Return to flip book view

Rufous Hummingbird: State of the Science and Conservation

Page 1

©VJAndersonSTATE OF THE SCIENCE AND CONSERVATIONRUFOUS HUMMINGBIRDWorld Migratory Bird Day

Page 2

3©Carlos PachecoSuggested CitationGillespie CR, Contreras-Martínez S, Bishop CA, Alexander JD. 2020. State of the Rufous Hummingbird science and conservation. Western Hummingbird Partnership, Boulder, CO. Caitlyn R Gillespie, Klamath Bird ObservatorySarahy Contreras-Martínez, Universidad de Guadalajara-CUCSUR Autlán de NavarroChristine A Bishop, Environment and Climate Change CanadaJohn D Alexander, Klamath Bird ObservatoryDocument design by Chu-Yu LinAuthor Ailiations

Page 3

4TABLE OF CONTENTS©bryanhansonRUFOUS HUMMINGBIRD: STATE OF THE SCIENCE AND CONSERVATIONSOCIAL BEHAVIOR, PHYSIOLOGY, AND MORPHOLOGYHABITAT USE DURING BREEDING AND POST-BREEDING MIGRATIONSPRING AND WINTER HABITAT USEDISTURBANCE AND FIREFOOD RESOURCES AND POLLINATIONCLIMATE CHANGE AND PHENOLOGYAGRICULTURAL PRACTICES, LAND USE, AND INVASIVE SPECIESTHREATS AND FULL LIFE CYCLE CONSERVATION" NO REGRETS" CONSERVATION ACTIONSREFERENCES6 10131415161820222324ACKNOWLEDGEMENTS This project was a collaborative eort of the Western Hummingbird Partnership and funded by US Forest Service International Programs. Contributing Partners represent the North American range of the Rufous Hummingbird, including University of Guadalajara – CUCSUR in Mexico, Klamath Bird Observatory, Environment for the Americas, US Forest Service, Bureau of Land Management, and Point Blue Conservation Science in the United States, and Environment and Climate Change Canada in Canada. This document was improved by reviews from Greg Butcher (US Forest Service) and Susan Bonfield (Environment for the Americas). Layout coordination and design was provided by Chu-Yu Lin (Environment for the Americas). Photographs were contributed by Jim Livaudais, Sarahy Contreras-Martínez, Gordon Leggett, Bryan Hanson, Ugo Mendes Donelli, Zefe Wu, Chu-Yu Lin, Jonathan Moran, Carlos Pacheco, Peter Neilsen, J Becky Matsubara, Larry Jordon, Avia5, and VJ Anderson.We recognize and acknowledge that the Rufous Hummingbird migrates and breeds within the traditional territories of many indigenous peoples throughout this species range.

Page 4


Page 5

6Why a Review?Rufous Hummingbirds are a charismatic and remarkable migratory bird, and through their role as pollinators they provide important ecological services across their range in Canada, the United States, and Mexico. There is a great opportunity for concerned communities, bird lovers, and conservation scientists to rally together to develop a full life cycle conservation strategy to protect this long-distance migrant throughout its entire range. This strategy should include the ranking of threats, the prioritization and implementation of conservation strategies and actions, and coordinated eorts to fill information gaps, monitor population trends and demographics, and measure the eectiveness of our conservation eorts.In this Review• Identification• Social Behavior, Physiology, and Morphology• Annual Migratory Cycle• Habitat Use• Disturbance and Fire• Food Resources and Pollination• Climate Change and Phenology• Agricultural Practices, Land Use, and Invasive Species • Summary of Threats and Information Gaps• “No Regrets” Conservation Actions• References • We review information about behavior, ecology, habitat needs, and threats throughout its geographic range, including non-breeding areas in Mexico and southeastern United States, breeding grounds in the Pacific Northwest, and the migratory stopover sites in between. • This document is intended to inform tri-national conservation planning and implementation for this species, through which information needs, threats, and conservation opportunities and strategies will be prioritized for action. • We identify important information gaps along with threats and key conservation opportunities throughout the full life cycle of Rufous Hummingbirds.This report summarizes the best available information about the biology and conservation of Rufous Hummingbirds (Selasphorus rufus)©Jim LivaudaisRUFOUS HUMMINGBIRD: STATE OF THE SCIENCE AND CONSERVATION

Page 6

7www.mbr-pwrc.usgs.govPercent Change per YearLess than -1.5-1.5 to -0.25>-0.25 to 0.25>0.25 to +1.5Greater than +1.5While still commonly observed throughout their range, Rufous Hummingbird populations are recognized as an at-risk species.1 Annual Breeding Bird Survey data indicate that their populations have declined by as much as 60% since 1974.1 While the causes of past declines are unclear, recent research indicates that accelerated climate change could result in extensive range loss in the United States.2 As a long-distance migrant, Rufous Hummingbirds require high quality habitat across a large geographic area for breeding, migratory stopovers, and wintering. Threats that may be factors in their population decline include the impacts of climate change on food and habitat resources, loss of natural and traditional fire regimes, and pesticide exposure. Because Rufous Hummingbirds likely encounter each of these threats repeatedly throughout their annual life cycle, more information is required to understand how and to what extent threats and stressors aect Rufous Hummingbirds in dierent geographic areas. Addressing these threats to Rufous Hummingbirds, like many other migratory species, is limited by information gaps about their breeding, migration, and wintering ecology. Details about their migration and wintering areas are especially limited. Given its rapid population decline, our eorts to determine the best approaches to coordinated research and population monitoring must accelerate and involve conservation scientists, bird lovers, and concerned communities that can provide an important voice to help advance the conservation of this species. RUFOUS HUMMINGBIRD: STATE OF THE SCIENCE AND CONSERVATIONBreeding Bird Survey Trend Map, 1966 - 201360% decrease since 1974The Breeding Bird Survey (BBS) is a large-scale avian monitoring program that gathers data about North American breeding bird population trends. Results from BBS data analyses show that Rufous Hummingbirds are suering population declines throughout much of their breeding range.

