Asking the pikas politely…
Investigates how bumble bees and solitary bees forage across alpine wildflowers, examining floral visitation rates, pollinator behavior, and the timing and temperature sensitivity of plant-pollinator mutualisms in high-elevation Colorado meadows.
Mountain meadows like those around the Rocky Mountain Biological Laboratory in Gothic, Colorado erupt each summer into a brief but intense display of wildflowers. For a few short weeks, hundreds of plant species compete for the attention of bumble bees, solitary bees, hover flies, butterflies, and hummingbirds. The mutual exchange at the heart of this spectacle — flowers offering nectar and pollen in return for the transport of pollen from one flower to another — is called a plant-pollinator mutualism. In the Gunnison Basin, this mutualism shapes which wildflowers set seed, which bee populations persist from year to year, and how meadows respond to a changing climate.
Understanding these interactions requires a handful of basic ideas. Floral resources — the total nectar and pollen on offer in a meadow at a given moment — drive pollinator foraging behavior, which describes how bees and other insects choose flowers, how long they handle each blossom, and how often they return. Bees often show floral constancy, sticking to one flower species during a foraging bout even when others are available, a tendency that affects how efficiently pollen moves between plants of the same species. The match between a bee's tongue length and a flower's corolla length determines which flowers a forager can profitably exploit. Together, these traits and behaviors assemble into plant-pollinator networks — maps of who visits whom — whose structure can be measured by properties like nestedness (the degree to which specialists interact with a subset of partners that generalists also use).
A second cluster of concepts concerns timing and life history. Phenophases describe the seasonal stages of a bee's flight period, from emergence to peak foraging to senescence, and the synchrony between bee emergence and flower bloom is critical for both partners. Voltinism — the number of generations produced per year — interacts with season length to determine bee population dynamics at high elevations. Many bees are cavity-nesting, using hollow plant stems or wood, while others nest underground. Climate-mediated indirect effects link snowpack, summer temperature, and drought to bee fitness both directly (through thermal stress) and indirectly (through floral resources). These ideas anchor the findings that follow.
Research on plant-pollinator ecology in Gothic helped establish much of the modern field. Inouye's classic removal experiments showed that two coexisting bumble bee species partitioned flower resources by matching their tongue lengths to corolla lengths, and that competitive release occurred when one species was removed , with follow-up work demonstrating that proboscis length systematically predicts handling time on different flowers . Thomson's studies in subalpine meadows showed that bees concentrate visits in denser flower patches and that surrounding plant species can facilitate rather than compete for visitation , and that pollen carryover from one flower to the next depends strongly on bee size, grooming, and nectar volume .
Mutually beneficial interaction between flowering plants and their animal pollinators where plants provide nectar/pollen rewards and animals provide p...
Behavioral choices and time allocation patterns of pollinators when visiting flowers, including flower choice, handling time, and visitation frequency
Frequency of pollinator visits to flowers measured as visits per individual per minute or visits per flower per minute
The total number of flowers available as nectar and pollen resources measured as flowers per meter
Management strategies and techniques aimed at supporting and maintaining bee populations and their ecological functions.
Availability of flowering plants that provide pollen and nectar for bee reproduction, quantified as floral density in standardized plots
Systematic observation of plant-pollinator interactions along fixed transects with timed observations and selective insect capture for identification....
Systematic observation of plant-pollinator interactions along established transects with standardized time intervals to capture natural temperature va...
Belt transect method for censusing lupine populations and collecting inflorescences for morphological analysis across sympatric and allopatric sites. ...
A field-based protocol for extracting nectar from flowers that have been exposed to bee visitation, then quantifying ethanol content using enzyme-base...
Installation and monitoring of artificial wooden nesting-blocks with multiple cavity sizes to track solitary bee nesting activity, timing, and reprodu...
Quantitative analysis of pollen grain composition in bee provisions using compound microscopy. Pollen samples stained with fuchsin and examined at 100...
