This collection contains the findings of scientific studies of tropical terrestrial and marine ecosystems, their components, and their conservation from Monteverde, Cuajiniquil, and other areas of Costa Rica.
This digital collection is a service of the Monteverde Institute, whose mission is to catalyze social, ecological and economic sustainability by integrating community initiatives with education, research and conservation.
Esta colección contiene los hallazgos de estudios científicos de ecosistemas tropicales terrestres y marinos, sus componentes y su conservación de Monteverde, Cuajiniquil y otras áreas de Costa Rica.
Esta colección digital es un servicio del Instituto Monteverde, cuya misión es catalizar la sostenibilidad social, ecológica y económica integrando iniciativas comunitarias con educación, investigación y conservación.
Debra Hamilton, Timothy Parshall, and Katherine Johnson
The Fundación Conservacionista Costarricense and the Monteverde Institute have collaborated to support reforestation on the Pacific slope of Monteverde, Costa Rica. Costs have been low, funded principally by donations and small grants. The production of at least 8000 trees per year has been necessary to meet the voluntary demand of landowners. Here, we present data on survival and growth rates of tree seedlings that were planted on conservation land, tagged, and followed over time. Since 1999, over 180,000 trees of 93 native species have been raised and distributed to landowners.
Dorsa Afsharjavan, Garrett Herbst, and Caitlin Keyes
This year’s program collaborated with the Cloud Forest School, located in the Monteverde Cloud Forest. Sustainable Future’s charge from CEC was to perform a campus wide water systems site analysis and campus water systems master plan, which will work toward reducing, conserving, and maintaining water consumption and usage. The master plan proposes a series of spatial water treatment systems reinforcing existing circulation, supplementing educational programs, and mitigating water consumption while establishing a greater campus identity.
Victoria La Rocca
Oak tree species (Quercus spp.) have been known to host a variety of fungi on several different substrates. This study compared the macro fungi species richness between the oak tree species, Quercus corrugata and Quercus insignis. These species are found at different elevations ranging below1 700m, as well as different substrates; including acorns, soil, roots, and leaf litter. A total of 30 trees were surveyed along the ridges and peaks on the Monteverde Cloud Forest Reserve in Costa Rica. Each tree contained several different species of fungi, some overlapping, some repetitive, and some unique. The fungi were identified using photographs, written descriptions, and substrate identities. A total of 31 species were observed on Q. insignis, 33 on Q. corrugata. Of the 64 species, 20 were known to have oak affiliations, indicating the spectrum of fungal species on Quercus spp. Overall, the data displayed no direct correlation with substrate association; soil and tree substrates were most common. This equilibrated frequency trend is very different than previous studies noting that Q. corrugata, at higher altitudes, is just as rich as the lower altitudinal Q. insignis. This could be an indicator of climate change effects in an area that was once too cold to support large quantities of fungi, but has now warmed and dried enough to establish a higher frequency.
Amphibian adaptability to habitat transformation and the effect of rainfall during the dry season on their activity pattern
Amphibians are being forced to change their habits and lifestyles to adapt to human transformations. Some species of amphibians are becoming dependent on man-made ecosystems to carry out their life cycles. Also, climate change is affecting the seasonality by changing the amount of precipitation and the phenology of amphibians. This study was conducted in San Luis Costa Rica in an area characterized by a pre-montane wet forest during the dry season (April 2011). Pitfall traps and drift fences were set up in a forest location and in a man-made pond location to compare the number species within each location. Rainfall was also measured, and amphibian activity was found to be positively correlated. B. marinus and Rana vaillanti were most abundant at the man-made pond site and were found to have significant difference when compared to other amphibian species inhabiting the same area and mammal species. The change of seasonality and land transformation initiated by humans could have devastating consequences on amphibian species.
Aquatic macro-invertebrate community composition differences between the Atlantic and Pacific watersheds in Monteverde, Costa Rica
There are large differences between slope seasonality in Monteverde, Costa Rica. The Pacific slope receives less rainfall, and has a better-defined wet and dry season. This study looked at how these differences affect aquatic benthic macro-invertebrates composition. Five different rivers were sampled, three on the Atlantic slope, and two on the Pacific slope. There was no significant difference between the two slopes in species richness, evenness, or number of species. There were differences in species composition between the two slopes. This study exemplifies how areas in close proximity can have different species compositions. For conservation purposes, this study demonstrates how even if a large area is being protected not all species in the surrounding area are necessarily protected.