Page 7

8Conservation Status The Rufous Hummingbird is identified as a species of continental concern on the North American Watch List.3 It also appears on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species as Near Threatened.4 IdentificationRufous Hummingbirds are among the smallest hummingbirds in the world, only 9-10 cm in length5 with a body mass of about 3.5 grams – that’s less than a nickel!6 Named for their distinctive coloration, male Rufous often have a solid rufous back, but many individuals have green back feathers and a few (especially young ones) are more than half green. Their crown is bright green, while cheeks and eyebrows and flanks are rufous. The adult male has a striking red gorget. The adult females are bright green above and white below, however they still have strongly washed rufous on sides, flanks, and undertail coverts to the edges of the rump. The face and sides of the female’s gorget are washed rufous. The female gorget is creamy white but can be heavily spangled with green to bronze to iridescent red feathers, which can vary from a few feathers to a small triangle or diamond. Adult Male Rufous Hummingbird©Avia5rufous back but may have some flecks of greenrufous tail with black tipsrufous superciliumrufous bellybrilliant red to orange gorgetwhite breastgreen backrufous wash on flanksgreen crownwhite throat heavily spangled in dark spots ; can have a few to ~20-25 iridescent feathers©Larry Jordanwhite tips on the outer three retrices of tailbu-rust chestAdult Female Rufous HummingbirdCorrect identification of Selasphorus hummingbirds requires knowledge of details in coloration and tail shape. ©Chu-Yu

Page 8

9Young or female Rufous Hummingbirds are diicult to identify and can be confused with similar species such as Allen’s Hummingbird (Selasphorus sasin).Allen’s Hummingbird©JBecky MatsubaraDistribution and population data for the Rufous Hummingbird can be complicated by incorrect identification of Rufous females and young, which can closely resemble similar hummingbird species. The immature Rufous males and females resemble adult females however the gorget on males is heavily striped and can have a few iridescent markings. Key morphological features that distinguish Rufous from Allen’s hummingbird (Selasphorus sasin) include the second tail feather on Rufous males that is distinctly notched on the inner web near its tip; this feature is less noticeable but also present on female Rufous, but not present on Allen’s. The male’s steep oval or J-shaped courtship display and courtship sounds the Rufous males make are also distinctly dierent than Allen’s.7,8 There is hybridization where the breeding ranges of these two species overlap near the California-Oregon border.9 © VJAnderson© VJAnderson© HarmonyonPlanetEarth© HarmonyonPlanetEarthImmature MaleImmature FemaleAdult FemaleAdult Male

Page 9

10Rufous Hummingbirds are highly territorial at breeding, migratory stopover, and non-breeding sites. Male Rufous Hummingbirds arrive on the breeding grounds before females where they establish territories and perform flight displays.10 When females arrive they choose nest sites, not necessarily within male flight display territories.10 Females exclusively build nests, incubate, and feed nestlings and fledglings. Nests may be reused from year to year. Females may cluster their nests in concentrations of up to 20 within a small area.11,12 Males copulate with multiple females if they can and then leave breeding territories; they may remain nearby for the season or move from coastal locations to interior or higher elevation locations where they may establish new breeding territories.13 Recapture rates of the Rufous Hummingbird reveal that they can live for at least five years, with annual survival around 60%.14Annual survival rate around60%e oldest recorded Rufous Hummingbird was nearly nine years old when she was recaptured and rereleased during banding operations in British Columbia. 8SOCIAL BEHAVIOR, PHYSIOLOGY, AND MORPHOLOGY©Peter Neilsen40% of adults don’t survive from one year to the next

Page 10

11TorporHummingbirds seem to compensate for high elevations and low temperatures by increasing net energy intake, likely through one or more behavioral modifications.15 For example, Rufous Hummingbirds conserve energy overnight by placing their bodies in a state of torpor (low-energy use, short-term hibernation).16 Torpor allows them to counteract for their small body size and energy loss in colder and sometimes oxygen-poor (i.e., high-elevation) environments.16–18 Information GapsMore data is needed to understand how hummingbird morphology, physiology, and social behavior will influence their ability to adapt to climate change and other stressors. For example, are drying conditions changing nectar volumes and/or shifting ranges of high-elevation nectar resources and impacting hummingbird populations? How will the unique behavioral and physiological characteristics that allow Rufous Hummingbirds to breed in northern latitudes and persist in high elevations adapt to a changing climate and multiple stressors at the same time? ©Jim LivaudaisWing morphologyHummingbirds often hover in flight, a behavior that is energetically demanding. Smaller wing sizes allow for some of the territorial flight displays of male Rufous Hummingbirds; female Rufous have slightly larger wing sizes than males.19