This is an archive of the data used in the publication: Ogilvie JE, Griffin SR, Gezon ZJ, Inouye BD, Underwood N, Inouye DW, Irwin RE. 2017. Interannu...
Many plants have evolved nutrient rewards to attract pollinators to flowers, but most research has focused on the sugar content of floral nectar resou...
Organisms inhabiting seasonal environments must fit their life cycle into a limited time window while also synchronizing periods of resource consumpti...
In mutualistic interactions, the decision whether to cooperate or cheat depends on the relative costs and benefits of each strategy. In pollination mu...
Food underpins fitness and ecological interactions, yet how nutrient availability shapes species interactions in natural communities remains poorly un...
PREMISE OF THE STUDY: Optimal Defense Theory predicts that selection should drive plants to differentially allocate resources for herbivore defense to...
These local studies fed into broader theory. Harder and Thomson's analysis of Erythronium grandiflorum revealed that bumble bees deposit only a tiny fraction of the pollen they remove, leading to the influential idea that flowers maximize pollen export by parceling out pollen across many visits (Harder & Thomson, 1989). Wilson and Thomson then showed that pollen-collecting bees remove far more pollen but deposit far less than nectar collectors, fundamentally complicating how pollinator effectiveness should be measured (Wilson & Thomson, 1991). Chittka and colleagues synthesized the behavioral side of this story, examining how flower color, reward, and morphology shape floral constancy and plant evolution (Chittka et al., 1999).
A central insight from work in Gothic is that plant-pollinator networks are far more dynamic than once thought. Weekly censuses across three years revealed that the partners a flower or a bee interacts with turn over rapidly within a single season, with this turnover dominated by interaction rewiring — species reshuffling their partners — rather than by species coming and going (CaraDonna et al., 2017). Species' positions within networks are extremely variable across time, with most plants and pollinators occupying largely unique roles week to week (untangled in Cuartas-Hernandez et al., 2020), and floral resource phenology emerges as a key driver of how bee communities assemble (Ogilvie & Forrest, 2017). Even brief removals matter: experimentally taking a single bumble bee species out of a meadow reduces floral constancy in the remaining bees and lowers plant reproduction, demonstrating that pollinator losses can have functional impacts well before species actually disappear (Brosi & Briggs, 2013). Removing flowers of a dominant generalist like Helianthella reduced community-wide visitation rates by nearly half (Wong & Forrest, 2022).
Climate change has emerged as a unifying theme. Trap-nest studies along an elevational gradient showed that both bee emergence and flowering are well predicted by accumulated degree-days, but bees generally require warmer thresholds than plants, raising the possibility of phenological mismatch (Forrest & Thomson, 2011). Long-term monitoring confirms that earlier snowmelt strongly advances bee emergence (Stemkovski et al., 2020) and that shorter snow cover predicts lower bee abundance the following year for most species studied (Quinlan et al., 2025). Drought severity and hot summer temperatures reduce individual reproductive output in solitary bees, with brood cell production falling by roughly a third under the harshest conditions (Wong et al., 2025). Life-history traits structure these responses: larger-bodied and comb-building cavity nesters have declined with warming while smaller soil-nesting species have increased (Pardee et al., 2022).
Floral biology and reward chemistry also shape outcomes. Nectar replenishment after removal is widespread, with most surveyed species producing 1.5 to 2.9 times more nectar when drained repeatedly (Ye et al., 2014). Specialization on Asteraceae pollen, despite its lower nutritional quality, protects mason bee broods from sapygid wasp parasitism (Praz et al., 2016). Bumble bee species partition into distinct macronutrient niches structured by tongue length, with long-tongued species acquiring higher-protein pollen (Bain et al., 2025).
