dry mire and a coastal biotic herbfield that is influenced by seabird and seal manuring. Moth larvae and adults, weevil larvae and adults, earthworms, spiders and flies made up >90% of the animal remains in the stomach contents over the year and, on average, the mice daily consumed 45 g (dry mass) ha^-1 of those invertebrates at the mire and 194 g ha^-1 at the biotic site. Moth larvae made up a substantial proportion of these amounts; average daily consumption was 30 g ha^-1 at the mire and 107 g ha^-1 at the biotic site. In terms of the amount consumed in relation to biomass, the heaviest impact of mice at both sites was on weevil adults; at the biotic site mice daily consumed 13% of weevil adult biomass in autumn and nearly 6 times the annual average biomass over the year. At the mire, slightly more than the annual average weevil adult biomass was consumed over the year. The consumption of invertebrates by mice found in this study (1992/1993) was about 20% greater than in 1979/1980. The most striking changes in annual average consumption rate between 1979/1980 and 1992/1993 were for weevil larvae (increased nearly fourfold) and earthworms (increased sixfold at the biotic site and threefold at the mire). In contrast, the consumption of spiders at both sites decreased between 1979/1980 and 1992/1993.     

Reproductive performance of the Bald Ibis Geronticus calvus in relation to rainfall and grass-burning

Reproductive performance of the Bald Ibis Geronticus calvus was studied during three consecutive nesting seasons (1978–80) at a single large breeding colony in Natal, South Africa. A focal sample of 22 nest sites (out of a total of 60 in the colony) was inspected at frequent intervals to determine clutch sizes, egg survival, hatching success, nestling mortality and fledgling production in each year. Mean clutch size was slightly lower in 1980, compared to the two previous years, although survival and hatching success of eggs were similar in all three years. However, nestling mortality was significantly higher in 1980, largely as a result of parental nest desertion and nestling starvation, so that the proportion of breeding pairs producing at least one fledged offspring, and the average brood size at fledging, were lower compared to 1978 and 1979.
The 1978 and 1979breeding seasons were both preceded by 12 months of above average rainfall, and Bald Ibises fed extensively on small invertebrates obtained in burnt grassland in the study area during the nesting period. By contrast, the onset of nesting in 1980 followed 11 consecutive months of sub-normal rainfall. As a result of the drought, and the consequent lack of controlled burning by landowners in the study area in 1980, very little burnt grassland was available during the Bald Ibis' breeding season, and the birds fed primarily in cultivated pastures during the customary burning period. The lower reproductive performance of Bald Ibises at the study site in 1980 is discussed in relation to the possible effects of drought on the abundance of invertebrate prey and the extent of controlled burning in the species' grassland biotope.     

PRODUCTION AND EFFECT OF SEED SIZE IN A GRASSLAND ANNUAL (ERODIUM BRACHYCARPUM,GERANIACEAE)

Over its fruit maturation period in the field, Erodium brachycarpum (Geraniaceae) exhibited a striking decrease in average seed mass; seeds produced in the 1st week of fruiting were twice the size of those produced 6 weeks later at the time of drought-induced plant senescence. Individuals with earliest fruit maturation produced the most seeds with the widest range of sizes and over a longer period than the others. In a greenhouse experiment, a similar decline in mean seed weight was generated by inducing drought conditions. Large seeds remained dormant longer and, once the seed coat was scarified, took longer to germinate than small seeds. This study indicates that small E. brachycarpum seeds (36% of the seed pool) produced late in the fruiting period are likely to germinate in the year of seed production, approximately 4–8 months after seed maturation. In contrast, the large seeds (23% of the seed pool), most of which are produced early in the fruiting period, are more likely to germinate in subsequent years (i.e., 15 months or more after seed maturation).     