Page 11

12Rufous Hummingbirds breed in coastal southeastern Alaska south through southwestern Yukon, British Columbia, southwestern Alberta, Washington, northern and central Idaho, western Montana, Oregon, and extreme northwestern California.5 During southward migration, they stopover in both the Pacific and Rocky Mountain flyways. Males depart for southward migration initially and generally follow a narrow path through the Rocky Mountains. Within 1 to 2 weeks females then depart and follow a broader southward route that includes the Rockies and mountain ranges farther west. Thereafter, juveniles migrate along the same route as females but a greater number move south along the eastern Sierra Nevada mountain range and even further west in California.20 They spend the non-breeding season in coastal southern California and Gulf Coast south to south central Mexico5,21 and more recently east along the northern coast of the Gulf of Mexico. Adult males initiate spring migration earlier than females5 and mainly follow the Pacific flyway through California northward.21©Carlos PachecoAnnual Migratory Cycle – An elliptical migrationRufous Hummingbirds migrate north in spring along the Pacific Coast to breeding sites in the northwestern United States, Canada, and Alaska. Their return migration in late summer and early fall follows the Rocky Mountains before reaching Mexico.66Breeding seasonNon-Breeding seasonPre-breeding migratory seasonPost-breeding migratory seasonRecaptures also show that some individuals may migrate from breeding sites in the northwest to wintering areas in the southeastern United States, including Florida and Alabama.67

Page 12

13Rufous Hummingbirds breed in second-growth forests and forest openings, as well as in mature forests, riparian areas, parks, fields, meadows, and other open areas. In western Oregon, nests were found in second growth forests from 16 to 120 years old.22 Females build well-concealed nests in low branches of trees and shrubs; nests are made of spider-webs and camouflaged with lichen. Rufous Hummingbirds produce 1-2 broods per year and will return to nest sites and even re-use nests in following years.11During post-breeding migration, Rufous Hummingbirds use high-elevation alpine meadows, where late-blooming nectar-producing flowers are abundant.23 Hummingbirds will use a large diversity of flowers including many that are not tubular or red.24 Hummingbirds can visit four to five thousand flowers a day.24 Both males and females defend territories during southward migration; territory sizes vary widely and are adjusted daily to maximize weight gain from nectar-producing flowers. Male territories tend to be smaller and have denser flower availability, while female territories can be larger.19 During the winter, Rufous Hummingbirds primarily occur in Mexican pine and pine-oak forests as well as high mountain meadows. They are one of the most abundant pine-oak specialists across their wintering range, regularly occurring with other hummingbirds including Mexican Violetear (Colibri thalassinus), Rivoli's Hummingbird (Eugenes fulgens), Amethyst-throated Mountain-gem (Lampornis amethystinus), Bumblebee Hummingbird (Atthis heloisa), Broad-tailed Hummingbird (Selasphorus platycercus), Calliope Hummingbird (Selasphorus calliope), Berylline Hummingbird (Amazilia beryllina), and White-eared Hummingbird (Hylocharis leucotis). Annual population modeling and full life cycle conservationLike many migrants, stressors that impact hummingbird populations at one part of their range likely have cascading eects throughout their annual migratory cycle. For example, limited food availability during spring migration may delay spring breeding arrival or cause individuals to arrive in poor condition, making it diicult to establish high-quality territories that can support successful breeding.12 Given their high metabolism, Rufous Hummingbirds likely need abundant, reliable and pesticide-free food resources to meet the energy demands of their long migrations. A full life cycle approach to conservation of Rufous Hummingbirds must take into account threats and opportunities throughout the annual migratory cycle and at multiple geographic locations. Full life cycle analyses are needed to reveal seasonal population limitation for the species and allow for more focused conservation actions.Visit 4000 - 5000 flowers a dayHABITAT USE DURING BREEDING AND POST-BREEDING MIGRATION

Page 13

14During winter, females and juveniles are more common at higher elevations, based on capture data at sites 1900-3100m in Western Mexico, while adult male Rufous Hummingbirds appear to be more common at lower elevations.25 Human land-use often varies greatly by elevation, thus creating dierent survival challenges. Hummingbirds from dierent breeding subpopulations, in particular coastal versus interior, select distinct sites during the non-breeding season in Mexico.21 Evidence from isotope analysis suggests that females from coastal breeding populations winter at higher elevations than males; but similar isotope dierences were not observed for interior populations. Relative abundance changes over time during the winter. The magnitude of this change can depend on the successional stage of forests and the abundance of flowering plants. Adults molt from December to February while juveniles begin to molt shortly after arrival on wintering grounds and can extend molting into spring migration.5 Molt is energy-expensive, and molting season can be a diicult time for birds.During spring migration, Rufous Hummingbirds commonly use riparian habitats and low altitudes where flowers bloom first in spring. Both male and female individuals establish and defend distinct territories around flowering plants.26 Females can outnumber males at some spring migration stopover sites on the central coast of California.27 Rufous Hummingbirds seem to arrive in Alaska before flowers bloom and are seen at sapsucker wells.68Do Rufous Hummingbirds move among sites during the non-breeding season, and if so why and how far do they move? More information is needed on the sex- and age-specific movement and distribution patterns during late fall, winter, and early spring. How do these movements aect survival? Detailed information about migratory connectivity is also needed. For example, do individuals that winter in dierent areas of Mexico come from distinct breeding areas in Alaska and western USA? Are there dierences in the relative abundance, survival, or reproductive success that vary with successional state of forested habitat?SPRING AND WINTER HABITAT USEInformation Gaps©Chu-Yu