Early work in the 1970s and 1980s established the basic mechanics of bee foraging, pollen transfer, and resource partitioning. Research in the 2000s and 2010s built network-level and phenological frameworks for understanding whole communities. Recent studies since 2020 have shifted focus toward climate stressors, individual-level fitness, and new molecular and tracking technologies. DNA metabarcoding combined with ecological filtering now allows researchers to identify the plant species in a single bumble bee's pollen load with high accuracy, opening up fine-grained reconstruction of foraging diets (Benkendorf et al., 2025). Radio-frequency identification tags have revealed the previously hidden life of foundress queens, who make many short foraging trips but suffer high rates of nest failure (Gustilo et al., 2025).
Other recent work probes how environmental variables shape interactions on short timescales. Temperature alters which flowers pollinators choose independently of community composition (Arrowsmith et al., 2025), and both temperature and humidity drive trade-offs between nectar volume and sugar concentration that ripple through to visitation (Wheeler, 2025). Non-native plants like dandelion can act as ecological traps, providing early-season resources that boost nest initiation but reduce larval survival (Cahill et al., 2025). Body size variation in bumble bees, which influences foraging range and pollination effectiveness, is itself being reshaped by climate, with earlier snowmelt producing smaller queens (Fitzgerald et al., 2024).
Many questions remain. How will repeated drought years interact with shorter snowpack to reshape bee communities over the next decade, and which life-history strategies will prove most resilient? Can the rapid rewiring of plant-pollinator networks buffer them against species loss, or are there thresholds beyond which function collapses? How do non-native plants, nectar-inhabiting microbes, and shifting nutritional landscapes combine to influence individual bee fitness? Tracking technologies, metabarcoding, and long-term datasets from Gothic offer unprecedented power to address these questions, but linking individual-scale physiology to community-scale outcomes — and to the management decisions facing the Gunnison Basin — remains the central challenge for the coming decade.
Arrowsmith et al. (2025). Temperature influences pollinators' choice of floral partners independently of community composition. Journal of Animal Ecology. →
Bain et al. (2025). Nutrient niche dynamics among wild pollinators. Proceedings of the Royal Society B. →
Benkendorf et al. (2025). Improving plant DNA metabarcoding accuracy with ecological filters and Angiosperms353. Applications in Plant Sciences. →
Brosi, B. J., Briggs, H. M. (2013). Single pollinator species losses reduce floral fidelity and plant reproductive function. PNAS. →
Cahill et al. (2025). Fitness costs and benefits of a non-native floral resource for subalpine solitary bees. Oikos. →
CaraDonna, P. J., Petry, W. K., Brennan, R. M., Cunningham, J. L., Bronstein, J. L., Waser, N. M., Sanders, N. J. (2017). Interaction rewiring and the rapid turnover of plant-pollinator networks. Ecology Letters. →
Chittka, L., Thomson, J. D., Waser, N. M. (1999). Flower constancy, insect psychology, and plant evolution. Naturwissenschaften. →
Cuartas-Hernandez et al. (2020). Untangling the seasonal dynamics of plant-pollinator communities. →
Fitzgerald et al. (2024). Intraspecific body size variation across distributional moments reveals trait filtering processes. →
Forrest, J., Thomson, J. D. (2011). An examination of synchrony between insect emergence and flowering in Rocky Mountain meadows. Ecological Monographs. →
Gustilo et al. (2025). Wild foundress queen bumble bees make numerous, short foraging trips. Ecology and Evolution. →
Harder, L. D., Thomson, J. D. (1989). Evolutionary options for maximizing pollen dispersal of animal-pollinated plants. American Naturalist. →
Inouye, D. W. (1978). Resource partitioning in bumblebees: experimental studies of foraging behavior. Ecology. →
Inouye, D. W. (1980). The effect of proboscis and corolla tube lengths on patterns and rates of flower visitation by bumblebees. Oecologia. →
Ogilvie, J. E., Forrest, J. R. K. (2017). Interactions between bee foraging and floral resource phenology shape bee populations and communities. →
Pardee et al. (2022). Life-history traits predict responses of wild bees to climate variation. →
Praz et al. (2016). Asteraceae pollen provisions protect Osmia mason bees from brood parasitism. →
Quinlan et al. (2025). Shorter seasonal snow cover poses a risk to solitary bee populations. Proceedings of the Royal Society B. →
Stemkovski et al. (2020). Bee phenology is predicted by climatic variation and functional traits. →
Thomson, J. D. (1981). Spatial and temporal components of resource assessment by flower-feeding insects. Journal of Animal Ecology. →
Thomson, J. D. (1986). Pollen transport and deposition by bumble bees in Erythronium. Journal of Ecology. →
Wheeler (2025). Temperature and relative humidity effects on nectar quantity, nectar quality, and plant-pollinator interactions. →
Wilson, P., Thomson, J. D. (1991). Heterogeneity among floral visitors leads to discordance between removal and deposition of pollen. Ecology. →
Wong et al. (2025). Up high, hot and dry: Individual reproductive output in subalpine bees declines with increasing drought severity. Global Change Biology. →
Wong, T. M., Forrest, J. R. K. (2022). Removing flowers of a generalist plant changes pollinator visitation, composition, and interaction network structure. →
Ye et al. (2014). Stimulation of flower nectar replenishment by removal. →
A measure of how successful a bird is at food acquisition, quantified through observations as foraging rate (number of forages divided by time observe...