Mast fruiting in a hawkmoth-pollinated orchid Habenaria glaucifolia: an 8-year survey

Aims The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants. It considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual. Orchids produce huge numbers of seeds per fruit and rarely experience seed predation. It remains unclear which factors may affect fluctuating fruit production in orchids, which generally suffer a widespread pollen limitation. To explore the temporal pattern of fruiting and potential factors related to fluctuation in fruit production, we investigated reproductive success of a long-spurred orchid (Habenaria glaucifolia) in an alpine meadow with thousands of individuals over 8 years.Methods To estimate reproductive success, pollinator observation was conducted by day and at night, and pollinia removal and receipt were recorded in the field population for 8 years. To examine whether fruit set and seed set are pollen limited, we conducted supplementary pollination experiments and compared fruit set, seed set and pollinia movement of open-pollinated flowers from 2011 to 2013. We measured lengths of spurs and pollinator proboscises, and nectar volume and concentration, to identify potential pollinators.Important findings Hawkmoths were seen to be effective pollinators for H. glaucifolia in 3 years, whereas in the remaining 5 years no pollinators were observed, and consequently pollinia were rarely transferred. Numerous pollinia movements were observed in 2012, 2013 and 2014 (pollinia removal: 48, 59 and 85%; pollinia receipt 51, 70 and 80%), and correspondingly fruit set was significantly higher in 2012 and 2013 (59 and 46%) than in 2011 (25%). It was fruit set, rather than seed set, that was pollen limited in this orchid in the 3 years, in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural. Three species of hawkmoths had proboscis lengths that matched the spur length of H. glaucifolia. Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths, resulting in significant temporal variation in fruit production. Mast fruiting in this alpine orchid could be attributed to a 'sit and wait' strategy, awaiting an abundance of effective pollinators.     

Sexual reproductive biology of the endangered Japanese red maple (<Emphasis Type="Italic">Acer pycnanthum</Emphasis>)

Japanese red maple, Acer pycnanthum, is an endangered wetland species having dioecious sex expression. Prior studies conclude that land development has caused severe loss of habitat, and seedling regeneration is rare. However, information is lacking on sexual reproduction, which is the first critical stage of regeneration. My research objective was to describe flowering and fruiting characteristics of Japanese red maple, focusing on tree sizes at the onset of flowering, factors affecting flowering regularity and fruit abundance, periodicity of fruit production, and sex ratio. In a study of a young population, Japanese red maple initiated flowering at a small size under 100% light intensity. Initiation of flowering occurred at relatively lower height in males than females, and males flowered more regularly than females. A survey of 1,106 clones from 46 natural populations revealed that male clones were significantly more abundant than female clones. In a 4-year study of mature populations, nearly all clones flowered regularly, and fruit abundance of dominant females was typically high. Fruit abundance at the population level also remained high, although fruit abundance of individual female clones varied year by year. Therefore, sexual reproductive ability is highly vigorous. Sex ratio exhibited a major deviation from a 1:1 ratio in populations with a small number of clones. In conservation planning, we should prioritize avoidance of an unbalanced sex ratio by increasing population sizes. In addition, populations having many clones >40 cm dbh with large, well-lighted crowns have a high potential of regular and abundant seed production.     

Effects of Single and Recurrent Wildfires on Fruit Production and Large Vertebrate Abundance in a Central Amazonian Forest

Wildfires are an increasing threat to tropical rainforests, yet little is known about their effects on fruit production and forest wildlife. We examined the effects of both single and recurrent wildfires on fruit production and large vertebrate abundance in a central Amazonian terra firme forest for 3 years following a large fire event. The estimated mortality of 42 and 74% of stems ≥10 cm in once- and twice-burnt forest led to a substantial loss of fruiting tree basal area (29 and 62% were lost in once- and twice-burnt forest, respectively) and crown coverage of fruiting woody lianas (89 and 97% were lost in once- and twice-burnt forest, respectively). Some important tree families producing fleshy fruits were less abundant than expected in once- and twice-burnt forest, suggesting that tree mortality was non-random in terms of species composition. Asynchronous fruit production was affected, and burnt forest transects sustained a much lower fruiting basal area, and fewer fruiting species during the dry season period of fruit scarcity. The number of fruiting trees in once- and twice-burnt forest was higher than the number predicted from actual levels of tree mortality recorded in each fire disturbance treatment, suggesting some surviving trees which may have benefited from higher irradiance levels and lower competition for resources. Many large frugivores and other vertebrate species declined in response to single fires, and most primary forest specialists were extirpated from twice-burnt forest, which sustained a higher number of species associated with second growth and other disturbed habitats.     