Page 14

15While Rufous Hummingbirds nest in both second-growth forests and older mature forest, post-disturbance mid- to early-successional habitats are important for breeding Rufous Hummingbirds. Post-fire habitats provide stopover habitat for Rufous Hummingbirds in the Sierra Nevada during their post-breeding migration; high numbers of migrating individuals have been observed when wildflowers are abundant following wildfire events.29 In the northern Rocky Mountains, studies demonstrate the importance of post-fire habitat for a number of bird species, including hummingbirds.30,31 It is also possible that increasing fire frequency and intensity, as well as timing of fire, have had negative eects on Rufous Hummingbird habitat and hence their populations. Reduced overall habitat availability at the landscape scale not only reduces resource availability for migratory bird species but can alter stopover habitat use. During winter in Western Mexico, Rufous Hummingbirds utilize plants that regenerate post-fire, such as sage (including Salvia iodantha and S. mexicana).32 Fires maintain plant species diversity in pine and pine-oak forests.33 Recently disturbed or burned habitat is important to Rufous Hummingbirds, as is a mosaic of dierent successional stages that primarily result from low-severity fires that occur every 11 to 30 years.33 Small areas (<3 hectares) aected by high severity fire that are surrounded by later successional forests are also important.34DISTURBANCE AND FIREInformation GapsHow do herbicide treatments specifically influence hummingbird populations? How does fire frequency, intensity, and timing influence Rufous Hummingbird habitat use and survival throughout their range? How have changes in land use and habitat loss on the breeding grounds, during stopover, and/or on the wintering grounds influenced Rufous Hummingbird declines?Because post-disturbance forest habitats are important for breeding Rufous Hummingbirds, fire management that suppresses fires, or changes fire cycles to occur more often and at higher intensity, may limit the availability of early-successional post-fire habitat. Fire Management Rufous Hummingbirds are abundant in timber stands immediately following harvest when floral resources are able to flourish. Their abundance can increase immediately after prescribed fire or logging,35,36 but removal of understory and shrub vegetation from these habitats may limit nesting and foraging habitat. The use of herbicides to remove deciduous understory to allow for ‘conifer release’ reduces the availability of wildflowers in forests, Mixed-successional forest across landscapes may also be beneficial for hummingbirds.Timber Management ©Sarahy Contreras

Page 15

16NectarRufous Hummingbirds feed on nectar from a variety of plant species and move in correlation with floral phenology throughout their range. In breeding and migratory stopover areas, typical flower species in their diet includes red tubular species such as red columbine (Aquilegia formosa), scarlet gilia (Ipomopsis aggregate), bearded tongues (Penstemon spp.), and paintbrushes (Castilleja spp.). They will also drink nectar from a variety of other flowers including sage (Salvia spp.), bouvardia (Bouvardia ternifolia), mint (Stachys coccinea), lilies (Erythronium grandiflorum, Lilium columbianum), purple larkspur (Delphinium barbeyi and D. geranioides), heath (Vaccinium ovatum, Menziesia ferruginea), currant (Ribes sanguineum), salmonberry (Rubus spectabilis), honeysuckle (Lonicera spp.), fireweed (Epilobium angustifolium), horsemint (Monarda menthifolia), toad-flax (Linaria vulgaris), snapdragon (Scrophularia montana), and bee-flower (Cleome serrulata).10,28,37–41 In Mexico, presence of Rufous Hummingbird coincides with the flowering peak coincides with peak flowering of the plant genera Salvia, Lobelia, Calliandra, Ipomea, and Senecio.25,32,42,43 ©Jonathan MoranFOOD RESOURCES AND POLLINATION

Page 16

17Habitat and resource selectionHow do Rufous Hummingbirds find flowers? While Rufous Hummingbirds return to known food sources, nectar from many dierent plant species is a less predictable yet important food resource. Rufous Hummingbirds use memory of previous foraging locations to find food sources more eiciently.48 Rufous Hummingbirds also rely on visual cues to find food sources.49 Large patches of blooming flowers are necessary to sustain Rufous hummingbird territories. Individuals maximize energy intake and may make daily adjustments to defend territory size.23 When flower numbers are reduced or destroyed by natural events, such as storms, Rufous Hummingbirds appear to leave the immediate area rather than settle into smaller or lower-quality territories.50While it is likely that hummingbirds act as pollinators on the wintering grounds, more research is needed to understand this important ecological role.25 In the spring, Rufous Hummingbirds act as pollinators for early blooming nectar-producing plants.44InsectsInsects such as gnats and aphids are consumed by Rufous Hummingbirds on their breeding grounds and throughout their life cycle but are particularly important as a food source for growing chicks.45 Insects also provide protein, an essential nutrient not found in nectar and needed for feather growth during molt.Other food resourcesWhile nectar-producing flowers are clearly an important food source, other sources are important in the diet of Rufous Hummingbirds. Early spring migrants may supplement their nectar-based diet with alternate food sources; some will feed on sap from sapsucker wells as a source of sugar.46 Calcium, an important nutrient for breeding females, does not occur naturally in nectar; calcium deposits from ash or soil near nest sites serve as a necessary mineral supplement47 and insects may also be a source of minerals.FOOD RESOURCES AND POLLINATION©Chu-Yu