Animals adopt a foraging strategy that provides the most benefit (energy) for the lowest cost
The progression through larval developmental stages with associated changes in size and feeding capacity
The degree to which specialists interact with subsets of species that generalists interact with, measured by weighted NODF
Diet breadth of bees classified as oligolectic (collect pollen from flowers in multiple plant families) or polylectic (collect pollen from flowers in ...
Transparent chambers commonly used in climate change experiments to raise air and soil temperature in remote areas by creating a passive warming effec...
A mode of sex expression where male sterile (female) plants and hermaphroditic plants coexist within a population
When sapygid wasps enter brood cells during the provisioning or brood cell construction stages and lay eggs in provisioned brood cells prior to wall c...
Bacterial communities that colonize and live within floral nectar, potentially affecting nectar chemistry and pollinator behavior
The length of flower tubes, which correlates with bumble bee proboscis length and determines flower accessibility
A network's sensitivity to simulated extinction of plants or pollinators, measured as secondary extinction cascades
The number and proportion of developed seeds produced by an individual plant, used as a measure of fecundity
Predicts that fast-growing plants in high resource environments invest less in defense because they can easily regrow after herbivory
Division of labor in social insects with distinct morphological and behavioral castes including queens, workers, and males
Genetic mechanisms that prevent self-fertilization by recognition and rejection of self pollen
The duration from when a flower's corolla first opens until either the corolla falls off or the stigma closes after opening
Measure of foraging specialization using standardized Hurlbert's niche breadth, where values closer to 1 represent generalized foraging and values clo...
The range of resources or interaction partners utilized by a species, in this context referring to the diversity of flower visitors to a plant species
The tendency for flower foragers to visit a single flower species during foraging trips even when alternative rewarding species are available
Sequential developmental stages of individual flowers progressing through male phases (M1, M2), inter-phase, and female phase
Statistical measure of variation used to quantify family-guild variation and compare across different taxonomic groups
Conflicts between opportunities of a flower to receive fitness contributions from different visitor groups due to competition over limited floral reso...