Flower color is an important attractant and many pollinators show distinct color preferences. This study determines if color preference and its lability differ between experienced and naïve Heliconius butterflies. Butterflies were offered nectar in Lantana camara inflorescences, which naturally have flowers of two colors (yellow and red) on a single inflorescence. Butterflies visited yellow flowers more frequently, with 76% of visits to yellow flowers when both flower colors offered nectar. When nectar was offered only by red flowers, yellow preference decreased significantly over time. Newly enclosed butterflies, offered inflorescences where only red flowers rewarded, showed a 56% yellow visitation rate over two days, 22% less than for butterflies previously offered inflorescences where both flowers were rewarded. These results suggest that yellow preference in Heliconius is both strong and innate, but can be weakened by experience. Further, it appears that naïve butterflies are more labile, allowing them to track changes in rewards more quickly. This reward-associated learning may help optimize foraging success by enabling individuals to adapt behaviorally to different environments.
Organisms, if capable, will invest in learning when it results in the improvement of overall fitness. Learning ability may allow organisms to outperform competitors or better survive in a variable environment. Order Hymenoptera exhibits a broad spectrum of learning abilities, including landmark navigation, time-place learning, and associative learning. These abilities are fairly well studied in North American genera such as Apis, but remain relatively unexplored in Neotropical species such as those in the genus Trigona, an essential stingless bee pollinator of rainforest ecosystems. In this study, I test whether Trigona bees in Monteverde, Costa Rica possess the capacity to associatively learn concerning foraging and extraneous markers. I conclude that like other Hymenoptera, the Trigona species studied have the capability to both associate an extraneous landmark with a reward and use this information to maximize foraging strategy. This association minimizes Trigona’s time and energy spent searching for a food source, thus improving colonial resource stores and supporting a larger colonial population.
Interspecific interactions between predators and prey have lead to a number of evolutionary adaptations that benefit predator and prey, such as pursuit-deterrent signals. These non-aggressive signals from prey to predator are advantageous for both: the predator wastes no energy on what would be an unsuccessful attack and the prey conserves energy by avoiding the need to escape. The blue-diademed motmot (Momotus lessonii) is a species that benefits from its pursuit-deterrent tail wag display, which tells predators that it is aware of their presence and is prepared to flee. The behavioral responses of M. lessonii in the Monteverde area to conspecific, predator, and control bird calls were quantified and compared. Subjects exhibited the pursuit-deterrent tail wag display and other predator avoidance behaviors in response to the predatory collared forest-falcon (Micrastur semitorquatus) call. They call continuously and approach more during conspecific calls as a form of territoriality, and may exhibit an extra territorial behavior in full tail wag displays. Finally, the control call of the white-throated robin (Turdus assimilis) had little effect on blue-diademed motmot behavior; they tended to continue typical behavior. These findings can shed light on pursuit-deterrent signaling and conspecific territorial displays, and suggest further research into conspecific calling by paired birds and possible extra territorial behavior.
Efficiency in food transport is vital for all organisms. Eusocial insects are efficient because of decentralized colony control, caste specialization, and unique behaviors. Bridge building in the army ant Eciton burchellii has been widely studied as a mechanism that augments prey transport efficiency. Little data exist on why bridges confer an advantage and how their dimensions facilitate rapid food delivery. It is also less well studied how efficiency on a bridge compares to the average efficiency of ant traffic on transport pathways that do not have ant bridges. Bridge lengths and widths were recorded and patterns were looked for between bridge dimensions and ant velocity, traffic density, and collision rate as proxies of food transport efficiency. Bridges were also compared to non-bridge sites and velocity, traffic density, and collision rates were compared between sites. Bridge dimensions were found to correlate with an increase in all three parameters. Non-bridge sites had significantly higher velocities and fewer collisions, and thus were more efficient. Larger bridges confer more efficiency up to the point where too many ants in bridges reduces the potential number of foragers. Areas without bridges were far more efficient than sites with bridges. This is possibly explained by the use of bridges only in uneven terrain; when compared to uneven terrain with no bridge, efficiency may be increased.