Page 17

18CLIMATE CHANGE AND PHENOLOGYSouthward migrationWarming temperatures and reduced snowpack in montane meadows have resulted in earlier flowering phenology in some plant species. Montane meadows in the Rocky Mountains have seen a reduction in mid-summer (July-August) flower abundance, which may aect pollinators including hummingbirds.55 Non-breeding/winteringIn Mexico, Rufous Hummingbirds undergo a complete molt on their wintering grounds,56an important and energetically taxing life-history event. Changes in the peak flowering phenology of hummingbird-associated plant species or declines in insect populations during this time could threaten Rufous Hummingbirds. Northward migrationDuring northward migration, early spring migrants may compete for limited resources that are aected by climate change and related phenology shifts in the flowering of nectar-producing plants. BreedingSpring arrival of Rufous Hummingbirds in the northern parts of their breeding range have shifted earlier in the last 10 years.53 Breeding success will likely depend on corresponding shifts in local floral and insect phenology, although research is still needed to quantify potential mismatches in local resource phenology across the breeding ranges. Declines in insect populations,54 in addition to climate-related shifts in phenology, have the potential to impact food sources for chicks. Rufous Hummingbird migration is closely timed with floral phenology; however, it is possible that shifts in local resource phenology may now be out of sync due to shifts in timing of migration as a result of accelerated climate change. Flowering phenology across habitats and elevations may be aected dierently by climate change in local temperature and precipitation regimes. Changes in the availability of resources could alter hummingbird habitat selection and migratory stopover behavior.51 Uneven changes in resource availability across geographies may impact Rufous Hummingbird survival at multiple times throughout the full life cycle and contribute to population declines.52 ©Sarahy Contreras

Page 18

19Information GapsWhile climate-related changes in habitat, resource, and migration phenology have the potential to impact Rufous Hummingbird populations, more research that builds on existing climate and bird conservation science is needed.2 Future warming will require many species to shift to northern latitudes or to higher elevations, but are there physiological constraints on Rufous Hummingbirds that would prevent similar range shifts? Climate change may produce long-term drought in current areas important to Rufous Hummingbirds, which may increase fire severity. Where is drought predicted, and how might this aect Rufous Hummingbirds? Climate-smart natural resource management that takes into account projections of future climate change scenarios may help mitigate some potential impacts of climate change on hummingbird populations. For example, landscape-level conservation planning may be able to prioritize forest management for hummingbirds within their expected range under future climate change scenarios.CLIMATE CHANGE AND PHENOLOGYPhenology describes the timing of events in nature, such as the flowering of plants or the arrival of migrants. The natural cycles of events rely on cues such as day length or temperature. Because climate change may aect the cues in dierent ways, a “mismatch” of timing of events that were historically aligned can occur. When this happens, migrants may arrive “too late for dinner” if nectar producing plants flower earlier than normal. For example, plants are now blooming earlier than the arrival of Broad-tailed Hummingbirds (Selasphorus platycercus) in the northern part of their breeding range.30©Sarahy Contreras

Page 19

20PesticidesThe eects of herbicide and insecticide use on Rufous Hummingbirds and the habitats and nectar-producing plants they rely on is an important and growing area of research. Exposure to widely-used systemic insecticides occurs in Rufous Hummingbirds.5 7, 5 8 ,65 Neonicotinoids from nectar or pollen have been known to aect pollinating insects59 and may represent a threat to birds as well.60 Pesticide exposure may have direct health eects on hummingbirds, similar to eects described in songbirds,61 but may also have indirect eects on hummingbirds by diminishing their food resources throughout their range. AGRICULTURAL PRACTICES, LAND USE, AND INVASIVE SPECIESGrazing and Agricultural PracticesLoss of wildflower resources in forested habitats due to ungulate grazing remains unquantified. Overgrazing by ungulates removes many floral resources, but some may persist if not preferred by the grazers. Thus, the extent to which grazing reduces food for hummingbirds on a landscape scale is unknown. The conversion of native meadows and openings to non-native grasses, which reduces forbs and nectar-producing plants, may also reduce the availability of floral resources. ©zefe wu©Ugo Mendes Donelli

Page 20

21Information GapsHow does habitat alteration from agricultural development, cattle grazing, and pesticide use aect Rufous Hummingbirds throughout their range?25Invasive SpeciesInvasive plants, especially grasses, outcompete native flowering plants in alpine meadows throughout the southward migratory route of Rufous Hummingbirds, potentially reducing food availability during energetically demanding migration at high altitudes.62 Invasive plant species that outcompete native wildflowers may have incorrectly timed phenology patterns for migrating hummingbirds. For example, the invasive Himalayan blackberry (Rubus armeniacus) outcompetes Salmonberry (Rubus spectabilis) in riparian habitats. Salmonberry is native and blooms in early spring throughout its range and is a typical Rufous Hummingbird food source in migration. Himalayan blackberry blooms later in the spring,63 after Rufous Hummingbirds have arrived on breeding grounds. DevelopmentRural and urban development removes native wildflowers. While Rufous Hummingbirds will utilize gardens and feeders during migration, those resources expose hummingbirds to other threats such as predation from cats and window collisions.5 With increased availability of land cover data, it may be possible to determine if changes in land use can account for the observed declines in Rufous Hummingbirds over the past 50 years. This information may be useful in quantifying hummingbird pesticide exposure by mapping changes in agricultural types and acreages across the range of Rufous Hummingbirds.©Gordon.Leggett.2018©Bryan Hanson