Investment by female bees in offspring through pollen provision size and number of brood cells produced
Chemical compounds overproduced by queens compared to workers that potentially regulate worker reproduction
Effects of climate variables on organism fitness that operate through changes in resource availability rather than direct physiological impacts
Statistical method to compare species richness across samples by generating accumulation curves based on individual encounters
Geographic variation in chemical profiles that may reflect phylogeographic drift in odor profiles between populations
Chemical inhibition of one plant by another through secondary metabolites, tested via leachate applications
Solitary bee species that construct nests in pre-existing cavities in wood, stems, or artificial structures rather than excavating ground nests
Hypothesis that parasitism of dominant plant species reduces their competitive ability, allowing less competitive species to increase in abundance
Systematic differences in detection or capture probability among species or groups due to sampling method
Loss of ovules to unfit heterospecific pollen that successfully reaches and occupies ovules but fails to produce viable offspring
The tendency of foragers to maintain a consistent foraging strategy across multiple floral visits rather than switching between different tactics
The identification of species from environmental DNA samples using target capture sequencing and database matching
The transport and distribution of microorganisms among different locations by animal vectors
The duration a pollinator spends foraging on each flower, calculated by dividing total foraging bout duration by number of flowers visited
Life history characteristics related to where and how bees construct their nests, categorized as above-ground or below-ground
The hypothesis that secondary metabolites in certain pollen types provide protection against natural enemies
Study of chemical interactions between organisms, including use of chemical signals for communication and resource location
Sampling methods that result in the death of collected organisms, potentially affecting population abundance and community structure
Signaling system where the signal reliably indicates the quality or quantity of rewards available to the receiver
Sodium being a limiting nutrient in natural systems, affecting organism behavior and ecosystem interactions
Statistical method to identify correlations between species traits and environmental variables
The energetic cost of provisioning brood cells, measured by number of foraging flights per completed cell and provision mass
Theory stating that foragers will leave a patch after the quality of the patch drops below the average quality of the overall habitat
The ability of bumble bees to regulate internal body temperature through muscle contraction
Upper temperature limit where organisms lose fitness and performance ability
The upper thermal limit when the bumblebee loses its motor function as a result of high temperatures
Mathematical moments describing trait distributions including mean, variance, skew and kurtosis that characterize central tendency, spread, asymmetry ...
Duration of favorable conditions for bee development and reproduction, shorter at high elevations
The number of generations produced per year, under both genetic and environmental control in insects
Pollination behavior where bumblebees make vibrations that knock pollen out of plant anthers, fertilizing the plant and allowing quicker seed and frui...
Theory stating that pollinator visitation rates are higher in areas of higher floral density while in sparse populations pollinators switch between pl...
Method of covering flowers with mesh bags to prevent pollinator access and allow nectar accumulation for sampling
Theory suggesting that offspring sex ratios might vary according to maternal condition, hence females should vary the sex of their offspring according...
The distribution of limited resources among competing physiological functions such as growth, reproduction, and defense
The ability to extract nutrients from consumed food, measured here by frass mass relative to provision mass and extent of pollen grain digestion
Spatial sampling design measuring wildlife responses at increasing distances from disturbance sources
Multiple individuals of solitary nesting species choosing to nest in close proximity to one another
Statistical methods for analyzing time-to-event data, here focused on summer survival probability
Lifetime reproductive output of individual organisms, measured as total brood cell production across all nests for female bees
Pollen-transport interactions were analyzed using network metrics including weighted connectance, linkage density, weighted nestedness, specialization...
A factorial experiment manipulating both flowering phenology (by moving plants between elevations) and water availability (through differential wateri...
Floral resource availability was quantified by counting flowers while walking in progressively larger circles from a central point until reaching 100 ...
Calculation of cumulative growing degree days from weather station data using species-specific base temperatures, correlated with biological events th...
Experimental manipulation of natural floral orientations combined with pollen supplementation to test effects on seed set and female fitness.
Collection of female halictid bees at nest sites using nets or vacuum devices, with individual storage and cryopreservation for chemical analysis. Inc...
Laboratory protocol for preparing yeast-inoculated synthetic nectar with species-specific concentrations and incubation conditions. Synthetic nectar d...
Statistical analysis of pollinator diversity using Shannon Diversity Index with ANOVA and post-hoc testing to compare plant visitation diversity betwe...
Extraction of cuticular compounds from individual bee specimens using n-pentane solvent followed by gas chromatographic analysis with flame ionization...
Using Generalized Additive Models to estimate emergence, peak, and senescence timing from sparse time-series abundance data. Models fit abundance curv...
Laboratory feeding trials exposing individual bumblebee workers to alkaloid-enriched sucrose solutions followed by behavioral activity scoring to asse...