Fruit production in Sorbus aucuparia L. (Rosaceae) and pre-dispersal seed predation by the apple fruit moth (Argyresthia conjugella Zell.)

Variation in fruit production and pre-dispersal seed predation by Argyresthia conjugella was studied in␣four populations of Sorbus aucuparia in northern Sweden.␣The number of infructescences, fruits per infructescence, consumed seeds and developed unattacked seeds per fruit were scored in marked trees from 1984 to 1990. The results showed that the number of fruits produced in each population determined the number of seed predators occurring in the host population, as the yearly number of seed predators was significantly and positively correlated with yearly number of fruits, in all but one population. The seed predators showed a delay in response to variation in number of fruits produced. This lag in response resulted in a large proportion of fruits being attacked and seeds consumed in a bad fruiting year that followed a good fruiting year, and vice versa. The proportion of fruits attacked and seeds consumed was largest in the population showing the greatest between-year variation in fruit production and lowest in the population showing the lowest between-year variation in fruit production. Furthermore, the individuals within the former population were synchronised, while they were not in the latter population. These results contradict one of the possible explanations of mast-seeding, where large synchronised between-year variation is supposed to reduce pre-dispersal seed predation. Instead, differences in attraction of the seed predator to differences in fruit crop size could explain the observed difference in seed predation between the two populations with opposite fruiting patterns. Within each population, irrespective of year, the proportion of fruits attacked and seeds consumed was independent of a tree's fruiting display. Therefore, trees with high fruit production, despite harbouring the largest number of seed predators, produced the largest number of developed seeds in absolute numbers, compared to trees that produced few fruits. Received: 25 February 1996 / Accepted: 30 November 1996     

Fruit removal of Coprosma quadrifida (Rubiaceae) by birds in south-eastern Australia

Abstract Removal of the fleshy fruits of Coprosma quadrifida by birds was examined in relation to fruit crop size, neighbouring fruit crop size and time in the season in montane wet sclerophyll forest in south-eastern Australia. On average, 84% of individual fruit crops were removed. Frugivores removed fruit in proportion to its abundance, indicating that they continually assess availability rather than respond to a critical abundance. The size of neighbouring fruit crops did not influence fruit removal rates, suggesting that there is little competition among neighbours for dispersers. The ripe fruits of C. quadrifida were eaten by 14 bird species, comprising 50% of the bird species trapped. Silvereyes (Zosterops lateralis) were the most abundant consumers of fruits. With the exception of the parrot, Platycercus elegans, all birds defecated seeds intact and had no influence on seed viability.     

THE POPULATION ECOLOGY OF A DUNE THISTLE,CIRSIUM RHOTHOPHILUM (ASTERACEAE)

A population study of a thistle, Cirsium rhothophilum, was carried out in the coastal dunes of northern Santa Barbara County, California during 1978 and 1979. Seedling establishment, growth, flowering, and fruiting were observed in permanently marked transects. A total of 1,041 individuals were recorded. Despite 41% mortality during the year of study, the average population features changed remarkably little. Cirsium rhothophilum was found to be monocarpic but relatively long-lived. Extrapolations from rosette size growth and proportions of rosettes in different size classes giving rise to flowering individuals suggest that the average plant may have a vegetative stage of more than 5 years. Growth analysis of c . rhothophilum is complicated by the subsurface branching of stems, presumed to be the result of insect damage and sand burial. Dissection of fruiting heads showed that sound achenes were only about 22% of the total number of potential achenes. Insect damage was evident on about 20% of the unsound achenes. Considering both the loss of achenes within heads and of entire heads which failed to mature, insects are estimated to destroy at least 25% of the achenes. Achenes germinate readily and do not appear to have more than mild dormancy. A burial experiment showed that emergence declined sharply with depth of burial to zero at 8 cm. Despite the dynamic nature of the dune habitat, C. rhothophilum populations appear stable. The relatively large size and ability to grow rapidly and adapt to burial allow C. rhothophilum to average out environmental vicissitudes.     