Ectoparasitic arthropods can decrease the fitness or survival of their hosts by increasing host energy expenditure. Bats harbor many species of ectoparasites; host biology, grooming, and roosting habits can affect intensity of parasite infestation. This study assessed ectoparasitism on three species of Neotropical bats by Streblid batflies (Streblidae) and bat mites (Order: Acari). Bats were netted and ectoparasites identified to the lowest taxonomic level possible. Host species had a significant impact on ectoparasite richness and abundance (Two Way ANOVA, F = 41.25, df = 2, p < 0.0001). Anoura geoffroyi suffered the most intense overall parasitism and parasitism by Streblids, but Hylonycteris underwoodi hosted more mites and had a greater richness of mites per bat (Tukey’s HSD tests, p < 0.05). Carollia perspicillata suffered very low parasitism rates by all measures. Host sex did not appear to impact ectoparasitism across species or between males and females of the same species. Ectoparasitism is likely impacted by roosting dynamics, grooming habits, and density of individuals in the colony.
Effect of resource manipulation on aggression in the Steely-vented hummingbird (Amazilia saucerrottei)
Hannah G. Crane
Amount of resource available for individuals within a species strongly influences levels of intraspecific competition. Aggression is a direct result of this competition. Aggressive behavior was studied in the Steely-vented Hummingbird (SVH, Amazilia saucerrottei) in normal and reduced resource treatments. The purpose of this study was to determine if reduction in resource availability affects amount of aggression in SVHs. Half of a resource (field of flowers) was covered with bug nets for an experimental condition. Number of chases between two or more hummingbirds was observed to quantify aggression. SVHs were significantly more aggressive with a limited resource, with anywhere from 1.5-3 times as many chases observed in experimental trials. This circumstantial increased aggression allows us to conclude benefits of territoriality (resource access) outweigh energetic costs when resource is limiting. Organisms with more aggression will have more resource and therefore higher fitness.
Passifloraceae and Heliconiine butterflies have coevolved around a cyanide defense against herbivory. This study focuses on the oviposition preference of Heliconius charithonia and Heliconius hecale on Passiflora biflora and Passiflora vitifolia. Changes in cyanide content and leaf toughness were studied as a function of leaf age of P. vitifolia and P. biflora in the Ranario Butterfly Garden in Monteverde, Costa Rica. In addition, P. biflora plants were compared with vines outside of the garden. For P. vitifolia, leaf toughness significantly increased with age while cyanide content significantly decreased. P. biflora sampled inside and outside did not show a significant relationship between leaf age and either cyanide or toughness. Cyanide was shown to significantly decrease as leaf toughness increased in P. biflora, however. P. biflora sampled from inside and outside showed very similar patterns of leaf toughness and CN. H. charithonia females preferred to oviposit on the youngest P. biflora leaves, while H. hecale showed no ovipositing preference based on leaf age. These results suggest that oviposition preferences varied, with H. hecale egg placement a result of interspecific insect interactions and H. charithonia preference based on leaf toughness.
Andrew M. Quinn
Young flowers of Lantana camara are yellow and positioned in the center of the inflorescence with a ring of older, red flowers around them. This study investigates how changes in flower color and presence/absence of nectar influence robbers and pollinators of L. camara. It was found that a significant proportion of older, red flowers (mean = 20.3 percent) contain nectar. In addition, the majority of yellow and red flowers (estimated 90 percent) appear to have pollen and are receptive to pollination. Both pollinators and robbers preferred yellow flowers. Pollinators took nectar from a greater proportion of yellow flowers (e.g. 57 percent) versus red flowers (15 percent). In addition, pollinators showed no preference for inflorescences with the characteristic ‘bulls-eye’ pattern: all yellow inflorescences (AY) that were the same size as normal (N), ‘bulls-eye’ inflorescences, received more visits from butterflies (22 versus 10 per hour), and had more nectar removed (only 12.6 percent of AY flowers had nectar versus 37.5 percent of N flowers). Robbers were about ten times more likely to rob inflorescences with only yellow flowers than inflorescences containing yellow and red flowers (e.g. mean robbery per inflorescence was 3.71 and 0.334, respectively), even when reward and inflorescence size were similar. In addition, a ring of red flowers reduced robbery of yellow flowers by a factor of 37. Robbers may pollinate L. camara, as inflorescences visited only by robbers contained significantly more flowers with pollen on or near the pistil (1.64 flowers/infl) than inflorescences that were not visited (0.364 flowers/infl). L. camara plants may enhance fitness benefits by prohibiting large-scale robbery from yellow flowers yet provide some reward for robbery in red flowers as a way to assure their pollination.