Page 21

22The Rufous Hummingbird is a long-distant migrant with declining populations. While still common in some parts of its range, breeding bird survey data suggest that there are 60% fewer Rufous Hummingbirds now than there were in the early 1970s. If this trend continues we may lose another 50% of the population by 2050.1 As a result, this species is widely recognized as an at-risk species. Like many migratory birds, Rufous Hummingbirds face threats throughout their full life cycle – they face threats on their wintering grounds in Mexico, on their breeding grounds in northwestern North America, and at stopover sites that they depend on as they make their spring and fall migrations. Climate change could impact key elements of their life history and food resources as increased temperatures, drought, fire-changed habitats, and phenological mismatches occur between flowers and birds. Lack of natural and traditional fire regimes, invasive species, overgrazing, forestry practices, and pesticides all contribute to loss of floral resources and habitat. These stressors can impact all species of hummingbirds; but because Rufous Hummingbirds migrate the furthest among all species of hummingbirds, they may be especially vulnerable to changes that occur in multiple geographic locations throughout their life cycle. They may be a useful umbrella species for other western hummingbirds and for other western pollinators, and thus the Western Hummingbird Partnership ( has prioritized the study of Rufous Hummingbird.An important next step in developing a full-life-cycle conservation strategy for western hummingbirds is to conduct an assessment of threats on the Rufous Hummingbird specifically. A broader threats assessment for migratory and resident western forest birds identified unsustainable agricultural expansion and practices, unsustainable livestock farming/ranching expansion and practices, unsustainable logging and wood harvesting, disruption of natural disturbance regimes, water management and altered hydrology, and inadequate forest restoration as the most significant threats.64 Which of these are the most significant threats to the Rufous Hummingbird, and are there important threats not included in this list? Despite population declines and apparent threats, we still lack critical information about Rufous Hummingbirds that will be needed to address these conservation issues. Information gaps about their breeding, migration, and wintering ecology remain broad and more information about their migration and wintering area habitat preferences is especially needed. Research on the eects of climate change and pesticide use, as detailed above, will also fill critical information gaps. Better information on survival and reproductive rates (and factors that aect these rates) will contribute important quantitative information.THREATS AND FULL LIFE CYCLE CONSERVATIONWinter RangeBreeding RangeBREEDING (April - July)MIGRATION (July - October)WINTERING (October - March)MIGRATION (March - May)

Page 22

23While we continue to improve our knowledge of these species, we need to undertake conservation now because Rufous Hummingbirds - along with other pollinators – are already declining. We know that all pollinators are completely dependent on flower availability throughout the year. We also know that many changes over the past 50 years have diminished the availability of flowers. Thus, the Western Hummingbird Partnership is focused on increasing flower abundance and diversity throughout the ranges of these hummingbird species. Native, locally adapted flowers are important for pollinators, and conservation eorts should focus on increasing the abundance and diversity of native plants whenever possible. Such conservation action must use climate-smart approaches that consider ongoing range shifts in flowering plants. Science-driven conservation works – there are many examples that demonstrate how at-risk species can be recovered when our society chooses to invest in their conservation. With this State of the Rufous Hummingbird Science and Conservation review we sound a call to action for the full-life-cycle conservation of western hummingbirds using the Rufous Hummingbird as the lead example." NO REGRETS" CONSERVATION ACTIONS©Sarahy Contreras

Page 23

241. Rosenberg, K. V. et al. Partners in Flight landbird conservation plan: 2016 revision for Canada and continental United States. (Partners in Flight Science Committee, 2016).2. Rufous Hummingbird. The Audubon Birds & Climate Change Report (2014).3. North American Bird Conservation Initiative (NABCI). The state of North America’s birds 2016. (2016).4. Rufous Hummingbird (Selasphorus rufus) - BirdLife species factsheet. Williamson, S. A Field Guide to Hummingbirds of North America. (Houghton Mifflin Harcourt, 2001).6. Dunning, J. B. Rufous Hummingbird. in CRC Handbook of Avian Body Masses 118 (CRC Press.).7. Allen’s Hummingbird Sounds, All About Birds, Cornell Lab of Ornithology. Rufous Hummingbird Life History, All About Birds, Cornell Lab of Ornithology. Myers, B. M., Rankin, D. T., Burns, K. J. & Clark, C. J. Behavioral and morphological evidence of an Allen’s × Rufous hummingbird (Selasphorus sasin × S. rufus) hybrid zone in southern Oregon and northern California. Auk 136, (2019).10. Calder, W. A. Rufous Hummingbird (Selasphorus rufus). Birds N. Am. (1993) doi:10.2173/bna.53.11. Bent, A. C. Life histories of North American cuckoos, goatsuckers, hummingbirds, and their allies. (1940).12. Baicich, P. J. & Harrison, C. J. O. A Guide to the Nests, Eggs and Nestlings of North American Birds. (1997).13. Johnsgard, P. A. The Hummingbirds of North America. (Smithsonian Institution Scholarly Press, 1997).14. Ruiz-Gutiérrez, V. et al. Survival of Resident Neotropical Birds: Considerations for Sampling and Analysis Based on 20 Years of Bird-Banding Efforts in Mexico. tauk 129, 500–510 (2012).15. Welch, Kenneth C. & Suarez, R. K. Altitude and temperature effects on the energetic cost of hover-feeding in migratory rufous hummingbirds, Selasphorus rufus. Can. J. Zool. 86, 161–169 (2008).16. Hiebert, S. M. Energy Costs and Temporal Organization of Torpor in the Rufous Hummingbird (Selasphorus rufus). Physiological Zoology 63, 1082–1097 (1990).17. Carpenter, F. L., Hixon, M. A., Beuchat, C. A., Russell, R. W. & Paton, D. C. Biphasic Mass Gain in Migrant Hummingbirds: Body Composition Changes, Torpor, and Ecological Significance. Ecology 74, 1173–1182 (1993).18. Hiebert, S. Seasonal Changes in Body Mass and Use of Torpor in a Migratory Hummingbird. The Auk 110, 787–797 (1993).19. Kodric-Brown, A. & Brown, J. H. Influence of Economics, Interspecific Competition, and Sexual Dimorphism on Territoriality of Migrant Rufous Hummingbirds. Ecology 59, 285 (1978).20. Rousseau, J. S., Alexander, J. D. & Betts, M. G. Using continental-scale bird banding data to estimate migratory demographic patterns for Rufous Hummingbird (Selasphorus rufus). Avian Conservation and Ecology (In Press).21. Moran, J. A. et al. An exploration of migratory connectivity of the Rufous Hummingbird (Selasphorus rufus), using feather deuterium. J Ornithol 154, 423–430 (2013).22. Meslow, E. C. & Wight, H. M. Avifauna and succession in Douglas-fir forests of the Pacific Northwest. in Proceedings of the symposium on management of forests and range habitats for nongame birds 266–271 (1975).23. Gass, C. L. Territory regulation, tenure, and migration in rufous hummingbirds. Can. J. Zool. 57, 914–923 (1979).REFERENCES