Calculation of interaction turnover between plant-pollinator networks at different sites by comparing shared taxa and their interaction frequencies. P...
Controlled experiment using marker bacterium to track microbial transfer from inoculated donor flowers to recipient flowers via butterfly foraging beh...
Experimental transplantation of completed mason bee nests from low to high elevation sites to test effects of season length and climate on offspring d...
Method to quantify microbial load on different butterfly body parts by direct plating on agar media. Samples tarsi/proboscis by dragging across plate ...
Standardized biochemical assays for quantifying protein, lipid, and carbohydrate content in pollen samples. Uses Bradford assay for proteins and sulfo...
Standard protocol for preserving unidentifiable specimens in ethanol, followed by pinning and taxonomic identification in laboratory conditions.
Systematic search and evaluation of published literature examining relationships between phenological shifts and demographic consequences using specif...
Comprehensive method for extracting quinolizidine and piperidine alkaloids from plant tissues using acid-base extraction followed by GC/FID and GC/MS ...
Analysis of larval fecal pellets to assess digestive efficiency by measuring frass mass relative to provision mass and quantifying undigested pollen g...
Statistical approach to identify correlations between species traits and environmental variables by calculating Pearson correlations between climate v...
Controlled removal of the most abundant Bombus species from plots using targeted aerial netting during 4-hour manipulation periods, compared to 4-hour...
Application of fine-mesh bags over flowers to prevent pollinator access while maintaining airflow and light penetration. Uses Del Star polyethylene ba...
Controlled heating and cooling assays to determine critical thermal maximum (CTmax) and minimum (CTmin) temperatures of bumblebees under field conditi...
Custom-built RFID system using paired antenna cards and microSD data logging to continuously track individual bee movements in and out of nest boxes. ...
Bayesian mixed effects modeling of body size distributions using four statistical moments (mean, variance, skew, kurtosis) to characterize trait filte...
Statistical method to compare species richness across samples with different sampling efforts by generating rarefaction curves. Uses individual-based ...
Simulations to model how fine-grained distribution of non-native resources affects native consumer population dynamics.
This is an Excel file containing one sheet with 23 columns. Each row represents the data and metadata for a single tissue sample from a single individ...
An Excel workbook of data for Heiling et al 2018. First sheet is a metadata file, all other sheets are arrange chronologically. Sheet names describe t...
Bumble bee queens initiate nests solitarily and transition to living socially once they successfully rear their first cohort of offspring. Bumble bees...
The overwhelming majority of research on wild bumble bees has focused on the social colony stage. Nest-founding queens in the early season are difficu...
Bumble bee occurrence data used for "Climate change winners and losers among North American bumble bees": These data comprise 649 407 specimen records...
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Climate change can impact species interactions by changing the spatial and/or temporal overlap of interaction partners, but interspecific interactions...
Many specialist herbivores eat foods that are apparently low quality. The compensatory benefits of a poor diet may include protection from natural ene...
A longstanding question in ecology is how species interactions are structured within communities. Although evolutionary theory predicts close size mat...
The global trade of species promotes diverse human activities but also facilitates the introduction of potentially invasive species into new environme...
Climate change poses a threat to organisms globally, but its effects may be particularly pronounced in multi-trophic systems. For example, pollinators...
One possible effect of climate change is the generation of a mismatch in the seasonal timing of interacting organisms, owing to species-specific shift...
Many specialist herbivores eat foods that are apparently "low-quality". The compensatory benefits of a poor diet may include protection from natural e...
Climate change is shifting the environmental cues that determine the phenology of interacting species. Plant-pollinator systems may be susceptible to ...
Incidence of parasitism by sapygid wasps on species of Osmia using different types of pollen, based on trapnests established at multiple field sites b...
1. Cultivation of bioenergy feedstocks is a growing land-use worldwide, yet we have a poor understanding of how bioenergy crop management practices af...
Testing Tweak tests that use the graph package.