DOI: 10.5061/dryad.t1g1jwth3
title: Data from: Foraging plasticity and physiological adaptations enable hummingbirds to subsist on dilute nectars

description: Hummingbirds frequently feed on small volumes (&lt; 30 µl) of
 sucrose-rich nectars. Climate change is expected to affect both the
 abundance and the concentrations of accumulated nectar. Using experimental
 feeding trials and field-collected measures of daily energy expenditure
 and floral nectar contents, we test the nectar dilutions at which
 hummingbirds can no longer meet their daily energy needs. We found across
 14 hummingbird species that they are limited in how much they can increase
 their feeding rate (compensatory feeding) with decreasing nectar
 concentrations: nectar consumption increased until dilutions of 4-6 %
 sucrose, where birds fed at a maximum feeding rate (0.70 gNECTAR gBODYMASS
 -1 hr-1), after which nectar consumption (and corresponding sucrose
 intake) decreased. Integrating lab-tested maximum feeding rate with daily
 energy expenditure estimated from free-living hummingbirds, we found most
 species could meet daily energy needs while feeding on dilute nectars, but
 there is an average dilution threshold (~7 % sucrose). Hummingbirds may
 cope with energy deficits caused by variability in resources and
 competition with other nectarivores by adjusting their time spent
 foraging. Our energy budget models show that to meet average daily
 energetic needs, hummingbirds could feed ~2 hours on concentrated nectars,
 or an unattainable 19 hours feeding on dilute nectars. We show that
 maximum feeding rates pose a physiological cap on hummingbirds’ ability to
 use dilute nectars, which has implications for hummingbird survival and
 ultimately pollination. Thus, nectars provided by trochilophilous plants
 should be more concentrated than this dilution threshold. This mechanistic
 understanding may inform future work on the impacts of changes in flower
 phenology and nectar quality on hummingbirds.
description: # Dryad dataset Dataset DOI:
 [10.5061/dryad.t1g1jwth3](https://doi.org/10.5061/dryad.t1g1jwth3) ##
 Description of the data and file structure Processed and incremental data
 used in estimating feeding rates, daily energy expenditure and nectar
 quality. Code for duplication of this processing can be found on GitHub
 ([https://github.com/eltingrosalee/FE_dilute_nectar_ecophys_public](https://github.com/eltingrosalee/FE_dilute_nectar_ecophys_public) ### Files and variables #### File: EPHI_transects_StLu_Maqui.csv **Description:** Field flower species diversity from walked transects.  ##### Variables * plant_species: species * plant_genus: genus * plant_family: family * plant_order:order * site: location at one of two field sites in Ecuador.  #### File: holger_nectar_data.csv **Description:** nectar data from both Ecuador sites ##### Variables * medida: measure whether standing crop or a bagged flowers  * observer: data collector  * date * site: which Ecuadorian site  * Transect: within the site * Species: plant flower species  * Plant: sample from within the species * flower: flower from within the plant * capillar size: ul capacity of the capillary tube  * total length: length of the capillary tube used.  * time * extraction: estimated volume of nectar extracted, not available for all plnts  * Brix: sugar content of nectar, in Brix units * Comment: if no nectar was found  * height: in meters, estimates * elevation: in meters * GPS: location  * Bagging time: time, if standing crop was bagged, as well as start and stop time (two subsequent columns), not available for all samples or standing crop measures.  * bagging start  * bagging stop * family: plant family #### File: eco_roles.csv **Description:** ecological roles for each hummingbird species  ##### Variables * species: four-letter code for species from this study  * role: estimated role (territorialist, generalist, trap-liner) based on Birds of the World species descriptions.  #### File: clade_list_mfr.csv **Description:** clades for each hummingbird species ##### Variables * clade: clade of species * species: four-letter code for species from this study  * species_name: Genus_species name #### File: dlw_shankar19.csv **Description:** Doubly labeled water data from Shankar et al., Functional Ecology  ##### Variables * SourceFile: Data file (this work or from published data) * ID: Bird individual ID * Lit_data: Data (this study) or literature * Site: location of field study * Big_site: Geographic region * Species: four-letter code for species from this study  * Sex: * Mass_g: mass, in grams * Release_mass: release mass, in grams * dose_ml: dose of stable isotope, in ml * dose_g:dose of stable isotope, grams, when available not present for all samples * Co2_produc_mol: estimate of carbon dioxide product (Mol) * Co2_produc_ml_hr: same estimate, ml/hr * Co2_produc_ml_hrg: ml/hr/gram of bird mass * kJ_day:estimates energy expenditure in kj/day * kJ_dayg: mass adjusted  * Comments : sample comments, not for all data points #### File: EPHI_filmed_plants_StLu_Maqui.csv **Description:** Plants filmed at sites, as well as their taxonomy. Allow for a estimate of general plant diversity.  ##### Variables * plant_species: * plant_genus: * plant_family: * plant_order: * site: #### File: breakpoint_data_ms.csv **Description:** Incremental data on breakpoint of feeding rate ##### Variables * species_name: genus_species * concentration: experimental nectar concetration * nectar_consumption_ms: mass-specific hourly nectar consumption rate #### File: lc_30min_intervals.csv **Description:** Load cell intervals of feeding rate for Washington species.  ##### Variables * lt_avg_head: average measure at start of last thirty minutes of trial  * lt_avg_tail: average measure at end of last thirty minutes of trial  * MFR_ID: individual identifier * nect_conc: trial concentration of nectar  * lt_cons_g: consumption in last 30 minutes, grams * ft_avg_head: average measure at start of first thirty minutes of trial  * ft_avg_tail: average measure at end of first thirty minutes of trial  * ft_cons_g: consumption in first 30 minutes, grams #### File: nectar_species_diversity.csv **Description:** nectar diversity of Ecuadorian sites ##### Variables * site: Santa Lucia or Maquipicuna * species: plant species * brix: sugar concentration in nectar, brix #### File: piecewise_regress_data.csv **Description:** Incremental data for piecewise regressions ##### Variables * formatted_species: species name in G. species format * concentration: experimental nectar concentration  * nectar_consumption_ms: mass-specific nectar consumption per hour  #### File: peak_feed.csv **Description:** Incremental data on peak feeding rate for each species ##### Variables * species: four-letter species code * species_name: Genus_species format * individual: individual identifier * peak: peak feeding rate met for individual * peak_conc: concentration where this peak was met.  #### File: filtered_nectar_data.csv **Description:** Incremental nectar data used in paper ##### Variables * site: Santa Lucia or Maquipicuna * species: Plant species * brix: nectar concentration, brix * family: plant family  * mean_brix: mean brix for site where plant was found  * below_10: categorical variable if below the 10th quantile mark  * below_bkpt:** **categorical variable if below the breakpoint estimated from breakpoint regression (where peak feeding is met) * below_highest_ndth: categorical variable if below the estimated nectar dilution threshold (to meet daily energy expenditure)  #### File: prepped_data.csv **Description:** All species incremental feeding rate data  ##### Variables * site: * species: four letter species code * individual: individual identifier * concentration: nectar concentration of trial * treatment_time: length of trial, hours * total_consumption: total nectar consumption, grams * initial_bird: bird initial mass, g, when available  * final_bird: bird final mass, g, when available  * initial_bird_mean: mean species mass for that concentration, g * clade: clade species is in  * species_name: Genus_species format * nectar_consumption_g: nectar consumption, in grams * water_consumption_mL: water consumption, in grams * sucrose_consumption_g: sucrose consumption, in grams * energy_obtained_kJ: kJ of energy from sucrose * initial_bird_avail: initial mass of bird, when available, or mean for that species and concentration, g * nectar_consumption_ms: nectar consumption, mass specific, g_nectar/g_bird * water_consumption_ms: water consumption, mass specific, g_nectar/g_bird * sucrose_consumption_ms: sucrose consumption, mass specific, g_nectar/g_bird * energy_obtained_ms: kJ of energy from sucrose, mass specific, kj energy/g_bird * delta_mass_wintreat: change in mass within treatment * formatted_species: G. species format * concentration_f: same as nectar concentration, but formatted as a factor #### File: hum294_forAlejo.tre **Description:** Tree courtesy of McGuire et al, for this study. #### File: MFR_drift_values_92922.csv **Description:** Estimates of drift from before and after feeder usage of trial. ##### Variables * MFR_ID: bird identifier * nect_conc: trial nectar concentration * trial_start_time: time of trial start * Zero_perch_mass_initial: mass of perch when no bird was on it, start of trial, grams * Zero_perch_mass_final: mass of perch when no bird was on it, end of trial , grams * Zero_feeder_mass_initial: mass of feeder holder with no syringe, start of trial , grams * Zero_feeder_mass_final: mass of feeder holder with no syringe, end of trial , grams * trial_end_time: end time of trial.  #### File: MFR_Data_Sheet_UW_RE_9822.csv **Description:** Data sheet for Washington species (later added to prepped_data). ##### Variables * MFR_ID: bird identifier * trial_name: if a number, trial or if 10_# this is an acclimation or control trial  * Nectar_conc: nectar concentration * time_in_cage: time in experimental set up  * time_start_feed: time beginning to regularly feed * trial_start_time: start time of trial  * Zero\_ perch_mass_initial: mass of perch when no bird was on it, start of trial, grams * Zero_perch_mass_final: mass of perch when no bird was on it, end of trial, grams * Zero_feeder_mass_initial: mass of feeder holder with no syringe, start of trial, grams * Zero_feeder_mass_final: mass of feeder holder with no syringe, end of trial, grams * feeder_mass_initial_scale : initial syringe weight from scale, in grams  * feeder_mass_initial_lc: initial syringe weight from load cell, in grams  * bird_mass_initial: initial mass of bird, grams (obtained from load cell) * bird_mass_final: final mass of bird, grams (obtained from load cell) * feeder_mass_final_lc: final syringe weight from load cell, in grams  * feeder_mass_final_scale: final syringe weight from scale, in grams  * trial_end_time: end of trial time * urine_mass: collected urine mass, grams * urine_concentration: sugar concentration of urine, Brix * trial_time: duration of trial, minutes * Comments: some blank, if comments about urine collection  #### File: mfr_csv_all.csv **Description:** All non-Washington species raw data. ##### Variables * site: site location * species : four-letter species code * individual : bird identifier * concentration : nectar concentration of trial * treatment_time: duration of treatment, hours * total_consumption: nectar consumption, grams  * initial_bird: initial bird mass, when availabe for sample, grams * final_bird: final bird mass, when availabe for sample, gram * initial_bird_mean: mean mass for species at that trial concentration ## Code/software Most files are .csv and can be read in Excel or R. Code to analyze data can be found here: [https://github.com/eltingrosalee/FE_dilute_nectar_ecophys_public](https://github.com/eltingrosalee/FE_dilute_nectar_ecophys_public)