Mile-a-minute weed (Persicaria perfoliata) and weevil (Rhinoncomimus latipes) response to varying moisture and temperature conditions

The combined effects of herbivory and water stress on growth and reproduction of mile-a-minute weed (Persicaria perfoliata (L.) H. Gross) were investigated in greenhouse trials over two years, with well-watered or water-limited plants either exposed or not exposed to herbivory by the mile-a-minute weevil (Rhinoncomimus latipes Korotyaev). Moisture limitation and weevil herbivory significantly reduced the number of seeds produced by P. perfoliata, with the fewest seeds produced when both factors were present. Seed weight was reduced by moisture limitation and weevil herbivory the second year, and seed viability was reduced by herbivory both years. Plant biomass was lower both years under conditions of water limitation, with an additional effect of herbivory the second year. Well-watered plants the second year also produced substantially more weevils than water-limited plants by the end of the season. Results are consistent with field observations suggesting that years of high rainfall allow resurgence of P. perfoliata plant populations that were previously suppressed by R. latipes. An additional environmental chamber trial assessed the interaction between the weed and weevil at two different temperatures. Here, plant mortality occurred only at the higher temperature with weevil herbivory, suggesting that herbivory has a greater negative effect on P. perfoliata under warm conditions. Additional studies on temperature effects are needed for a more complete understanding of interactions between P. perfoliata and R. latipes under different abiotic conditions.     

Spatio–temporal Variations in Post‐dispersal Seed Fate1

The post‐dispersal fate of Chrysophyllum lucentifolium (a canopy tree; Sapotaceae) seeds was analyzed in French Guiana over three consecutive years. Experiments using 750 thread‐marked seeds were performed to investigate seed removal, predation, and caching by terrestrial vertebrates on howler monkey (Alouatta seniculus) defecation sites, where clumps of intact C. lucentifolium seeds were observed. Year‐to‐year variations in seed fate during the peak fruiting period were considered in relation to overall fruit and seed resource availability estimated by a raked‐trail survey. The effect of two forest areas, which differed in soil and floristic composition, was examined with conspecific fruiting tree density as a covariant. Exclosure versus open treatment was used to discriminate small rodents (not larger than a spiny rat) from other vertebrates. The presence of fresh howler dung did not affect seed fate after 20 days as shown by comparisons between defecation sites and control during the first year. There was a significant effect of year on the percentage of seeds remaining after 20 days. Low seed removal in 1995 and 1996 (compared to 1997) corresponded to higher overall fruiting and higher fruiting of C. lucentifolium, or the presence of alternative resources for rodents. An effect of forest area was observed on the seed removal rate, which varied with years and protection. Comparatively, an effect of forest area on the percentage of seeds lost was observed in 1996 and an effect of treatment on the percentage of seeds eaten was seen in 1995. The mode of seed caching suggested that spiny rats were the main seed remover. Results of this study suggest that greater seedling recruitment may occur when large fruit crop and high howler dispersal co‐occur with a lower impact of rodents (i.e., when rodents are saturated by abundant and diversified fruit resources such as in 1995). Such event synchrony, however, is highly unpredictable after only three years of study.     

Large acorns benefit seedling recruitment by satiating weevil larvae in <Emphasis Type="Italic">Quercus aliena</Emphasis>

Plants can enhance their seed viability and survival through reducing the fitness costs of herbivory by satiating seed predators at either plant or seed level, or both. The former satiates with production of large crops while the latter with large-sized seeds, enhancing the probability of seed survival. We analyzed both types of satiation in the interaction between the Quercus aliena and the weevil Curculio spp in 2 years with different crop size and acorn size. Larger crop size seemed to satiate less effectively weevils due to higher proportions of the seeds were attacked in oaks producing more crops of smaller acorns. However, prematurely abscission of infested acorns in large crop year might compensate this ineffectiveness. Larger acorns in lean year well satiated weevil larvae, as a larger acorn size increased the likelihood of embryo survival and seedling establishment. Although effective satiation by larger acorns would be negated by smaller seed crops, the proportion of attacked acorns that survived increased with large acorn size in lean year. These results highlighted the importance of annual variation in acorn size of Quercus aliena in satiating and defending weevil larval predations, consequently in successful seedling recruitment and establishment.