Page 24

2524. Waser, N. M., CaraDonna, P. J. & Price, M. V. Atypical Flowers Can Be as Profitable as Typical Hummingbird Flowers. Am. Nat. 192, 644–653 (2018).25. Schondube, J. E., Contreras-Martínez, S., Ruan-Tejeda, W., Calder, W. & Santana, E. Migratory patterns of rufous hummingbirds in West México. in Conserving migratory pollinators and nectar corridors in Western North America (ed. Nabhan, G. P.) (Arizona- Sonora Desert Museum, The University of Arizona Press, 2004).26. Cody, M. L. Interspecific territoriality among hummingbird species. Condor 70, 270–271 (1968).27. Howell, S. N. G. & Gardali, T. Phenology, sex ratios, and population trends of Selasphorus hummingbirds in central coastal California. Journal of Field Ornithologists 74, 17–25 (2003).28. Maintaining and Improving Habitat for Hummingbirds in Alaska - A Land Manager’s Guide. 16 (2016).29. Burnett, R. D. Personal communication with Ryan Burnett, Director, Sierra Nevada Group, PRBO Conservation Science. (2012).30. Hutto, R. L., Bond, M. L. & DellaSala, D. A. Chapter 3 - Using Bird Ecology to Learn About the Benefits of Severe Fire. in The Ecological Importance of Mixed-Severity Fires (eds. DellaSala, D. A. & Hanson, C. T.) 55–88 (Elsevier, 2015). doi:10.1016/ B978-0-12-802749-3.00003-7.31. Alexander, J. D., Williams, E. J., Gillespie, C. R., Contreras-Martínez, S. & Finch, D. M. Effects of restoration and fire on habitats and populations of western hummingbirds: A literature review. Gen. Tech. Rep. RMRS-GTR-408. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 408, 64 (2020).32. Arizmendi, M. C. Multiple ecological interactions: nectar robbers and hummingbirds in a highland forest in Mexico. Canada Journal of Zoology 79, 997–1006 (2001).33. Jardel-Pelaez, E. J., Asbjornsen, H., Contreras-Martínez, S., Rodríguez-Trejo, D. A. & Santana, E. Efectos del fuego sobre la biodiversidad en ecosistemas forestales. in Capital Natural de México. Vol. II. Estado de conservación y tendencias de cambio (Comisión Nacional para el Conocimiento y Uso de la Biodiversidad., 2009).34. Contreras-Martinez, S. Personal Communication, August, 2020. 35. Morrison, M. L. & Meslow, E. C. Bird community structure on early-growth clearcuts in western Oregon. American Midland Naturalist 110, 129–137 (1983).36. Bettinger, K. A. Bird Communities in 5- to 34-year-old managed Douglas-fir stands on the Willamette National Forest, Oregon cascades. (Oregon State University, 1996).37. Maintaining and Improving Habitat for Hummingbirds in California - A Land Manager’s Guide. 26 (2017).38. Maintaining and Improving Habitat for Hummingbirds in Colorado, Wyoming and South Dakota - A Land Manager’s Guide. 24.39. Maintaining and Improving Habitat for Hummingbirds in Idaho, Montana, and North Dakota - A Land Manager’s Guide. 26.40. Maintaining and Improving Habitat for Hummingbirds in Oregon and Washington - A Land Manager’s Guide. 24 (2014).41. Maintaining and Improving Habitat for Hummingbirds in Nevada and Utah - A Land Manager’s Guide. 24.42. Ornelas, J. & Arizmendi, M. Altitudinal Migration: Implications for conservation of avian Neotropical migrants in western Mexico. Conservation of Neotropical Migratory Birds in Mexico. Maine Agricultural and Forest Experiment Station. Miscellaneous Publications 727 (1995).43. Contreras-Martínez, S. Dinámica espacio-temporal de colibríes (Trochilidae), en bosques de pino-encino post-incendio en la Reserva de la Biosfera Sierra de Manantlán, Jalisco, México. (Ciencias en Biosistemática, Ecología y Manejo de Recursos Naturales y Agrícolas. Departamento de Ecología y Recursos Naturales. Universidad de Guadalajara-CUCSUR, 2015).44. Grant, V. & Temeles, E. J. Foraging ability of rufous hummingbirds on hummingbird flowers and hawkmoth flowers. PNAS 89, 9400–9404 (1992).45. Moran, A. J., Prosser, S. W. J. & Moran, J. A. DNA metabarcoding allows non-invasive identification of arthropod prey provisioned to nestling Rufous hummingbirds (Selasphorus rufus). PeerJ 7, e6596 (2019).46. Sutherland, G. D., Gass, C. L., Thompson, P. A. & Lertzman, K. P. Feeding territoriality in migrant rufous hummingbirds: defense of yellow-bellied sapsucker (Sphyrapicus varius) feeding sites. Can. J. Zool. 60, 2046–2050 (1982).47. Adam, M. D. & Lauriers, J. R. des. Observations of Hummingbirds Ingesting Mineral-Rich Compounds (Observaciones sobre