The International Tropical Timber Organization (ITTO 2002) estimated that secondary forest make up 60% of all tropical forests. By definition, that means that a majority of tropical forests have gone through succession in the recent past. In the present study I looked at differences between foliage dwelling insects at different stages of succession. A total of eight sweep samples were taken from a regenerating field (RF), a new growth forest (NGF), and an old growth forest (OGF) in San Luis, Puntaranes, Costa Rica to assess the diversity and evenness during the dry season and at an altitude of around 1200 meters. Of 34 morpho-species, the NGF had the greatest amount of diversity and evenness, followed by OGF and finally RF, which suggest that insect foliage sampling and composition analysis has potential to be used for monitoring forests for succession progress and disturbances.
The determinants of territorial behavior patterns in aggressive organisms are not well understood. Hummingbirds provide an ideal model for studying territoriality as they exhibit obvious territorial behaviors that are likely to change in response to food resource manipulations. I studied trends in territorial behaviors of hummingbirds in response to varied food density. Observations were made on three different arrangements of hummingbird feeders: small: with twelve feeders in a 1m squared square, medium: with twelve feeders in a 25m squared square, and large: with six feeders in a 50m squared, 5x10m rectangle. There was no significant difference in the number of territorial interactions per unit time between the different feeder arrangements. However, the composition of species and sex of visitors to the feeders did differ, with a lesser proportion of males and a greater proportion of females tending to visit the more distant feeders in most species. Territorial interactions significantly changed between feeder arrangements; the percentage of total aggressive interactions that were intraspecific rose from 12.9% in the small arrangement to 33.3% in the medium and 69.2% in the large, with the rate of interspecific interactions inversely diminishing. The similar rate of territorial interactions between density conditions indicates that territoriality is determined by more than simple energy economics, which would make defending the densest resources most beneficial. Instead, it appears that differences between species and sexes' feeding strategies predict territorial patterns.
The predation risk allocation hypothesis (RAH) theorizes that animals display more anti-predator behavior in high-risk situations, and should spend less time foraging in high risk situations. Hummingbirds are risk sensitive foragers, and this study examines whether several different species of tropical hummingbirds can assess risk, supporting the RAH. Hummingbirds were presented with feeder location and view obstruction risk situations, and their preferences and foraging behaviors were used to determine their ability to assess risk. This study indicated that hummingbirds have the ability to assess risk, although species differed in their ability depending on the type and severity of the risk situation. Striped-Tailed, Coppery-headed Emerald, Purple-Throated Mountain Gem, and Violet Sabrewing all showed significant preferences for a certain feeder height and/or position. The Green-crowned Brilliant spent significantly less time at the three feeder treatments (view obstruction) and scanned significantly more than the other hummingbird species. Hummingbirds scanned significantly less at the normal and clear blinder flower type than the red blinder flower, which suggests view obstruction is a risk for all hummingbirds while foraging.
Nathan A. Sellers
Army ants are superefficient in their retrieval of prey. There are four distinct worker castes in Eciton burchellii each important to the high efficiency of foraging. When prey is too large for an individual it is segmented by workers into manageable pieces then conveyed to the bivouac. Workers carrying prey were collected to determine the relationship between prey size and the worker(s) carrying prey as well as examine prey as an evolutionary pressure for selection of the submajor caste. Results show length and width are poor determinants of which caste is performing the retrieval task, as all castes are equally as likely to carry prey of any size. Prey biomass was shown to be a significant factor in determining which caste carried which prey, with the submajor caste carrying the heaviest of prey items.
Vegetation may obstruct echolocation signals bats use to forage. To compensate, frugivorous bats may use olfaction to locate fruits from a distance, saving echolocation to pinpoint fruits at close range. I observed how discovery time and total fruits taken by bats were impacted by foliage cover. Flight cage experiments found a significantly greater number of ripe fruits taken from feeding stations free of vegetation. Of 511 ripe fruits removed in total, uncovered fruits were taken 70 percent of the time. Also, fruits from uncovered stations were found significantly faster than fruits from covered stations. On average, uncovered fruits were discovered three times faster than covered fruits. Greater removal from feeding stations free of vegetation suggests that olfaction is used to initially find food and that echolocation is compromised and/or vegetation presents a direct, physical barrier that impedes foraging. Surrounding vegetation could compromise seed dispersal of some bat-dispersed plants. Plants should be selected to present fruits away from vegetation.