Page 25

26 Zumbadores Ingiriendo Compuestos Altos en Minerales). Journal of Field Ornithology 69, 257–261 (1998).48. Henderson, J., Hurly, T. A. & Healy, S. D. Rufous hummingbirds’ memory for flower location. Animal Behaviour 61, 981–986(2001).49. Hurly, T. A., Franz, S. & Healy, S. D. Do Rufous Hummingbirds ( Selasphorus rufus) use visual beacons? Animal Cognition 13, 377–384 (2010).50. Gass, C. L. & Lertzman, K. P. Capricious mountain weather: a driving variable in hummingbird territorial dynamics. Can. J. Zool. 58, 1964–1968 (1980).51. McGrath, L. J., Van Riper III, C. & Fontaine, J. J. Flower power: tree flowering phenology as a settlement cue for migrating birds. Journal of Animal Ecology 78, 22–30 (2009).52. Jones, T. & Cresswell, W. The phenology mismatch hypothesis: are declines of migrant birds linked to uneven global climate change? Journal of Animal Ecology 79, 98–108 (2010).53. Courter, J. R. Changes In Spring Arrival Dates of Rufous Hummingbirds (Selasphorus rufus) In Western North America In the Past Century. The Wilson Journal of Ornithology 129, 535–544 (2017).54. Wagner, D. L. Insect Declines in the Anthropocene. Annu. Rev. Entomol. 65, 457–480 (2020).55. Aldridge, G., Inouye, D. W., Forrest, J. R. K., Barr, W. A. & Miller‐Rushing, A. J. Emergence of a mid-season period of low floral resources in a montane meadow ecosystem associated with climate change. Journal of Ecology 99, 905–913 (2011).56. Howell, S. N. G. Molt in North American Birds. (Houghton Mifflin Harcourt, 2010).57. Bishop, C. A. et al. Hummingbirds and bumble bees exposed to neonicotinoid and organophosphate insecticides in the Fraser Valley, British Columbia, Canada: Hummingbirds, bees, and neonicotinoids in Canada. Environmental Toxicology and Chemistry 37, 2143–2152 (2018).58. Graves, E. E. et al. Analysis of insecticide exposure in California hummingbirds using liquid chromatography-mass spectrometry. Environ Sci Pollut Res 26, 15458–15466 (2019).59. Godfray, H. C. J. et al. A restatement of the natural science evidence base concerning neonicotinoid insecticides and insect pollinators. Proceedings of the Royal Society B: Biological Sciences 281, 20140558 (2014).60. Hallmann, C. A., Foppen, R. P. B., van Turnhout, C. A. M., de Kroon, H. & Jongejans, E. Declines in insectivorous birds are associated with high neonicotinoid concentrations. Nature 511, 341–343 (2014).61. Eng, M. L., Stutchbury, B. J. M. & Morrissey, C. A. A neonicotinoid insecticide reduces fueling and delays migration in songbirds. Science 365, 1177–1180 (2019).62. Averett, J. P. et al. Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem. PLOS ONE 11, e0147826 (2016).63. Rubus armeniacus. Alexander JD, Macias CC, Contreras SM, Younkman D, Luszcs T, Maria RV, Smith B, Casey D. 2020. An integrated conservation strategy for western temperate, Mexican pine-oak, and tropical cloud forest Birds: North America to Central America (DRAFT). Partners in Flight and Klamath Bird Observatory, Ashland, Oregon.65. Bishop CA. Woudneh MB, Maisonneuve F, Common J, Elliott JE, Moran AJ. 2020. Determination of neonicotinoids and butenolide residues in avian and insect pollinators and their ambient environment in Western Canada (2017, 2018). Science of the Total Env. 737 (2020) 139386. Fink, D., T. Auer, A. Johnston, M. Strimas-Mackey, O. Robinson, S. Ligocki, B. Petersen, C. Wood, I. Davies, B. Sullivan, M. Iliff, S. Kelling. 2020. eBird Status and Trends, Data Version: 2018; Released: 2020. Cornell Lab of Ornithology, Ithaca, New York. Hill, G., Robert R. Sargent, & Martha B. Sargent. (1998). Recent Change in the Winter Distribution of Rufous Hummingbirds. The Auk, 115(1), 240-245. doi:10.2307/408913568. Jason R. Courter "Changes In Spring Arrival Dates of Rufous Hummingbirds (Selasphorus rufus) In Western North America In the Past Century," The Wilson Journal of Ornithology, 129(3), 535-544, (1 September 2017)

Page 26

©Jim Livaudais 