Soil pH can have a large effect on the growth and fitness of plants. Coffea arabica (Rubiaceae) is an extremely important crop for the economy of Costa Rica. Coffee plants become more susceptible to the detrimental infection of Mycena citricolor, a fungus, with lower pH. pH can also have an effect on Vesicular-Arbuscular Mycorrhizae (VAM) amounts in the roots, therefore limiting the mutualistic fungus’s ability to help increase plants growth. Previous studies have also shown that M. citricolor increases closer to the forest, while mycorrhizae decrease slightly. This study, in Cañitas, Costa Rica, shows that pH increased significantly with distance from the forest but never exceeding 6.5. Mycorrhizae showed only a slight trend towards increased abundance in the center of the plot. This suggests that increased pH creates a better environment for mycorrhizae and decreased M. citricolor infection. Common garden seedling experiment also supports this: pH 7 is the optimal pH growth for the coffee plants. pH 7 had a larger increase diameter growth and a higher number of mycorrhizae per root than acidic and basic conditions, however, all seedling heights were similar. These results are helpful to coffee farmers because it indicates that by increasing the soil pH of coffee plots to 7 they can have a better crop growth.
Mist frequency and butterfly emergence from the chrysalis: Implications for tropical cloud forest climate change
The cloud bank in Monteverde, Costa Rica is rising due to global warming. This is causing fewer misty days and is impacting the habitats of local organisms. Butterflies have been shown to be negatively impacted by moisture in terms of livelihood. Heliconius charithonia, a butterfly species occurring from 0-1200 meters, and Heliconius hecale zuleika, occurring from 0-1700 meters, were exposed to intermittent (five minutes mist, five minutes dry over the course of the day) and intense mist conditions (10 hours of constant mist a day) to measure the effect of mist on survivorship, days to eclosion, and development (in terms of mass, wing length, and wing quality). As the climate of Monteverde becomes dryer, these butterflies may move up in elevation to take advantage of the dry conditions. Intermittent mist had no effect on survival or days to eclosion. Twenty butterflies eclosed from the intermittent mist tank and 27 from the dry. In dry conditions, 88% (n=17) of H. charithonia survived while 71% (n=17) of H. hecale zuleika. Ten of each species survived in the misted environment, therefore 59% (n=17) survival for both. The intermittent mist did significantly decrease wing quality, wing length, and mass for H. charithonia, but not for H. hecale zuleika. For wing length of H. charithonia, the average length was 4.19 +/- 0.16 cm in the dry and 3.53 +/- 0.2 cm in the wet. The masses of H. charithonia were nearly significantly different between the two climates; in the dry tank their mass was 0.19 +/- 0.02 g and in the wet was 0.15 +/- 0.02 g. H. charithonia may not be as well adapted to mist as H. hecale zuleika, since H. charithonia showed decreased development. Constant mist killed most of butterflies and caused the eclosion rates of those that did eclose to increase. A total of seven butterflies eclosed from the constant mist and 29 from the dry. In the dry tank, H. charithonia had 79% (n=17) of the butterflies survive; H. hecale zuleika had 93% (n=17). In the wet tank, 30% (n=17) of the H. charithonia survived and 7% (n=17) of the H. hecale zuleika. In the dry tank, the average days to eclosion was 8.6 +/- 0.5, almost 3 days less than those in the wet tank, 11.8 +/- 0.49; Constant mist was not shown to affect development, but probably because of the low number of butterflies that eclosed. Overall, as the mist recedes and the number of dry days increases, the conditions improve for these butterflies to move up in elevation. H. charithonia may move up to Monteverde for breeding and living, also, H. hecale zuleika may increase their breeding and time in Monteverde.
Nectarivorous bat (Anoura geoffroyi, Glossophaga soricina and Hylonycteris underwoodi) preference for nectar quality
In pollination mutualisms, plants offer rewards for pollen delivery. In the case of nectarivorous bats, the reward is food, and in order to maximize net energy gain, bats need to forage optimally. Presumably, nectar offering a more balanced diet would allow the bat more time to forage at flowers. To see if bats prefer nectars of higher quality, 24 individuals comprising three species of nectarivorous bats were presented with a variety of solutions of variable sugar type and amount, with and without additional nutrients, like proteins and amino acids. Preference was determined by number of visits to each solution type and the amount (ml) consumed. This study took place in a flight cage at The Bat Jungle of Monteverde, Costa Rica, using Anoura geoffroyi(N=17), Glossophaga soricina(N=3), and Hylonycteris underwoodi(N=4). For all five experiments, there was statistical preference for sugar solutions without other added nutrients (chi-squared goodness-of-fit test, df=1, P<0.05). These results suggest that bats have not evolved to detect or prefer more balanced nectar. Thus, they must augment nectar-based diets with insects or other food items. Perhaps the cost is sufficiently low that this can be done with little compromise.
Optimal foraging in leafcutter ants (Atta cephalotes) selection of leaves based on proximity to the nest
Robert O. Snowden
The foraging tendencies of Atta cephalotes, a leaf-cutting ant, have been widely studied. Optimal foraging theory dictates that ants should maximize rate of energy intake while minimizing costs by harvesting from suitable food sources closer to the nest. However, actual foraging patterns are more disparate and do not always reflect optimal strategies. Here I measure harvesting rates and recruitment speeds at different distances from the nest of A. cephalotes colonies by offering six leaf disk samples every 15 minutes at 5, 10, and 15 meters from the nest entrance. Harvesting rate was significantly higher closer to the nest, with 54% of leaf disks selected at 5 meters. Recruitment was also faster closer to the nest, as ants selected leaf disks within the first three minutes in 63% of the trials at 5 meters. Communication between workers may determine selection of closer leaf offerings and thus optimize foraging on a colonial level. Other factors, such as nutritional qualities from a plant, can influence foraging choices, but when leaf offering vary solely by distance, A. cephalotes exhibit time and distance-maximizing foraging patterns.
Christine R. Isabella
Sexual reproduction increases genetic variation and allows offspring to be transported away from their parent plant. However, many plants in tropical forests are capable of reproducing from fragments, leading to a high density of clones in close proximity to the parent plant. Most plants require animals for pollen and seed transport, and in some cases plants have a specialist relationship with an animal, relying exclusively on them for successful reproduction. Other plants have generalist relationships with pollinators and dispersers with many animals able to complete reproductive tasks for the plant. This is the first study to examine the relationship between plant’s pollination and dispersal syndromes and the prevalence of asexual reproduction from fragments in natural habitats. I collected plants species with specialist pollinators (Piper sp.), specialist dispersers (Anturium obtusilobum), generalist pollinators and dispersers (Inga marginata, Psychotria spp., Lonchocarpus oliganthus, and Chamaedorea sp.), and ballistic dispersal (Aphelandra sp.). Each plantlet was identified as growing from a seed or a fragment and the percent of fragment regrowth was compared between species. Piper sp. and A. obtusilobum showed the highest rates of asexual reproduction, followed by Aphelandra sp. The species with generalist pollination and dispersal syndromes showed the lowest rates or asexual reproduction. This study shows specialist syndromes to utilize asexual reproduction as a means of proliferation, presumably due to the inefficiency of specialist syndromes. These results have important implications in understanding the vegetative properties of the understory.
Specialization between plant and pollinator species has resulted in the development of pollination syndromes in which suites of floral traits attract specific pollinators. While plants use nectar as a reward to attract pollinators, they must also defend themselves, either chemically or morphologically, against nectar robbers. Brugmansia (formerly Datura; Solanaceae) has been described as possibly sphingid, hummingbird, bee, or bat pollinated, underscoring how little is known about pollination in this genus. It is also heavily protected chemically, including the flowers. One aim of this study was to examine floral traits and compare them to known pollination syndromes to determine the most likely pollinators of B. suaveolens. Additionally, I looked for possible chemical protection of nectar and petals against nectar robbers. I studied the change of pollen load and the sucrose concentration in nectar every morning and night for 70 flowers in Cañitas, Costa Rica; I also did two experiments regarding ant preferences of B. suaveolens nectar and petals. Pollen load decreased over time, mostly at night, suggesting nocturnal pollinators that were recruiting to the flowers. Sucrose concentrations in nectar also decreased over time and were higher in the morning than at night, possibly due to evaporation and condensation. My data suggest that the dominant pollinators of B. suaveolens are most likely bats and hawkmoths; bees may be secondary diurnal pollinators. Neither petals nor nectar deterred ants suggesting there is no chemical protection against nectar robbers in the flowers. Nectar thievery by insects, possibly including bees, appears to be especially prevalent in older flowers.